Big Block Headers vs. Stock Manifolds
Thread Starter
Instructor
Joined: Mar 2017
Posts: 131
Likes: 3
From: Beaverton OR
Big Block Headers vs. Stock Manifolds
My L36 rebuild is nearly complete and I'm debating on whether to go with headers or stick with the stock manifolds. I'm not a fabricator of any sort nor do I want to make any changes to current frame/body configuration. I'm thinking shorties or mid-length headers might fit nicely but I have no experience. I'd appreciate recommendations on specific headers, or none at all if the entire concept is a PITA. I'm also shopping for nice sounding mufflers 
Thank you very much!
Thank you very much!
Race Director
Joined: Dec 1999
Posts: 11,096
Likes: 990
From: Sierra Foothills CA
My L36 rebuild is nearly complete and I'm debating on whether to go with headers or stick with the stock manifolds. I'm not a fabricator of any sort nor do I want to make any changes to current frame/body configuration. I'm thinking shorties or mid-length headers might fit nicely but I have no experience. I'd appreciate recommendations on specific headers, or none at all if the entire concept is a PITA. I'm also shopping for nice sounding mufflers Thank you very much!
Thank you very much!I'd stay away from Hookers because they hang low and ground clearance isn't very good. I have Hedman headers, which have 2"primary tubes. They tuck up better than the Hookers and performance gains are solid. I did need to put a small dimple in a tube where it would tap the frame while idling. This was easy to do, can't be seen from above, and it won't hurt performance a bit.
I didn't want to write a book if you decide against headers, so I can point you towards good gaskets and give a bit more info if you want.
Thread Starter
Instructor
Joined: Mar 2017
Posts: 131
Likes: 3
From: Beaverton OR
V2, the only performance upgrades are a Howards Cam (advertised 282 deg. duration, 0.555" valve lift) and a Weiand intake manifold (8005). The rest is a stock L36, 10.25:1 compression and stock Qjet carb. Better performance is what I'm looking for along with accompanying audible improvements The stock under-the-hood look isn't terribly important provided I don't have to get out the hacksaw or torch. I'll keep the stock manifolds (I have the stock intake too) if that ever becomes important. Thanks!
The stock under-the-hood look isn't terribly important provided I don't have to get out the hacksaw or torch. I'll keep the stock manifolds (I have the stock intake too) if that ever becomes important. Thanks!
Le Mans Master
Joined: Mar 2001
Posts: 5,738
Likes: 644
From: Lincoln, CA
I only had to make a little room by denting the Hedman header to clear the frame on the passenger side. Otherwise they drop right in.
You do need to have mid pipes made to connect to the back half of the exhaust.
When I switched it was a VERY noticeable difference in power.
BTW I had my coated in black so they don't stand out.
You do need to have mid pipes made to connect to the back half of the exhaust.
When I switched it was a VERY noticeable difference in power.
BTW I had my coated in black so they don't stand out.
Race Director
Joined: Dec 1999
Posts: 11,096
Likes: 990
From: Sierra Foothills CA
V2, the only performance upgrades are a Howards Cam (advertised 282 deg. duration, 0.555" valve lift) and a Weiand intake manifold (8005). The rest is a stock L36, 10.25:1 compression and stock Qjet carb. Better performance is what I'm looking for along with accompanying audible improvements The stock under-the-hood look isn't terribly important provided I don't have to get out the hacksaw or torch. I'll keep the stock manifolds (I have the stock intake too) if that ever becomes important. Thanks!
The stock under-the-hood look isn't terribly important provided I don't have to get out the hacksaw or torch. I'll keep the stock manifolds (I have the stock intake too) if that ever becomes important. Thanks!
Conversely, you'd be leaving a lot on the table by not getting headers.
Thread Starter
Instructor
Joined: Mar 2017
Posts: 131
Likes: 3
From: Beaverton OR
I'd stay away from Hookers because they hang low and ground clearance isn't very good. I have Hedman headers, which have 2"primary tubes. They tuck up better than the Hookers and performance gains are solid. I did need to put a small dimple in a tube where it would tap the frame while idling. This was easy to do, can't be seen from above, and it won't hurt performance a bit.
I didn't want to write a book if you decide against headers, so I can point you towards good gaskets and give a bit more info if you want.
I didn't want to write a book if you decide against headers, so I can point you towards good gaskets and give a bit more info if you want.
