Finally pulling everything off this motor and cleaning things up before putting it back in.

Two questions:

I am going to check compression to determine if I really need a rebuild now or not. I know it wouldnt be a bad thing to do but it runs fine and I am just ready to be driving it again. What compression would be acceptable before a rebuild seemed necessary?

Second, do I really need all the tin back on the motor? I get why it is there for moving air around the motor from the fan shroud but wouldnt removing it all allow more air to circulate the motor just naturally? It just seems like it would be so much easier to work on when in the car so much easier to keep the whole thing clean etc. Does anyone encounter problems when running without the tin?

You will overheat the engine without any tin to force the air around the cylinders.
You need every piece of tin, no exceptions.

Motor might last an hour, that is about it.

A compression test will only produce valid results when the engine is warmed up, it will give wacky readings when cold.

When you do the test, as long as it's consistent across all cylinders, you should be fine.

I saw a 914 at the track with everything stock except it had no tins in it.

I even asked the owner, "Dont you need the tins for cooling?!?"
He said Oh, it does fine without them.

All I could do is walk away shaking my head thinking "whatever".

I never saw that car at the track again.....

With my Ghia, if the engine tin seal was out of place the engine would overheat.

Yes, run the tin, it is there for reason...

Slight hijack, wonder if replacing the tin with aluminum sheet metal instead of steel would help with cooling?

You want the compression readings to be at least 120 PSI, typically. More important than that is that they're close to even from cylinder to cylinder. (Many things can affect the exact pressures you get; battery charge, how strong your starter is, your electrical connections, your altitude, and so on and so forth.)

Block the throttle wide open and remove all the other plugs after you get the engine warmed up. The PSI readings should go up pretty quickly and come close to stabilizing after maybe 5 cycles. Use the same number of cycles on each cylinder.

You need all the tin, PLUS you really really need the cooling flaps. Especially the one on the right side!!!!


I think aluminum tins would have no detectable effect on engine temps--the alu would tend to make the temps above and below the tin a little closer, but I'm not even sure that would be enough to measure.

--DD

Tins, who needs no stinken tins !

Click to view attachment

You don't need 'em if you only drive your car 1/4 mile at a time... Heck, why bother driving that power-robbing fan, either?

--DD