ChocDog

Hello. I'd love some advice about the headers on my project. It is a '69 427/390 which currently has Hooker headers on it. Mechanic bro-in-law says they flow better than the stock cast headers. Since I do have the stock headers (PO found them buried in his garage when I picked up the car), it seems a shame not to use them - not to mention issues of heat, etc. Any opinions????

Thanks! Kelly

1981Z06Vette

That depends more on you and your goals for the car...if you want it to look original, go with manifolds. If you are more into performance, stick with the headers.

FRSTR90

I think you are referring to the exhaust manifolds. I would stick with the headers. The manifolds disgustingly chokes an engine down. Hold them side by side and you'll see what I mean. I will never put exhaust manifolds on any of my cars!

LOTSARED

OK, just to make sure you get both opinions fed back to you... ( )
I say stick with the stock cast iron manifolds. Why? 1) You already have them, 2) heat, 3) maintenance free, 4) no real benefit to headers.
I drive a 427/390 and have run it both ways. The headers poured obscene amounts of heat into the engine bay. In fact, I melted a hole in the side of my plastic ws washer resevoir because I had let it go empty. (Nice... an original black '68 unit destroyed.) I also had to top off my steering box lube routinely because is thinned out and leaked. So, I'm sure that incredibly hot ambient air being sucked into the carb didn't help performance. Oh... also had to replace one or the other header gasket every year or two. All those issues went away when I went back to the cast manifolds. And, while I didn't do a dyno check, I noticed absolutely no difference in performance.
Some of these problems may be worse on a big block car vs small block. Also, while some cars (including small block vettes) came with restrictive cast manifolds, that just not true for the bb vettes. Take a look at the manifold design... it's essentially a short tube header. I just had my 427/390 rebuild by a very reputable shop. Their input was that headers would add no benefit. Hey, whatever you decide, ENJOY!!

Fscott

I'm only familiar with my situation, but when I bastardized my 82 with aluminum head, cam manifold and carb I figure it would be a shame not to have the Hookers....the only way to go for performance!

Gordonm

On a stock motor tha tdoes not get run above 5000 rpm to much you will not notice much of a difference. On a L88 run on a dyno manifolds vs a set of good headers 50 HP was gained with the headers. They ran the L88 to 7000 rpm so heavy breathing was needed. A lot depends on what you want from the car. Me, I would never run manifolds on anything but a stock motor. Just to restrictive. Yes the BB manifolds are probably one of the best exhaust manifolds out there but they can never compare flow wise to a set of headers.
I actually noticed my engine bay is cooler with Jet Hot coated headers than with the manifolds. Also after shutdown I can touch the headers within a few minutes and they are cool. Try that with iron manifolds.

ChocDog

Thanks for all the suggestions both ways. I guess the main thing is I have to decide is what I want the car to be. I'm not building a 'trailer queen' as they say, and the headers are already on the car, but the simplicity of the cast headers - especially if the BB version aren't too bad - is tempting. I'm not planning on hot rodding around, but there's nothing more heart pounding than the low growl escaping from under the hood of a BB muscle car.

If I keep the Hookers, I feel like I need to keep the stock ones around anyway since it is a #'s matching car - space may be an issue as well...

lots to consider...

LOTSARED

Yes! If you do decide to run the Hookers, do yourself a favor and hang onto the original cast manifolds. It's a shame to seperate a car from it's significant parts. We just completed an engine rebuild of our original 427/390 and chose to do a few mild mods (heads, cam, crank). I've tucked the original heads, crank, balancer etc safely away just to keep them with the car. Here's the important thing... it's your car, it's your call. Either way, have fun!

birdsmith

20/20 hindsight being what it is, whether you put the cast manifolds on now or not my guess is you'll seriously consider putting them on a year from now. Unless they're Jet-Hot coated, tubular headers are a major PITA and even with the coating they're still a minor PITA. Unless your Vette is a race car that's going to spend most of its life in the 6000-plus RPM range they're just not worth it. If the car is gonna be a driver (vs. racer) and you're not so vain or macho (I know, if you weren't at least a LITTLE vain or macho you wouldn't be driving a shark in the first place) that you just can't live without those spaghetti tubes sticking out of your engine then the cast manifolds have all the advantages. They're MUCH quieter, MUCH cooler, take up a LOT less space in an already-overcrowded engine bay, you can buy a pre-fit exhaust system that's made for the car from dozens of catalog vendors for around $300, and once they're in, they're in. No retightening, no rusty pipes, nice mellow sound, and a lot less heat. Hmmmm-tough call.

gq82

I think you'll appreciate the look and sound of a stock exhaust system.

