Marking on my crank ....???

[71 Bee Man]

Hi guys,

well.....doesn't seem anyone can help with what my piston numbers are, so I'll try this.
My crank has this large "74" stamped on the end of it. Does it mean anything ??

[c00nhunterjoe]

Not sure what the 74 means, but the edges of the weights make it look like a cast crank.

[71 Bee Man]

Not sure what the 74 means, but the edges of the weights make it look like a cast crank.

It wouldn't mean it's a 1974 crank, would it ?
I've since found that the pistons are actually factory made 9.7 compression pistons.
Looks like it's had some work before.

[chargerbr549]

Looks like a forged crank to me.

[jlatessa]

Looks forged to me too.

Joe

[71 Bee Man]

Looks forged to me too.

Joe

Here's another shot of the whole crank. Probably be easier if I ripped it out. Sorry.
And for those that don't know....this motor is in a 71 Charger Superbee  (383), and numbers matching. Also has a Maltese Cross on the stamp pad which apparently indicates 0.010 Undersized bearings. Why would they do that ?
No ideas on the "74" mark

[Challenger340]

Looks forged to me too.

Joe

Here's another shot of the whole crank. Probably be easier if I ripped it out. Sorry.
And for those that don't know....this motor is in a 71 Charger Superbee  (383), and numbers matching. Also has a Maltese Cross on the stamp pad which apparently indicates 0.010 Undersized bearings. Why would they do that ?
No ideas on the "74" mark

From the Pics
* Forged Crank
* Cast Rebuilder Pistons (Badger, Silvolite, etc), low compression.

Although it may be numbers matching, It appears to have rebuilt at some point with different parts than factory(Pistons), so maybe best check the current bore size before proceeding ?
I have no idea what the "74" means ?  I have seen it on many Cranks over the decades, still no idea.

[71 Bee Man]

Actually, the pistons are Chrysler made. I posted another topic on it and got no response. A guy emailed me down here saying they are 9.7 : 1 pistons.

[PRH]

The only way to know if it's "9.7:1" is to measure the deck clearance, cc a head, then do the math and see where you're at.

While it's certainly "possible" it's 9.7:1....... It's also not "likely" to be that high.

[BSB67]

Actually, the pistons are Chrysler made. I posted another topic on it and got no response. A guy emailed me down here saying they are 9.7 : 1 pistons.

They look like Chrysler pistons.   I cannot tell you what they are, but I can tell you what they are not..... and that is 9.7:1.  If they are a 1970 piston, they would be rated at 9.5:1, but actual would be about 9:1, if they are 1971 pistons, they would be rated at 8.5:1, but actual would be about 8:1.

If you measure the compression height of the piston, I can tell you what the actual compression ratio would be for a given head on an uncut block.

[c00nhunterjoe]

As tp the forged crank, aint the 1st time i was wrong. Lol.
Compression: with the low cranking numbers you posted, its most likely 8:1.  Did you measure the deck clearance as i suggested?

[BSB67]

The only way to know if it's "9.7:1" is to measure the deck clearance, cc a head, then do the math and see where you're at.

While it's certainly "possible" it's 9.7:1....... It's also not "likely" to be that high.

Good point.  I guess a 68-69 piston might be close to 9.7:1 actual, but would be rated at 10:1.  It seem unlikely a 68-69 piston would end up in a 71 block, but it is possible.

[BSB67]

As tp the forged crank, aint the 1st time i was wrong. Lol.
Compression: with the low cranking numbers you posted, its most likely 8:1.  Did you measure the deck clearance as i suggested?

You're right (115 - 120- psi) and that just about confirms it....8.5:1

[PRH]

I found a reference to that piston number, it just said "1974".

Are we sure it's a 383 and not a 400?

Someone measured the bore, looked at the block casting number?

The number is "new" enough(high enough) that it's def not from the 60's.

[71 Bee Man]

I found a reference to that piston number, it just said "1974".

Are we sure it's a 383 and not a 400?

Someone measured the bore, looked at the block casting number?

The number is "new" enough(high enough) that it's def not from the 60's.

The blocks cast number is 1970, and everything else on it shows to be 71 gear.
"2468130" and it's a 1970 cast.

[PRH]

Okay, so it's a 383 block.

Do you have a way to measure the c/h of the piston?

Measure from the top of the pin bore to the top of the piston, then add .547".