rdisney

Assume your engine is interference until proven not. Whether its interference by design, carbon buildup, or some other reason. I had a 1980 US Auto I was doing a timing belt and water pump job on. When I turned the engine by hand it would stop with a clunk. After rotating the cams a little I was able to turn the crank a little further. I never investigated why the engine was interference but I don’t recall carbon on the pistons when I replaced the head gaskets and I don’t recall how much carbon was on the valves.

How many reasons might a 16V engine be interference?
Factory “special”
Carbon buildup
Machined heads
Machined engine block
Thin gasket
?
?

tv

I'm with this ^

Lizard928

That is the 10:1CR 300bhp CIS engine and it would not have been interference from the factory. Someone has done some work internally, or you've got a lot of carbon build up.

R.Pires

So my 83S stock M28.11 is supposed to be non interference UNLESS it has a lot of carbon build up. How can I know that? Is there a way to find out without disassembling the engine? Is there some kind of additive to mix with oil or fuel that can help with the carbon build up?

TIA for your answers.

Regards

17prospective buyer

Seafoam works. I've done it on plenty of motors, but you have to realize you need to attack carbon at the cause or source, Seafoam will get rid of it but it'll just come back.

depami