Tuning help

[VintageMusclecar]

Joseph;

I just spent a little time scouring through the parts book comparing the published specs between the 2 carbs.

I don't normally like to publicly offer tuning advice like this anymore, but for starters you might try just bumping up your primary jetting by 2 sizes to see if that improves the situation or not. Leave the power piston and primary metering rods alone until you see how the jet change works.

If you need parts, let me know.

Eric

[PeteLeathersac]

Before you dig into the carb, are you positive you don't have a vacuum leak anywhere?.
Besides checking lines, fittings, advance system components plus power brake and modulator parts if applicable, I seem to recall some Oldsies had a ported point on top of the intake that required a sealed bolt intstalled if unused?.

Always tough replicating problems in the shop that only show up driving under load at certain revs but if a manual inspection of the components show nothing amiss, sometimes intake leaks can be found at stand-still by hooking up a remote tach and trying different constant revs while keeping a close eye on the tach for variations as you mist methal-hydrate out of a spritzer bottle onto suspect vacuum areas...be careful of course and keep a fire extinguisher at hand!.

May be best if equipped to isolate brake boost and modulator system parts out of the equation and doing a drive first just in case...then onto the other things?.
Good luck!.

~ Pete

[JOZW30]

You guys are awesome! Thanks so much for the advice!!

I will re-check my vacuum to be sure before messing with anything else.

I re-built the carb before finishing the motor. It's really clean.

Car has the correct manual disc brake set-up mandatory with the 4-speed W30 package.

Eric, I will double check the obvious and make sure my basic timing is good. If I still have this issue, I'll try your advice above. After that I'll contact you privately for some "professional" help.

I really think this car can run alot better than my limited exp./skills can manage. But I love learning too.

Thanks again!

[SmallHurst]

Also, check to see if the vacuum advance is working properly. It could be that you have a leak in the canister and it does not show itself until the advance is needed. Pull a vacuum on the canister and see if it advances the weights like it should. Personally, when I am at the track, the advance is unhooked so that it has no possibility of coming into play. (Not like it would have a chance under a full throttle blast!)

[JOZW30]

Just one more general tuning question, I have the info for the initial timing for the stock motor set-up. But if you have have "upgraded" internals for performance (cam, higher compression psitons), do you still start at the factory initial setting?

How much advance can you go with? I've always been told to back off once you start to feel it pinging. Is this true?

It's hard to tell with the cam, I usually just advance until the motor smooths out and start from there. How much is too much initial timing?

[SmallHurst]

What I have done is what has been told for me to do. Personally, I do not worry about initial timing. When I set up the timing, I am looking for my total timing and in by a certain time. For instance, on the Olds BB, you have enough torque to bring the full timing in by 2500 rpm. My setup likes to go 36 degrees all in by 2500. When I am running with that much advance, the gas had better be good. I have tried to go farther with the timing, but it seems that my track time decreases. Brought the timing back to 36 and the track time came back.

[JOZW30]

Thanks for all the help guys. Seems I've got my tuning woes surrounded.

The two size up jet change realy helped the lean surge (it's almost completely gone).

When I went to really dial the timing in, I discovered that I am only getting 11 degrees of mechanical advance. It is there at about 1900 RPM, and doesn't go any further. It's not the original distributor (generic re-manned 455). I do have it though.

I'm assuming this is not good. My question is, what is my best solution? Can someone recommend a distributor guru? How much does a dialed-in distributor (I'd prefer to leave this to an expert)cost? Is it possible to buy them "off the shelf", or is it only possible to get your original re-done?

Last question, is it OK to drive the car this way? I mean, am I hurting anything or just giving up performance?

Thanks again!

[VintageMusclecar]

Joseph;

Check your PM's

Eric