Thread Starter
Instructor
Joined: Mar 2017
Posts: 131
Likes: 3
From: Beaverton OR
I only had to make a little room by denting the Hedman header to clear the frame on the passenger side. Otherwise they drop right in.
You do need to have mid pipes made to connect to the back half of the exhaust.
When I switched it was a VERY noticeable difference in power.
BTW I had my coated in black so they don't stand out.
You do need to have mid pipes made to connect to the back half of the exhaust.
When I switched it was a VERY noticeable difference in power.
BTW I had my coated in black so they don't stand out.
What specific Hedmans did you go with?
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Melting Slicks
Joined: Mar 2008
Posts: 2,666
Likes: 289
From: Spring Park MN
Go with a long tube header, the short ones don't do that much for you.
Headers with a 2.5" exhaust system and free flowing mufflers will make a huge difference for you.
Make sure you recurve your distributor also. Lot's to gain there too.
Mike
Headers with a 2.5" exhaust system and free flowing mufflers will make a huge difference for you.
Make sure you recurve your distributor also. Lot's to gain there too.
Mike
Race Director
Joined: Dec 1999
Posts: 11,096
Likes: 990
From: Sierra Foothills CA
Thanks, and yes, I'm serious about headers but only if they don't come with major installation headaches or post-install regrets. It sounds like there's "a way" for success. So with that, I'm definitely interested in more info. What specific Hedmans did you go with? Thanks.
https://www.summitracing.com/parts/hed-68096
Thread Starter
Instructor
Joined: Mar 2017
Posts: 131
Likes: 3
From: Beaverton OR
Thanks Mike. Can you recommend a specific spring/weight kit?
Melting Slicks
Joined: Mar 2008
Posts: 2,666
Likes: 289
From: Spring Park MN
I take it you probably have the stock points distributor yet. You can get kits with springs and weights from Jegs or Summit for your distributor. You will have to play with the springs to dial in the full advance RPM and the advance limiting bushings in the kit. You also might want to get a vacuum advance limiter from Lars or make one yourself.
The amount of intial timing and full advance will depend somewhat on your cam, how tight you set your squish, and the octane of the fuel available.
A build like yours will probably like around 12 to 14 degrees initial timing with 36 to 38 degrees total advance all in at 3000 to 3200 rpm. Limit the vacuum advance somewhere between 10 and 14 degrees of advance.
Mike
The amount of intial timing and full advance will depend somewhat on your cam, how tight you set your squish, and the octane of the fuel available.
A build like yours will probably like around 12 to 14 degrees initial timing with 36 to 38 degrees total advance all in at 3000 to 3200 rpm. Limit the vacuum advance somewhere between 10 and 14 degrees of advance.
Mike
Thread Starter
Instructor
Joined: Mar 2017
Posts: 131
Likes: 3
From: Beaverton OR
I take it you probably have the stock points distributor yet. You can get kits with springs and weights from Jegs or Summit for your distributor. You will have to play with the springs to dial in the full advance RPM and the advance limiting bushings in the kit. You also might want to get a vacuum advance limiter from Lars or make one yourself.
The amount of intial timing and full advance will depend somewhat on your cam, how tight you set your squish, and the octane of the fuel available.
A build like yours will probably like around 12 to 14 degrees initial timing with 36 to 38 degrees total advance all in at 3000 to 3200 rpm. Limit the vacuum advance somewhere between 10 and 14 degrees of advance.
Mike
The amount of intial timing and full advance will depend somewhat on your cam, how tight you set your squish, and the octane of the fuel available.
A build like yours will probably like around 12 to 14 degrees initial timing with 36 to 38 degrees total advance all in at 3000 to 3200 rpm. Limit the vacuum advance somewhere between 10 and 14 degrees of advance.
Mike
Safety Car
Joined: Oct 2007
Posts: 3,729
Likes: 267
From: Austin Texas
Corvette of the Year Winner 2017
2016 C3 of Year Finalist
Corvette BB manifolds are some of the best oem flowing manifolds available.
I got tired of all the problems associated with headers, kept the manifolds.
and stuffed more HP in the motor. made the Side pipes nice and easy to connect.
I got tired of all the problems associated with headers, kept the manifolds.
and stuffed more HP in the motor. made the Side pipes nice and easy to connect.
