Hi Glenn:
I mentioned earlier that there might be a possibility of a timing chain
skip. This is not unknown and could cause problems of the sort you
describe. The only other thing I can think of is an overly lean condition
- a sure symptom being excessive backfire. Check your fuel delivery system
including float height. Make sure you don't have a plugged fuel filter or
a sticking needle valve in the float bowl.
John McEwen
>Well thanks to everybody who responded. Here's what's up so far;
>
>The carbs are freshly rebuilt - nothing wrong with them although I did NOT
>replace the jets or the float needles. The floats are fine and the jets are
>in good shape IMO. BTW, the vacuum on the HIF's came off the manifold and
>the HS4's off the carb right after the throttle plate.
>
>Went back to check on the timing AGAIN and the points gap AGAIN, checked
>compression (120 lbs. across all four - not good, especially for a HC
>engine, but consistent), found one vacuum leak (intake manifold plug - fixed
>it), took everything back to ground zero and retuned to another nice idle
>and as soon as I got out the drive it STILL ran like shit. Started
>backfiring to an embarrassing level. Took it back in and started over.
>
>I noticed that when I'd rev it up to 2.5k to clear it for a minute it would
>stay there for about 20 seconds and then slowly start to fade back down to
>1k or less without my having moved the throttle. I'm starting to believe
>myself it's something other than the exhaust , but I'm damned if I can
>figure what it is. At the end of the evening I pulled the diz to take it
>inside and pulled it apart. I did notice the top plate wasn't sliding around
>very well so I took it all apart, cleaned it up and put it all back together
>again. Maybe, just MAYBE that was it. It did kind of act like the advance
>wasn't advancing or to be more precise the retard wasn't unretarding.
>
>The upshot is; I could tune it so it revved fine through the range, but as
>soon as I put a load on the engine it acted like a virgin at a frat party
>("You want me to WHAT??!!) Now all I can get is backfire anytime I rev it.
>I'm about to put the old beatup exhaust back on just as a control if the
>dizzy work doesn't.
>
>Todd, I'll have to check, but I bought the system as a 1 7/8" OVERSIZE. I
>just went out back to check and OD on BOTH systems is 1 13/16", taken right
>before the front silencer position. So ID on both would be about 1 3/4", or
>what I thought was factory.
>
>Glenn "Maxima driver" Schnittke
>-----------------------------------------
>No one in Tuna knows what I do for a living.
>Why should they care what I say?
>
>Glenn Schnittke Recovering Musician
>Nashville TN 615-385-2800
>schnittke@mindspring.com
>
>-----------------------------------------
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