Will 2 head gaskets lower compression
Race Director
Joined: Oct 2000
Posts: 15,013
Likes: 79
From: central FL, near the beach.
lugging at 1800 is poor driving, not the fault of the 5 speed. is this when it pings? 
Thread Starter
Drifting
Joined: Oct 2005
Posts: 1,331
Likes: 479
From: Appleton Wisconsin
Safety Car
Joined: Oct 2000
Posts: 4,282
Likes: 172
From: Lake Wylie, South Carolina
Gary,
I am running Edelbrock Performer RPM heads and the matching intake. The heads are 110cc and with my pistons I am supposed to be right around 10:1. I have a 5-speed as well and even chugging along in 5th I don't have any pinging. I have not checked my vacuume with this cam yet but hope to tune on it this weekend if this heat will go away.
The cam I have now I realy like but I can't knock the 282s as it did run good for me as well.
Wade
Thread Starter
Drifting
Joined: Oct 2005
Posts: 1,331
Likes: 479
From: Appleton Wisconsin
Thread Starter
Drifting
Joined: Oct 2005
Posts: 1,331
Likes: 479
From: Appleton Wisconsin
Gary,
I am running Edelbrock Performer RPM heads and the matching intake. The heads are 110cc and with my pistons I am supposed to be right around 10:1. I have a 5-speed as well and even chugging along in 5th I don't have any pinging. I have not checked my vacuume with this cam yet but hope to tune on it this weekend if this heat will go away.
The cam I have now I realy like but I can't knock the 282s as it did run good for me as well.
Wade
I am running Edelbrock Performer RPM heads and the matching intake. The heads are 110cc and with my pistons I am supposed to be right around 10:1. I have a 5-speed as well and even chugging along in 5th I don't have any pinging. I have not checked my vacuume with this cam yet but hope to tune on it this weekend if this heat will go away.
The cam I have now I realy like but I can't knock the 282s as it did run good for me as well.
Wade
Safety Car
Joined: Oct 2000
Posts: 4,282
Likes: 172
From: Lake Wylie, South Carolina
Wade, I think I'm going to maybe try backing my cam timing back 4 deg if that doesn't do it. I might order the cam you have since you tried them both and you like this one better. Let me know how your vacuum is when you check it, did you change anything else when switched cams.
Will do. I am betting that once you install that cam straight up your detonation will clear up. From what I remember in researching the XS282 before I bought it, most recommended not advancing the Extreme series cams due to the amount of advance ground in them.
Yes I went with a set of ISKY EDM oiling lifter with the little hole in the face. I also went with a roller bearing style timing chain set as the comp set was eating up my block. Other than that I did not change anything else
Good luck I hope it solves your problem.
Wade
Last edited by ImBatman; Jul 31, 2008 at 09:35 PM.
Race Director
Joined: Oct 2000
Posts: 15,013
Likes: 79
From: central FL, near the beach.
u r in luck!
limit the weights max advance about 4-6 degrees, takes an hour or so. Hint: there is a bushing on a pin
good luck
i realize these are hobby cars, so if u want to spend more time and $$$, thats
limit the weights max advance about 4-6 degrees, takes an hour or so. Hint: there is a bushing on a pin
good luck
i realize these are hobby cars, so if u want to spend more time and $$$, thats
Last edited by Matt Gruber; Aug 1, 2008 at 08:53 AM.
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Pro
Joined: Jan 2004
Posts: 535
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From: Darwin, Australia NT
215 psi at cranking
That says your cam is probably too small for your setup and 93 fuel.
Retarding the cam back the 4 plus another 4 or better yet just go up a size on cam, perhaps even with a wider lobe separation angle which will help bleed off some but retain idle.
Also:
1. Slow advance with heavier advance springs. (just try one heavy at first)
2. Delete intake manifold exhaust heat and get a cold air intake
3. Slightly fatten carb
4. heat shield or plastic spacer on carb
I built a 383 for a friend with old iron heads, a smallish cam, 10.5/1 and stiff gearing (glide) and with a bit of tinkering we are able to get it to run sweetly on 91 with 36 total.
