I finally got a replacement for my old GF-432 filter. I installed it today and took the car out for a spin. I couldn't believe the difference! I had been convinced that I had bad problems with my valve springs. In the past my car would pull hard up to 4500 rpm then just slowly die. It felt like valve float to me, I was convinced that the springs were totally dead.
This afternoon after the change I was cruising around and met up with a buddy who has a 96 or 97 Z-28 (I can't remember which) we stopped and talked for a while then he said, "Hey, lets see what that decrepit old car can do." He pulled out on to the highway and spun his tires a little, I followed and pulled up beside him at about 35-40 mph. We signaled me to go, I jumped him about a length as we sped up he pulled up beside me but did not pull ahead until I was over 100 mph.
My car pulled strong all the way to 5300 rpm, no bog, no sag at all!
After he pulled ahead I slowed down immediately and and we both pulled over. He was amazed that an old car could stay up with his car for so long.
I didn't bother to tell him the secret was that at 35 mph my car still had some low gear left. His 4L60E, was stuck in second gear. It wasn't until he really started to wind up that he jumped ahead.
I know I wouldn't have any chance from a standing start. This is with me running a 450 cfm Holley Economaster! :U I wonder how the car will run when I put on my 650 double pumper?

 

And I thought I was undercarbed with a 570 Avenger,Steve.
My old Q-Jet rebuilt by Lars is going back on next week.

 

This brings up a good point. Where is the filter originally installed in a 78?

 

Joe,
I wish I had a correct 69 Q-jet to send to Lars. All I have is an parts store piece of junk Q-jet. I have a brand new Holley 650 DP with mechanical secondaries, and an electric choke (damn the mileage, full speed ahead) I tried to put it on last week, but there was no way my air cleaner was going to fit. I had the little economaster (also brand new) in a box on the shelf. I bought it from a guy about 18-20 years ago to put on my gas hog 4wd 76 Blazer. I sold the Blazer and and bought a Mazda pickup (I drove the wheels off that thing!!) The carb had just been sitting there, so I said to myself, "self, it can't be any worse than that POS Mystery-jet, let's try it!" It has worked admirably, it fired up the car as soon as it got full of gas and has been running good since then.
It cured my ultra rich condition that I have been struggling with since I put on that mystery jet carb.
I'm going to install my Vortec heads in a couple of weeks, so I'll need a carb that has an electric choke. I guess I'll find out how the Holley 650 runs then. I've got an air cleaner on order that is supposed to work with a the 650 Holley, so I guess I'll find out then. I'd really like to try out an Edelbrock/Carter with an electric choke with the Vortec heads and Vortec Performer manifold.

 

Steve,send the junk q-jet to Lars.
He'll check it out and tell you if he can do his magic.

My q-jet is off a 75 chevy,maybe a truck reworked by Bubba a bit to make it somewhat vettable!
Lars changed rods,jets,diaphram,tanked it,set it up to match my mods.
The cost was soooooooo resonable.$129!

 

It MAY be where there fuel line enters the carb - not certain.

 

I'm not sure where the filter is supposed to be on a 79, but I do know that the 69 had (2) filters. The first is a large canister type filter mounted on the A.I.R. pump bracket and an second sintered brass filter at the fuel inlet to the carb.
I replaced the large canister GF-432 with a "unbranded" replacement from Paragon Reproductions. I tried ordering a GF-432 from several sources and had no luck, finally found a place that had them listed at $150.00 with the disclaimer "if in stock, call."

 

the best flowing filter you can buy is, AC GF 61 P which was used on the 3X2 pontiacs and has 3/8 hose fittings on both ends. i have used this filter on many race engines. :chevy

 

Correct, in carb at fuel line. External filter rec. for performance.

:cheers:

 

Ganey,

If you add an external filter, would you remove the little filter inside the carb, or leave it alone?

Thanks,
-Pedro

 

Remove. Esp. the brass one.

:cheers:

 

Thanks, Ganey!

-Pedro

 

Pedro (and Ganey), if you add an inline filter you could certainly try removing the little in-the-carb filter - it is easily reversible. In 68 and 69 they used both. Also, I recall reading more than once people experiencing problems (flooding? too much gas?) after removing the little in-the-carb filter. I know, it doesnt really make sense to me either! Just be aware, and if you have problems just put the little filter back in.... or heck, put a new one back in - good opportunity to change the 99 cent filter! Also, all instructions for changing that little filter stress using 2 wrenches to unscrew, and being extremely careful when replacing to not cross thread the connection at the carb. MJ

 

Clem, would this fitler screw right into my stock fuel line? (68 bigblock). I have been looking for such a filter for 2 years!! Closest I came was the GF481 which "appears" to fit - the threads are the right size - but actually requires a special O-ring fitting. This is where lars stepped in and explained how to use this filter and fabricate a fuel line to fit. MJ

 

Clem is right: The Pontiac Tripower fuel filter is a nice flowing unit, but it has 3/8" rubber hose fittings (plain male nipples) on both ends. It will not accept screw-in fittings. You have to use a piece of rubber line with a clamp on the filter, and this is why I like to use the '85 Vette O-Ring filter.

Rubber line can be used with success on the pressure side of the system, but it should be checked and maintained. After seeing a few engine fires caused by pressure-side rubber lines (one of them on a Tripower Pontiac), I just don't trust rubber lines for a street-driven vehicle, and I use the hard-plumbed systems with screw-on connections on the entire pressure side of the system. Makes me feel a little more secure...

 

Thanks, Mark!

I think I'll try Lars' plan and install a cool inline filter. Will remove the small filter, but keep one handy in case I experience flooding or something...

-Pedro

 

you can cut off the raised part of the hose fitting and use swedgelock type fittings on the filter and fuel lines. these will not leak as these fittings are used on very high pressure. also any type of compression fitting will work. :chevy

 

I REMOVED THE IN CARB BODY FILTERS OM MY TRI POWER, AS ITS EASY AFTER AWHILE TO STRIP THE BODIES
OUT IN THE HOLLYS. THE SAME CAN HAPPEN TO QJETS. I USED A NEW 427/L36 IN LINE FILTER, AND
MOUNTED IT JUST LIKE THE L36 SET UP. FOR A 79, THE FILTER MOUNTS IN THE CARB BODY, JUST BEHIND THE
FUEL LINE :chevy

 

MELVIN, that is interesting - you have the tripower setup but you continue to use the rochester-style fuel filter with the fuel return line. For some reason the factory installed tripowers did not use the fuel return line. Any idea as to why the rochester carb needed a fuel return line but the 3 holleys did not? I guess it cant hurt to use the GF432 and fuel return line with the holleys, but GM didnt think it was needed. MJ

 

JACK. THATS VERY GOOD QUESTION. I DONT KNOW WHY THE TRI POWERS DIDNT USE A RETURN LINE (VAPOR RETURN LINE)? I WAS A LITTLE PERPLEXED ABOUT THAT ONE AS WELL. ANYHOW, THERE SEEMS TO BE NO PROB USING THE L36 FILTER WITH THE TRI POWER.