When are 1 7/8" headers needed?
Thread Starter
Joined: Jun 2003
Posts: 7,128
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From: Pittsburgh, PA
When are 1 7/8" headers needed? When is it beneficial to run the 1 7/8" headers? Stroker engines? Only forced induction? Stock 346 running a large cam or healthy head/cam package?
For those running the 1 7/8, why did you choose them?
For those running the 1 7/8, why did you choose them?
Last edited by DMNSPD; Jun 9, 2005 at 10:59 PM.
I wouldn't use it unless i had larger cubes- The only instense i might use the 1 7/8" LT's is if they were QTP w/ a HVM collector. Otherwise i May consider stepped 1 3/4"-1 7/8" Those are the only reasons i see using 1 7/8" Primary tubes
Well, according to the formulas from A. Graham Bell’s Performance Tuning in Theory and Practice, 346cid would need to be revved to 7500rpm for the 1-7/8" to be optimum. For a 383 it would be around 6800rpm, and if you were doing a 402/408 around 6500rpm. Anything larger than that and you really need 2" headers to acheive optimum high rpm power. If you want lots of torque, a 1-7/8 would be great on a 427.
Originally Posted by JakeFusion
Well, according to the formulas from A. Graham Bell’s Performance Tuning in Theory and Practice, 346cid would need to be revved to 7500rpm for the 1-7/8" to be optimum. For a 383 it would be around 6800rpm, and if you were doing a 402/408 around 6500rpm. Anything larger than that and you really need 2" headers to acheive optimum high rpm power. If you want lots of torque, a 1-7/8 would be great on a 427.
What is suggested for a 395/396 with a .595" lift cam? (Lunati 009)
I have read where everyone suggests to use the stock exhaust gaskets, so I ordered a new set. The I.D. of the gasket was bigger than my stock LS1 & 317 heads. When my AFR 225s showed up, the ports match the exhaust gasket. I measured teh exhaust gaskets and its less than 1 3/4" . IIRC, it was 1.737. SO this has me really wondering about going with 1 3/4 instead of the 1 7/8" as I was planning. The 1 3/4 stepped to 1 7/8 are a lot more expensive for a header that is already expensive.
I have read where everyone suggests to use the stock exhaust gaskets, so I ordered a new set. The I.D. of the gasket was bigger than my stock LS1 & 317 heads. When my AFR 225s showed up, the ports match the exhaust gasket. I measured teh exhaust gaskets and its less than 1 3/4" . IIRC, it was 1.737. SO this has me really wondering about going with 1 3/4 instead of the 1 7/8" as I was planning. The 1 3/4 stepped to 1 7/8 are a lot more expensive for a header that is already expensive.
Im a 346 and next set of headers I buy will be 1-7/8. More and more people are starting to run them with good results. Theres a set of QTP HVMC out there with my name on em.
