Home » Public Forums » GMCnet » The pause that makes you heart skip
| The pause that makes you heart skip [message #70594] |
Tue, 12 January 2010 01:49  |
jtblank
Messages: 237
Registered: June 2007
Location: Tulare, CA
Karma: 1
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Senior Member |
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Just in the last couple of days I have experienced the "pause that makes your heart skip". Under mild acceleration only occasionally the engine pauses for just a fraction of second and you think out of gas? bad coil? I've only noticed it under easy acceleration and while turning, no evidence while hard acceleration like freeway on ramp. I checked the distributor wire from battery and is hard as a rock and insulation was cracked in one spot so I wrapped with electrical tape but.... today it did it again pulling away from curb, just a quick fractional second lack of power like someone turned off key and back on as fast as you can.
Now this makes me start thinking... just recently I checked plugs and were light tan, no carbon or buildup, just what you want but I changed rotor as it was arced up a bit, I was going to change the cap also but couldn't find it, could of sworn I had a spare in my spare parts bin. Guess I'll find it when I look for something else! Besides changing the rotor I cleaned the buildup on the advance weights, springs and rest of distributor base and relubed sparingly with white lithium grease and silicon spray lube. Anyway, since I changed the rotor the tone of the exhaust seems a bit different kind of rich like the sound of stuck choke, popped off the air cleaner cover and choke wide open so it not that... now I'm wondering if I'm imagining it all! Having changed the rotor I can't imagine that the timing changed and did not use too much grease.
The good side of this story is that I think I have better acceleration and power. Cleaning and relubing the distributor and weights helps and sucking on the vac tube it seems the advance reacts better. I hope this is not just a placebo effect, but what about the "pause that makes your heart skip"?
Any ideas?
Thanks for pondering,
John Blankenship
'76 Palm Beach
John Blankenship
'76 Palm Beach
Tulare, CA
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| Re: [GMCnet] The pause that makes you heart skip [message #70597 is a reply to message #70594] |
Tue, 12 January 2010 05:38  |
Steven Ferguson
Messages: 3447
Registered: May 2006
Karma: 0
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Senior Member |
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John,
If you found arcing on the rotor, it may well be that the cap, plugs
and wires need inspecting too. Nothing magic about that cap as it is
used on nearly all GM V8 applications.
In general terms, misfiring through the carburetor is often caused by
ignition, through the tailpipe is usually a fuel problem. Ths is also
true for a change in exhaust note.
What plugs are you using?
On Tue, Jan 12, 2010 at 12:49 AM, John Blankenship <jtblank@yahoo.com> wrote:
I hope this is not just a placebo effect, but what about the "pause
that makes your heart skip"?
Any ideas?
--
Steve Ferguson
'76 EII
Sierra Vista, AZ
Urethane bushing source
www.bdub.net/ferguson/
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| Re: The pause that makes you heart skip [message #70612 is a reply to message #70594] |
Tue, 12 January 2010 07:45 |
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RF_Burns
Messages: 2277
Registered: June 2008
Location: S. Ontario, Canada
Karma: 3
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Senior Member |
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Here's my take on it. Fuel usually doesn't cause an abrupt engine die, but electrical can, so I think its an electrical problem.
-You had the distributor apart so lets look there first.
-Engine dies when you just touch the gas, not when you step on it..
-When you just touch the gas, the vacuum advance will move the plate slightly. I'm guessing one of the connectors in the HEI modules is loose or corroded. When you were working on the advance etc, you disturbed this connection and now each time the advance moves the assembly, it causes this connection to open. When you step on it, the advance moves further and then connector moves quickly past the intermittent connection point.
Open the distributor and check the connections on the HEI module. make sure they are clean, tight and well seated.
Just my 2cents from a guy that spends all day troubleshoot "it doesn't work" problems.
Bruce Hislop
ON Canada
77PB, 455 Dick P. rebuilt, DynamicEFI EBL EFI & ESC.
