aaronz28

So........

i recently acquired a 64 L84 that had been "worked on" by a Corvette Specialist. without going into details, it was a mechanical wreck, oil leaking, exhaust leaking, terrible state of tune -

they tried "solving" the issues by installing the 097 cam - to get more vacuum....


over the last 2 weeks, i pulled the motor apart, installed the -346 (30-30 cam) and completely overhauled the FI unit, rebuilt the distributor etc.

The car now runs 1000% better - but I'd like to make sure the FI is top shape.

It starts without issue, idles beautifully down as low as 700rpm - although I keep it at 850-900. Part throttle cruising is super smooth, and responsive. Before I went through it - it would break up under full throttle at anything above 4000 in 2nd gear (seems like 1st gear would be ok - don't know why unless it was being starved for fuel)

now - it revs smoothly through the rpm range in all gears (at least through 3rd - i don't dare take it up to 5k in 4th gear lol) i'm just not 100% certain that the power and economy stops are set properly given how it ran before.... and God only knows what the last people did...

so as a test - i made an adjustment to the power stop - and the car seems to pull smoother, although it doesn't have the sudden "ON" when it hits 5000 rpm - which tells me one of two things - either its picked up enough in the bottom end that you don't feel the surge - or the top end is flatter than it was....

i could spend days making 1/4 turn adjustments - but i'd rather have some advice from people with experience tuning these things... there is no chassis dynometer within a reasonable distance that i could take it - where they'll allow me to make the adjustments.

i've heard of the manometer - but i do not have one - but if they are still available, or if someone can make a recommendation as to how best to get these stops in the idea position - please let me know -

thanks in advance

jim lockwood

I have experience setting up Rochester FI.

Without ready access to either a chassis dynamometer or at least a wide-band air/fuel gauge, you are pretty much stuck with seat-of-the-pants tuning. And it seems that you've done a pretty good job of it.

No, the two stop screw are probably not in their optimum position.

But, if your engine isn't running hot or surging (suggesting a lean mixture) or blowing black smoke (rich mixture), and if there is no hesitation when you suddenly press the accelerator, and if your fuel mileage is somewhere in the 18 - 21 mpg range, then I suggest you leave the stop screws alone and enjoy driving the car.

I would not spend money to buy a manometer. They were good in their day but they work only on un-modified units, an increasingly rare commodity.

That's my $0.02....

Jim

MikeM

I think that's very good advice short of having the unit accurately calibrated.