Race Director
Joined: Mar 2016
Posts: 14,406
Likes: 8,212
From: Napa Valley California
Headers are one of the best things you can do to obtain better breathing for your motor and with the cam you installed the additional exhaust flow will help you achieve more hp/tq. Tube diameter is an important factor. I watched this you-tube video that was posted on the forum that gives some good technical information regarding tube size. I've never had any issues installing or maintaining headers on any car, motorcycle or boat I've owned.
.
Last edited by OldCarBum; Aug 9, 2017 at 07:40 PM.
Safety Car
Joined: Oct 2007
Posts: 3,729
Likes: 267
From: Austin Texas
Corvette of the Year Winner 2017
2016 C3 of Year Finalist
ROTFL, ... never burnt a plug wire/boot, never had header flange bolt become loose,
never melted nearby components, never had a collector gasket flow out, never drug headers over a speed bump. ... ok if you say so !
never melted nearby components, never had a collector gasket flow out, never drug headers over a speed bump. ... ok if you say so !
Racer
Joined: Apr 2016
Posts: 493
Likes: 65
V2, the only performance upgrades are a Howards Cam (advertised 282 deg. duration, 0.555" valve lift) and a Weiand intake manifold (8005). The rest is a stock L36, 10.25:1 compression and stock Qjet carb. Better performance is what I'm looking for along with accompanying audible improvements The stock under-the-hood look isn't terribly important provided I don't have to get out the hacksaw or torch. I'll keep the stock manifolds (I have the stock intake too) if that ever becomes important. Thanks!
The stock under-the-hood look isn't terribly important provided I don't have to get out the hacksaw or torch. I'll keep the stock manifolds (I have the stock intake too) if that ever becomes important. Thanks!I'd spend that same amount of money again, after doing it. And I would spend the money gladly, it was that simple and easy. But, mind you, I am a fabricator, and have been for over 40 years. The pipes weren't that hard, really
Racer
Joined: Apr 2016
Posts: 493
Likes: 65
I'd stay away from Hookers because they hang low and ground clearance isn't very good. I have Hedman headers, which have 2"primary tubes. They tuck up better than the Hookers and performance gains are solid. I did need to put a small dimple in a tube where it would tap the frame while idling. This was easy to do, can't be seen from above, and it won't hurt performance a bit.
I have to strongly disagree. I have Hooker Super Comps, coated long tube and I have no fitment issues at all, not even the "small dimple" you admit to having to put in for your Hedmans.
Are you sure you're talking about true Hooker headers? Maybe some cheap knock offs? My Hookers were around $700, so they're not the most expensive, but surely not some Blackjack from back in the day.
Race Director
Joined: Mar 2016
Posts: 14,406
Likes: 8,212
From: Napa Valley California
Team Owner
Joined: Jul 1999
Posts: 26,545
Likes: 46
From: Huntersville NC
I put Hooker Supercomp headers on my 68 L-36. Did it all by myself! 
I ordered them direct from Jet Hot, with the silver coating. I messed around with flexhose and pre-ordered tubes with little success and finally took it to an expert exhaust shop, where this pic was taken. Unfortunately, the headers don't look nice like this any more. 
But they haven't given me any trouble. Big unexpected bonus was the engine runs much cooler with the headers. I always wondered what benefits could be achieved by porting and polishing the stock manifolds, ie grinding out some of the insides so they would flow better.
Since photobucket charges for 3rd party hosting, does this work?
Yes, there is one plug boot that I had to wrap with insulation to keep it from getting fried, and YES, they can scrape on a big speed hump. They do hang low and reduce ground clearance, but it is rarely a problem.
I ordered them direct from Jet Hot, with the silver coating. I messed around with flexhose and pre-ordered tubes with little success and finally took it to an expert exhaust shop, where this pic was taken. Unfortunately, the headers don't look nice like this any more. But they haven't given me any trouble. Big unexpected bonus was the engine runs much cooler with the headers. I always wondered what benefits could be achieved by porting and polishing the stock manifolds, ie grinding out some of the insides so they would flow better. Since photobucket charges for 3rd party hosting, does this work?
Yes, there is one plug boot that I had to wrap with insulation to keep it from getting fried, and YES, they can scrape on a big speed hump. They do hang low and reduce ground clearance, but it is rarely a problem.
Last edited by PRNDL; Aug 10, 2017 at 11:49 AM.