Home » Public Forums » GMCnet » Caddy 500 camshaft recomendations
| Caddy 500 camshaft recomendations [message #267726] |
Wed, 17 December 2014 20:26  |
mild bill
Messages: 98
Registered: November 2014
Location: Edmonton, Alberta, Canada
Karma: 0
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Starting to think about my 1973 caddy 500. Stock soap bar Pistons, small chamber heads.
Trying to decide on camshaft. Want to run regular gas so not so sure I want a torque cam, don't want excessive cylinder pressure going up mountains when things get hot. Wouldn't mind more lift and duration, don't think torque would drop significantly at cruise rpm with potential gains in second gear.
Don't want so much lift or ramp rate that I would have to worry about wiping out a cam or stressing stock rockers.
How bad is a stock re grind, can't seem to find numbers for them? It seems like a safe bet with great torque at cruise with a slight decrease of torque say in second gear, 3500-3800 rpm.
How many rpm would a gmc do at say 50 mph in second gear?
My fear of a torque cam comes from my neighbours GMC, I fear perhaps PO put in a torque cam and he has been running regular gas. He has additional problems, it's equipped with a very early fuel injection system that he seems unable to get information for. He said he contacted the manufacture and he said they do not provide any information for that system anymore. The module is mounted on a piece of plywood under the passenger seat and he has nice headers on it but burns almost as much oil as gas (doesn't smoke) however going up steep hills he says say press on the gas at 2200 rpm the engine detonates like crazy, puts the pedal to the floor and detonation stops even without dropping to passing gear.
I went and checked it out for him in the driveway last week and set his initial at about 10 degrees, didn't take note where it was set initially however way advanced. Revved up the engine and while he has a fuel injection distributor that has no mechanical or vacuum advance his computer is not giving any advance and will however drop advance with manifold vacuum drop so Map sensor is working at least so guessing he had his initial set at somewhere around 25-35 degrees. Anyway he's looking for an engine to build, wants me to build and change but I don't se me having time in the near future. Oil analysis doesn't look good and I suggested picking up a leak down tester and checking, mine is home made and one gauge is toast.
Anyway I want to replace the original 25 year old camshaft, wouldn't mind more power but not at the expense of Valvetrain reliability and detonation. Can't find any real numbers as to what the re grind is, if it's th '73 cam I could be happy with that as that's what the MTS 5 is based on.
Also, Falcon engine parts on ebay, any good?
[Updated on: Wed, 17 December 2014 20:30] Report message to a moderator |
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| Re: Caddy 500 camshaft recomendations [message #267738 is a reply to message #267726] |
Thu, 18 December 2014 00:21  |
roy1
Messages: 2126
Registered: July 2004
Location: Minden nevada
Karma: 6
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Senior Member |
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Sounds like your friend is running a high compression engine 10 to 1 ? My 455 olds with 8 to 1 Pistons does well with a high torque comp cam and a carburetor . It doesn't detente when the distributor is advanced either.
Roy Keen
Minden,NV
76 X Glenbrook
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| Re: Caddy 500 camshaft recomendations [message #267742 is a reply to message #267726] |
Thu, 18 December 2014 01:49 |
mild bill
Messages: 98
Registered: November 2014
Location: Edmonton, Alberta, Canada
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He doesn't know what he has. Bough it out of Texas I think, at least the 97 tracker toad I bought off him had Texas inspection stickers on it. Twin beds in the back. Pretty sure 1977. 455 fuel injected with stainless headers, hydra boost if that rings any bells. Both toad and motorhome mostly cream or off white.
But I think he power timed it and he said at torque converter stall he couldn't get it to detonate so who knows what he had for timing. Like I say the computer wasn't doing anything and I asked him if he had any info re: setting initial, like jumping pip or whatever but no info but like I said setting 10 degree initial and reving up Retarded to 2 degrees so his initial must have been cranked. Told him if he couldn't find any info or If it couldn't be fixed he's looking at $1800 to $3000 for a new fuel injection system. News I don't think he wanted to hear considering he's probably already ruined his 455. He's retired, has a business selling soap and probably spends more time on it than I get a chance to spend on mine, put his rear brakes together for him last year,was a challenge bleeding with the master pretty much lower than the wheel cyls on his sloping driveway, pressure blend from the back to the mc.Put a 4 bag system on it I don't recall seeing on this site and says he doesn't really like it. But way prettier than mine at the moment. Out of country inspection mechanic wouldn't pass it because of wheather checked tires so trips that summer he just put the plate from his Lexus on it. Told him he needed brake cables and hoses and wheel cyl and on and on and he eventually agreed with we and replaced all that stuff.
