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-   -   64 GTO "Bucks" Under Hard Acceleration (https://forums.maxperformanceinc.com/forums/showthread.php?t=852371)

geeteeohguy 08-08-2021 07:40 PM

I would verify fuel delivery before going into the carb. Had the same issue with my '67 GTO twice.....first time was a collapsed sock at the pick-up, second time was cracks in the rubber line from the tank pick-up to the steel line letting the pump suck air. Also, you could simply have a low float level setting in your carb. It can happen. I won't even get into junking the trick distributor and installing a stock points and condenser unit, which I run in all my cars. No issues in over 40 years.

Koppster 08-09-2021 03:31 AM

Thanks everyone, lots to think about and some things to test.

Still wanting a part number or source for an air filter that works for the RPM Performer with a Quadrajet installed?

sdbob 08-09-2021 07:45 AM

I do not know how to diagnose electronic ignitions,no experience. I've kept points and condensers in all my cars.Worked for my life even racing. The SD distributors use only points unless you make a sleeve for a hei. For me it's simple. I carry spares in trunk.

Cliff R 08-09-2021 09:33 AM

Decades ago I swapped out my factory intake for any RPM.

The required a 1" shorter air filter moving the lid 1" closer to the carburetor.

Any attempt at full throttle and the engine just "puked" all over itself and refused to rev. Drove fine otherwise until you went to full throttle.

I removed the lid and it was fine.

So I made a custom air filter for the Shaker opening and run no air filter or lid, no issues........Cliff

padgett 08-09-2021 10:11 AM

Back in the day, Pontiac was notorious for limiting HP in lower line cars by playing with carbs and air filters. The "Firebird tab" is well known but limiting the A-body tripower with pretty but too small pots while the B-body got a single 1,000 cfm paper element.

Look at the brochures from back in the day. Same engine, same carb(s), same cam had different hp rating for each car line.

Koppster 08-09-2021 10:51 AM

Will this work with the 64?

https://butlerperformance.com/i-2445...tegory:1234772

Tom Vaught 08-09-2021 01:53 PM

My opinion, not without a bunch of work. Works great on Trans Ams though.

Tom V.

Koppster 08-09-2021 02:42 PM

Interesting, I don't remember having any air cleaner clearance issues with the Edelbrock, I had a 3 inch K&N filter on with that carb. What's different about Quadrajets?

Kenth 08-09-2021 03:46 PM

Quote:

Originally Posted by padgett (Post 6270766)
Back in the day, Pontiac was notorious for limiting HP in lower line cars by playing with carbs and air filters. The "Firebird tab" is well known but limiting the A-body tripower with pretty but too small pots while the B-body got a single 1,000 cfm paper element.

Look at the brochures from back in the day. Same engine, same carb(s), same cam had different hp rating for each car line.

Still, the highest horsepower Tripower 421īs got the "small pots".

Also, different hp ratings , same engine, for the car lines was due to the 1 hp per 10 pound insurance policy.

FWIW

steve25 08-09-2021 06:06 PM

Kop, before he spends hard earned money on a new filter set up why the heck has the car yet to be test driven without a air cleaner assy to see if the problem is still present?

Koppster 08-09-2021 06:51 PM

Quote:

Originally Posted by steve25 (Post 6270960)
Kop, before he spends hard earned money on a new filter set up why the heck has the car yet to be test driven without a air cleaner assy to see if the problem is still present?

Steve, I spoke with him today. He is going to do the following:

1. Run without an air filter

2. Run with fuel filter removed

3. Run with secondaries locked out

Not buying anything until we narrow it down, just thinking ahead.

Thanks,
Rick

Cliff R 08-09-2021 09:09 PM

Good plan. In any and ALL cases troubleshooting saves time and money.

My bet is that things will improve if you simply remove the air cleaner lid......

Ceopro 08-11-2021 12:07 PM

Higher volume fuel pump
 
Try a higher volume mechanical fuel pump like 110 gpm with the same pressure, say 6psi. Also, make sure the rubber hose coming out of the fuel sender to the metal hose is the right size. Best to just put on a new piece of hose. These two things stopped the bucking at higher rpms in my 65.

z man 08-11-2021 02:51 PM

Fuel
 
After eliminating the air filter, you could consider an inline 12v electric fuel pump. This will push some extra fuel to your starving carb under load. The extra 5-7 psi will not push through your inlet valve and cause flooding. You can flip the switch and use it on demand. To priming a cold engine before starting to feeding the engine under high RPM

goatman1970 08-12-2021 08:26 AM

look for a drop base for your air cleaner, that will allow you to put a 3" air filter in it

KEN CROCIE 08-12-2021 11:52 PM

Will somebody tell this guy to put a temporary fuel pressure gauge on this thing.

Koppster 09-05-2021 02:24 PM

Friends:

I drove down to FL to help my brother troubleshoot. We have a winner and several of you had it pegged. Took the 1 inch air filter off and it ran like a r@3ed ape. Put the filter back on and the buck started again.

I am so embarrassed, I would have sworn I had tried that years ago. We even found an area on the filter that had collapsed a little under acceleration presumably.

We also put a fuel pressure gauge on it, reading 3.5-4.0.

Going forward will have to find a drop base filter that works or go with something besides the Quadrajet.

Thank you ALL for your patience and assistance.

Rick

steve25 09-05-2021 02:31 PM

Great news,, but he may not be out of the Woods yet!
Is that pressure reading at idle, or full throttle and 5000 rpm?

Koppster 09-05-2021 02:35 PM

Quote:

Originally Posted by steve25 (Post 6277793)
Great news,, but he may not be out of the Woods yet!
Is that pressure reading at idle, or full throttle and 5000 rpm?

Idle and full throttle, not sure what rpm, I was working it under the hood.

steve25 09-05-2021 02:38 PM

I think Moroso Offers a drop base cleaner and some other company make just the drop base, but there not cheap, but then again any thing that can add even just 25 hp, no less maybe 50 to any motor is well worth 100 bucks!


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