I just had my 8ba motor rebuilt. It has a 4" merc crank, egge 3 5/16 3 ring pistons and eab heads and max 1 cam. I told the builder about Egge piston clearance problems I've heard of, he said that's BS order the Egges. I asked the tech department at Speedway about Egge piston problem. He said "I haven't heard about that problem, we have sold many sets and no problem". He also said I should contact Egge if I want to tell them about a product is not right. Basicly we just sell them. I told the builder not to mill the eab heads before claying. But they went ahead and cleaned them up first at .010 cut. They were pitted and they only went as far as they needed to clean them up. Now they clayed the head it has a .035 piston to head clearance. The valves have lots of clearance. The builder called Egge they said you should have .040 clearance but the piston will ony grow .003 so I should be ok with .035. Since they had work in the heads they figure go with the .035. They put the heads on it that way. Need less to say I'm not pleased with the outcome. I would like .015 more but it is what it is. I've thought about getting a different set of heads for it. I do have another pair of eab heads that need milling to clean up. The builder measured them and said they would be worse than what I have when they get cleaned up. I need to hear from someone that has run with .035 clearance. Is .035 enough ? Gene
No experience, but at one time they were selling weird conical domes. Are your domes spherical looking or...strange? Are your clearances relatively even across the chamber or is there one area close and others wider? Just trying to sort the fog of currently available pistons.
Run them with .035 clearance. I used to build engines full time and to get the "quench" right in the combustion chamber in a lot of engines we used to run between .035 and .040 clearance. It is completely acceptable and you will not hurt anything. While this is a flat head and the "quench" approach is not the same as in an overhead valve the clearance issue is still correct. Run it and enjoy the thing. You have thought through the whole proce3ss and the "numbers" still stack - nothing fouling, nothing hitting, good clearance - it sounds as though you will have a good engine if all then other factors like machining clearances, bearing clearance, piston to cylinder wall clearance etc are all right. If the basisc are sound - you will be happy
Shouldn't the head gasket allow for more clearance? When you "clayed" the engine was the head gasket in place?
They clay the head with shim washers the same thickness as a installed head gasket. I think if you use a gasket the clay has no were the squish out to. You could use a old gasket that I don't have or ruin a new gasket. Standard procedure is spacers. The builder is a old timer that has done this for allmost 50 years. Thanks 35 Desoto for that info. The engine is bored, balanced and has all new parts. It should be perfect other than I would like a little more clearance. If you say it should be fine I'll go with that. Egge says it should be ok. I just got a little concerned when they said my $3000 flatty SHOULD be ok. I pick it up tomorrow. I think it will be a strong runner. Thanks again - Gene