[1932bantam]

I've got all 8 ex .valves that touched pistons. springs are 143@1.900-383@1.250, cam is flat tappet .579 in. 639 ex. anybody shed any light on this. The only thing I did notice today , valve pocket is 1.610 and running a 1.550 spring could this cause problem? have clayed it and also pic of clearance with a head we cut apart to check clearance, you can see there is plenty, this one has me stumped , blown 427 injected alky, was running dry blk also could the heat be doing something? going to run water in blk this year. thanks

[vinniekq2]

contact the cam manufacturer for correct valve spring spressures and installed heights

[1932bantam]

did, there stumped

[vinniekq2]

consider a rev kit

[1932bantam]

FLAT tappet camshaft

[engineczar]

Is it a solid lifter or hydraulic? You only say it's a flat tappet.

[cobalt327]

Originally Posted by 1932bantam

I've got all 8 ex .valves that touched pistons. springs are 143@1.900-383@1.250, cam is flat tappet .579 in. 639 ex. anybody shed any light on this. The only thing I did notice today , valve pocket is 1.610 and running a 1.550 spring could this cause problem? have clayed it and also pic of clearance with a head we cut apart to check clearance, you can see there is plenty, this one has me stumped , blown 427 injected alky, was running dry blk also could the heat be doing something? going to run water in blk this year. thanks

I'd like to see you using a cup to better locate the spring, but the cup also has to fit tightly to the guide boss OD or the spring seat of the head ID so it can't move around. You want a little clearance for the cup, not a press fit.

So the fix might be to increase the pressure by tightening up the installed height (if possible w/o coil bind issues), by using a set of +0.050" locks, and use a spring cup. Depending on the thickness of the spring cup, you might need to shim the spring to get what you need for installed height if using the +0.050" locks.

[lmsport]

Needs more valve spring or less RPM, assuming P-V clearance is at or above 0.080".
.630+ lift with a flat tappet is alot.

[ssmonty]

Any chance that there was an accidental downshift while at high rpm? Could the cam be retarded or slack in the chain?
I've seen retainers deform some valve stem seals pretty bad after I had an accidental downshift with a stock automatic shifter. Embarrasing as it is to admit, there was plenty of clearance before the "slip". I had once believed that it couldn't happen because the loss of valve control would keep the engine from turning any higher rpm, but it was wound out in 2nd when I went to shift to 3rd, and went too far to nuetral, tried to go back to 3rd, and the sudden decelaration caused me to go all the way to 1st. Man did it cause a racket. I was lucky as hell not to do more damage than I did!
Before anyone suggests it, I've already bought and installed a ratchet shifter a long time ago.
FWIW,
ssmonty

[1932bantam]

yes it is solid flat tappet, I was on the same thinking as the spring cup , as far as more spring pressure , which would be more important open or closed, I was kind of thinking maybe keeping around the same closed and getting a spring with more open? or should other way around, or increase both ?? Afraid of flattening it out. Doing the burn out would maybe be a chance of excessive rpm , going to put rev limiter on mag, But I start in drive let it shift itself. 100 inch blown altered 1300lbs there is no sense of starting in low and trying to shift and keeping it under control, I have actually had all 4 wheels of the ground, 350 turbo 3.73 gear with 31 tall slick

[ap72]

What springs? If you can lighten the valvetrain, that'll do a lot more than just throwing more pressure at it. Maybe consider going the beehive route as well if resonance is a problem- and they lighten the valvetrain.

[bullheimer]

Did you check deck clearance?

Wondering about piston's wrist pin location.

[cobalt327]

Originally Posted by 1932bantam

yes it is solid flat tappet, I was on the same thinking as the spring cup , as far as more spring pressure , which would be more important open or closed, I was kind of thinking maybe keeping around the same closed and getting a spring with more open? or should other way around, or increase both ?? Afraid of flattening it out. Doing the burn out would maybe be a chance of excessive rpm , going to put rev limiter on mag, But I start in drive let it shift itself. 100 inch blown altered 1300lbs there is no sense of starting in low and trying to shift and keeping it under control, I have actually had all 4 wheels of the ground, 350 turbo 3.73 gear with 31 tall slick

Open is only where you're seeing loss control of the valve- it's lofting. If you're not losing power/laying down right before shift points, then I'd agree more open pressure should help, all else staying the same. But if there IS a loss of power the valve(s) are bouncing on the seat, and that means more pressure seat and open. Or lighter valve train, less rpm, etc. as I'm sure you know.

Springs lose pressure over time/use. If they were ever good, you might have just worn them out, especially if they're lower cost springs.

Is there any chance the exhaust pushrods are thinner wall, less diameter? If they're not stiff enough, that can "pole vault" the valve sure as hell.

Is the intake valve relief deeper? I'm wondering why the intakes aren't hitting- after all they're heavier.

[1932bantam]

This was 4th 1/8 mile pass on valvesprings same on .080 wall pushrods, checked pushrods there straight. as far as power loss can't really tell in this condition, it ran 125 mph 1/8 mile , haven't put bigger fuel tank on yet so have ran 1/8 and getting out of it , but it still felt like it would pull, we heard a noise almost like a whistle putting hand over 1 zoomie pipe it would quit, so we new it was ex valve thought got hot and tweaked a bit we figured when it warmed up it might seat back, after that tore It down to find all of them were leaking and small impression on every piston as the 1 I posted. Only thing I can think of on the Intake is that its only .579 lift were ex is .639 lift and intake running cooler as to what is saving it. I think it is losing control at open , I can't see it bouncing of the seat that much I've got over .200 clearance. but i've been wrong more than right on this thing

[cobalt327]

I'd give it some more spring pressure on the exhaust side. Even w/o a cup if you can get control of the exhaust valve w/some shimming it would be an improvement. Just watch the installed height vs. coil bind and retainer to guide clearances.

Ever considered using alky?