Advancing Camshaft
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Joined: Dec 2013
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From: Pacifica CA
Advancing Camshaft
Would there be any advantage to advancing the camshaft 4 degrees in an 1980 L82 with an automatic transmission (TH350c)? Most of the power comes on above 3k rpm and is rather soft below. I have already recurved the distributor and replaced the exhaust system with a Flow Master unit and high flow cat converter; got to keep it looking smog legal in California 
. Should I replace the heads, more so for higher compression rather than better breathing?
. Should I replace the heads, more so for higher compression rather than better breathing?
Le Mans Master
Joined: Apr 2011
Posts: 6,284
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From: Hermosa
If you only have to keep it looking smog compliant then you have more freedom to do what you want.
Replacing the heads for more compression would require determining the condition of the rings first. So a leak down test would be the best way to do that.
If you up the compression with weak ring seal you'll be blowing smoke from oil burning after the bump.
Advancing the cam 4* may help with that cam. I'd give it a shot if you got the time and know how. Replace timing chain set while your at it if it's still stock.
Is the Q-jet (?) still stock configuration. If so a good rebuild can do wonders for performance from it as well.
Replacing the heads for more compression would require determining the condition of the rings first. So a leak down test would be the best way to do that.
If you up the compression with weak ring seal you'll be blowing smoke from oil burning after the bump.
Advancing the cam 4* may help with that cam. I'd give it a shot if you got the time and know how. Replace timing chain set while your at it if it's still stock.
Is the Q-jet (?) still stock configuration. If so a good rebuild can do wonders for performance from it as well.
Thread Starter
Advanced
Joined: Dec 2013
Posts: 79
Likes: 2
From: Pacifica CA
If you only have to keep it looking smog compliant then you have more freedom to do what you want.
Replacing the heads for more compression would require determining the condition of the rings first. So a leak down test would be the best way to do that.
If you up the compression with weak ring seal you'll be blowing smoke from oil burning after the bump.
Advancing the cam 4* may help with that cam. I'd give it a shot if you got the time and know how. Replace timing chain set while your at it if it's still stock.
Is the Q-jet (?) still stock configuration. If so a good rebuild can do wonders for performance from it as well.
Replacing the heads for more compression would require determining the condition of the rings first. So a leak down test would be the best way to do that.
If you up the compression with weak ring seal you'll be blowing smoke from oil burning after the bump.
Advancing the cam 4* may help with that cam. I'd give it a shot if you got the time and know how. Replace timing chain set while your at it if it's still stock.
Is the Q-jet (?) still stock configuration. If so a good rebuild can do wonders for performance from it as well.
Team Owner
Joined: Jan 2006
Posts: 37,637
Likes: 3,118
From: Crossville TN
If that is the ONLY thing you are going to do, then NO...it's not worth the effort and the RISK that you might end up with some leaks you presently do not have.
If you are going to do other engine work, and you don't want to spend money on a better cam, advancing the cam a bit MIGHT be worth the trouble.
If you are going to do other engine work, and you don't want to spend money on a better cam, advancing the cam a bit MIGHT be worth the trouble.
Le Mans Master
Joined: Oct 2007
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From: RI, Now Franklin/Nashville TN
I did exactly that cam advance by 4 degrees on my OEM L-82 cam when i did the timing chain and all it did was lower peak HP and torque by 500 RPM, hardly worth the effort if all you are doing is advancing the cam. I know the 78/79 L-82 had a factory aluminum intake and I thought the 80 L-48/L-82 as well but I might be wrong about the L-48's.
Le Mans Master
Joined: Oct 2007
Posts: 7,451
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From: RI, Now Franklin/Nashville TN
Would there be any advantage to advancing the camshaft 4 degrees in an 1980 L82 with an automatic transmission (TH350c)? Most of the power comes on above 3k rpm and is rather soft below. I have already recurved the distributor and replaced the exhaust system with a Flow Master unit and high flow cat converter; got to keep it looking smog legal in California . Should I replace the heads, more so for higher compression rather than better breathing?
. Should I replace the heads, more so for higher compression rather than better breathing?
Thread Starter
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Joined: Dec 2013
Posts: 79
Likes: 2
From: Pacifica CA
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Le Mans Master
Joined: Oct 2007
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From: RI, Now Franklin/Nashville TN
Yes I think that changing the stock heads will always help. I have read good comments about the Summit aluminum heads. I don't think I would go AFR's without a combined parts replacement plan. As far as the 2-1-2 exhaust, it can made decent by what you have done with a high flow cat and free flowing mufflers but it will never match 2.5 inch true duals. There is a forum member out in your neck of the woods who has a 78 with 2-1-2 with 2.5 inch head pipes converging into a single 3.5 inch straight pipes where the cat is located and a 2.5 inch split pipes out back. This system will flow quite a bit better than the stock Y pipe and exhaust system. I think you would be very happy with the increased power.
Le Mans Master
Joined: Oct 2010
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From: melbourne florida
2023 C3 of the Year Finalist - Modified
IF you have the L-82 cam and IF you need to do the timing chain then yes advancing that cam is worthwhile. again IF you have that cam a good set of 64 cc chamber heads will boost compression and power. with that cam a set of 1.6 rockers will help and you would have a very drivable car with power just everywhere.
