With a std size rod bearing in it, add 2.439 + .975 together, devide by 2 = 1.707.

Measure between the 2 bearing holes, with calipers and add the 1.707 and that will give you the approx length. The dist should be ~4.781 for a 6.488 rod.

Did you mean the head gasket is a 8554 PT FelPro?

I ran your numbers using a standard Scat/Mahle 18cc piston (H beam rod piston) with 0.00 deck clearance and 65.5cc heads and only got 10.36 CR with the 8554 gasket. They are 12.7cc.

With your, 70° IVC, it puts you at 7.95 DCR, a bit out of the 92/93 oct gas range for your 280 cam, you could try reducing the lash to .018. That will give you a little later IVC and see if that helps any.

If you change cams, you'll need to go to at least a 284 duration on a 110 ICL. A custom cam something like a 284-6/294, 114 LSA/110 ICL with mild lobes. Howards has lobes that would fit nicely in that range.

I ran a few number and you will need at least a 22cc piston dish to get it in the pump gas range.

A better estimate can be done if we know the deck clearance, head gasket and what ever the piston cc is.

Here is my take on it:

Based on what he did with the C1 heads and what Steven Magnotti did with the C8-H heads, I would say that your in the 270-275 cfm range, at best.

270 cfm is about the best you can expect from OOB Edelbrock 2.09/1.65 with a good VJ.

So, it's only a weight issue for those but, you can pick up a lot of hp with TFS or Blair built BBM's.

I would try to find someone to flow your heads and see what you actually have. Please report back if you do.

I had to abandon my .309 valves because they were no longer in stock with my valve supplier and would have to wait 4 mo to get them.

I was going to run them with 11/32, 1.75 ex valves, to match in/ex weight, so, I had to buy both at 11/32 and have them drop to Jay so, he can drop ship them to Blair, with the heads, for his 7 angle valve job.

Hey Ross, the reason that the curves don't cross at 5252 is because each axis is on a different scale.


 

I'm glad you finally figured it out.

That is not enough to worry about.

Since all you have done, has checked out good, here is a pretty easy test you can do, loosen the bolts that the header flange, both sides or at the collector, if headers and see if it will start and run.

When I was a mechanic, I had a Buick come in with no power and over heating, after a lot of head scratching, to turned out to be that the muffler had pluged up.

As for the head gasket, pull all the plugs and have someone spin the engine over. Check for moisture or water coming from a cyl, another easy check but it could have been just over heating that caused it to blow the water.