68/70Vette

One thing that, I think, would really help the stock exhaust for a BB is to upgrade the exhaust pipes to a larger diameter all the way back to the mufflers. The iron manifolds have a nice large diameter output, but the exhaust pipes, particularly where they go under the differential, look to be the most restrictive portion of the exhaust pipes. There the exhaust pipes are flattened and some corregated bends occur and make the pipes much narrower than need be. Looks like their effective diameter is a little less than 2 inches (?).

bytor

Very good info. I was considering headers vs. stock manifolds and was concerned about the additional heat with headers on a small block. I need to have some exhaust work done anyway and am considering going to true duals on my 78 L-82. Will I notice any difference doing this and sticking with my manifolds?

jb78L-82

I have a basically stock 78 L-82 4 speed with 2.5in duals, monza turbo mufflers, and 6 months ago I added McJack's Shorty headers which are an exact replacement for the stock exhaust manifolds (they hook up directly to stock duals). McJack's headers are a nice compromise between the stock exhaust mainfolds and full length headers with none of the issues associated with headers including block hugger headers which require custom duals. McJack's headers are perfect for engines running no more than 5,500 RPM without the low end losses from full length headers. As stated above, unless you intend to race or rev above 6,000 RPM's, why bother with the fit, heat, and ground clearance issues with full length headers. Also, if you use lock washers with high temperature loctite on the header bolts along with good quality header gaskets, no leaks and no constant bolt tightening on the header bolts.

eastltd

Consider yourself lucky to have the stock manifolds Kelly. I don't and went the Hooker side pipe route. What concerns me is the potential to be shut down after the car hits the road by the emissions police for lack of emission components. In this area they perform random checks on the road rather then a yearly sniff test.

As it stands, my car will be missing the EGR & AIR pump which could be a $300 fine and possible impoundment of the car. To make the car legal, I would have to scrap my new heads and intake for compliant EGR pieces, buy all the AIR components and tap the headers for the injector tubes.

I don't think the emission laws are going to relax in the coming years so you may want to consider this when making your decision.

That being said, you can still build a nice looking emissions legal motor and have all the advantages/disadvantages of headers.

Check your car's specs and determine what emissions components it came with and go from there.

Good Luck

ChocDog

Excellent suggestions and information, guys. Thanks. Around here, a '69 is not required to pass emissions - although I don't want to be adding to the pollution in our mountain air anyway. Since I won't be driving the car all the time, our 'carbon footprint' won't be too bad.

How do I tell what AIR or other pollution equipment came on the car? I can't find a tank sticker and so far there's nothing behind the dash. Is there a way to tell by looking at the exhaust manifolds themselves?

BTW, engine is '69 427/390 w/ 4-speed.

Thanks.

eastltd

Have a look at the firewall emissions sticker just above the brake booster. You should see A.I.R. and/or EGR in the text somewhere. If there's nothing there related to those two systems, let me know and I'll buy one of those stickers for my car

LemansBlue68

For sure, all the '68 and '69 427's were originally equipped with smog pumps. Even the L88's. If you don't have the smog pump installed, your exhaust manifolds should at least have holes in each runner for the tubes, which have no doubt been plugged if you're still running them. Some big blocks prior to '68 were available without smog pumps so there were manifolds available that didn't have holes for the A.I.R. tubes. I'm not totally sure about the 454's for '70 -'74 but I believe they all had smog pumps too.

For what it's worth, I have a set of cerma-chromed Hooker Super Competition headers on my '68 427/390. I had a local shop apply the coating. They also applied a thermal coating inside the tubes as well. The coating looks fantastic and has managed to keep the heat down in the engine compartment pretty well. I'm still considering going back to the original exhaust manifolds. I've gotten tired of fighting the leaks at the header collectors. I must be getting old .

chvet73

Hooker is it