1 ton front end
http://www.gmcmhphotos.com/photos/showphoto.php?photo=29001
My Staff says I never listen to them, or something like that
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| Re: The pause that makes you heart skip [message #70707 is a reply to message #70594] |
Wed, 13 January 2010 07:51 |
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Matt Colie
Messages: 8547
Registered: March 2007
Location: S.E. Michigan
Karma: 7
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Senior Member |
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| jtblank wrote on Tue, 12 January 2010 02:49 |
Just in the last couple of days I have experienced the "pause that makes your heart skip". Under mild acceleration only occasionally the engine pauses for just a fraction of second and you think out of gas? bad coil? I've only noticed it under easy acceleration and while turning, no evidence while hard acceleration like freeway on ramp. I checked the distributor wire from battery and is hard as a rock and insulation was cracked in one spot so I wrapped with electrical tape but.... today it did it again pulling away from curb, just a quick fractional second lack of power like someone turned off key and back on as fast as you can.
Now this makes me start thinking... just recently I checked plugs and were light tan, no carbon or buildup, just what you want but I changed rotor as it was arced up a bit, I was going to change the cap also but couldn't find it, could of sworn I had a spare in my spare parts bin. Guess I'll find it when I look for something else! Besides changing the rotor I cleaned the buildup on the advance weights, springs and rest of distributor base and relubed sparingly with white lithium grease and silicon spray lube. Anyway, since I changed the rotor the tone of the exhaust seems a bit different kind of rich like the sound of stuck choke, popped off the air cleaner cover and choke wide open so it not that... now I'm wondering if I'm imagining it all! Having changed the rotor I can't imagine that the timing changed and did not use too much grease.
The good side of this story is that I think I have better acceleration and power. Cleaning and relubing the distributor and weights helps and sucking on the vac tube it seems the advance reacts better. I hope this is not just a placebo effect, but what about the "pause that makes your heart skip"?
Any ideas?
Thanks for pondering,
John Blankenship
'76 Palm Beach
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John,
In the industry it is called a "mid-throttle miss" and it is a serious PITA to tie down. It is usually related to secondary ignition issues and that basically means the wires, cap, rotor and coil (inside the cap)in your case.
I can't give you any better ideas about where to start. I've had two of these of my very own and worked on several others. We either buy new parts one at a time or swap in parts from a donor until it goes away. There is just nothing else you can do. Even the OBD equipped vehicles only report it as a misfire, and if you have access to a real secondary ignition analyzer (big oscilloscope that shows spark plug voltage) there is no bet that you will see it.
I did find one with the "water mist in the dark" trick. (Spray a mist of tap water over the secondary stuff and see if something lights up.) That only worked for one (and that wasn't mine - **** - ).
Best bet (IMHO):
Start changing parts. If you have a friendly local men's mall, go see if you can grab a hand full of cap and wires from a BB Chevy, Toro or Caddy of close to the right period. (IIRC - that is almost any GM big block - you need the longer wires - from '75 to '95?.)
Good Luck and let us know when you find it.
Matt
Matt & Mary Colie - Chaumière -'73 Glacier 23 - Members GMCMI, GMCGL, GMCES
Electronically Controlled Quiet Engine Cooling Fan with OE Rear Drum Brakes with Applied Control Arms
SE Michigan - Near DTW - Twixt A2 and Detroit
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| Re: [GMCnet] The pause that makes you heart skip [message #70715 is a reply to message #70707] |
Wed, 13 January 2010 08:35 |
Mike Kilroy
Messages: 80
Registered: July 2006
Location: Farmersville, OH (near D...
Karma: 0
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If nothing else shows up, is this a 455 engine? I fought similar issue
for a couple years before finding the issue was a cracked intake
manifold. Hesitation only happened after engine warmed up good so the
crack expanded. hope this is not your issue.
On 1/13/2010 8:51 AM, Matt Colie wrote:
>
> jtblank wrote on Tue, 12 January 2010 02:49
>
>> Just in the last couple of days I have experienced the "pause that makes your heart skip". Under mild acceleration only occasionally the engine pauses for just a fraction of second and you think out of gas? bad coil? I've only noticed it under easy acceleration and while turning, no evidence while hard acceleration like freeway on ramp. I checked the distributor wire from battery and is hard as a rock and insulation was cracked in one spot so I wrapped with electrical tape but.... today it did it again pulling away from curb, just a quick fractional second lack of power like someone turned off key and back on as fast as you can.............................
