305 header size ???
 

What would be the best header size to run. The combo is 175/248. Thanks.

Re: 305 header size ???
 

Found power on the dyno going down from 1 &3/4 to 1 & 5/8

Re: 305 header size ???
 

The late great Jere Stahl strongly recommended 1 5|8 on my 305 ; it made real good horsepower .

Re: 305 header size ???
 

How much Horse Power love to know??
lol

Re: 305 header size ???
 

Just straight 1 5/8" or with a step.

Re: 305 header size ???
 

Just straight 1 5/8" or is that a step header.

Re: 305 header size ???
 

I would probably do a 1 1/2 to 1 5/8 step.

Re: 305 header size ???
 

My dish piston 305 2bbl made the most with 11/2"-15/8"step with a merge collector

Re: 305 header size ???
 

Based on past experience, assuming it is an auto trans, I'm thinking that 1 1/2 / 1 5/8 is going to work best with a 2 1/4 to 2 2/4 merged collector.

Re: 305 header size ???
 

Brian Fink, I thought you had Jack Davis small tube step headers on your car, per 2007 Hemmings Muscle Machines.

Re: 305 header size ???
 

The Jack Davis headers were 1 1/2 to 1 5/8 to 1 3/4 ;Stahl 1 5/8 were quicker . Jere recommended playing with extensions as opposed to a step design which I did .

Re: 305 header size ???
 

Jere wasn't a real fan of stepped headers. He also wasn't a fan of merged collectors. He said, "if your car picks up with a merged collector then your primary tube is too big".

Re: 305 header size ???
 

Yep!

Re: 305 header size ???
 

1 1/2” x8”Lg. to 1 5/8”Lg. x8” to 1 3/4” is the best I have found.

Re: 305 header size ???
 

Are you looking for a conventional header or a tri-y?

Re: 305 header size ???
 

Either just looking for ideas. Hoping I pick the correct ones.

Re: 305 header size ???
 

Ya know, you don't post with a real name so I can't tell if you're a Newbie or a veteran of Stock. If this is your first build, then good luck picking the "correct ones" the first time around. Heads, intakes, carbs and cams change over time and that will change the working range of this combo. Unless this is a "top shelf, best of everything" build by a known builder, who knows the combo, then I would stay away from a tri-y header to begin with.

Re: 305 header size ???
 

A correctly done tri-y will make more torque and still run up high. It may not show as big a h.p. number on the dyno but may very well go down the track quicker. If you're willing to go further, cam changes can find more power and torque, depending on where you're at now with the cam numbers. Think of the tri-y's as a stepping stone because they are are also a considerable investment. Needless to say, we're talking about a really good set of stainless tri-y's here...something from Cal Elston, Performance Welding or someone that understands exhaust port dynamics, not a set of ebay special tri-y's. ;)

Just my experience with them, FWIW.

For a conventional 4-1 header, I'd happily pick up the phone and order a set of 1 5/8" and go racing:

https://acpheaders.com/

Ben Line is a real craftsman and makes great headers:

https://www.headersbyben.com/

Re: 305 header size ???
 

Ben is very good!