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Old 03-22-2003, 09:03 AM
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Post 74 Vette 350 engine troubles

I bought this car from a guy who said he had an engine fire, and had replaced the block. My troubles began a few days after i got it, when i noticed the engine 'loaping', i guess is the best description... at any speed, it goes thru a small spot where theres less power, the rpm's drop slightly, and theres a noticeable change in the exhaust (dual, no crossover) sound... heres what he said he's done to it:

1. put a 400 cam in it
2. new engine block
3. wiring harness

heres what ive checked:

1. timing
2. dwell
3. checked spark on an oscilloscope (all even spikes, no jumping around either)
4. new plugs, cap, rotor, wires, coil
5. vacuum at 15-17 inches
6. used premium fuel for awhile, no difference
7. tuned carb (holley 650), even put a like for like on and same issue, i have 2
8. compression test (all cylinders around 145 lbs)
9. new vacuum hoses and pcv valve

im sure im overlooking something... talked to some gear heads and they all swear i have a bad valve or lifter... but wouldnt that show up in the compression test? someone also said the 400 cam just 'does that, live with it'...

any help would be appreciated...

also, is there a chat room associated with this site? i havent seen a link...
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Old 03-22-2003, 12:18 PM
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well a 400 cam is not a 350 cam so thats your probellem. replace the cam , usally 350 and 400 parts can't interchange as theres always something different
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Old 03-22-2003, 03:31 PM
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The cam's are the same in all sbc's from 1957 thru 1987 , could be your power valve is coming in ,secondaries are opening a little, distributor advancment not working.

[ March 22, 2003: Message edited by: 1BAD80 ]</p>
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