solarofthesix

im no trained tech, but the 643's look like the way to go

METALBEAST

The 561s are on the 96-97 LT1s correct? That sux for me

billk1

A little off topic but i have a set of steel lt1 heads off a 94 caprice , I heard they flow a tad better than stockers , also have a set a edelbrocks untouched, intend on throwing the motor in a carburated 67 comaro, which heads to use with a mild (500) lift cam?

METALBEAST

The iron heads do flow a tad better (about 10%) but the larger combustion chambers means its gonna lower your CR even with some thinner Impalla head gaskets.

rickreeves1

Does any know?

Also, how could one tell how much extra hp could be had from porting ....
LT1 castings vs. LT4 vs. Trickflow vs. Edelbrock vs. AFR?

In order which are best and how far apart are they?

Could the LT4's be worth 10 more? Would the Trickflows potential be worth 20 more hp etc.. I don't seem to have ever been able to get an answer on that question, just recommendations. Just trying to learn and make the best decision.

Thanks

MeanGreen97Z

Potential of the castings are in the hands of the porter and the cam designer. I've seen ported stock castings make more power than ported trick flows simply because of cam selection.

rickreeves1

I get that but what if it was same porter/quality and the same cam?? What would be the choice of heads for porting, in order, and approximately how much difference would each step up make if any?

Thanks

Critter

374 or 643, then the 561's

i think they can just more flow out of the 374's because there is more to take out of them.

Pig Pen

This is probably a question for Mr. Elliot himself but; If your just going with the LE1 heads does it matter which casting number is used?

rickreeves1

I want to go with the best porting available for the heads. This is for my current stock block but eventually for a 396 short block.

rickreeves1

The new AFR Eliminators are tempting me also.
Paging Mr. Lloyd and StrokerAce?? Please see question in first quote above.

Thanks

ttt

SStrokerAce

T/A LT1 (aka Later, Clint) on here is going from a LE ported TFS to a LE3 stock casting setup on his 355 and from what Lloyd told me on the phone yesterday it should walk all over the TFS castings on that motor.

On a stroker its a different game, a TFS head will work very well. But if you are going to do a stock or 355 cube motor then go with the stroker later on a LE3 head would work killer for you. Just change the cams when you change the cubes.

Bret

airflowdevelop

Trivia question...why are 561 castings in a shortage currently, if they are so bad?

Found this thread by accident...Bret, you are not allowed to answer!

Dennis

Javier97Z28

Hey I'm curious now too! I sold my 561's to port 643's.. what's up?