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-   -   305 header size ??? (https://classracer.com/classforum/showthread.php?t=75506)

71novastocker 02-19-2020 07:24 PM

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

dragracer502 02-20-2020 11:20 AM

Re: 305 header size ???
 
Found power on the dyno going down from 1 &3/4 to 1 & 5/8

Brian Fink 02-20-2020 11:27 AM

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

Mark Callanan 02-20-2020 02:45 PM

Re: 305 header size ???
 
Quote:

Originally Posted by Brian Fink (Post 608485)
The late great Jere Stahl strongly recommended 1 5|8 on my 305 ; it made real good horsepower .

How much Horse Power love to know??
lol

71novastocker 02-20-2020 06:13 PM

Re: 305 header size ???
 
Quote:

Originally Posted by dragracer502 (Post 608484)
Found power on the dyno going down from 1 &3/4 to 1 & 5/8

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

71novastocker 02-20-2020 06:17 PM

Re: 305 header size ???
 
Quote:

Originally Posted by Brian Fink (Post 608485)
The late great Jere Stahl strongly recommended 1 5|8 on my 305 ; it made real good horsepower .

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

Billy Nees 02-20-2020 06:33 PM

Re: 305 header size ???
 
I would probably do a 1 1/2 to 1 5/8 step.

jmoneyfoot 02-20-2020 06:58 PM

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

Jim Caughlin 02-20-2020 07:28 PM

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.

Tom Moock 02-21-2020 01:55 AM

Re: 305 header size ???
 
Brian Fink, I thought you had Jack Davis small tube step headers on your car, per 2007 Hemmings Muscle Machines.

Brian Fink 02-21-2020 09:11 AM

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 .

Billy Nees 02-21-2020 09:26 AM

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".

Ed Wright 02-21-2020 05:19 PM

Re: 305 header size ???
 
Quote:

Originally Posted by Billy Nees (Post 608551)
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".

Yep!

James Jeschke Jr 02-21-2020 11:21 PM

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.

Alan Nyhus 02-22-2020 08:47 AM

Re: 305 header size ???
 
Quote:

Originally Posted by 71novastocker (Post 608461)
What would be the best header size to run. The combo is 175/248. Thanks.

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

71novastocker 02-22-2020 09:14 AM

Re: 305 header size ???
 
Quote:

Originally Posted by Alan Nyhus (Post 608600)
Are you looking for a conventional header or a tri-y?

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

Billy Nees 02-22-2020 09:43 AM

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.

Alan Nyhus 02-22-2020 09:58 AM

Re: 305 header size ???
 
Quote:

Originally Posted by 71novastocker (Post 608602)
Either just looking for ideas. Hoping I pick the correct ones.

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/

MEXJOE 02-23-2020 10:45 PM

Re: 305 header size ???
 
Quote:

Originally Posted by Alan Nyhus (Post 608606)
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/

Ben is very good!


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