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Gday everyone.

Ive got an 866 with an irregular miss in it. It only happens every now and then when its idling, but its really noticeable when it starts to rev. Ive just had injectors done, it starts very easily and doesnt breathe heavily. The RHS bank has new rings in it, and the heads have been overhauled. To me it sounds like a fuel pump problem, and the smoke that it blows under revs is fuel smoke. The sound is almost like a sticky engine brake but is not regular and cosistent enough. I am going to check the timing tomorrow. Has anyone got any thoughts?

Thanks, Dave W

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What he said.

I had one at one time that was missing and pulled the pump and pump shop told me its doing what it should do. Come to find out it runs on 8 cyls when needed or certain rpm. At 1000 rpm it runs on 4 and picks up two after that till its got all 8 fueling. Pump shop said he had never seen them before but had specs for it. I replaced it with a normal pump from a junk engine.

glenn akers

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Thanks for the input guys. I would be pretty confident that the RHS heads would be ok as they were done up. The LHS could be an unknown quantity. Would a loose valve seat cause it to blow smoke under light revs? From my experince with a loose valve guide on a 6 cylinder it made the popping sound when you backed off the revs. This V8 seems fine when you back off. This engine and pump sat around for a long time before my cousin bought the truck to restore it. And when we first started it up it flew out to full revs and I had to block the intake to stop it. The LHS rack was stuck in the pump but i managed to get it freed up without removing the pump so we dont know what the pump is like. Could it have a sticky element or maybe a worn cam to make it miss?

Also, how do you go about timing this engine? Is it similar to a 6 cylinder?

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Reread which part Glenn? I doesnt sound like it is popping when it is turning off. And do you reckon it woud cause the engine to miss and blow smoke? Let me know what you think. Thanks mate

What fjh is talking about i alot of V8 mack engines when they were in the 865, 866 models would losen the valve seats which in most cases will get lose when hot.

glenn akers

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