VERY tight new Chevrolet engine

[E55BOF]

A friend of mine has just fitted a new 1987 Chevrolet big block petrol V8 in his old Winnebago. When it's hot, he has to allow it to cool down before restarting it; it's already broken two starter motors - it's so tight, it won't turn over on the starter when hot. It runs perfectly well when it's running.

He's pulled it apart and checked all the clearances; they're all fine. There were no signs of picking up on bores or pistons when he stripped it (through the sump, without removing the heads). Foolishly in my view, he put some Slick 50 or similar in to try to ease the problem, but it changed nothing.

One answer might be to put a couple of thousand miles on it, but with single-figures mpg that's not a cheap option...

I can't see how it can be anything other than the pistons or piston rings. Does anybody have any ideas?

 

[boxbrownie]

Might want to check the earth strap on the engine, if it's a poor connection (or even the +feed to the SM) the starter will not be getting all the juice it needs to turn the engine over when hot.

 

[carat 3.6]

Bit of a long shot... Some chev starter motors need shimming the correct distance from the block, otherwise they can bind or jam completely.

 

[jonnyboy]

+1 on the earth strap, but it sounds like Carat may have the definitive answer?

 

[LTD]

Isn't a Winnebago meant to do serious miles travelling ?

 

[flango]

What block is it? The LS6 was known for this issue a lot of F1 stock car racers use this engine. You need to use proper coolant. The usual antifreeze and corrosion inhibitors + water doesnt work well in this engine. You need proper high performance coolant.

Failing that you can do what the stock car boys do, dry sump it and fit a hydraulic starter

 

[Anthony 69]

If it is a case of running in the engine, might be worth considering using some running in oil. Made precisely for the purpose of allowing the engine to receive a little helping hand over the initial running period.

 

[carat 3.6]

If it isn't the starter motor jamming, I'd take another look at the gaping of the piston rings.

 

[Bellow]

Is it tight, or kicking back against the starter due to over advanced ignition timing?

 

[E55BOF]

Thanks guys. Some good stuff there. I think it just won't turn over when hot. I'll pass on all the suggestions; I already suggested running-in oil to promote 'bedding in' - i.e. some wear.

As a first step, it occurs to me to suggest seeing if he can turn it over with a big socket on the crank pulley, both cold and hot. If there's little or no difference in the force needed, it's not something binding inside the engine.

 

[boxbrownie]

Thanks guys. Some good stuff there. I think it just won't turn over when hot. I'll pass on all the suggestions; I already suggested running-in oil to promote 'bedding in' - i.e. some wear.

As a first step, it occurs to me to suggest seeing if he can turn it over with a big socket on the crank pulley, both cold and hot. If there's little or no difference in the force needed, it's not something binding inside the engine.

If he uses a torque wrench he can compare the two more accurately than just "by feel" also.