rx7speed

just found a 307 that was bored .040 over at my moms house from a 70-73 car

number was 970020 for the block has 10% nickel in it I guess 20% something else or atleast what I am guessing due to the 10/20 right near the casting number on the block

the heads are casting number 993



looking for all the info I can as far as the 993 heads. flow number how good they are blah blah blah blah

and can you puta 350 crank into a 307 block fairly easily

asking this b/c of the crank flange looks like one from a 350 rather then a 307

that or someone put a notch into the crank flange

AJ_92RS

According to www.mortec.com .........

"3998993....72-73...307/350......75cc chambers
3998993....current..350.........Goodwrench crate motors,"Hecho en Mexico",75cc chambers"

I'm not sure but I think that means "Made in Mexico" :sillylol:

POS heads. Not bad if you're trying to go ultimate cheap, but that's about it. Better for propping doors open.

Is this the actual block #?

"3970020....307...70-73...2"

And 10/20 is tin/nickle

Yes a 350 crank will work and that would give you a standard bore CID of 328. It'd be different. If you went .030" over, you'd have a ~333 (actually 333.4), or a 334. Just like a stroked 305, but backwards. (305 with 3.75" crank)

Like I said, it'd be different.

AJ

Damon

The 350 crank will physically drop right in but where are you going to buy pistons that will fit a 307's bore (to work with the block) but with a 350's compression height (to work with the crank)?? Anything's possible but I doubt ANYONE makes an inexpensive off-the-shelf piston for this.

F-BIRD'88

The 993 heads are low perf, low compression heads
The cr of your 307 will be quite low with these heads.

Swapping on a set of 58cc 305 heads will boost the compression ratio quite a bit. Right up where ya want it.
Shave 'em a bit and up grade to 350sized valves and thouroughly port them
and you'll have a good budget performance 307.
Do it right and you'll spank your share of 350's.

The 305 heads to look for are 416's or 081's.(centerbolt)
As stated above there are no redially available 307 pistons for a 350 sized stroke. So such a build would not be cost effective.
But a 307 crank (3.25" stroke) in a 350 block will make a 327 motor. Requires 327 pistons.
(You'd need to rebalance it.)

307's are good lil motors. I've had a few in cars in the past.
Oh!, to be in the 60's again!!!! LMFAO
I'd leave the bore and stroke as is and concentrate on induction cam and exhaust.
A performer RPM intake combined with some tweeked 305 heads
and a mild/ moderate performance hyd cam would make a good street motor.

rx7speed

I haev no clue about the motor

we found it in my moms storage

I don't know how they crank fit or what not

I'm just taking a look at the flange

I might be able to get some pictures up there for you


with these heads how well do you think they would repsond to porting and milling?

F-BIRD'88

I wouldn't bother with the 993 heads.

You won't be able to shave enough off the 993 heads to get the cr up to even near what you need. for the 307.

look for some 305 heads andwork with those. They're cheap.