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Reply to "Mangusta 8MA1010 project - running quad Weber DCNFs with a stock jackshaft"

V8J,

There is a Goose (#590) running around, re- sold back in the 90's, with a Gurney Eagle top end where the installer was able to utilize the jackshaft also!  I think it went in the center under the carb.

It appears that your bellhousing has had the RH mounting boss removed, making it difficult to move the alternator to that boss.

While alternators mounting in the RH area are uncommon, my car (#878) had it there with no apparent evidence that it ever was in the center position.

Of course once you choose a center position, you have things like the distributor, possibly the water outlet, and the water pump pulley to deal with!!!! Never a free lunch......  I am not sure how the builder of #590 dealt with this....no pics!

If you do need a center mount for the jackshaft, you will definitely want an adjustable version......as this has been hashed around on this forum quite a bit...... with aluminum manifolds & heads now more common, trying to keep three holes in perfect alignment is near impossible.  I really don't understand how the Italian builders made it happen such that we don't see reports of busted jackshafts in early writeups.

My own experience was such that I just tossed the center bearing idea in the rotary bin as what I did on the intake off the engine wasn't even close to how it turned out when mounted (alloy intake), and another owner, with stock cast iron engine, broke his shaft in two....with probably at least one more instance in more recent times!  (I had a jackshaft bracket made of 1/2" steel (Boss 302 engine) and the shaft installed easily indicating pretty well aligned.....but still shucked that center bearing after 15-20K miles on it....)

I never experienced any vibration issues with my new 331 and only the end bearings. But my shaft had already been rebuilt/replaced before I bought the car, so was not a stock shaft.... materials could have been better(?).....   Spinning that engine up to 6K would put the shaft speed at around 7K or so with the pulleys that were utilized (fairly common versions).   The bearings are definitely rated for way more RPM than that......

Nice job on your car!!!

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