Home » Public Forums » GMCnet » Pulling the heads on this 455
| Pulling the heads on this 455 [message #361257] |
Tue, 29 December 2020 19:27  |
daveblanchard
Messages: 13
Registered: December 2020
Location: Gadsden, AL
Karma: -26
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Junior Member |
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I'm going to pull the heads off this 455 here soon and do some much needed top end maintenance. The motor was built years ago by some shop down in Texas and runs good, but there are a few problems which have developed over the years, which the previous owner passed on to me: leaky valve covers, leaky valve stem seals, and carbon buildup in the combustion chambers leading to dieseling on hot shutoff. Probably plenty of carbon to be found in the valley area also, I'm guessing. All that plus the leaky header gasket on one side.
So I'm just going to pull the heads off, refurbish them, and solve all these problems in one go. Maybe do some port work too while I'm in there, because why not? At 10k feet in the mountains she could use a little extra grunt.
I'm just wondering if there any known snags or potential trouble areas in the head pulling process on these coaches that I should know about before getting started. Thanks for any advice.
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| Re: Pulling the heads on this 455 [message #361264 is a reply to message #361257] |
Wed, 30 December 2020 07:11  |
C Boyd
Messages: 2629
Registered: April 2006
Karma: 18
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Senior Member |
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Sir, since the Olds valve adjustment is preset you will need to have the head gaskets so the machine shop can set up valve lash properly. Try to get all the antifreeze out of the engine before removing heads. If coolant does get in cylinders vacuum or wipe it out ASAP. It will rust cylinder walls and rings and will be harmful to rod and main bearings. It will be a good time to check timing chain and gears and expansion (freeze) plugs.
daveblanchard wrote on Tue, 29 December 2020 20:27I'm going to pull the heads off this 455 here soon and do some much needed top end maintenance. The motor was built years ago by some shop down in Texas and runs good, but there are a few problems which have developed over the years, which the previous owner passed on to me: leaky valve covers, leaky valve stem seals, and carbon buildup in the combustion chambers leading to dieseling on hot shutoff. Probably plenty of carbon to be found in the valley area also, I'm guessing. All that plus the leaky header gasket on one side.
So I'm just going to pull the heads off, refurbish them, and solve all these problems in one go. Maybe do some port work too while I'm in there, because why not? At 10k feet in the mountains she could use a little extra grunt.
I'm just wondering if there any known snags or potential trouble areas in the head pulling process on these coaches that I should know about before getting started. Thanks for any advice.
C. Boyd
76 Crestmont
East Tennessee
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| Re: Pulling the heads on this 455 [message #361276 is a reply to message #361257] |
Wed, 30 December 2020 15:19 |
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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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Dave,
This is not an unreasonable thing to do, but I didn't do it which is why I will make some suggestions:
Plan to use the Dick Paterson cross over block off kit. This means you also now need an electric choke.
If you have stock manifolds, the Dave Lenzi copper gaskets work great but they do need several retorquings.
--If the mating surface is not flat, find a big belt sander to fix that.
Look for the block side coolant drains (2) so you don't have to deal with coolant in the cylinders.
Plan to remove the wheel well liners and front tires to get enough room to swing the big guns to get the exhaust manifolds off.
Plan to rig lifting gear to both lift and lower the heads - They are heavy. You do not want to drop them onto the new gaskets.
You can hang the A/C pump under the floor and not break the system - if you care.
Doing the water pump and timing chain will be way easier if you remover the radiator.
--It is not that big a job and the condenser can be rotated out to the right if you did open the system.
The bolts and springs for the exhaust flanges are easy to get, so cut them if they are tough.
It sounds like you already have the intake off, so you might have completely removed the steel fuel line to the carburetor.
--If not, you will want to do that.
That is all I can think of right now, but I am sure others will add to this.
I took my whole engine out the front because it needed more than just a valve job.
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: Pulling the heads on this 455 [message #361279 is a reply to message #361257] |
Wed, 30 December 2020 19:48 |
jhbridges
Messages: 8412
Registered: May 2011
Location: Braselton ga
Karma: -74
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Senior Member |
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If you or your shop are going to replace valve seats, make damn sure you or they know what you're doing. Trying to put Chev big block seats in will destroy the heads beyond further use. If the shop chief says "Hey, and Olds 455 head - haven't seen one of those in a while" you found the correct shop to build them. OTOH if s/he says 'Off a 454 huh?' take your custom elsewhere.
