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1990 OMC 5.7L Chevy

T

timinmtta

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I have been having problems w/ acceleration & top end, I have gotten the carb. rebuilt/ Electronic upgrade/ put on temp. electric fuel pump because the pump pressure would go below 4 at WOT. anyway now I have checked the plug wires, they read 2.5k to 3.4k, I also have a merc. inboard same engine they read 12.4k to 13.2k, it runs fine, could these wires be bad?My OMC will only go to 3500 rpm with a 15.5 prop. the compression is 150 to 152 on all cylinders. I am at a loss any help woud be greatly appreciated. Thanks
 
unplugged esa, did not change anything.After that, I advanced the timing to 12 degrees BTDC, It actually got above 4 to 42 or so, but I noticed if I left it there, it started to surge, like it wanted to go more(if that makes any sense).Could my carbration be wrong?
 
every engine likes it different, you don't have water in the gas ? Got me maybe someone else can chime in.

Only thing i can think of is the timing chain loose ? Rarely you see one jump a tooth if really loose.

Above is my opinion that the dist. shaft is nice and tight and all is good inside.
 
When you said electronic upgrade in the first post I assume you meant electronic ignition?? Was the coil changed as well and were the plugs gapped differently (wider)?
 
Yeah, I meant the ignition, I did not change the gap though, I did pull them and make sure the gap was 35, should it be wider? I kept the original coil the paperwork gave ohms, mine was within the tolerance, so I left it the same.I am thinking of trying another carb. I was going to ask, like I said in the first post I have put on a electric fuel pump the extra vent on the carb. that went to the mech. pump, I plugged it off, that couldn't restrict anything could it?
 
Yeah! I think hstat hit it on the nose, haven't been out for long, but it does seem now like it goes to full throttle with some strength. Removed anti-siphon valve completely. Thanks everyone.
 
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