Super_GTA

I just got a new roller cam for my gta. The new cam has .497 gross lift at the valve. I'm running stock 193 heads that came on the rebuilt motor about 10,000 miles ago. I was pleased when I pulled the old cam out and found it was a flat tappet cam with roller lifters. Anyway, I have a set of worked over 305 heads on the way to take .600 lift. My question is, can I get away with the stock heads for about a week until my new heads get here? Thanks for your help, Scott.

Stekman

I'd worry about the cam to lifter mismatch first.

Super_GTA

I now have a roller cam to go with the roller lifters. I was not happy when I pulled the old cam and found it wasn't a roller. Just to clarify, I have taken care of the mismatch. Also forgot to mention. I have tightened down the rocker arms and the motor turns over without binding. I am still worried though. Please tell me I'll be okay for a week as this is my only car.

88TAJeff

FWIW, I have been using a .480 / .487 cam W/ stock springs for over 4 yrs now with no coil bind, however I stay away from 5000 RPM - there's nothing up there anyway.

Dialed_In

iTrader: (3)

why? Of course theres no power up at 5000, you're floating the valves.

I don't think you'll reach coil bind, but I'd be worried about guide/retainer clearances. Can you wait to do the heads and cam at the same time?

Token

Super_GTA

Problem is, I've already torn into the motor and installed the new cam along with geardrive. My timing chain was stretched, after only 10k miles. I could move it almost an inch! I could wait until the heads get here, but that leaves me without a car. What kind of damage will be done if the retainer hit the valve seal? Next week these heads come off and I'm done with them. Is it possible for me to run these heads for one week? That's all I need is one week. Until then, these heads probably won't see anything above 2000rpms. Thanks for your help guys.

88TAJeff

Ummm.... maybe I should rephrase that. I don't go beyond 5000 on the street, and no not b/c I'm getting coil bind. The motor doesn't shut down, it just doesn't keep making more power. Yes the cam is prob. the upper limit of the springs, but I think this guy can get by with the stockers for a little while anyway. Anybody out there "pulling to 6500" with TPI ??

Zed'er

Why would anyone go throught the hassle of putting on a set of heads for a few days, just to have to do it all over again? You should leave it alone for a few days, and use your thumb, or bum a ride.

Dialed_In

iTrader: (3)

wait till you get the new heads.

Super_GTA

Well, installed the gear drive, and it jams against the cam retaining plate bolts. Won't move with the cam bolts even hand tight. So I may not have a choice but to wait. Thanks for your help.

Dialed_In

iTrader: (3)

why are you putting a gear drive in it?

Do you have the proper spacer/bearing behind the gear? Is it a roller block?

Damon

Yeah, why the gear drive? I good chain set is all you'll ever need on the street. I have also heard of guys getting "false knock" signals from the knock sensor when using a gear drive on a factory FI car. GM makes a single-row full roller chain for late model roller cam blocks that seems to work just great on street performance engines and will NEVER have interference problems with factory roller cam gear or a stock timing chain cover.

BTW- I'll back up what others say about using that much lift- you'll bang the retainers into the top of the valve guide seals before you'll bind up the stock springs. They can actually take quite a bit of lift before binding- I've measured them no less than .500 and some as high as .520. Unfortunately, that's because they are low pressure springs with small wire diameter- they don't stand a prayer of actually controlling valve movement on any performance cam with lift anywhere near that high.

If you have interference problems you'll end up with mashed guide seals at best (no biggie since the heads are coming off soon anyway), bent pushrods more likely (especially after the first time you float the valves at elevated RPMS), or much more serious valvetrain carnage at worst.

Super_GTA

I'm installing gear drive because when I pulled the old cam out, I could move the timing chain back and forth almost an inch!! It had stretched that much in 10k miles. I told myself, I can't be changing timing chains every 10k or so miles. So... gear drive was the solution for me. I didn't want to have to worry about a chain stretching again. I'm honestly not surprised the chain stretched like it did. They did a poor job on my motor. I am very unsatisfied. But, it runs and gets me around. I can't really complain. I don't know what retainer plate i've got. Yes it is a roller block. I wouldn't be surprised if it was the wrong retainer plate (cursed engine rebuilder). How do I find out if it's the wrong retainer plate? Thanks again for your help.

Damon

Cheap chains stretch like crazy. Also, putting them on without lubrication will cause them to stretch quite a bit in only the first few minutes of running.

1. GOOD quality chain. Nothing that costs $30 or less is going to be quality. Expect to spend about $50 or more on a high quality piece. Also, you want a true roller type chain.

2. Soak the chain in a bowl of motor oil with a splash of moly lube overnight or BAKE the chain in it @ ~300* for a few hours in the oven (if the wife will let you use the over for stuff like that).

Like many things, theres a trick to making a chain live a long and happy life. That's my trick. I have one on my Malibu (see sig) that's in it's 2nd engine and has over 40K miles on it. When I had the cam out a few weeks ago there was no noticable slop in the chain. It's a Cloyes true roller that I prepped as described, above.