--johnny
Foolish Carriage, 76 26' Eleganza(?) with beaucoup mods and add - ons.
Braselton, Ga.
I forgive them all, save those who hurt the dogs. They must answer to me in hell
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| Re: Pulling the heads on this 455 [message #361281 is a reply to message #361257] |
Wed, 30 December 2020 21:12 |
daveblanchard
Messages: 13
Registered: December 2020
Location: Gadsden, AL
Karma: -26
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Junior Member |
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I haven't taken it apart yet, just collecting parts and getting ready for it. Maybe the heads will just need a good cleaning and seal replacement, but if any seat or guide work is needed, I do know a good place to handle that.
This coach has headers, and I don't think they are too rusted on there, so maybe that part will go smoothly.
How do you time the ignition on these motorhomes? That's something I wondered about. Seems like the timing marks would be hard to see, but it's been a while since I looked.
Thanks for the tips everyone.
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| Re: Pulling the heads on this 455 [message #361334 is a reply to message #361257] |
Fri, 01 January 2021 15:12 |
jhbridges
Messages: 8412
Registered: May 2011
Location: Braselton ga
Karma: -74
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Senior Member |
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It's possible to see the marks but it ain't easy. While you have the heads off, set the #1 to TDC. Use a dial gauge to be sure it's at the exact. Check the mark to make sure the dampener hasn't slipped (If it has, replace it,it wil slip again). Now make another TDC mark with a scribe where you can see it, and make a pointer for it. Then back the engine up till the 8degree mark on the dampener lines up. Scribe your new place again. Mow you're set, you can static time it without being a contortionist and you can use a timing light when you get it running.
--johnny
Foolish Carriage, 76 26' Eleganza(?) with beaucoup mods and add - ons.
Braselton, Ga.
I forgive them all, save those who hurt the dogs. They must answer to me in hell
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| Re: Pulling the heads on this 455 [message #361341 is a reply to message #361334] |
Fri, 01 January 2021 16:03 |
C Boyd
Messages: 2629
Registered: April 2006
Karma: 18
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Senior Member |
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Sir, it is much easier to see 0 (tdc) than it is to see 8-14*. Try to find a timing light that has a dial on it to preset timing degrees. If you want 12* set the timing light on 12* then set timing on the engine at 0 (tdc).
jhbridges wrote on Fri, 01 January 2021 16:12It's possible to see the marks but it ain't easy. While you have the heads off, set the #1 to TDC. Use a dial gauge to be sure it's at the exact. Check the mark to make sure the dampener hasn't slipped (If it has, replace it,it wil slip again). Now make another TDC mark with a scribe where you can see it, and make a pointer for it. Then back the engine up till the 8degree mark on the dampener lines up. Scribe your new place again. Mow you're set, you can static time it without being a contortionist and you can use a timing light when you get it running.
--johnny
C. Boyd
76 Crestmont
East Tennessee
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| Re: [GMCnet] Pulling the heads on this 455 [message #361352 is a reply to message #361351] |
Sat, 02 January 2021 11:29 |
James Hupy
Messages: 6806
Registered: May 2010
Karma: -62
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Senior Member |
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Did you ever wonder why Olds chose to use just a machined slot in the
compensating balancer instead of a row of marks on it? It is because the
"HIGH ZOOT" Kent Moore Shop diagnostic scope had a magnetic pickup instead
of a timing light. All that stuff appeared magically upon the screen, after
you had correctly attached the various leads from the scope. On the 403 and
other engines later than the 455, there is a provision on the timing
pointer for the magnetic pickup on the scope to keep it out of harms way
with the engine running. Remember, that engine was grabbed off of the
automobile production line.
Jim Hupy
Salem, Oregon
On Sat, Jan 2, 2021, 8:51 AM Matt Colie via Gmclist
wrote:
> jhbridges wrote on Sat, 02 January 2021 10:47
>> I'm too dam' cheap to buy a settable light :)
>>
>> --johnny
>
> Johnny,
>
> They are some that are cheap at Hazard Fright, but some have been reported
> to not work right.