>>
>>
>
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Mike (AC8V) & Vickie Kilroy
'73 Canyon Land 26' sidebath
455/ceramic filled crossovers
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| Re: The pause that makes you heart skip [message #70723 is a reply to message #70594] |
Wed, 13 January 2010 10:52 |
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when I had light throttle hesitation was a bad accelerator pump adjustment. if its cutting out all together, then I will join the chior and say its something in the ignition....
73 Canyon Lands, (a.k.a. The Yellow Submarine) West Los Angeles CA
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| Re: The pause that makes you heart skip [message #70776 is a reply to message #70707] |
Thu, 14 January 2010 02:55 |
jtblank
Messages: 237
Registered: June 2007
Location: Tulare, CA
Karma: 1
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Senior Member |
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Well the verdict is in.... and almost by accident. I've been driving the GMC daily to work, which is only a short distance, to see if this "pause that makes your heart skip" continues. Tonight I found the problem and luckly kept from crashing for lack of brake boost.
As Paul Harvey use to say, "now the rest of the story, stand by for news".
Leaving work tonight I decided to go the long way home to see if I could get a hiccup. Actually I drove a couple extra miles instead of the few blocks from work to home. I was going to wait 'till the weekend to dig into the problem but wanted to see if warmed up on the longer drive made a difference. Well I was going about 55 on the old business 99 hiway and was approaching the turn toward home and lost all power, but unlike the bird strike NY flight that landed in the Hudson, I had no one to call in my Mayday. Full flaps, I hit the brakes and not much there, no vac, immediately to second and made it around the turn rather easily, but the thing coasted forever it seemed like. It was a good thing that nobody was in front of me going slow or they would of had a rather noticable push!
Now at the side of the road I hit the starter and nothing, well to0 far to walk so I decided to pop the cover and have a quick look before calling for help and a pull home. First I checked to see if I was getting fuel, top of air cleaner off, pushed throttle saw fuel so must me electrical. Started at step one, battery to distributor/tach connection........ can you believe it the clip was partially unplugged (loose)! Now I know I plugged it in from before but didn't check to see if would pull out easily, but I do remember I was hard to get out when I worked on the distributor last weekend. The metal clips inside must have bent and lost tension to hold it in. Let this be a lesson check connections for tightness. I then drove for at least 10 miles stop and go and freeway to see if I had fixed the previous problem of the intermittent pause, no problems, I think that the loose distributor power wire was the problem.
Now I am going to attend to the no brakes with a dead engine problem I experienced tonight. I have a auxiliary vac storage tank system that I got from Jim B awhile back. I never got around to hooking it up, but after going around the turn tonight on three wheels, it's on the top of my list. It's a 4"x36" pvc tube plumbed into the booster to provide for a few extra pumps of the brakes. Maybe Jim if you are reading can tell the others if you are still using and selling the kits, it seems a lot easier and reliable that a booster pump that may or may not be working. If not Jim maybe someone else want to pick up the subject and start a new post to discuss the topic! I sure like stirring the pot but I'm off to say my prayers. Good Night!
Like usual, one problem solved, another new one.
Thanks to all for your thoughts
John Blankenship
'76 Palm Beach
Tulare, CA
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| Re: The pause that makes you heart skip [message #70777 is a reply to message #70776] |
Thu, 14 January 2010 03:17 |
midlf
Messages: 2212
Registered: July 2007
Location: SE Wisc. (Palmyra)
Karma: 1
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| jtblank wrote on Thu, 14 January 2010 02:55 |
Well the verdict is in.... and almost by accident. I've been driving the GMC daily to work, which is only a short distance, to see if this "pause that makes your heart skip" continues. Tonight I found the problem and luckly kept from crashing for lack of brake boost.
<lotsa snip>
Like usual, one problem solved, another new one.
Thanks to all for your thoughts
|
Thanks for getting back to us with what you found.
