head swap

[Anonymous]

howdy folks: I have an early 80's 200ci in my 62 econoline. Just had it rebuilt after blowing 2 pistons. The engine was only about 15K old and somthing still unknown caused pistons 3 and 4 to end up looking like burnt charcoal. So I've got it all back together and put a duraspark II in. It seems to run OK except the number 4 plug has developed a hard whiteish appearance over the first 500mi, the engine also has a stumble, like misfire, when you hit exactly 2600 to 2700 RPM.
I wrote a previous post "one lean plug" and becausue I can't come up with anything else at this point (been around the whole head with engine idling with a propane torch, WD-40 etc, looked all around for cracks-can't find any), not sure what to do except try a head swap to see if that's what's causing that number 4 plug to look lean.
In the interest of NOT buring up another long block, seems like a good idea to have a looksey at the #4 piston anyway. Also, did a timing curve as suggested; my initial timing is 8 deg and my advance is up to about 38 or so at 2500 rpm....
I have an extra 68-69 head, also a no-adjust rocker arm setup. How can I figure out if I can just swap that head on? are there a couple critical measurements I can make? Should I just swap and go? thanks for all your help and happy thanksgiving.... David SoCal

 

[CZLN6]

Howdy Back David:

The 1980 casting will have combustion chamber volumes of about 62 ccs for a rated CR of 8:1. The "'68-69 Head" will likely have chamber volumes of 52 ccs and was rated at 8.8:1 CR.

AKT the stock OEM steel shim head gaskets were .025" thick while the aftermarket composite type gaskets are.045" to .055" thick depending on brand. The thinner gaskets raise CR, the thicker lower CR, but seal much better. The OEM gaskets are no longer available, except rarely in New Old Stock finds.

The cubic centimeter volumes are an aproximation. The only way to be sure on your exact heads is to measure for your self.

Adios, David