Thirim

Doing an LT1 Swap. (89 305TPI for a 96 LT1)
I'm not a mechanic, though by the end of this I will be

What are some reccomendations on headers that will install with little mods? Also I see 1-5/8 and 1-3/4 reccomendations for primaries.. down to 2.5 into the Y, out to 3" back to muffler, 2.5" dual tail pipes.. personally i'll be leaving the cat on the shop floor.

Anyway.. looking for Header / Y pipe little mods reccomendations.

I see all the posts but I find it hard to pick one over the other when it comes to lt1 in a 3rd gen. I guess its because I'm new to it all..


Thanks..

ShiftyCapone

iTrader: (7)

You will want to get a set of 1 3/4" primaries. This will help overcome the size and shape differences with the LT1 D port heads while using 3rd gen headers. You could use 1 5/8, and grind the inside lip of the header primary ro make a smooth entrence into it but it is just easier to buy bigger headers. I would look at SLP 1 3/4" shorties.

Thirim

so i buy 3rd gen headers and adjust them to fit the d shaped lt1's? What's wrong with lt1 headers?

ShiftyCapone

iTrader: (7)

Lt1 headers are made to fit in 4th gen engine bays. Therefore they do not follow the same route to avoid stuff under the hood the same way 3rd gen ones do. Since the LT1 has the same external dimensions as a small block in a 3rd gen you can use 3rd gen headers. However, most if not all 3rd gen headers are for round exhaust ports found in stock 3rd gens. Since the LT1 has D ports you need a header primary that covers that entire D. so 1 3/4 will cover the D port and follow the stock exhaust routing without any custom fab work.

Thirim

1-3/4 it is then.now 3rd gen headers on an lt1 should put the exits for the headers in the right spot for a 3rd gen y pipe in stock location?

ShiftyCapone

iTrader: (7)

Yup. You are exactly correct. You can order any 3rd gen exhaust set-up and it will bolt to your LT1 motor just like it did to whatever motor you previously had in there. The only thing was the D port issue which we already covered.

Thirim

yet more problems .. the couple of local parts stores can't find 1-3/4" primary 2.5" collector headers for a 89TA. .. What's everyone using? any P/N's?

Thanks

25THRSS

hedman makes d port headers for third gens.

Thirim

thanks! .. based on that i want p?N 68479 or 66479 i think. though i don't understand some of there chart.

Z28ricer

iTrader: (2)

www.slponline.com 82-92 f body headers 1 3/4" choose the y pipe / cat arrangement and air tubes or not based on your own install.