Steve Southworth
1974 Glacier TZE064V100150 (for workin on)
1975 Transmode TZE365V100394 (parts & spares)
Palmyra WI
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| Re: The pause that makes you heart skip [message #70802 is a reply to message #70776] |
Thu, 14 January 2010 10:46 |
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you might wanna check the booster and make sure its still holding vac while your at it. had an old lincoln which had its booster quit when it wouldnt hold vac. a booster should 2-3 pumps before all vac is gone...
| jtblank wrote on Thu, 14 January 2010 02:55 |
Well the verdict is in.... and almost by accident. I've been driving the GMC daily to work, which is only a short distance, to see if this "pause that makes your heart skip" continues. Tonight I found the problem and luckly kept from crashing for lack of brake boost.
As Paul Harvey use to say, "now the rest of the story, stand by for news".
Leaving work tonight I decided to go the long way home to see if I could get a hiccup. Actually I drove a couple extra miles instead of the few blocks from work to home. I was going to wait 'till the weekend to dig into the problem but wanted to see if warmed up on the longer drive made a difference. Well I was going about 55 on the old business 99 hiway and was approaching the turn toward home and lost all power, but unlike the bird strike NY flight that landed in the Hudson, I had no one to call in my Mayday. Full flaps, I hit the brakes and not much there, no vac, immediately to second and made it around the turn rather easily, but the thing coasted forever it seemed like. It was a good thing that nobody was in front of me going slow or they would of had a rather noticable push!
Now at the side of the road I hit the starter and nothing, well to0 far to walk so I decided to pop the cover and have a quick look before calling for help and a pull home. First I checked to see if I was getting fuel, top of air cleaner off, pushed throttle saw fuel so must me electrical. Started at step one, battery to distributor/tach connection........ can you believe it the clip was partially unplugged (loose)! Now I know I plugged it in from before but didn't check to see if would pull out easily, but I do remember I was hard to get out when I worked on the distributor last weekend. The metal clips inside must have bent and lost tension to hold it in. Let this be a lesson check connections for tightness. I then drove for at least 10 miles stop and go and freeway to see if I had fixed the previous problem of the intermittent pause, no problems, I think that the loose distributor power wire was the problem.
Now I am going to attend to the no brakes with a dead engine problem I experienced tonight. I have a auxiliary vac storage tank system that I got from Jim B awhile back. I never got around to hooking it up, but after going around the turn tonight on three wheels, it's on the top of my list. It's a 4"x36" pvc tube plumbed into the booster to provide for a few extra pumps of the brakes. Maybe Jim if you are reading can tell the others if you are still using and selling the kits, it seems a lot easier and reliable that a booster pump that may or may not be working. If not Jim maybe someone else want to pick up the subject and start a new post to discuss the topic! I sure like stirring the pot but I'm off to say my prayers. Good Night!
Like usual, one problem solved, another new one.
Thanks to all for your thoughts
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73 Canyon Lands, (a.k.a. The Yellow Submarine) West Los Angeles CA
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| Re: [GMCnet] The pause that makes you heart skip [message #70828 is a reply to message #70776] |
Thu, 14 January 2010 19:42 |
GMCWiperMan
Messages: 1248
Registered: December 2007
Karma: 1
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Senior Member |
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John,
For a while, some years back, I made vacuum tanks like you describe to sell
at rallies.
It's basically a 30" (IIRC) length of 4" OD Sched. 40 PVC pipe (the white
stuff; DON'T try to use thinner pipe) with a cap PVC-cemented on each end.
Into one of the end caps I drilled a hole to fit a vacuum check valve
exactly like that in the GMC booster. I used "Plumber's Goop" to seal the
valve in place. Into the side of the pipe, near the end with the check
valve, I threaded a brass 1/4"MPT X 3/8" hose barb, also sealed with
"Plumber's Goop".
I secured them into the front frame crossmember (ahead of the radiator)
using 3 long 75# TyWraps: two around the ends and the bottom of the
crossmember, the 3rd at the center around the top of the crossmember, with
the check valve at the driver's side. Move the vacuum supply line to the
engine from the booster check valve to the reservoir check valve. Add a new
vacuum line from the side fitting on the reservoir to the booster check
valve. That's it -- 2 to 3 additional boosted stops. After an engine
failure, DO NOT PUMP the brake pedal -- push it and hold it until you're
stopped and have the wheels chocked! My tests documented on the photo site
show 725' stopping distance from 55 mph without boost!
