Header collector size

[monstertruck]

Trying to find the collector sizes on different headers for the 302. I haven't done my swap yet but I have a 1990 Lincoln mark vii with a H.O. 5.0 I am going to use and R2 tranny. I also have a pair of pro comp alum heads I bought for a 351w project I am doing for the mark. But I've been thinking of putting them on the 5.0 for the ranger. The exhaust ports measure about 1 3/8 x 1 3/8. So this is my concern I don't want to buy headers with to small primaries that it chokes my exhaust flow. Right now the motor has a set of early 351w heads hand ported and the stock shorties are definately a restriction.

 

[COPPERHEAD85]

iam running shortys on my 302.
the collectors are 2 1/2/

 

[baddad457]

I ran the Shelby tri-y's on my 400+hp 331 and although some may think these aren't enough header, you couldn't tell. I welded the outside of the tubes around the flanges then ported the insides to better match the ports on the Canfield heads I had on it. I've never measured the primary tube sizes, they're likely 1-5/8" the collectors are 2-1/2".

 

[monstertruck]

Thanks guys, but what I meant to say was primary tube size. But I am considering the tri-Y's and doing exactly what you did, weld around the flang and port to match my heads. I did call james duff and there headers are only 1-1/2" primary tube, and to me that seams to small. Are there any specific tri-y's that fit better than others or not? The reason I ask is because I looked on ebay and it seams there are a few different styles for the 65-70 stangs. Thanks for the replies.