My engine has vortec heads on a 400ci block. It has 175psi cranking. Even with 93 octane the valves rattle when the converter locks up. I'm running no more than 32* total and 12* initial.

I'll describe it: At about 1/2 to 3/4 throttle when the trans goes into 4th, the converter will immediately lock up and bog the engine and the valves clatter LOUD. The valves rattle ONLY when the conv locks.

What do I need to do to fix this, thanks.

Are you sure it's not detonation when the engine becomes loaded in OD?

the lockup of the converter will not make valves rattle- what you have is detonation, and yes, you should fix it.
i see you have your cam, gear, and induction combo in your sig- but how much timing are you running- initial, total, and vacuum advance? how is your carb set up?

the lockup of the converter will not make valves rattle- what you have is detonation, and yes, you should fix it.
i see you have your cam, gear, and induction combo in your sig- but how much timing are you running- initial, total, and vacuum advance? how is your carb set up?
Not the engine in sig.
Are you sure it's not detonation when the engine becomes loaded in OD?
I'm thinkin detonation also.

Balancer slip?
What's your C/R with those heads ?

Yup,bet its detonation when more load is applied to motor when trans/converter locks up.

scott

what rpm does this occur at?

Patrick,
Vortec heads on a 400 engine is probably close to 11 to 1 compression depending on the pistons. Probably not much you will be able to do about it other than get some VP or Cam2

The kemco supreme 130 real lead octane booste will likely fix his detoantion ssues even at 11:0 comp.and itrs considerably cheaper if he buys it at the 2 case /12 qts per case discount with free shipping.

1qt kemco to 18 gals 93 fuel = 97.5 octane but a true 11:0 may need more octane which you can get with the kemco,you can mix for over 100 octane with 93 fuel and still be cheaper then race fuel without the hastle of having to go out special to get race fuel,the kemco comes to your door and can be kept in the trunk to be used at fillup.

It has storrage life of 18 months per mfg.

Scott

The kemco supreme 130 real lead octane booste will likely fix his detoantion issues even at 11:0 comp.and it's considerably cheaper if he buys it at the 2 case /12 qts per case discount with free shipping.

1qt kemco to 18 gals 93 fuel = 97.5 octane but a treu 11:0 may need more octane which you can get with the kemco. You can mix the kemco for over 100 octane with 93 fuel and still be cheaper then race fuel without the hastle of having to go out special to get race fuel. The kemco comes to your door and can be kept in the trunk of your car to be used at fillup.

It has storrage life of 18 months per mfg.

Scott

Patrick,
Vortec heads on a 400 engine is probably close to 11 to 1 compression depending on the pistons. Probably not much you will be able to do about it other than get some VP or Cam2
I used the stock dished pistons. I think my CR should be about 9.5:1

I think I might need one of those delay lock up swithes that TCI sells. My friend George just suggested this. Here is what he said:
You have a 700r4..you can delay the lockup feature with a manifold vacuum sensing switch.TCI supplied mine at the trans and gearstar has a firewall mount.3/4 throttle input and low vac #,s are not lock up friendly and will lead to the death rattle.Grab your OD..but delay lockup until you at cruise speed at part throttle.If you roll into the throttle in OD without a downshift to D3..the low manifold vac will be sensed by the switch and open up the lockup ckt.Think of a lock up as trying to accelerate in 4th gear with a manual trans without a downshift.

Yes its pingin with a 64cc head and even a dished pistion, crankin compression 175 holy smokes you have at least 10:1 compression. Locking up the converter just loads it up incredibly. 400's were always bad for pinging when they were in Ma & Pa big Chevy Impala. GM added EGR valves to get rid of the ping. I don't think it will go away unless you are rich and can add all those additives suggested when gas prices are absolutely nuts.

Dave