BlackRocket

I found the engine build on a newly acquired '69 coupe and the paperwork indicates to me that a stock crank was used with a 0.40 over bore. This would make it a 358 as far as I know. (Top end utilized an obsolete Holley Systemax II package with a flat tappet cam and aluminum heads).

Any inputs would be appreciated!




Now considering scrapping plan to replace cam with a roller and just start fresh with better block and rotating assy.


Thanks!

B-R

Shark Racer

I don't think it's definitive from that that it's a 3.48 or 3.75 crank - the engine may have already had a 383 crank prior, or a second crank was brought in. That said, if they were mating a new crank to that block, they likely would have quoted for block clearancing as well.

gkull

You need to look near the bottom. the pistons are + .060 and $376.80

The mains and rods are .010 So that means that it has a cast crank that was damaged enough that polishing didn't take the scores out.

It was balanced.... good thing1

BlackRocket

Engine has about 950 miles and was blowing some smoke after I took it down from Jack Stands from doing the rear suspension. Now back on stands doing the front. I'll have to drive it a bit once I get it back on the road to determine if it is just residual oil from sitting so long. I was considering replacing the cam with a better roller cam, but the valve springs, bronze dist gear, cam button and the hassle maybe not worth it.

Either way...I'm not convinced this motor is worth throwing more $$$ at. Thinking of getting a new LS larger cu in short block like a 427 Dart and building on a stand and then swapping out in the future.

gkull

Buy the sleeved on dizzy gear cam. Then you don't have to use a different kind of dizzy gear

do you remember when we met up at the wine country classic historic racing in 2007.

keithl1967

the "Flywheel" part number comes back to a Flexplate that is made for a 5.7 motor, internally balanced. BEP34000
https://www.carid.com/big-end-perfor...mpn-34000.html

Not being weighted, this is more than likely a 358, as you note in your original post. You can also check the balancer and see if it is weighted...

Not ALL 400 cranks were externally balanced (the aftermarket makes some internally balanced ones, but form a summation of evidence, this is likely not a 383.

derekderek

L2256 is a 350, not 383 forged flat piston. And at .060, block is on it's last rodeo. So it is a 360. Your call, but less than 1000 on rebuild with forged pistons, I would put a hotter cam in it and beat it to death...

Jebbysan

FYI, the Holley system max heads are great units and obsolete only in availability. They actually have a 20 degree valve angle as opposed to the standard 23 degree. Keep them......with a little clean up and bowl work they will hold their own against newer units......

Jebby

cv67

^^they arent bad at all and have decent potential
wish they still made that 300-36 Z/28 type intake that was a good performing piece!

Jebbysan

BlackRocket

So Jebby, can I run a roller cam with these heads?

They only have 900-1,000 miles n them,,, Just not sure those tapered valve seats can handle the higher lift numbers close to .6

Thanks!

TedH

If the heads were set up with a hydraulic flat-tappet cam, you will need to update your valve springs for the (retro) roller cam. In late 2013, I went with the Comp Retro Roller kit for about $1,000 that came with all of the fresh cylinder head pieces (springs, keepers, locks, seals) matched to the retro roller. With the new spring package properly installed, you will be assured you won't have any spring bind either. Mine with the 1.52:1 rockers is right at .502/.509" I/E lift. Well within limits of the flat-top pistons with valve reliefs.

Jebbysan