Corvette Forum : DigitalCorvettes.com Corvette Forums banner

1 - 10 of 10 Posts

·
Registered
Joined
·
226 Posts
Discussion Starter #1
Just curious if anyone has used the long tube 1 5/8 headers from summit? At 109.00 they are very appealing. is 1 5/8 ok for size? I have heard of 1 7/8 a lot and didnt know thanks! Also, are claims from other folks of 30-40 hp just BS? that sounds like a lot for just headers. BTW I have true duals, no cats and flowmasters with 2 1/2 inch pipe thanks on my 77 L 48
 

·
Premium Member
Joined
·
78 Posts
Just curious if anyone has used the long tube 1 5/8 headers from summit? At 109.00 they are very appealing. is 1 5/8 ok for size? I have heard of 1 7/8 a lot and didnt know thanks! Also, are claims from other folks of 30-40 hp just BS? that sounds like a lot for just headers. BTW I have true duals, no cats and flowmasters with 2 1/2 inch pipe thanks on my 77 L 48
You did not say what size engine you have.
1 5/8" is the correct primary tube size for most
small block Chevys that make power under 6,000 RPM.

10% is a good number for horse power gain from headers.
They are the only performance part that increases gas mileage...
 

·
Registered
Joined
·
411 Posts
I purchased the exact ones you are talking about, But i have not been able to see how they perform. They fit right on the block and have all the right bends to clear the steering, frame, and anything else that could get in the way. However, I should be starting up my enine hopefully sometime in the next month, so once i do i will post some videos
 

·
Registered
Joined
·
2,948 Posts
Performance gains from headers can range between 10% and 50% but only when paired with other modifications.

Intake, heads, cam, compression, and exhaust. That's a good recipe for power.

Just exhaust will help a little bit with performance and a lot with sound. Not much else.
 

·
Registered
Joined
·
552 Posts
If your L48 already has 2.5 true duals hooked to OE vette manifolds you're not going to see much gain. Maybe 10 hp at some point on the power curve, but probably not at the top.

What it will do is make the L48 holler & sound bad*ss. From the driver's seat, that's what most of the change will be. Sound, not power

As our cars already have decent manifolds, I wouldn't install cheap hedders because they rust and look so bad, so fast. Hedman elites are a pretty good value for coated hedders. Coating still doesn't end rust.

If you're thinking about some fancy hedder paint, (por-20)those only work when the manufacturing oils have been baked off first. Major PITA to do so.

1 5/8 is preferred for the majority of street small blocks. If you're making BBC power with a SBC, then it's time to think about the larger primary tubes.

good luck with the project
 

·
Registered
Joined
·
1,078 Posts
I put the same pair on my 77 also. Fit nice, gained a little more power, but definitely a lot more sound. The pain will burn off. So if your going for show, get the coated ones. I also ben told if you wrap them with header wrap they will rott out faster. Mine have been on about 7 years no wrap, no problems. Word of advice, I put heavy duty lock tight, grade 8 bolts with lock washers, and 5 layer aluminum gaskets from Mr gasket and have had no leak issues or loosening bolts. They were 1-5/8'' 1-7/8'' are for the high horse power. Good luck.
 

·
Registered
Joined
·
226 Posts
Discussion Starter #7
My engine is the original stock 350. It has about 100k on it and I drive it about 2500 miles a year. I am about to put on a new set of vortec heads and upgrade the cam. The most it should put out is 400hp so I guess the 1 5/8 should be good. Thanks for the responses, I am not too concerned about them rusting it won't be for show and if they last 2 years they will be worth the 100 bucks to me. Thanks again!
 

·
Registered
Joined
·
117 Posts
i have headers on my 74 350 and i do not lile them , they were on it when i purchased the car, they leak, drag when goung over a curb or speed bump. look lik crap, heatup the floors ,have problems with ac compressor mount and belt tension unless you are wanting performance improvements , stock manifolds are the way to go, my opinion
 

·
Registered
Joined
·
297 Posts
I don't have any experience with the 1 5/8" primary headers, but the 1 7/8" ones I have gave me a very noticeable performance increase. I believe the larger the primary, the higher up in the RPM band noticeable power is at, which I think is good for me with my '76 with a TH350 and 3.08 rear gears. I do a lot of freeway driving, and the extra power is very noticeable when I'm above 1500 RPM. Very torquey, I'm getting all excited just thinking about the driving I did in it today; I'm getting better gas mileage as well for sure.
 

·
Registered
Joined
·
170 Posts
As a compromise, I went with the block hugger headers with ceramic coating. I was having some heat issues with the rams horn manifolds, and they were certainly holding back what the ZZ4 could do. I looked at many long tube installations and just wasn't comfortable with the reduced ground clearance for a grocery getter that occasionally goes a 1/4 mi.
 
1 - 10 of 10 Posts
Top