I am having the heads redone on a 1980 Euro S 4.7L ENGINE that I bought as a non-runner. When I took the heads and oil pan off everything looked clean and straight. The machine shop just told me I have 4 bent exhaust valves and need all 8 exhaust guides replaced. OK, but what could have caused this and what else should I take a look at before I put the engine back in the car? He took a look at one of the lifter tappets I brought to him and he said if they are all like that I'm good as far as that's concerned. Gunar

 

Did you do a compression check before pulling the heads?

 

Extreme wear on the valve guides, carbon build up on the pistons or overmachining of the heads can all contribute to valve damage. I would have the machinist check the guides on the front and back of each head for minimum depth to make sure they weren't previously cut too far. If below minimum the optional thick head gaskets should be used.

Dennis

 

The guys in Florida that had it before me did and they said it showed for 80 to 140 which is a fail(don't know much about this procedure). I think bent valves contributed to a low compression test.

 

Bent valves will definitely contribute to low compression numbers.

Over-revving can also cause valve impact. If the valves start to "float" they can fall out of sync with the piston and make contact.

 

Timing Belt?

 

the 80 is supposed to be a non interference engine if the heads were not fly cut then the most likely possibility is an over revved episode.

 

Over rev where the valves float and stay open too long is most likely. But it does answer the why of the low compression.

 

You took the previous owner's word? Man this is a big no, no.....always do you own diagnosys. Go the the shop and see what they found, least you can do is see if they actually found the valves bent. If this an non interferance engine, there shouldn't ever be contact between the piston and the valves.

 

As far as I know, all Euro S engines are interference engines. Maybe had a cam belt/assembly issue, before you bought it. If the heads were removed at the wrong crankshaft position, I could see them "snapping" the cams backwards and bending vavles, when it got disassembled.

Valve guide wear is normal. We usually always replace the exhaust guides, minimum, on the 16 valve engines.

BTW...this is kind of "normal" stuff...and the major reason why people have heads freshened. If everything was perfect...it would be silly to be messing with it.

 

Can someone help me with the part # for the exhaust valve guides. Pet 6 is confusing me with the 1st oversize in the listing. I think the part # is 94410432851. By the way Greg, I took the heads off myself but the engine had no timing belt on it so I didn't know I needed to position the cams. Gunar

 

I believe there is lots of discussion asserting that the 10:1 CR 4.7 is NOT interference, but the 10.4:1 CR is....
jp 83 Euro S AT 52k

 

I've seen USA engines with bent valves. You get some carbon in there and the entire "interference" thing changes. I'd not want the belt to break on my Euro S engine....regardless of the compression ratio.

 

Agree with all that ... they are definitely interference .. and you can bend valves. Low comp engines may not be .. but it doesn't take much (carbon, valve float, etc) to crash valves.

 

Yup, happened to me on my '83 Us 4.7L.