After building the reservoirs, I always pumped them down to 25+" Hg. and
tested them for at least 30 minutes for leakage. From that I quickly
learned to never buy a new check valve from the "Help" rack. 4 of 5 would
not pass my test. On the other hand, as I collected them from the junk
yard, I'd find a surprising percentage that would go "swoosh" when I pulled
them from cars obviously there for months, if not years.
Ken H.
Americus, GA
'76 X-Birchaven
www.gmcwipersetc.com
On Thu, Jan 14, 2010 at 3:55 AM, John Blankenship <jtblank@yahoo.com> wrote:
>
> ...
> Now I am going to attend to the no brakes with a dead engine problem I
> experienced tonight. I have a auxiliary vac storage tank system that I got
> from Jim B awhile back. I never got around to hooking it up, but after
> going around the turn tonight on three wheels, it's on the top of my list.
> It's a 4"x36" pvc tube plumbed into the booster to provide for a few extra
> pumps of the brakes. Maybe Jim if you are reading can tell the others if
> you are still using and selling the kits, it seems a lot easier and reliable
> that a booster pump that may or may not be working. If not Jim maybe
> someone else want to pick up the subject and start a new post to discuss the
> topic! I sure like stirring the pot but I'm off to say my prayers. Good
> Night!
>
>
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| vapor lock [message #70845 is a reply to message #70723] |
Thu, 14 January 2010 23:01 |
bukzin
Messages: 840
Registered: April 2004
Location: North California
Karma: 0
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Senior Member |
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In another direction...
My vapor lock problems have a simular effect.
Bukzin
1977 Palm Beach
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| Re: [GMCnet] The pause that makes you heart skip [message #70865 is a reply to message #70777] |
Fri, 15 January 2010 09:18 |
jimk
Messages: 6734
Registered: July 2006
Location: Belmont, CA
Karma: 9
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Senior Member |
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John,
There is a plastic clip that should be used to avoid disconnect.
We also stock the same with a tachometer connection all in one.
It's all on our site.
On Thu, Jan 14, 2010 at 1:17 AM, Steve Southworth <midlf@centurytel.net> wrote:
>
>
> jtblank wrote on Thu, 14 January 2010 02:55
>> Well the verdict is in.... and almost by accident. Â I've been driving the GMC daily to work, which is only a short distance, to see if this "pause that makes your heart skip" continues. Â Tonight I found the problem and luckly kept from crashing for lack of brake boost.
>>
>> <lotsa snip>
>>
>> Like usual, one problem solved, another new one.
>>
>> Thanks to all for your thoughts
>
>
> Thanks for getting back to us with what you found.
>
> --
> Steve Southworth
> 1974 Glacier TZE064V100150
> Palmyra WI
> _______________________________________________
> GMCnet mailing list
> List Information and Subscription Options:
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--
Jim Kanomata
Applied/GMC, Fremont,CA
jimk@appliedairfilters.com
http://www.appliedgmc.com
1-800-752-7502
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Jim Kanomata
Applied/GMC
jimk@appliedairfilters.com
www.appliedgmc.com
1-800-752-7502
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| Re: [GMCnet] The pause that makes you heart skip [message #70893 is a reply to message #70865] |
Fri, 15 January 2010 17:40 |
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USAussie
Messages: 15912
Registered: July 2007
Location: Sydney, Australia
Karma: 6
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Senior Member |
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Jim,
I just looked through the following sections in your on line catalog and
couldn't find it:
Accessories
Instrumentation
Engine / Ignition / Cooling
I also did a search for "Tachometer" and got "No products matched your
search criteria"
Where is it?
Regards,
Rob Mueller
Sydney, Australia
AUS '75 Avion-The Blue Streak TZE365V100428
USA '75 Avion-Double Trouble TZE365V100426
-----Original Message-----
From: gmclist-bounces@temp.gmcnet.org
[mailto:gmclist-bounces@temp.gmcnet.org] On Behalf Of Jim Kanomata
Sent: Saturday, 16 January 2010 2:18 AM
To: gmclist@temp.gmcnet.org
Subject: Re: [GMCnet] The pause that makes you heart skip
John,
There is a plastic clip that should be used to avoid disconnect.
