CC89Formula

im going to be installing an LT4 hot cam and some valve springs good to .550 lift, but i need to know what timing chain to use. seems like everything i find says not for use on a factory roller block. also can anyone tell me the difference between the chain used for OEM roller and non roller? seems like they would be basically the same to me thanks in advance

tenpin842

I bought Summits SUM-G6601 Roller timing set. I have a 305....but is should be the same for a 350.

dynomaximal

When you install a larger cam, do you need to modify the computer or chip?

tenpin842

Depends on how big you go. I know with that LT4 hot cam u will. Thats got a bretty big lift.
I have a hypertech chip.....so that might be ok on mine....but ill know in a couple days when I put mine back together.

phoenix305

#1 you can't use that high of a lift cam on stock heads #2 hypertech chips suck and absolutely will not compensate for higher cam lift and duration. For aftermarket cams you need to either learn how to burn your own or find someone that can make one for you.

tenpin842

U can use the LT4 cam.....you need new rockers (1.6) and new springs. Its got a 525 lift.
Im putting 452/465 in mine and all i needed was new springs.
I might have to get it tunned....but i think it will be ok. And if Hypertech chips are junk.....then why are they the most sold aftermarket chips around? I liked mine, I could really tell the difference.

phoenix305

do a search and you will find that the prom guru's say they suck. In fact someone actually uploaded the program from one and the only thing it has done is have more added timing. But if you want your car to run like crap thats up to you. Also stock heads can't handel over around .480 lift and no springs are going to fix that. Also 1.6 rocker would just make the problem worse by adding even more lift. But if you think you know what you're doing go for it and good luck.

tenpin842

lol were post whoring this thread! But mine did more the advance the timing. Shifting points were different. And after I installed the 160 degree thermostat it ran alot better.
And I called Cran and Comp cams they said you could to a LT4 cam with stock heads. But for my motor it would hurt it more then gaining anything. Thats why I went with the 104224 cran cam.
And CC89Formula you could always install a gear drivin timing set. People would think you have a blower lol!

CC89Formula

i wasnt really aware of that fact, im still using the 1.5 rockers, which means the cam is going to be about a .495. and ive heard of and seen a lot of people running more lift than that on stock heads. i HOPE its going to be ok

your right i could, i have thought about that also. but from what im told it *could* mess with the knock sensor (even the quiet ones) and from what i read they weigh more and can actually rob HP through heat and friction. but mostly the reason i dont want one is cost...

tenpin842

Yes, I agree. Thats why I just went with the one from Summit. I got it yesterday, havent had a chance to put it on yet. I'm waiting for my buddy. Hes got the tool to thread into your spark plug hole, then you can blow air in the cylinder to keep the valves up when your changing your springs. I hope we can start tomarrow. Best of luck with swapping your stuff out! We will have to exchange notes LOL!

RPOL98

I installed the LT4 HOT cam in my '90 L98 (speed density, not MAF). I went with the "factory-roller"-specific Cloyes true-roller timing chain. I think it has something to do with the clearance req'd for the factory thrust plate. It's not a widely-advertised part and requires some research to find the part number.

I'm using 1.5 rockers to make it milder (it's my daily driver) at least for starters. In tuning my own ECM program, I notice that the Volumetric Efficiency (VE) at idle for the LT4 cam is way less than the factory cam. This means if you don't tune the ECM (e.g. change the chip), you'll be way-rich at idle. if you're MAF, mebbe the computer can fix that for you...

incidentally, before I changed the cam, while I was still on the factory cam, I had the Hypertech chip in it, headers & all, and IMHO the Hypertech chip is pretty darn good, regardless of how much they get slammed. Admittedly, they might have done just some simple mods, but it's knowing which mods to do that makes a difference.

Some of the factory settings, I wouldn't mess with. I bought a custom chip, supposedly tuned to my build-specs, it ran like crap, couldn't even drive it down my street. After I got a Moates Flash-n-burn and made my own chip, it ran so much better when I compared it to GM's settings, and put some of the factory settings back into it. At least then it was driveable.

so, moral of the story, just because they didn't change ALL of the factory settings, doesn't mean they needed to be changed to prove their worth. or something like that.

Brisk

iTrader: (25)

well just for arguments sake, I've just installed a LT4 hotcam into a 305 with MAF and I'm still running the stock chip.. its taking a while for it to reprogram itself, but it is working well. (other than some idling issues)

fun Pain

factory heads and over .480 lift....answer screw in studs....got mine done for 70 bucks at the local machine shop... they have to machine the bosses down to compinsate for the nut on the stud and tap them ofcourse....then I ported the bowls and gasket matched (1205 HSR)/// that just one answer to the problem........tuning will always make you faster then the next guy