304LTxFbody

i am running a xfi 280 in this build and im really stuck at the heads im sure there is a thread out there but i couldnt find exactly what im looking for i want to know i still have my stock alum heads should i put 2.02 1.60 valves 3 angle valve job etc etc etc or just buy a set of after market heads i would use the stock heads way they are but i know i wouldnt get full potential out of this cam and the spring seats are barely big enough to run a spring that will hold the seat pressure and the lift i need anybody out there run into this or had a buddy run into it or hell read it somewhere else idc just want some opinions im kinda wanting to go cheaper route with the stock heads and get them done PLEASE HELP

BALLSS

you should send your stock AL heads to either Lloyd Elliott or Advanced Induction. either will spec a valve size.

FWIW my heads have 2.02/1.60 but they were done long time ago by another shop. I have a smaller XFI cam

englundjd

send your stock heads to Lloyd Elliot for the LE2 head upgrades and you'll be all set for that cam...

304LTxFbody

yeah ive heard he does really good work i am spraying not huge just a 58mm plate kit prob 150 shot anyone know what the stock castings would hold up to and anyone know a could spring for that cam lift it about .570 .577 with 1.6s and i have proforms i know not the best i know this was a loaded reply but i have just one last one anyone know how much llyod elliot charges to have a stock set done for the valves and springs etc etc

bufmatmuslepants

iTrader: (3)

I dont know what you mean by "what will the stock castings hold up to" after you mentioned nitrous, I dont know if you mean will they break with too much nitrous, or how much HP are the stock castings capable of supporting NA. The deck thickness on stock castings is not as thick as aftermarket, so yes the limit of how much cylinder pressure stock castings can withstand is less than an aftermarket head with a thicker deck, but you will most likely never find this limit with a 150 shot, especially if you use head studs. The highest dyno Ive seen on stock castings is somewhere around 370rwhp. Fully ported stock castings like AI200s etc have put down over 450 on a 383 or 425 on a stock longblock 350.

Just installing 2.02/1.6 valves with a valve job will not give you almost anything, the restriction in the stock heads is not in the valves, its in the runners. There are plenty of people using stock valves on ported heads with over 420rwhp. However, just having any random SBC shop port your stock castings because "theyve been working on SBCs for years" doesnt mean they can port LT1 heads, they are different than SBC heads as far as where they would hit water and the geometry of the porting needed. If you have the stock castings ported, have it done by someone with a lot of LTx experience, like LE or AI or TFS. Until you start aiming for over 450rwhp do you have to step up to an aftermarket casting, which has more meat for porting, but as cast aftermarket heads often will flow less than ported stock castings, and an as cast aftermarket head often costs more than ported stock castings. So once you buy the aftermarket head and ship it off to be ported, youve spent considerably more than just getting the stock heads ported.

And just to reiterate, STAY AWAY FROM EDELBROCK LTx HEADS, they flow **** and dont have meat for porting. Use Dart or Trickflow or AFR if you go aftermarket.

bowtienut

iTrader: (1)

304LTx, If I'm reading you correctly, you won't find the limit of stock castings. Power won't break them; doing something wrong will.
I don't feel I'm near their limits and I'm 520 at the wheels on the 100 shot. There are some people making over 500 at the wheels NA on stock castings for years without issues.

Mystery Bird

iTrader: (7)

I ran that cam down to mid 11's with home ported heads including 2.0 and 1.55 valves with a race weight of 3700ish pounds. I used the CC 918 springs.

BALLSS

the XFI cam card will say use Comp 26918 springs. PAC 26918 would also be fine