What would the draw backs be of running gen 1 headers on a LT1? I know that the LT1 has "D" ports & the gen 1 has circle shape. Seems to me that would be a restriction. What would the effect of milling the lt1 head to accept gen 1 headers. Any help would be great.

 

I was told for my LT1, as long as the headers are 1 3/4 they will swallow up the D port just fine. Apparently you run into issues when they are 1 5/8 and not d ported. So I just ordered hedman 1 5/8 D ported Long tubes #68469 and are only $180 on summitracing.com. Don't know if this helps? Peace!

 

I happened to receive my Hedman Hedders today. I ordered the HED 68468s and they definitley will not work on my LT4 heads...The D port is 1.38 inches across the floor of the port where as the headers are 1.27. The height of the headers is 1.55 but the D port is 1.28 inches. At first is seems that all you have to do is grind out about a tenth of an inch on the width but upon looking a little more, I noticed that the relationship of the hole in the head to the bolt holes versus the relationship of the hole in the headers to the bolt holes would the roof of the D port to be about .3 inches higer than the opening on the header...I don't think that grinding more than a quarter inch out of the roof of the header pipe would be smart, actually I don't think grinding the .1 inch out of the sides would be smart either since they were coated. Kind of defeats the purpose of the coating. Aside from the coating, if you grind out the .3 inches for the roof clearance, I think it would grind through the weld bead and cause exhaust leaks...

Sucks because I really wanted to put those headers on tonight, already have the motor lifted and all. I should have done my homework a little better apparently. Smart move on your part to ask ahead of time!

Edit: PS-- the headers I ordered were 1 5/8"

 

SLP 1.75's will completely cover the LT1 ports without modification, however a/c with them proves to be quite challenging because there is little hope for a low pressure connection that wont be so close to the header that it will kill a/c performance.

I hate the build quality of the edelbrock headers, the fit isnt that great either, though they do route in such a manner that a/c isnt much trouble, and I believe the ports didnt do too bad on a stock LT1 head, you may also be able to use LT1 4th gen edelbrocks with a thirdgen or custom Y pipe as i've had one set in my posession and I believe they were the same header just different hookups and Y pipe, though I didnt have thirdgen edelbrocks out of a car to do a side to side, its something to look into if you actually want a/c and dont mind the mismatched-not even 1 5/8" in some spots-poorly built edelbrocks.

JDud dont know if you've got a typo or actually ordered the 68468's cause that wouldnt make sense when the 68469 is hedmans D port thirdgen header....

 

No typo, I actually ordered the wrong hedders...
I have since found part number 66469 but haven't found the ones you mentioned...68469.
Z28*****, can you confirm that part number for me? I don't want to order the wrong thing twice in a row..

 

Both are correct, the 66469 you found is the 68469 header with their "HTC" coating on it.

 

hate to jump in, but what headers would be best with a 383 LT1 in a 89 rs? do i have to go with 4th gen D ports, or could i just run 1 3/4 and mod them?
i am poping my post cherry, but i read threads all the time...