Help with heads, crank... [Archive] - Chevy Nova Forum

: Help with heads, crank...

11th-January-2007, 12:31 PM
First of all, I do not know the size of my intake valves. The emblem on the heads is like a backwards "L". Is this the 1.72", or the 1.94"? Second, does anyone make a forged crank for the 307 motor?

11th-January-2007, 12:43 PM
What's the casting# on the heads?

Paul Wright
11th-January-2007, 12:46 PM
The 3927185 307 head might have a Layed down L shaped casting mark.
The valves are 1.72/1.5 and have 70 cc chambers.
The crank is cast. A forged large journal 327 crank could be used if you rebalance it.

Uhh...what are you trying to do?

11th-January-2007, 02:58 PM
Hehehe, I am not trying anything yet.:rolleyes: I want the best for my little 307 when I rebuild it, of course if those heads are 1.72's, I might as well go with another set. The smallest performance valves I know of are 1.94's, so I will need those... I don't remeber the casting number, something like 8827188? Just did the intake and valve cover gaskets the other day, but I can't remember!!!

stock z/28
11th-January-2007, 03:29 PM

Pauls right about the crank. I have a few steel large journal cranks, but in my opinion the cast crank is a very good crank. Its much stronger than a cast 350 crank, and I have seen several very high rpm 327s hold up well. I would not be afraid to use it.

11th-January-2007, 03:40 PM
so are there any websites that decode cylinder heads?

11th-January-2007, 03:47 PM
so are there any websites that decode cylinder heads?

11th-January-2007, 03:53 PM
Use the 1.84/1.50 valved 305HO heads or the L-98 vette heads. The 1.94's have a reasonable chance of whacking the top of the cylinder bore and will be shrouded by the bore very badly.

A 307 is a 283 with a big(ger) crank. Remember to keep things small!

If you insist on 1.94 valves, the L-98 Corvette TPI engines have aluminum heads with 58 cc chambers... perfect to keep compression up with a little 307.


12th-January-2007, 12:37 PM
If I remember my number right, it says it is a 327 head with 74cc combustion chambers... Huh! What was the intake valve size on those?

12th-January-2007, 12:44 PM
1.72/1.50. I have a set of 307 and 283 boat anchors in my garage. They're going to the scrap yard because they're junk. I also have some 305 HO heads sitting around if you're interested.

Kev (played around on the midget mouse motors for a long time!)