hi guys, well i know im going to get the 23 trick flow heads for my l98 , 383,
they are in my price range, my guestion is, which ones should i get i will be running a 383,lt1intake, lt4 hot cam with 1.6 rockers,combo, so i have three choices to go with,
1/ just the heads with 1.47 vaulves ($995)
2/ same heads but has cnc chambers, ($1145)
3/ same heads but with cnc chambers and dual 1.46 springs for cams up to 600 lift, ($1225)

now my guestions are, dual springs, anyone have a clue on these, what would the benifits be by using these other then higher cam lift, and how would that affect rocker's

and for the cnc ,is the extra money worth it for the heads to be ported, (cnc)

they say in summit book that the 1.47 valve spring heads can take up to 540 lift , is that kinda pushing it with lt4 cam with 1.6 rockers, ?, and im looking at future referance to where i might want to go with a slighty bigger cam, would i be better off with the higer lift heads, and does it hurt to run higher lift heads but with a combo that doesnt come close to the suggest lift specs (600) of a certian head, i woudnt think it would, but just wondering,

sorry for the long post just, trying to get my combo right before i order,

 

Well, I really am not sure what their CNC process does to the heads characteristics, so I really can't comment on that part....

But I can comment on the springs. It will not hurt you to run more spring than you currently need. The lift of the LT4 HC with 1.6:1 rockers is .525" and is well within the limits of the 1.47" single springs that will allow lift up to .540" ... I am using the .540" springs with the LT4 HC and Crane 1.6:1 rockers. Everything works fine. It is less important to match valve springs to the cam when dealing with a roller setup versus a flat tappet one. The main thing is to make sure that the springs and heads will allow enough lift to accomodate the cam, and that they have an adequate amount of seat pressure. I am not certain what springs the TFS heads come with, but since they are designed as a replacement for roller engines, I am kinda banking that they are adequate for roller cams when it comes to seat pressure. I have not had a problem with the ones on my TFS heads. If you are nervous about the springs, go with the dual ones that will handle .600" lift as they will certainly give you enough seat pressure and will allow you to go bigger in the future on the camshaft without worrying about the springs. But I will add that you will probably want to replace the valve springs later on if you rack up any appreciable amount of miles on the ones that come with the heads while running the LT4 HC.... They do not last forever in engines with aggressive camshafts and they are cheap insurance for the engine.... Running the dual springs will have no effect on the rocker arms.

Well, I'm sure there are others that can give more specific data on spring needs for different cams, but there is some background info...

EDIT: Oh, another thing I might add, is that you really should look at some high quality replacement lifters that are designed to be used with high lift cams and beefy valve springs as the stock ones leave a lot to be desired..... Mine are the original ones with ???? thousand miles on them and my valvetrain can be a bit noisey at times....

Laterzzzz,
Matt

 

WOW thanks man, you answered all my guestions, yeah i just wasnt sure on the dual springs heads, i have never dealt with dual spring heads so had no clue , how they work, or what if anything needed to be changed with them, but all and all sounds great, i think i will probally go with the dual springs up to 600 lift, but i think i will hold off on the cnc process , im kinda on a budget anyhow thanks a bunch for taking the time to answer my guestion,

 

On the issue of CNC vs. Non-CNC... looks like at higher lift, there is not much difference (258.5 CNC vs 254.3 @ .600"). However at lower lift, there is a bigger difference (64.2 CNC vs. 50.6 @.100")

HTH...

 

HEY Go to www.JDSPerformance.com I got my heads there and for the upgraded springs they price was 914.99 for the 87-> centerbolts. They har at least 80 bucks cheaper there then at summit. They had my heads to me within 3 days and shipping was ONLY 4 bucks.

 

Mkos1980,
Thanks for that link! Those prices are significantly lower than Summit.