Help with forensic archaeology

[techweenie]

I have two engines, both anecdotally 'enlarged." One is a 1980 3.0 case; the other a 1985 3.2 case.

The SC case is supposed to have larger pistons/cylinders installed, making it a 3.2 SS. My question is, what is the outer diameter of the cylinders for this kit?

Similarly, my 3.2 is supposedly enlarged to 3.4. Again, I need to know the outer diameter of the larger cylinders at the spigot so I can compare with what I have.

Any help is appreciated.

[onboost]

Tech,

If I'm understanding the question correctly, then the spigot is the same as this is a slip in conversion. Both conversion use 98mm bore/piston. In essence same bore size on both the 3.0 & the 3.2.. the crank/stroke being the difference in SS 3.2 vs. 3.4

[techweenie]

You may well be right, but it was my understanding that both displacement changes [3.0 >3.2SS and 3.2>3.4] were made by using larger cylinders.

A short stroke 3.2 implies that.

[Steve@Rennsport]

"Onboost" is telling you something here.

The BORE sizes are different, however the cylinder spigot diameters are identical, allowing these upgrades to be a slip-fit requiring no machine work.

[techweenie]

Thanks, Steve.

But not looking to measure the spigot, but the outer wall of the cylinder, which I believe would be greater than stock in both instances. Yes? No?

[onboost]

Thx Steve..

And I would think that if the spigot size remains the same (the outer wall) with the larger bore, the inner wall would be thinner with (bore size).

Therefore when you get into the larger P/C's like 100mm and up (I believe unless noted as
"slip-fit") you then begin to need to modify the spigot for fitment because of both the larger bore, and the need for a required wall thickness to be maintained.

Put another way, if the bore is bigger, then the thickness on the outside of the cylinder will have to increase to maintain a given wall thickness, thus requiring the spigot to be enlarged.

[Steve@Rennsport]

Originally Posted by techweenie

Thanks, Steve.

But not looking to measure the spigot, but the outer wall of the cylinder, which I believe would be greater than stock in both instances. Yes? No?

The OD didn't change in order to accommodate the cooling deflectors and not impeding airflow; the bore size is just larger, making the 98mm ones a thin-wall cylinder.

[techweenie]

Steve: that's the answer. Had hoped the wall thickness was proportional, but oh well.

Really appreciate the info.