He wanted to buy my caddy, then my 403. I told him his headers. While they would work on the 403 he would have to make the couplings narrower so build a 455. Then his awning removed itself from the coach, I kinda feel bad for him because he has a lot invested. He had a house with a couple slide outs and a Ford V10 for a year or 2 and got the gmc bug, maby I feel sorry for all of US? lol
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| Re: Caddy 500 camshaft recomendations [message #267771 is a reply to message #267726] |
Thu, 18 December 2014 10:27 |
Larry
Messages: 2875
Registered: January 2004
Location: Menomonie, WI
Karma: 10
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Senior Member |
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Bill,
IIRC from reading Doc Fromanders book on the BB Cad, if you are going to use a stock cam, the camshaft from the 73' 500 is the best "stock" cam to use. I'd be inclined to take it out and mic it to see how much wear has taken place. If wear is minimal, get a new set of lifters and put it back in. Reground Camshafts are called reground for a reason. They basically grind them smaller with an attempt at getting the original profile. Because the base circle is smaller, it causes problems with lifter preload, so that has to be addressed. If you are going to put in an aftermarket cam, I would get a cam from either of the two BB Cad distributors. That would be MTS (Maximum Torque Specialities) or "The Cad Company". They have put a fair amount of R&D into developing cams specifically for the BB Cad motor. Other companies have put most of their efforts into the Chevy BB and SB, Ford BB and SB and other more common motors out there, and little or none on the Cad 500.
No matter what you do, IMO, you should replace the stock "T" pedestal rocker system with any of the shaft rocker systems that are available from MTS or CadCO. The stock rocker system is the achiles heal of that motor. Over time, the "T" pedestals and the rockers do not wear square with the rest of the valve train, putting side pressure on the valves, wearing out valve guides to the extent that eventually the valve will hang, the piston will strike it and bend a valve. The result can also be bent pushrods, which can fall out of place resulting in a lifter that will pop out of the bore, and complete loss of oil pressure. Go ahead...ask me how I know this. Knowing what I know now, (10yrs of experience, pulled heads 3 times, towed home once, drove 3K miles on a bent valve) I would not assemble a 500 for use in my MH unless it had a shaft rocker system. You can choose to go cheap now, but you will pay for it in the future. I bought a non-adjustable shaft rocker system for my 500. IF I had just redone the heads paying close attention to valve stem height when the heads were assembled...(by the way, when the head is done correctly, you should be able to put a straight edge across the top of the valve stems and find no difference in height) a non adjustable shaft system should work fine. But if the heads are original or reworked by your standard valve jocky machinest, chances are the stem heights are not correct or consistant in height. Knowing this, I would spend the extra on the adjustable rockers. More money...yes...but the ability to adjust each valve to the correct lifter preload. This is all JMHO and hope it helps.
Larry 
78 Royale w/500 Caddy
Menomonie, WI.
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| Re: Caddy 500 camshaft recomendations [message #267772 is a reply to message #267726] |
Thu, 18 December 2014 10:36 |
Larry
Messages: 2875
Registered: January 2004
Location: Menomonie, WI
Karma: 10
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OH yes, as for the FI system on your friends MH, I would either change to one of the newer FI systems out there, or put a stock manifold with a Qjet back on. After going through the "home brewed" FI upgrade, using Dynamic EFI's EBL, P4 software, and all of the time spent in minipulating fuel and spark tables etc., I might be convinced to try one of the new "Plug and Play" units that are self learning. Anybody out there tried one of these?
Larry
78 Royale w/500 Caddy
Menomonie, WI.
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| Re: [GMCnet] Caddy 500 camshaft recomendations [message #267779 is a reply to message #267772] |
Thu, 18 December 2014 11:21 |
Mr ERFisher
Messages: 7117
Registered: August 2005
Karma: 2
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Senior Member |
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READ HERE
http://gmc49ers.blogspot.com/
it runs great
more coming , keep in touch
erf
On Thu, Dec 18, 2014 at 8:36 AM, Larry wrote:
>
> OH yes, as for the FI system on your friends MH, I would either change to
> one of the newer FI systems out there, or put a stock manifold with a Qjet
> back on. After going through the "home brewed" FI upgrade, using Dynamic
> EFI's EBL, P4 software, and all of the time spent in minipulating fuel and
> spark tables etc., I might be convinced to try one of the new "Plug and
> Play" units that are self learning. Anybody out there tried one of these?
