Primary Tube Size for 350

Thought I would start a separate thread to focus on the question of primary tube size. As I posted in the header coating thread, I have the option of the 1 5/8in primary from TA or 1 3/4in from Dougs.

The engine build is very mild (TA 212 cam, TA stage 1 intake, 10.5:1 pistons, factory heads).

TA recommends the 1 5/8in, which I agree is all that is necessary. But will I lose anything (other than space) in going with the 1 3/4in? Asking because of header availability. Unfortunately TA is on backorder with the chrome 1 5/8in, but Dougs are in stock.

 

I'd go 1¾. Back when Hooker is all that was available they seemed to run very well on my 1st 350 mild build. I don't see any downside to the larger tube dia.

 

In this day and age, I'd go with what's available. Backorders could be 2 days or 2 years.

 

I ran 1-5/8" on my supercharged 340 with a .500" lift cam and was VERY satisfied with them.

Jim

 

Go big!
The 350 Buick won’t loose anything down low going to a bigger header.

 

Seems it doesn't matter anymore. Got my TA order today and to my surprise the headers were in the box.

 

Yep, those are the "right" ones!

 

I suggest a small block rated torque converter and a distributor recurve kit, then rejet carb for more air flow the headers produce. Forged pistons? Or cast? Cast pistons tend to only be 9.2 compression if it’s the 340p. So if you need that higher compression you may need to mill heads now before you get headers on.