> So, your only choice is to plop yourself on the belly board and keep
> fiddling with things until you are tired.
>
> 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
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>
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| Re: [GMCnet] Pulling the heads on this 455 [message #361357 is a reply to message #361352] |
Sat, 02 January 2021 12:37 |
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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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James Hupy wrote on Sat, 02 January 2021 12:29Did you ever wonder why Olds chose to use just a machined slot in the compensating balancer instead of a row of marks on it? It is because the "HIGH ZOOT" Kent Moore Shop diagnostic scope had a magnetic pickup instead of a timing light. All that stuff appeared magically upon the screen, after you had correctly attached the various leads from the scope. On the 403 and other engines later than the 455, there is a provision on the timing pointer for the magnetic pickup on the scope to keep it out of harms way with the engine running. Remember, that engine was grabbed off of the automobile production line.
Jim Hupy
Salem, Oregon
Jim,
Nice thought, but that Kent-Moore system can only go with the plastic "timing saw" scale that came along with the HEI ignition. Those were the first with the place to plug in the magnetic pick-up. I have seen it on some of the 455s too.
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] Pulling the heads on this 455 [message #361360 is a reply to message #361357] |
Sat, 02 January 2021 13:06 |
James Hupy
Messages: 6806
Registered: May 2010
Karma: -62
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Senior Member |
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Heck, I didn't say that it was right, or exact, or anything like it. I have
been factory trained (brainwashed) at GM Training Centers, as well as
attended seminars from Mitchell's and Motor's manuals.
So, I have a foot in both worlds. GM was not too generous with what
they considered "proprietary information" and didn't want to share it with
Independent Shop owners. Not until they lost a class action lawsuit,
anyway. Just the way it was/is.
Jim Hupy
Salem, Oregon
On Sat, Jan 2, 2021, 10:38 AM Matt Colie via Gmclist <
gmclist@list.gmcnet.org> wrote:
> James Hupy wrote on Sat, 02 January 2021 12:29
>> Did you ever wonder why Olds chose to use just a machined slot in the
> compensating balancer instead of a row of marks on it? It is because the
>> "HIGH ZOOT" Kent Moore Shop diagnostic scope had a magnetic pickup
> instead of a timing light. All that stuff appeared magically upon the
> screen,
>> after you had correctly attached the various leads from the scope. On
> the 403 and other engines later than the 455, there is a provision on the
>> timing pointer for the magnetic pickup on the scope to keep it out of
> harms way with the engine running. Remember, that engine was grabbed off of
>> the automobile production line.
>> Jim Hupy
>> Salem, Oregon
>
> Jim,
>
> Nice thought, but that Kent-Moore system can only go with the plastic
> "timing saw" scale that came along with the HEI ignition. Those were the
> first
> with the place to plug in the magnetic pick-up. I have seen it on some of
> the 455s too.
>
> 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
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>
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| Re: Pulling the heads on this 455 [message #361363 is a reply to message #361362] |
Sat, 02 January 2021 17:44 |
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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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daveblanchard wrote on Sat, 02 January 2021 18:08Well I got the heads pulled off today. The engine was very clean inside, no gunk or carbon built up anywhere; looks like a new one in there. The only surprise was a bent pushrod!
Not sure how this happened; maybe a sticking valve? The one pushrod is pretty warped, but everything else looks great.
The motor ran fine, although it was somewhat cold natured, which I thought was due to the cam; it wouldn't idle well until warmed up. Come to think of it, it was a bit lumpy when turning over, like compression was down on one cylinder.
Anyone know if a bent pushrod/sticking valve can cause dieseling? There definitely wasn't enough carbon in the chambers to cause a problem.
Anyone got a couple extra pushrods laying around? 
Dave,
First is, yes, I have a few because I ended up with a nearly complete 455 that is scrap. Actually, I have to look and make sure that they are in there.
Problem: Your sigfile (hint) gives no location. At lease you called out 455, so we can get that right.
Second...
Push rods live their entire existence with a gnat's wing span of failing. They flex enough that this extra motion has to be accounted for in the cam profile.
Lastly, a question for you.
Was it an Exhaust or and Intake, and on which cylinder??
While I would suggest replacing the valve guide seals (unbrellas), my engine was 75K off a cheap rebuild and it didn't need any head work, but I had it done anyway. Now it is in my book and the SO will get a complete picture of what was done.