>
> --
> Larry
> 78 Royale w/500 Caddy
> Menomonie, WI.
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
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>
--
Gene Fisher -- 74-23,77PB/ore/ca
“Give a man a fish; you have fed him for today --- give him a URL and
-------
http://gmcmotorhome.info/
Alternator Protection Cable
http://gmcmotorhome.info/APC.html
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| Re: [GMCnet] Caddy 500 camshaft recomendations [message #267794 is a reply to message #267771] |
Thu, 18 December 2014 14:28 |
Ken Henderson
Messages: 8726
Registered: March 2004
Location: Americus, GA
Karma: 9
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Senior Member |
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Bill,
After breaking two rocker pedestals during my round trip to CA last summer,
I second Larry's rocker shaft recommendation. Talking Allstate's RV
Roadhelp service into towing the GMC 384 miles wasn't easy. :-)
Ken H.
Americus, GA
On Thu, Dec 18, 2014 at 11:27 AM, Larry wrote:
>
> ...
>
No matter what you do, IMO, you should replace the stock "T" pedestal
> rocker system with any of the shaft rocker systems that are available from
> MTS
> or CadCO. The stock rocker system is the achiles heal of that motor.
> Over time, the "T" pedestals and the rockers do not wear square with the
> rest
> of the valve train, putting side pressure on the valves, wearing out valve
> guides to the extent that eventually the valve will hang, the piston will
> strike it and bend a valve. The result can also be bent pushrods, which
> can fall out of place resulting in a lifter that will pop out of the bore,
> and
> complete loss of oil pressure. Go ahead...ask me how I know this. Knowing
> what I know now, (10yrs of experience, pulled heads 3 times, towed home
> once, drove 3K miles on a bent valve) I would not assemble a 500 for use
> in my MH unless it had a shaft rocker system. You can choose to go cheap
> now, but you will pay for it in the future. I bought a non-adjustable
> shaft rocker system for my 500. IF I had just redone the heads paying close
> attention to valve stem height when the heads were assembled...(by the
> way, when the head is done correctly, you should be able to put a straight
> edge
> across the top of the valve stems and find no difference in height) a non
> adjustable shaft system should work fine. But if the heads are original or
> reworked by your standard valve jocky machinest, chances are the stem
> heights are not correct or consistant in height. Knowing this, I would
> spend the
> extra on the adjustable rockers. More money...yes...but the ability to
> adjust each valve to the correct lifter preload. This is all JMHO and hope
> it
> helps.
> --
>
>
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Ken Henderson
Americus, GA
www.gmcwipersetc.com
Large Wiring Diagrams
76 X-Birchaven
76 X-Palm Beach
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| Re: [GMCnet] Caddy 500 camshaft recomendations [message #267798 is a reply to message #267793] |
Thu, 18 December 2014 15:35 |
Mr ERFisher
Messages: 7117
Registered: August 2005
Karma: 2
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Senior Member |
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On Thursday, December 18, 2014, Robert Mueller
wrote:
> Gene,
>
> Does installing this kit ($2,500) negate Fisher's Law of GMC mileage of
> 8-10 miles per gallon? ;-
No change
Same price as Howell on sale
But new parts and no computer
>
> VVVVVBG!
>
> Regards,
> Rob M.
> Sydney, Australia
> AUS '75 Avion - The Blue Streak TZE365V100428
> USA '75 Avion - Double Trouble TZE365V100426
>
>
> -----Original Message-----
> From: gene Fisher
>
> READ HERE
> http://gmc49ers.blogspot.com/
>
> it runs great
> more coming , keep in touch
> erf
>
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
>
--
Gene Fisher -- 74-23,77PB/ore/ca
“Give a man a fish; you have fed him for today --- give him a URL and
-------
http://gmcmotorhome.info/
Alternator Protection Cable
http://gmcmotorhome.info/APC.html
_______________________________________________
GMCnet mailing list
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| Re: Caddy 500 camshaft recomendations [message #267886 is a reply to message #267879] |
Fri, 19 December 2014 18:58 |
kingd
Messages: 592
Registered: June 2004
Karma: 2
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But a Chevy won't bolt up to the bell housing on the
Olds transmission and the right side drive shaft
goes through the oil pan and gets hit by the crank.
DAVE KING
lurker, wannabe
Toronto, Ontario, Canada
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| Re: [GMCnet] Caddy 500 camshaft recomendations [message #267901 is a reply to message #267886] |
Fri, 19 December 2014 21:47 |
powerjon
Messages: 2446
Registered: January 2004
Karma: 5
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Senior Member |
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Actually a Chevy BB will fit in the GMC and has been done many times. Dave Lenzi has an 8.1 version that is a monster. There is an adapter plate for the transmission bolt up and the drive shaft is close but does not hit the crank.
