Chevrolet12

Yesterday we were tuning my 385 and had to swap the distributor cause the rotor slipped on the shaft. Put in a the stock one, fired it up and had a steady pop from carb. Pulled valve covers and noticed exhaust on cylinder 3 wasn't moving much. It's a comp 12-690-47 cam ground on small base circle. Talked with them and they say my valve Springs are too much. They are 165 seat at installed height 1.750 and 425 open at 1.110. And they list a spring 178 at 1.900 and 459 at 1.275 which is heavier than mine.. And with my 558 lift it should only be 1.192 so it shouldn't even be 425 open. I just wanted some opinions on the situation here. I have built many engines and never had this problem. Broke in with zinc additive and ran for 30 minutes varied between 2000-3000 rpm. Rechecked lash 4 times. The engine has ran probably 4 hours total and haven't driven down the road yet.

BOOT77

Many use break in rockers or remove the inner spring for break in. idk bout mech flat-tap cams but I've herd like 80-100 seat for hydraulic on break in and then you can raise them.

Chevrolet12

The cam was well past break in period. And I had 110 seat 330 open Springs during break in. Break in was not the issue. Springs shouldn't have been the issue either since they recommend heavier ones unless it was a misprint.

DanielRicany

165 seat and 425 open is a LOT of pressure for a flat tappet. I have a hydraulic flat tappet in my engine, broken in with stock springs and now running springs provided by AFR at 140 seat and 356 open. I think the most recommended seat pressure for a hydraulic flat tappet is like 120 and 130 for race applications. Not 100% but 165 is a lot for a flat tappet.

My cam has not wiped a lobe, thank God. Hopefully mine will never experience that, or at least hold off until I do the 400 with roller cam that I wanted.

Those springs could be the problem.

However, happening only 4 hours after break in and no mileage would typically indicate an incorrect break in.

Chevrolet12

My cam is solid not hydraulic... Idk if that makes a difference. This is where I get mixed reviews. Some say they are OK and some say no and on comps website they recommend a 26094 spring. Look at the specs on those Springs. Alot more than mine and they are recommended for the 12-690-47 cam I have.

Chevrolet12

I've built alot of circle track engines with solid lifter cams and never had this problem. I don't do anything different with the break in. Always the same. So break in shouldn't be the issue. I have always had bad luck with comp cams. I normally use Elgin and never have any problems.

DanielRicany

I have heard of occasional hardening problems with comp cams. That could also be the problem as well.

Chevrolet12

What about the nitride treatment they offer? Would that help with the heavier Springs?

cv67

Every comp cam ive had went flat, even had a HR cam here that went flat. Went back to Isky never happier.

BOOT77

Only cam I lost was a comp so far

Chevrolet12

So what I'm hearing is that I'm not the only one that has problems with comp cams.. I've used Elgin isky and lunati and not once had a problem. But the two comps I've used both did this.

aDigitalPhantom

No you're not the only one. Might want to look at a roller cam. IMO this page does a decent job explaining it.

Chevrolet12

I have thought about roller cam but the cost is what's going to get me on that.. If someone could find a decent roller for cheap I'd look into it but just cam and lifters I'm over 600 plus the Springs... Unless we find on that will work with my Springs. Or u could go with a cam that I know works and that I have had good luck with. If I go with a roller I need a high rpm cam and those get expensive from what I seen.

rklessdriver

Define "high RPM".

Your idea and mine may be different. Hyd rollers are far more capable than most think.

As for the cost... I know it's more initial outlay but compare the cost of a couple wiped flat tappets and the damage all that metal does to the brgs.... Hyd roller = install it and forgot it.
Will

Chevrolet12

High rpm for my application I consider anywhere from 7200-8000 rpm. The one u had in there was supposed to be good to 7400 I think.

rklessdriver

In a 3.48 stroke itd make peak power at 7200 and fall off at 7400.

In a 3.75 stroke it'll be 7000 and 7200.

Honestly that's a 550hp cam with good heads and induction. You can make the same power with a milder hyd roller make peak power at 6500 and still turn it 7000 if you want.
Will

Chevrolet12

I have a 3.750 stroke 11-1 compression 220 cc aluminum heads 64cc chambers 2.02 1.60 valves flat top 2 valve relief pistons weiand team g intake heads and intake are port matched. Long tube headers and 3 inch exhaust.

Chevrolet12

Also have a 3500 stall th400 manual valve body. I would like to spend as little as possible if I do go roller. If possible use the Springs I already have...

rklessdriver

The spring pressure you have is fine but I need to know the coil bind height and rocker ratio you have to make sure that they will work with a hyd roller.

Is your block a factory roller or older flat tappet?
Will

Chevrolet12

Installed height 1.750 165 seat pressure coil bind 1.080 425 open at 1.110 it's a 75 4 bolt block non roller.