Tuning

[serpent710]

Go back to what the carb came with and was calibrated for, so 63 in the primaries and 73 in the secondaries. I always get the right timing dialed in with the right plugs before ever getting at the carb mods/changes.

Need to start from a set baseline. Those Ultra's have a unique Emulsion package and don't have changeable air bleeds, so your limited with that model to a point.

So you think I should go lower on the jets?

 

[G72Zed]

Yep, go back to stock jetting, your 9 sizes larger on the primaries, all that's doing is wasting fuel and wearing out your bores real fast!!!

If your jetting is off by 4 sizes +/-, something is off with the carb or engine-application.

Keep in mind Holley's are on the safe side out of the box in most all cases.

 

[serpent710]

Well, I seem to be well over my head at this point. Nothing I have done has worked. The car will be getting dropped off at a shop tomorrow that deals with Carbureted engines, old cars still and has a good reputation.

 

[jeff swisher]

I ran an Edelbrock RPM Air Gap on my 350, that 350 I have had many heads and intakes and cams in it since 1992
It is a flat out runner and has seen more RPM than my 400 Kawasaki LTD.

Worst intake by far was that RPM Air Gap!
I had to jet way up and really increase the pump shot to eliminate hesitation when you nailed the throttle.
You could nail it from a roll at 3000 and it would still stumble if you did not pour the fuel to it.

NO matter where the timing was at.
All my timing was in by 2400 and 35-38 total There was only 3HP difference on a wheel dyno between 35 and 38.

I tried many carbs and spacers with that Air gap intake.
I run 175cc Iron heads and have plenty of heat in them.
When temps got to 85 or higher outside then the stumble would be less and at 95 outside there was no more stumble.

It gets to -10 and colder here and I drive in that .
I eventually pulled that intake off and went back to the old RPM Intake and WOW! so much better.
I pulled a bunch of fuel out of it and downsized the squirters and was able to run an 8.5 power valve instead of the 10.5.
Zero stumble and much better MPG and manners.

Did I mention I hate that Air Gap intake.
I have it sitting in the shed collecting dust.

I have ran tall Tunnel-rams and the 300-25 Strip Dominator and never had an issue with stumble with those.
Only that Edelbrock RPM Air Gap.

 

[G72Zed]

Well, I seem to be well over my head at this point. Nothing I have done has worked. The car will be getting dropped off at a shop tomorrow that deals with Carbureted engines, old cars still and has a good reputation.

Perhaps having another set of eyes on it will help, and if they are good with carbs, they may have a know quality tuned carb to narrow this down for you. Again, some stuff leaving some companies have a lot to be desired in the QC dept....I've seen some stuff that would drive the average owner crazy, and 99% would never figure it out, even taking it apart and looking at it.

Good luck, hope they find the issue for you.

 

[serpent710]

Perhaps having another set of eyes on it will help, and if they are good with carbs, they may have a know quality tuned carb to narrow this down for you. Again, some stuff leaving some companies have a lot to be desired in the QC dept....I've seen some stuff that would drive the average owner crazy, and 99% would never figure it out, even taking it apart and looking at it.

Good luck, hope they find the issue for you.

Thanks, getting it back today. Can't wait! Then I hit the jackpot. The owner knows the guy across from his shop that has a dyno so we can finish up the tune now.

 

[G72Zed]

Good to hear this, keep us posted on the progress and results.

 

[djorgensen3]

Did I mention I hate that Air Gap intake.
I have it sitting in the shed collecting dust.

I have ran tall Tunnel-rams and the 300-25 Strip Dominator and never had an issue with stumble with those.
Only that Edelbrock RPM Air Gap.

Send it to me. I want to try one.

 

[jeff swisher]

Send it to me. I want to try one.

Grandmother lived in Peoria AZ and actually had grass in her yard!
She also had a Lemon Tree with Lemons bigger and sweeter than Oranges that we get here.
I may just have to box it up and I bet the temps there it will work well.

I parked my 82 Mustang under her carport in the summer for 2 weeks and the windshield wipers had kind of melted/stuck to the windshield and the rear tire had grown about 8" taller just sitting there BAKING in the shade.
The tread separated from the sidewalls.

SO hot and dry there.

 

[djorgensen3]

Yes it does get a bit hot here. Not uncommon to see 140+ temps inside the car when its parked and don't touch anything metal...lol.

What part of Peoria (if you can remember)? I am in the Northwest valley not far from Lake Pleasant.