JR Wright
78 Buskirk Stretch
75 Avion
Michigan
> On Dec 19, 2014, at 7:58 PM, Dave King wrote:
>
> But a Chevy won't bolt up to the bell housing on the
> Olds transmission and the right side drive shaft
> goes through the oil pan and gets hit by the crank.
> --
> DAVE KING
> lurker, wannabe
> Toronto, Ontario, Canada
> _______________________________________________
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J.R. Wright
GMC GreatLaker
GMC Eastern States
GMCMI
78 30' Buskirk Stretch
75 Avion Under Reconstruction
Michigan
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| Re: [GMCnet] Caddy 500 camshaft recomendations [message #267956 is a reply to message #267901] |
Sat, 20 December 2014 22:30 |
jimk
Messages: 6734
Registered: July 2006
Location: Belmont, CA
Karma: 9
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Senior Member |
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Bill,
Listen to what Ken H said about the rocker stand,
Lot of us have had that failure, and your not able to pick up that part
easily at a parts store.
On Fri, Dec 19, 2014 at 7:47 PM, John Wright wrote:
> Actually a Chevy BB will fit in the GMC and has been done many times.
> Dave Lenzi has an 8.1 version that is a monster. There is an adapter plate
> for the transmission bolt up and the drive shaft is close but does not hit
> the crank.
> JR Wright
> 78 Buskirk Stretch
> 75 Avion
> Michigan
>
>> On Dec 19, 2014, at 7:58 PM, Dave King wrote:
>>
>> But a Chevy won't bolt up to the bell housing on the
>> Olds transmission and the right side drive shaft
>> goes through the oil pan and gets hit by the crank.
>> --
>> DAVE KING
>> lurker, wannabe
>> Toronto, Ontario, Canada
>> _______________________________________________
>> GMCnet mailing list
>> Unsubscribe or Change List Options:
>> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List 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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www.appliedgmc.com
1-800-752-7502
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| Re: Caddy 500 camshaft recomendations [message #268024 is a reply to message #267726] |
Mon, 22 December 2014 10:57 |
cbryan
Messages: 451
Registered: May 2012
Location: Ennis, Texas
Karma: 3
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Senior Member |
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Bill,
I have waited to post because I am not as qualified as you or the folks who post here on engine topics. However, I have some experience I think I have that might add a little to the discussion. As you see from the signature block, I bought a coach with a Cadillac 500 (.030 over), rebuilt, with sequential Accel EFI circa 2002, no mass air sensor, no knock sensor.
The computer control was a case of arrested development. Like Ken Henderson, I suspect that the PO found that the thing ran so well generally that they left things alone ("I'll get to the power enrichment after this mountain trip to see the grandchildren") and then burned a valve or two. Sold it to me. I am happy with it, but work still needed to be done. Acceleration enrichment, cold start enrichment, prime squirt, partially blocked injector (460 Ford Bosch injector), all needed to be tweaked.
Still runs pretty well, but not like a sewing machine. Dreading taking the heads off.
Now, what I did find: It had a "torque cam" (so said the PO). I don't know the particulars, but the engine was built by a Cadillac guru, speculation has it, the fellow in Soddy-Daisy Tennessee. Quality build, I think. While changing the parameters for the cold start, I saw where just off idle, the "tip in" timing was retarded quite a bit. I thought I would advance it so it would be like the rest of the table.
Boy, oh boy, it knocked. I had never heard it knock before. I thought it had low compression, but actually it seems that the first tuner got all knock out of it. I got that advance back out of it pronto, no damage. It knocked worse than my Dad's '62 Chevy Biscayne 235 6 on regular.
I think that you might well do well suppressing knock with the software available to better control things, despite the torque cam. You are a professional who can solve problems in minutes that takes me months to get some sort of handle on. However, I have that luxury and enjoy it, to each his own. There are tables out there for the throttle body regime that have been laboriously tweaked for ideal running. I now know that Carbs and power enrichment circuits are nonlinear (they really dump the gas on WOT) and I have to be careful about full power enrichment with injectors.
I guess really the best solution is to use the BBC. Despite some of the drawbacks, development on that engine has proceeded so far as I can tell, and the power available with the right cheap components is staggering. Especially since I see them on air boats and used as marine engines. I plan to put the shaft rocker system on the 500. It's starting to look like we 500 aficionados are nothing more than a cult who are willing to pay the price for performance and reliability.
