Just got an 83 sd that wasnt running well. Pulled injecter pump, retimed, and put a goog set of injecters in. After tinkering a bit it runs great, dare I say almost quick.

Here's the problem....If I start off slowly then get into the throttle all is great. If I get into the throttle from the start, I get a thumping noise for a couple of seconds. only at low speed and deep throttle. Its like someone is faintly hitting the floor/trans tunnel with a rubber mallet.

Ideas??

Thanks in advance Rick

flex discs!

I had the exact same thump

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Cheers,
Robert

I did scan previous thump posts. First instinct is to agree with flex discs. Just seems wierd that the noise goes away so easily. Either way, old car, sitting for last few years, they should be changed .