We also stock the same with a tachometer connection all in one.
It's all on our site.
--
Jim Kanomata
Applied/GMC, Fremont,CA
jimk@appliedairfilters.com
http://www.appliedgmc.com
1-800-752-7502
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Regards,
Rob M. (USAussie)
The Pedantic Mechanic
Sydney, Australia
'75 Avion - AUS - The Blue Streak TZE365V100428
'75 Avion - USA - Double Trouble TZE365V100426
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| Re: [GMCnet] The pause that makes you heart skip [message #70905 is a reply to message #70828] |
Fri, 15 January 2010 20:29 |
Bob de Kruyff
Messages: 4260
Registered: January 2004
Location: Chandler, AZ
Karma: 1
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Senior Member |
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""For a while, some years back, I made vacuum tanks like you describe to sell
at rallies.""
Here's a link to my installation:
http://www.gmcmhphotos.com/photos/showgallery.php?cat=3384
It gives me at least 6 pumps even when sitting for months. However when we first started discussing these, we found that many boosters "consumed" vacuum not only while depressing the pedal, but also while holding the pedal down. There were some indications that the sensitized boosters were especially suspect. A good booster should only use vacuum during pedal depression--not when static whether up or down.
Bob de Kruyff
78 Eleganza
Chandler, AZ
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| Re: [GMCnet] The pause that makes you heart skip [message #70912 is a reply to message #70893] |
Fri, 15 January 2010 20:50 |
jimk
Messages: 6734
Registered: July 2006
Location: Belmont, CA
Karma: 9
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Senior Member |
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Rob,
The part your looking for is only in our catalog.
I'll see if our staff can put it up Monday.
On Fri, Jan 15, 2010 at 3:40 PM, Rob Mueller <robmueller@iinet.net.au> wrote:
> Jim,
>
> I just looked through the following sections in your on line catalog and
> couldn't find it:
>
> Accessories
>
> Instrumentation
>
> Engine / Ignition / Cooling
>
> I also did a search for "Tachometer" and got "No products matched your
> search criteria"
>
> Where is it?
>
> Regards,
> Rob Mueller
> Sydney, Australia
> AUS '75 Avion-The Blue Streak TZE365V100428
> USA '75 Avion-Double Trouble TZE365V100426
>
>
> -----Original Message-----
> From: gmclist-bounces@temp.gmcnet.org
> [mailto:gmclist-bounces@temp.gmcnet.org] On Behalf Of Jim Kanomata
> Sent: Saturday, 16 January 2010 2:18 AM
> To: gmclist@temp.gmcnet.org
> Subject: Re: [GMCnet] The pause that makes you heart skip
>
> John,
> There is a plastic clip that should be used to avoid disconnect.
>
> We also stock the same with a tachometer connection all in one.
>
> It's all on our site.
> --
> Jim Kanomata
> Applied/GMC, Fremont,CA
> jimk@appliedairfilters.com
> http://www.appliedgmc.com
> 1-800-752-7502
> _______________________________________________
> GMCnet mailing list
> List Information and Subscription Options:
> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
>
> _______________________________________________
> GMCnet mailing list
> List Information and Subscription Options:
> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
>
--
Jim Kanomata
Applied/GMC, Fremont,CA
jimk@appliedairfilters.com
http://www.appliedgmc.com
1-800-752-7502
_______________________________________________
GMCnet mailing list
List Information and Subscription Options:
http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
Jim Kanomata
Applied/GMC
jimk@appliedairfilters.com
www.appliedgmc.com
1-800-752-7502
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| Re: [GMCnet] The pause that makes you heart skip [message #70921 is a reply to message #70905] |
Fri, 15 January 2010 21:28 |
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USAussie
Messages: 15912
Registered: July 2007
Location: Sydney, Australia
Karma: 6
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Senior Member |
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Bob,
At first glance I thought the installation looked very good.
I then thought about it and said to myself; "Hey, wait a minute; that's
doesn't seem to be a good place to put the tank, it's just behind the front
bumper! If Bob crashes into anything it will break and he'll loose the
vacuum and brakes."
