383 tapping noise

[F-BIRD'88]

The cam you have now is a more powerfull "blower cam"
You are going to need to step on it a bit to get to 600 hp.

Whats the chance of getting a quick intake port flow test.
(@.400" lift and @ peak best intake valve lift.
eg- .550". or.600' lift.
(don't need more info than that to know "the tale of the tape" on them in as cast form) (power potential)
Those heads are a unknown to me.
But I bet they need some "step on"...

[allencr267]

Take a look at the slipper/skirt that didn't break, contact point at the rod for sign of abuse.
Thanks. Good luck.

[c1500sbc]

The cam you have now is a more powerfull "blower cam"
You are going to need to step on it a bit to get to 600 hp.

Whats the chance of getting a quick intake port flow test.
(@.400" lift and @ peak best intake valve lift.
eg- .550". or.600' lift.
(don't need more info than that to know "the tale of the tape" on them in as cast form) (power potential)
Those heads are a unknown to me.
But I bet they need some "step on"...

I could send them off somewhere to get flow tested. I don’t think anyone locally does it. I’ll call around. I’ve been curious myself also.

The cam I have now is a 236/240, .550 lift, which is great but it’s a 110 LSA.

They offer some larger duration cams that are in line with what I’m running already but on a wider 112 or 114 LSA but I just don’t know how that large of a duration cam will act with such low SCR before boost comes on.

[c1500sbc]

I’m definitely open to cam suggestion. There’s a cam guy here on this forum, right?

[rfoll]

A forged piston is going to have a smaller diameter than the cast piston. It is likely going to be too loose in the bore.

[c1500sbc]

A forged piston is going to have a smaller diameter than the cast piston. It is likely going to be too loose in the bore.

I did call Mahle about this. The pistons i'm looking at should measure at 4.037. Cylinder walls are measuring at 4.04. I would think that would be just about perfect?

[F-BIRD'88]

The cam lobe separation does not qualify or disqualify it as for supercharger use..
There is a example of a very powerfull 383 w/177 blower well over 600 hp. with a 108 LSA cam.

110 LSA cam work great in these motors with relative low boost and a relative small cid blower.
Its about when the valves open and close not about LSA.

EG114 LSA ='s "blower cam"

Its not how much boost you make on a guage, its about how much air gets in to make power by combusting it with fuel.
Boost is a measure of back pressure in the manifold.
It is a measure of what IS NOT getting into the engine.
The valve has to be open (at the right amount, at the right time for air to enter the engine.
Its like a gate. If its not open, air cannot go in.
Thats what "boost" is. Air that is NOT getting in.
Its backing up in the manifold.

[F-BIRD'88]

What if you get 2 replacement KB pistons ,re assemble that 10:1++ CR 383 short block. Put it aside and build a simple Blower motor short block.. say 355 cid. with low compression. (Can be cast crank)

Then really step on those aluminum heads for power.

I bet that 383 has a cast steel crank not forged, if its a Eagle rotating kit.. Something to check.

[F-BIRD'88]

Are the cylinders in really good shape now?
Any signs if wear or stress in the other pistons and the bearings?
If 2 pistons have broken skirts you want to measure check those connecting rods to verify they are nit slightly "tweeked".

[c1500sbc]

What if you get 2 replacement KB pistons ,re assemble that 10:1++ CR 383 short block. Put it aside and build a simple Blower motor short block.. say 355 cid. with low compression. (Can be cast crank)

Then really step on those aluminum heads for power.

I bet that 383 has a cast steel crank not forged, if its a Eagle rotating kit.. Something to check.

It is actually a 4340 forged steel crank and 5140 forged steel I-beam rods. At least that is what is listed under the part number. Curious as to why you would recommend builing a separate 355 low compression motor rather than just going with the fully forged set up of a low compression 383? With about 800 bucks worth of pistons, balancing the assembly, i'd be in it less than trying to have another block machined and purchasing a complete (even cast) rotating assembly. With much less money, using the current parts I have, I could have a fully forged 383 versus a cast 355. I'll have to measure the rods and make sure they aren't tweaked at all.

I understand boost is just the measurement of the air not getting through the motor. Cam specs selection is really an artform. Seems like the best engine builders are the ones who can properly spec a cam for the given application. That is something I am far from mastering.

[af2]

The 4032 piston is well beyond what you need. Available with every MFG. The original bore will determine the clearance. The piston will have the clearance built into it.
I ran the 4032 Mahle at .0055" for 15 years in a drag deal with no problems at all.

If you want to go low on the compression use a 350 piston on the 383 and have it down .125" Then run any gas you want.

[c1500sbc]

The 4032 piston is well beyond what you need. Available with every MFG. The original bore will determine the clearance. The piston will have the clearance built into it.
I ran the 4032 Mahle at .0055" for 15 years in a drag deal with no problems at all.

If you want to go low on the compression use a 350 piston on the 383 and have it down .125" Then run any gas you want.

So many mixed opinions on this. I know a lot of guys are running hyper pistons with boost and no issues. All in the tune I guess. Saving money is great and i'd much rather spend the 300 bucks on some hyper dished pistons than forged. I just know when they break, they really break!

[af2]

The 4032 piston is well beyond what you need. Available with every MFG. The original bore will determine the clearance. The piston will have the clearance built into it.
I ran the 4032 Mahle at .0055" for 15 years in a drag deal with no problems at all.

If you want to go low on the compression use a 350 piston on the 383 and have it down .125" Then run any gas you want.

So many mixed opinions on this. I know a lot of guys are running hyper pistons with boost and no issues. All in the tune I guess. Saving money is great and i'd much rather spend the 300 bucks on some hyper dished pistons than forged. I just know when they break, they really break!

300 compared to 550? Hmm Gaskets, flush, got lucky? All good your call

[c1500sbc]

The 4032 piston is well beyond what you need. Available with every MFG. The original bore will determine the clearance. The piston will have the clearance built into it.
I ran the 4032 Mahle at .0055" for 15 years in a drag deal with no problems at all.

If you want to go low on the compression use a 350 piston on the 383 and have it down .125" Then run any gas you want.

So many mixed opinions on this. I know a lot of guys are running hyper pistons with boost and no issues. All in the tune I guess. Saving money is great and i'd much rather spend the 300 bucks on some hyper dished pistons than forged. I just know when they break, they really break!

300 compared to 550? Hmm Gaskets, flush, got lucky? All good your call

Sorry, that came out wrong, i'm going with forged for sure. Too much of a gamble on hyper pistons. I must have misread what you said previously. I took it as you meant that the 4032 piston was way more than I should be spending money on! I can't find any pistons with a deep enough dish in the $500 range, though. There is a weisco option with a -20cc dish for $550 but I need something a little bigger. The Mahle's are $850.

[af2]

Flat top 350 piston will put you around the goal you need and will not care of the octane rating. Got one now with a 6-71 that will scare the crap out of you on the street at 3000 lbs.