Retarding the cam back the 4 plus another 4 or better yet just go up a size on cam, perhaps even with a wider lobe separation angle which will help bleed off some but retain idle.
Also:
1. Slow advance with heavier advance springs. (just try one heavy at first)
2. Delete intake manifold exhaust heat and get a cold air intake
3. Slightly fatten carb
4. heat shield or plastic spacer on carb
I built a 383 for a friend with old iron heads, a smallish cam, 10.5/1 and stiff gearing (glide) and with a bit of tinkering we are able to get it to run sweetly on 91 with 36 total.
Race Director
Joined: Oct 2000
Posts: 15,013
Likes: 79
From: central FL, near the beach.
if it has extended tip plugs,
i've seen regular tip plugs really help.
.
this is a good topic because 10.5 is not high for high test, but shows what poor tuning/set-up can do.
Fix it ANY way u please and u PASS this real life final exam.
i've seen regular tip plugs really help.
.
this is a good topic because 10.5 is not high for high test, but shows what poor tuning/set-up can do.
Fix it ANY way u please and u PASS this real life final exam.
Last edited by Matt Gruber; Aug 2, 2008 at 07:05 AM.
Race Director
Joined: May 2005
Posts: 10,674
Likes: 122
From: Millington Illinois
St. Jude Donor '08-'09
I've read old smokeys books. The only problem with them is he was leading the pack in the engine field nearly 40 years ago. He was locked into that days technology. He would have to be retrained to even work at a modern race engine shop.
Two head gaskets would be so weak. I'm replacing a quality head gasket without the overpressure of one detonation.
I've built two motors with to small of cams and had to lower my dynamic compression ratio. bigger cam doesn't mean radical idle if you put some thought into it. Don't use or trust some $8 per "Techy" at CC.
Before I would tear everything apart maybe try retarding the cam 4 degrees.
"Read" your spark plugs. The wrong heat range plug can cause detonation as well as preignition. If the insulators around the electrodes on your plugs appear yellowish or blistered, they may be too hot for the application. Try the next heat range colder spark plug. Copper core spark plugs generally have a broader heat range than ordinary plugs, which lessens the danger of detonation.
Check for engine overheating. A hot engine is more likely to suffer spark knock than one which runs at normal temperature. Overheating can be caused by a low coolant level, a slipping fan clutch, too small a fan, too hot a thermostat, a bad water pump, or even a missing fan shroud. Poor heat conduction in the head and water jackets can be caused by a or steam pockets (which can result from trapped air pockets).
Check for a lean fuel mixture. Rich fuel mixtures resist detonation while lean ones do not. Air leaks in vacuum lines, intake manifold gaskets, carburetor gaskets can all admit extra air into the engine and lean out the fuel mixture. Lean mixtures can also be caused by dirty fuel injectors, carburetor jets clogged with fuel deposits or dirt, a restricted fuel filter or a weak fuel pump.
If the fuel mixture becomes too lean, "lean misfire" may occur as the load on the engine increases. This can cause a hesitation, stumble and/or rough idle problem as well.
The air/fuel ratio can also be affected by changes in altitude. As you go up in elevation, the air becomes less dense.
A carburetor that's calibrated for high altitude driving will run too lean if driven at a lower elevation.
Two head gaskets would be so weak. I'm replacing a quality head gasket without the overpressure of one detonation.
I've built two motors with to small of cams and had to lower my dynamic compression ratio. bigger cam doesn't mean radical idle if you put some thought into it. Don't use or trust some $8 per "Techy" at CC.
Before I would tear everything apart maybe try retarding the cam 4 degrees.
"Read" your spark plugs. The wrong heat range plug can cause detonation as well as preignition. If the insulators around the electrodes on your plugs appear yellowish or blistered, they may be too hot for the application. Try the next heat range colder spark plug. Copper core spark plugs generally have a broader heat range than ordinary plugs, which lessens the danger of detonation.