Matt
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: Pulling the heads on this 455 [message #361364 is a reply to message #361257] |
Sat, 02 January 2021 17:58 |
daveblanchard
Messages: 13
Registered: December 2020
Location: Gadsden, AL
Karma: -26
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Junior Member |
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I'm near Gadsden AL.
Unfortunately, I didn't think to check if it was an exhaust or intake pushrod, until after it was already removed and mixed with the others. It was on cylinder #3 or #5.
Given that everything else was fine, and has been for many miles, I assume there isn't a problem with pushrod length, and this was most likely caused by a sticking valve. Maybe due to starting on old gas.
Did some searching about dieseling, and looks like this could very well be the source of the problem, particularly if the throttle were adjusted open extra to help the idle.
One time my dad started a truck on old gas which quickly turned to varnish, seized valves, and bent several pushrods. I learned the lesson and always pour fresh gas in a vehicle before starting if it's sat for a while. I guess this must have happened under a previous owner and the pushrod has been bent like this for no telling how many miles.
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| Re: [GMCnet] Pulling the heads on this 455 [message #361365 is a reply to message #361363] |
Sat, 02 January 2021 17:56 |
James Hupy
Messages: 6806
Registered: May 2010
Karma: -62
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Senior Member |
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In your case, it is very likely that the valve stuck in the guide, rather
than something in the cylinder obstructing the opening of the valve. So,
the head needs to come apart, and the valve to guide clearance carefully
checked. Obviously lube issues need to be checked for, bent valves, etc.
Something caused the problem. Needs to be found and corrected.
Jim Hupy
Salem, Oregon
On Sat, Jan 2, 2021, 3:45 PM Matt Colie via Gmclist
wrote:
> daveblanchard wrote on Sat, 02 January 2021 18:08
>> Well I got the heads pulled off today. The engine was very clean inside,
> no gunk or carbon built up anywhere; looks like a new one in there. The
>> only surprise was a bent pushrod!
>> Not sure how this happened; maybe a sticking valve? The one pushrod is
> pretty warped, but everything else looks great.
>> The motor ran fine, although it was somewhat cold natured, which I
> thought was due to the cam; it wouldn't idle well until warmed up. Come to
>> think of it, it was a bit lumpy when turning over, like compression was
> down on one cylinder.
>> Anyone know if a bent pushrod/sticking valve can cause dieseling? There
> definitely wasn't enough carbon in the chambers to cause a problem.
>> Anyone got a couple extra pushrods laying around? :roll:
>
> Dave,
>
> First is, yes, I have a few because I ended up with a nearly complete 455
> that is scrap. Actually, I have to look and make sure that they are in
> there.
> Problem: Your sigfile (hint) gives no location. At lease you called out
> 455, so we can get that right.
>
> Second...
> Push rods live their entire existence with a gnat's wing span of failing.
> They flex enough that this extra motion has to be accounted for in the cam
> profile.
>
> Lastly, a question for you.
> Was it an Exhaust or and Intake, and on which cylinder??
>
> While I would suggest replacing the valve guide seals (unbrellas), my
> engine was 75K off a cheap rebuild and it didn't need any head work, but I
> had
> it done anyway. Now it is in my book and the SO will get a complete
> picture of what was done.
>
> Matt
>
> 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
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>
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| Re: Pulling the heads on this 455 [message #361366 is a reply to message #361257] |
Sat, 02 January 2021 18:22 |
daveblanchard
Messages: 13
Registered: December 2020
Location: Gadsden, AL
Karma: -26
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Junior Member |
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I will get the heads disassembled tomorrow and see if there are any problems with the guides or valves. Going also tomorrow to see if I can round up a "new to me" air compressor since my old one died. Hope so cause I want to get some port work done on these "J" heads and intake, while everything's apart. 
[Updated on: Sat, 02 January 2021 18:22] Report message to a moderator |
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| Re: [GMCnet] Pulling the heads on this 455 [message #361597 is a reply to message #361390] |
Sun, 10 January 2021 01:59 |
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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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I would suggest you think twice about "port work" on your 455; the reason being increasing port size will decrease flow velocity in the rpm range the engine of the GMC normally runs at. You could wind up having an engine that performs worse.
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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