head replacement
Thread Starter
Drifting
Joined: Aug 2007
Posts: 1,838
Likes: 13
From: Kingman AZ
head replacement
I have an 1976 L-48 and need to be concerned about smog. I have heard the vortec heads will really bring some life to these engines. However I understand that you also have to change intakes and possibly modify hole size and threading for temp unit etc. Plus change of mainfold means increased overall engine height. My questions are
A) Would it be worth replacing the heads with something like the brodix after market heads and a mild upgraded cam using the stock intake and the stock Q jet carb. (and of course port matching)
B) a waste of time spending that kind of cash and not upgrading the intake and carb
C) Fill in the blank with your best answer.
remember I wanna try and stay smog legal. Right now it passes with flying colors at 60,000 mile. Therefore I need to make it look unchanged externally
A) Would it be worth replacing the heads with something like the brodix after market heads and a mild upgraded cam using the stock intake and the stock Q jet carb. (and of course port matching)
B) a waste of time spending that kind of cash and not upgrading the intake and carb
C) Fill in the blank with your best answer.
remember I wanna try and stay smog legal. Right now it passes with flying colors at 60,000 mile. Therefore I need to make it look unchanged externally
Team Owner
Joined: Aug 2006
Posts: 24,125
Likes: 15
From: Columbia Missouri
Vortec heads are not set up for EGR, nor are the manifolds. They won't pass in CA. You'll need after market heads that support EGR and still give you better flow.
I don't have any experience digging up parts for CA cars so someone will chime in...I just know that Vortec won't work for what you need it to.
I don't have any experience digging up parts for CA cars so someone will chime in...I just know that Vortec won't work for what you need it to.
Le Mans Master
Joined: Apr 2005
Posts: 6,350
Likes: 423
From: Seattle Area WA
I can think of a couple issues if you need to stay smog legal. I assume you have a stock exhaust system, 2 into 1 which feeds into that old style Cat converter.
Yes you can make more power and still stay smog legal.
To make like easier, I would look at the 64cc Summit or Dart cast iron heads with heat crossovers to use your stock Q-jet carb choke and EGR system. The Q-jet is a very good carb when tuned. If it needs work, you may have to ping Lars for a rebuild.
I would suggest the Performer 3701 intake with EGR and provisions for your Q-jet choke to stay legal.
Then to make any power you'll need to add true dual exhaust, something like 2 1/4" since this is a little motor and use two high flow, CA legal catalytic converters. Something like the Walker Dynomax Super converters.
A short duration cam will complement your new setup. You'll want something that will provide a good idle and work with the stock exhaust manifolds assuming you keep them. A GM "151" 327/350 HP cam might be something to look into, it idles very well and provides good torque with a stock exhaust system.
It may be handy to keep two distributors, one recurved for performance which may or may not pass smog, and a stock HEI for test day.
Yes you can make more power and still stay smog legal.
To make like easier, I would look at the 64cc Summit or Dart cast iron heads with heat crossovers to use your stock Q-jet carb choke and EGR system. The Q-jet is a very good carb when tuned. If it needs work, you may have to ping Lars for a rebuild.
I would suggest the Performer 3701 intake with EGR and provisions for your Q-jet choke to stay legal.
Then to make any power you'll need to add true dual exhaust, something like 2 1/4" since this is a little motor and use two high flow, CA legal catalytic converters. Something like the Walker Dynomax Super converters.
A short duration cam will complement your new setup. You'll want something that will provide a good idle and work with the stock exhaust manifolds assuming you keep them. A GM "151" 327/350 HP cam might be something to look into, it idles very well and provides good torque with a stock exhaust system.
It may be handy to keep two distributors, one recurved for performance which may or may not pass smog, and a stock HEI for test day.
Intermediate
Joined: Nov 2007
Posts: 36
Likes: 0
From: Canyon Country CA
kalifornia
doing my '79 l48, went with Edlebrock 6909 heads, 3701 intake,cam and lifter set, all 50 state legal but, rams horn headers hit the block and head and require grinding, intake accepts the hot air choke but the heads don't, I cut the hot air tube bent it and brazed it to stay inside the intake, true dual exhaust isn't legal if your car didn't come stock with them, someone makes headers for the A.I.R, but I started out wanting to keep the rams ,the vortec are not an option due to your year.
Check the forum for advice, not summit,not edelbrock!!!
Check the forum for advice, not summit,not edelbrock!!!
Thread Starter
Drifting
Joined: Aug 2007
Posts: 1,838
Likes: 13
From: Kingman AZ
One thing my system doesnt have is A.I.R pump. Was a Colorado Vehicle so its 49 federal. Wonder how that would effect things? Still requires smog. Smog station did check exhaust and cat
http://s188.photobucket.com/albums/z...Picture024.jpg
http://s188.photobucket.com/albums/z...Picture024.jpg
Last edited by rayluka; Mar 5, 2008 at 03:49 PM.
Le Mans Master
Joined: Apr 2005
Posts: 6,350
Likes: 423
From: Seattle Area WA
I think the only thing the 49 states does for you is not require the CA smog pump. If you can't run true duals then you will have to investigate a good 2 into 1 with a single high flow cat then back to your dual mufflers.
For the above reasons the high perf cast iron heads would be an easier installation.
Since you are in Long Beach, make a trip to Lomita to Sebring's Service Center on Normandie and check out the various heads in stock etc, and what exhaust/system and shop they would recommend for performance to stay CA legal.
For the above reasons the high perf cast iron heads would be an easier installation.
Since you are in Long Beach, make a trip to Lomita to Sebring's Service Center on Normandie and check out the various heads in stock etc, and what exhaust/system and shop they would recommend for performance to stay CA legal.
Thread Starter
Drifting
Joined: Aug 2007
Posts: 1,838
Likes: 13
From: Kingman AZ
I was thingking an L-82 exhaust is 2.25 or 2.5. That with a low restiction cat should do the trick for the exhaust. mabey even some magnaflows. Factory setup should be legal. I'll check into the heads like you recommend. I do know better than to ask a manufacturer. Answers are too general. They just want to make a sale. Guys here have done upgrades and can report accuratly as they've "been there done that". Thats why I love this board
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Thread Starter
Drifting
Joined: Aug 2007
Posts: 1,838
Likes: 13
From: Kingman AZ
Went from Colorado to Michigan. Had it shipped from Michigan to here. Got it from my brother-in-law and sister for a steal. Told em it was a gift. No taxes,nothing. Regular DMV fees 135.00. Just had to pass smog as it was originally. Since its totally original...no prob.
Last edited by rayluka; Mar 5, 2008 at 06:38 PM. Reason: sp
Le Mans Master
Joined: Apr 2005
Posts: 6,350
Likes: 423
From: Seattle Area WA
I believe that the last year for factory 2 1/2" exhaust was for a 1974 L-82 and that was true duals. After that, the 2 into 1 catalytic converter system was used and was 2" for either engine. It would be nice to find a set of 2 1/2 rams horns to keep the performance and keep the stock look too.
Thread Starter
Drifting
Joined: Aug 2007
Posts: 1,838
Likes: 13
From: Kingman AZ
SO the L 82 exhaust I would want doenst exist. My luck. In regards to the rams horn I may be wrong but actually the manifold is smaller and then the pipes widen in diameter about 3 inches down. Saw a photo here on this sight once I believe. I cant recall the description from that post in regards to why it was like that, so thats why I say I may be wrong on that one
Last edited by rayluka; Mar 5, 2008 at 08:08 PM.