1973 340 upgrade.

[01freeman]

I am ready to start on my 340 engine for my E Body.  I want to add a pro charger or something similar.  My question is this what cam, pistons (compression ratio) to run.  What heads should I run, valve size.  What intake and carb.  I want somewhere between 450-550 hp at the wheels.  Any help is appreciated. What is the best centrifugal supercharger to get to work with this engine.

[Chryco Psycho]

the 73 340 had a cast crank so replace everything , I would go to a 408 stroker kit with H beam rods steel crank & a good forged piston around 8:1 compression . Alum heads will help absorb heat effectiely lowering compression as well , Look at the RHS heads . Cam design will be critical , shorter duration with minimal over lap & 112* CL is what you need have a split profile with added exhaust lift & duration will definatly help .
 No experience with centrifical superchargers so I cannot help there.

[Tonker1]

Chryco, are you suggesting to stroke out the 340 first and then supercharge it?
Would the old block be strong enough for the power created by that combination?

[Chryco Psycho]

I believe so the crank & rods will be stronger & the piston weight lighter so nothing is working as hard , go easy with the boost & it will make serious power .
 I built  mild 440 a few years back stock block heads & crank , ported the heads , installed a good cam , dropped the compression with pistons , under drove the blower making 4-5 psi if that , good headers exhaust trans , converter & suspension & in a lightened 71 GTX around 3600 lbs race weight it ran 10.4 /133mph on a mild tune , we were going to increase boost & tune some more but the goal was low 10s , we hit it right out of the box !!

[Tonker1]

Chryco, Is there a generally accepted hp rating for a stable build on the old 340 blocks?
ie, exciting and street-able but not going to lead to a premature death of the block. I'm aware this is case by case dependent and that the block should be inspected before any form of performance build?

The reason I ask is I'm beginning to plan and make decisions about a build on my 340 which will probably be fairly similar to 01freeman's. I'm not going to start buying parts for a couple years until I can allocate the full amount of money required and I hate to spend all that money then render the whole load useless!

[Tonker1]

To be more specific I was thinking of doing the exact same thing as '01 freeman' but, with a mild cam build on top of that. I want to stay well away form pushing at the block and to be honest I'll be building more for torque than hp. I'm just trying to workout if the changes mentioned above will require a modern 340 replacement block or R3 block, which I simply won't be able to afford for along time (due to all the little costs, pumps, seals, cylinder heads and so on)?
If it would I'll reduce reduce the build significantly. Maybe I'll just cam it go for new lightweight pistons crank etc with a stock stroke length and than supercharger on top of that.

I'm not really sure, this will be the first time I've tried to build on an engine.

[Chryco Psycho]

 Well with this 422 ci 550 + hp & tq
http://www.forebodiesonly.com/forum/showthread.php?5429-422-Stroker-Small-Block
 so roughly 1.25 X the ci seems reasonable

[Tonker1]

Awesome link, that looks like a much better (and more affordable) way to go about what I was planning on doing! Thank you Chryco

Freeman01, sorry if I hijacked your post, hopefully you also found this information useful.