I thought about it for a few more seconds and realized that loosing the
vacuum and brakes AFTER you crashed into something wouldn't matter! DUH!
Thought you would get a laugh out of this!
Regards,
Rob Mueller
Sydney, Australia
AUS '75 Avion-The Blue Streak TZE365V100428
USA '75 Avion-Double Trouble TZE365V100426
-----Original Message-----
From: gmclist-bounces@temp.gmcnet.org
[mailto:gmclist-bounces@temp.gmcnet.org] On Behalf Of Bob de Kruyff
Sent: Saturday, 16 January 2010 1:29 PM
To: gmclist@temp.gmcnet.org
Subject: Re: [GMCnet] The pause that makes you heart skip
""For a while, some years back, I made vacuum tanks like you describe to
sell
at rallies.""
Here's a link to my installation:
http://www.gmcmhphotos.com/photos/showgallery.php?cat=3384
It gives me at least 6 pumps even when sitting for months. However when we
first started discussing these, we found that many boosters "consumed"
vacuum not only while depressing the pedal, but also while holding the pedal
down. There were some indications that the sensitized boosters were
especially suspect. A good booster should only use vacuum during pedal
depression--not when static whether up or down.
--
Bob de Kruyff
78 Eleganza
Chandler, AZ
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Regards,
Rob M. (USAussie)
The Pedantic Mechanic
Sydney, Australia
'75 Avion - AUS - The Blue Streak TZE365V100428
'75 Avion - USA - Double Trouble TZE365V100426
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| Re: [GMCnet] The pause that makes you heart skip [message #70925 is a reply to message #70921] |
Fri, 15 January 2010 22:36 |
Bob de Kruyff
Messages: 4260
Registered: January 2004
Location: Chandler, AZ
Karma: 1
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Senior Member |
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""I thought about it for a few more seconds and realized that loosing the
vacuum and brakes AFTER you crashed into something wouldn't matter! DUH!
Thought you would get a laugh out of this!""
Well it took me a minute and then I came to the same realization as you did:)
I do have a bit of a story about this and i hope it doesn't get me into trouble. When I was still a young kid at GM, I was part of the first DFMA (design for failure mode analysis) and we looked at making the front (tubular) cross member of the Corvette
into a vacuum reservoir for the headlamps. However, at the same time we had problems with defective check valves that could cause the brake booster to fill with gasoline. I was alarmed with the thought that the front cross member of a Corvette would or could fill with gasoline. And then there is the rest of the story....!
Bob de Kruyff
78 Eleganza
Chandler, AZ
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| Re: [GMCnet] The pause that makes you heart skip [message #70926 is a reply to message #70925] |
Fri, 15 January 2010 22:45 |
GMCWiperMan
Messages: 1248
Registered: December 2007
Karma: 1
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Senior Member |
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Better the front crossmember than the booster! Maybe. :-)
Why'd you put the reservoir ahead of the crossmember -- to gain more length?
All of mine went inside the crossmember -- behind it. But that did
restrict the length, volume, and number of available pedal operations.
Wonder why I never though of using just one check valve? Just not a pro, I
guess. :-)
Ken H.
On Fri, Jan 15, 2010 at 11:36 PM, Bob de Kruyff <NEXT2POOL@aol.com> wrote:
>
>
> ""I thought about it for a few more seconds and realized that loosing the
> vacuum and brakes AFTER you crashed into something wouldn't matter! DUH!
>
> Thought you would get a laugh out of this!""
>
> Well it took me a minute and then I came to the same realization as you
> did:)
>
> I do have a bit of a story about this and i hope it doesn't get me into
> trouble. When I was still a young kid at GM, I was part of the first DFMA
> (design for failure mode analysis) and we looked at making the front
> (tubular) cross member of the Corvette
> into a vacuum reservoir for the headlamps. However, at the same time we had
> problems with defective check valves that could cause the brake booster to
> fill with gasoline. I was alarmed with the thought that the front cross
> member of a Corvette would or could fill with gasoline. And then there is
> the rest of the story....!
> --
> Bob de Kruyff
> 78 Eleganza
> Chandler, AZ
> _______________________________________________
> GMCnet mailing list
> List Information and Subscription Options:
> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
>
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