Burning Brakes
Joined: Jun 2010
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From: Bellmore NY
Race Director
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From: Millington Illinois
St. Jude Donor '08-'09
That cam is the same as the L46 cam but your engine is 9 to 1 and L46 was 11 to 1. L46 had 350 HP. A set of better flowing, aluminum small chamber heads will make a huge difference. That said the operating range of that cam is pretty high. Cure is lower gear differential or 2400 stall convertor. Advancing the cam will drop peak power and operating range.
Burning Brakes
Joined: Sep 2012
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From: coon rapids mn
if you remove the timing chain cover and balancer ,check to see what cam you have .if it is a stock GM cam ,maybe find a cam that will pass emissions and make good torque .great heads with a ok cam is better then a bigger cam only .
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From: Pacifica CA
Wow, this is really great! I would like to say Thank You All for sharing your knowledge and experiences.
I think I will leave the cam timing alone for now, since I really don't know what's in there. Sometime down the road I will probably spring for the Summit aluminum heads with 62cc combution chambers, possibly 1.6 ratio aluminum roller rockers and a 2,400 rpm stall lock up torque converter. I'm going to keep the 3:08's in the rear since I do cruise on freeway at times. I read somewhere that modern high stall torque converters of today do not slip at slow speeds like the old days; is this true even for a TH350c?
I think I will leave the cam timing alone for now, since I really don't know what's in there. Sometime down the road I will probably spring for the Summit aluminum heads with 62cc combution chambers, possibly 1.6 ratio aluminum roller rockers and a 2,400 rpm stall lock up torque converter. I'm going to keep the 3:08's in the rear since I do cruise on freeway at times. I read somewhere that modern high stall torque converters of today do not slip at slow speeds like the old days; is this true even for a TH350c?
Safety Car
Joined: Jan 2009
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From: anchorage ak
Wow, this is really great! I would like to say Thank You All for sharing your knowledge and experiences. I think I will leave the cam timing alone for now, since I really don't know what's in there. Sometime down the road I will probably spring for the Summit aluminum heads with 62cc combution chambers, possibly 1.6 ratio aluminum roller rockers and a 2,400 rpm stall lock up torque converter. I'm going to keep the 3:08's in the rear since I do cruise on freeway at times. I read somewhere that modern high stall torque converters of today do not slip at slow speeds like the old days; is this true even for a TH350c?
I think I will leave the cam timing alone for now, since I really don't know what's in there. Sometime down the road I will probably spring for the Summit aluminum heads with 62cc combution chambers, possibly 1.6 ratio aluminum roller rockers and a 2,400 rpm stall lock up torque converter. I'm going to keep the 3:08's in the rear since I do cruise on freeway at times. I read somewhere that modern high stall torque converters of today do not slip at slow speeds like the old days; is this true even for a TH350c?oops!
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Joined: Dec 2013
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From: Pacifica CA
Im not for sure but I think the summit heads are dart Shp with the summit logo which do ok, but as Gary said great heads with an ok cam will pass emissions an make great torque and hp. There's other up grades that need to be done, but before we can go that wrote you'll need to know you applicable emissions laws.
oops!
oops!
The exhaust cannot be modified from the original 2-1-2 configuration; I'm all for clean air and would be willing to put on two cats to have a true dual system but the EPA and Air Rescources Board doesn't see it that way. This makes it very challenging in order to make improvements in both power and efficiency.
Burning Brakes
Joined: Nov 2012
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From: Indianapolis IN
2 - 2 &1/2" (mandrel-bent pipes only) into a single 3 1/2" is exactly what we used on a restricted class stock car.
With a high-flow cat it can be far better than an OEM original exhaust if there is room for it. IMHO
Would this flunk a visual inspection ?
We had to use iron manifolds too and 'vette ramhorns filled the bill nicely.
Do you any options for better manifolds or exempt headers ?
You may not make great improvements - but you may be able to make some.
With a high-flow cat it can be far better than an OEM original exhaust if there is room for it. IMHO
Would this flunk a visual inspection ?
We had to use iron manifolds too and 'vette ramhorns filled the bill nicely.
Do you any options for better manifolds or exempt headers ?
You may not make great improvements - but you may be able to make some.
Safety Car
Joined: Jan 2009
Posts: 3,736
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From: anchorage ak
Unfortunately in California, any car from 1975 and newer is subject to a biennial smog inspection. Everything has to be visually there, functioning properly during that time period and pass the sniffer test as well. The exhaust cannot be modified from the original 2-1-2 configuration; I'm all for clean air and would be willing to put on two cats to have a true dual system but the EPA and Air Rescources Board doesn't see it that way. This makes it very challenging in order to make improvements in both power and efficiency.
The exhaust cannot be modified from the original 2-1-2 configuration; I'm all for clean air and would be willing to put on two cats to have a true dual system but the EPA and Air Rescources Board doesn't see it that way. This makes it very challenging in order to make improvements in both power and efficiency.oops!
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From: Pacifica CA
Well the parts you buy need to have a carb number, you can do a little research about it at one of the local Im stations, buy the guy a few beers, ask some questions. Maybe go with 3" Madrel bent with a set of 2.5" rams horns with some extensive port work and bead blast through them some to smooth out the casting flaws, single oversized high flow cat, afr heads with a c.a.r.b. number, a roller cam with it as well, it would take a little research enginuity, work and tuning for emissions to past the pipe test but it's doable.
oops!
oops!