Check for engine overheating. A hot engine is more likely to suffer spark knock than one which runs at normal temperature. Overheating can be caused by a low coolant level, a slipping fan clutch, too small a fan, too hot a thermostat, a bad water pump, or even a missing fan shroud. Poor heat conduction in the head and water jackets can be caused by a or steam pockets (which can result from trapped air pockets).
Check for a lean fuel mixture. Rich fuel mixtures resist detonation while lean ones do not. Air leaks in vacuum lines, intake manifold gaskets, carburetor gaskets can all admit extra air into the engine and lean out the fuel mixture. Lean mixtures can also be caused by dirty fuel injectors, carburetor jets clogged with fuel deposits or dirt, a restricted fuel filter or a weak fuel pump.
If the fuel mixture becomes too lean, "lean misfire" may occur as the load on the engine increases. This can cause a hesitation, stumble and/or rough idle problem as well.
The air/fuel ratio can also be affected by changes in altitude. As you go up in elevation, the air becomes less dense.
A carburetor that's calibrated for high altitude driving will run too lean if driven at a lower elevation.
Probably tuning and or cooling issues. I would bet you install the cam straight up and time it properly with a good A/F ratio your problems are solved. That cam should run well at your cruising RPM.
Racer
Joined: May 2008
Posts: 398
Likes: 0
From: Sacramento California
I know ppl that have run 2 head gaskets on mtorcycle engines to lower compression with good results (for their goal) so you should be able to do it, and it will lower compression just a bit though i'm not sure how much with any given gasket thickness.
Kelly
Kelly
Le Mans Master
Joined: Feb 2000
Posts: 7,032
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From: Newburgh NY
I agree with the cam swap as originally suggested. But for the record, even GM put two head gaskets in engines on occasion.
My July 63 Fuelie had two heads gaskets when I pulled it apart and I was like WTF! You could tell the motor was never apart before. In researching it I got ahold of a copy of a factory Service Bulletain instructing the use of two heads gaskets on the line to solve complaints from customers about detonation. Go figure. I guess they figured that was a cheap fix at the time instead of doing it right which would have cost considerably more.
My July 63 Fuelie had two heads gaskets when I pulled it apart and I was like WTF! You could tell the motor was never apart before. In researching it I got ahold of a copy of a factory Service Bulletain instructing the use of two heads gaskets on the line to solve complaints from customers about detonation. Go figure. I guess they figured that was a cheap fix at the time instead of doing it right which would have cost considerably more.
Thread Starter
Drifting
Joined: Oct 2005
Posts: 1,331
Likes: 479
From: Appleton Wisconsin
Thanks everyone for all the advice, I installed a A/f meter, found out I'm a little lean. I'm going to richen the carb and try the next colder plug. If that doesn't work I will back my cam timing 4 deg. It may be a week or two before I get the cam backed off, I will post me results when I get this corrected. Thanks again. Gary
Burning Brakes
Joined: Oct 2006
Posts: 1,044
Likes: 0
From: Henrico VA
So did all the 63's after a certain date have the two head gaskets? Sounds like some good trivia.
I agree with the cam swap as originally suggested. But for the record, even GM put two head gaskets in engines on occasion.
My July 63 Fuelie had two heads gaskets when I pulled it apart and I was like WTF! You could tell the motor was never apart before. In researching it I got ahold of a copy of a factory Service Bulletain instructing the use of two heads gaskets on the line to solve complaints from customers about detonation. Go figure. I guess they figured that was a cheap fix at the time instead of doing it right which would have cost considerably more.
My July 63 Fuelie had two heads gaskets when I pulled it apart and I was like WTF! You could tell the motor was never apart before. In researching it I got ahold of a copy of a factory Service Bulletain instructing the use of two heads gaskets on the line to solve complaints from customers about detonation. Go figure. I guess they figured that was a cheap fix at the time instead of doing it right which would have cost considerably more.