I post this for what it's worth.
Respectfully submitted,
Carey
Carey from Ennis, Texas
78 Royale, 500 Cadillac, Rance Baxter EFI.
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| Re: [GMCnet] Caddy 500 camshaft recomendations [message #268025 is a reply to message #268024] |
Mon, 22 December 2014 11:10 |
James Hupy
Messages: 6806
Registered: May 2010
Karma: -62
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Senior Member |
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I have had various Cadillacs over the years. 1949, 2 1951's, a 1977 SDV, a
1961 CDV, and presently have a baby 500 engine sitting on an engine stand
in my shop. It has the prone to fail trunnion pin rocker system like Ken
had on his 500. Before you do anything else like after market camshafts or
valve springs, do yourself a huge favor and eliminate those trunnion pin
style rocker stands. Either use a stud mounted chev type system, or a full
rocker shaft system. There are systems out there that have torrington
roller bearings and roller tips. Those are very $$$$$. and unnecessary for
the revs we turn in a GMC. But, it is your money. Spend it like you had it.
Jim Hupy
Salem, OR
78 GMC Royale 403
On Mon, Dec 22, 2014 at 8:57 AM, Carey Bryan wrote:
> Bill,
>
> I have waited to post because I am not as qualified as you or the folks
> who post here on engine topics. However, I have some experience I think I
> have that might add a little to the discussion. As you see from the
> signature block, I bought a coach with a Cadillac 500 (.030 over), rebuilt,
> with
> sequential Accel EFI circa 2002, no mass air sensor, no knock sensor.
>
> The computer control was a case of arrested development. Like Ken
> Henderson, I suspect that the PO found that the thing ran so well generally
> that
> they left things alone ("I'll get to the power enrichment after this
> mountain trip to see the grandchildren") and then burned a valve or two.
> Sold it
> to me. I am happy with it, but work still needed to be done.
> Acceleration enrichment, cold start enrichment, prime squirt, partially
> blocked
> injector (460 Ford Bosch injector), all needed to be tweaked.
>
> Still runs pretty well, but not like a sewing machine. Dreading taking
> the heads off.
>
> Now, what I did find: It had a "torque cam" (so said the PO). I don't
> know the particulars, but the engine was built by a Cadillac guru,
> speculation
> has it, the fellow in Soddy-Daisy Tennessee. Quality build, I think.
> While changing the parameters for the cold start, I saw where just off idle,
> the "tip in" timing was retarded quite a bit. I thought I would advance
> it so it would be like the rest of the table.
> Boy, oh boy, it knocked. I had never heard it knock before. I thought it
> had low compression, but actually it seems that the first tuner got all
> knock out of it. I got that advance back out of it pronto, no damage. It
> knocked worse than my Dad's '62 Chevy Biscayne 235 6 on regular.
>
> I think that you might well do well suppressing knock with the software
> available to better control things, despite the torque cam. You are a
> professional who can solve problems in minutes that takes me months to get
> some sort of handle on. However, I have that luxury and enjoy it, to each
> his own. There are tables out there for the throttle body regime that
> have been laboriously tweaked for ideal running. I now know that Carbs and
> power enrichment circuits are nonlinear (they really dump the gas on WOT)
> and I have to be careful about full power enrichment with injectors.
>
> I guess really the best solution is to use the BBC. Despite some of the
> drawbacks, development on that engine has proceeded so far as I can tell,
> and
> the power available with the right cheap components is staggering.
> Especially since I see them on air boats and used as marine engines. I
> plan to put
> the shaft rocker system on the 500. It's starting to look like we 500
> aficionados are nothing more than a cult who are willing to pay the price
> for
> performance and reliability.
>
> I post this for what it's worth.
>
> Respectfully submitted,
>
> Carey
>
>
> --
> Carey from Ennis, Texas
> 78 Royale, 500 Cadillac, Rance Baxter EFI.
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
>
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| Re: [GMCnet] Caddy 500 camshaft recomendations [message #268052 is a reply to message #268025] |
Mon, 22 December 2014 19:48 |
cbryan
Messages: 451
Registered: May 2012
Location: Ennis, Texas
Karma: 3
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Senior Member |
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Thanks, Jim. Will put a shaft rocker system on it. Will wait until the valve job to see if adjustable will be required. The local machine shops will give you a great job. If you want it on time, that's problematic.
Carey
Carey from Ennis, Texas
78 Royale, 500 Cadillac, Rance Baxter EFI.
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