THERMOQUAD FUEL PUMP PLUNGER???

[Gold Rush]

When I bought my '74 SE eight years ago the TQ leaked like really bad! Phenolic main body was warped and I could not locate a replacement. Bought a rebuilt TQ from Summit Racing. It ran and didn't leak but obviously needed tuned. That helped but still didn't run the way I remembered my original '74 SE did. Some time later I was doing some research and found the TQ Summit sold me as an exact fit for the '74 400 N code engine was not jetted correctly. Luckily, original jets and metering rods were interchangeable. Did that with significant improvement. While apart I went ahead and installed the full "HYGRADE" rebuild kit.

A couple months ago I discovered pump nozzles were not squirting well at all! At an engine builder friend's recommendation, I got a Walker rebuild Kit. I went through the entire typical rebuild sequence, including soaking in solvent. Lucky for me I had stumbled onto a really good rebuild manual actually published by Carter. It provided procedures to functional test the pump before assembling the carburetor. I went through three plungers and also three bore check valves (even had to coat the valve plate with gas proof sealer) before I got squirt. Fully assembled the TQ and got it installed this morning. WHAT A DIFFERENCE!!!!

Now the meat of this post. I suspect during the initial rebuild process too much material was removed from the pump bore inner wall; thus not getting good plunger seal and also not sealing the bore check valve completely. I see several sources for just the pump plunger and check valve. Some of the old style leather plungers are even still available. Does anyone have experiences similar to mine and found better sources for the pump parts?

BTW Here is a link to that manual I found.... Manual

 

[T2R9]

Thermoquads are fantastic carbs when setup properly. You found the right resource and got that done. Enjoy!

 

[DodgeBoy5150]

When I bought my '74 SE eight years ago the TQ leaked like really bad! Phenolic main body was warped and I could not locate a replacement. Bought a rebuilt TQ from Summit Racing. It ran and didn't leak but obviously needed tuned. That helped but still didn't run the way I remembered my original '74 SE did. Some time later I was doing some research and found the TQ Summit sold me as an exact fit for the '74 400 N code engine was not jetted correctly. Luckily, original jets and metering rods were interchangeable. Did that with significant improvement. While apart I went ahead and installed the full "HYGRADE" rebuild kit.

A couple months ago I discovered pump nozzles were not squirting well at all! At an engine builder friend's recommendation, I got a Walker rebuild Kit. I went through the entire typical rebuild sequence, including soaking in solvent. Lucky for me I had stumbled onto a really good rebuild manual actually published by Carter. It provided procedures to functional test the pump before assembling the carburetor. I went through three plungers and also three bore check valves (even had to coat the valve plate with gas proof sealer) before I got squirt. Fully assembled the TQ and got it installed this morning. WHAT A DIFFERENCE!!!!

Now the meat of this post. I suspect during the initial rebuild process too much material was removed from the pump bore inner wall; thus not getting good plunger seal and also not sealing the bore check valve completely. I see several sources for just the pump plunger and check valve. Some of the old style leather plungers are even still available. Does anyone have experiences similar to mine and found better sources for the pump parts?

BTW Here is a link to that manual I found.... Manual

I love my Thermo Quads! When set up and functioning properly they are one of the best street carburetors IMHO!
Similar experience for me when I rebuilt this TQ for my Cordoba-- plunger check valve fell off into the bowl after a few drives and the plastic w/rubber plunger had too much play in the travel.
I ended up using some small dabs of JB weld steel epoxy to hold the check valve--has been good for a couple years now-- and got a leather plunger with no slop.
This has been a good place for TQ parts for me-- TQ, Thermoquad 4 Barrel Carburetor Parts

 

[Geoff 2]

I have used heaps of TQs, even have them on GM cars replacing QJs. The pump plunger rubber cup is too flimsy, poorly made. I had one, fairly new, that turned inside out. They are loose in the bore [ I doubt the bore has been enlarged ] & there is some delay/leakage before it seals....& starts pumping fuel. I use the leather seal when I can get them, & have used late model Carter AVS plungers [ modified ], 13/16" diam.

 

[Gold Rush]

Well, I've ordered a leather plunger. Anyone have some sage advice on installation tricks? I'm sure it needs to be wet but anything more???

TIA

 

[T2R9]

Soak it in some WD40.

 

[Geoff 2]

No, WD40 dries out. Use auto trans fluid or PS on it, it will lubricate it for the initial start up.

 

[Thrashingcows]

I'm another TQ lover and have been using them for close to 20 years on my mopars. My 68 T/C wagon has been sitting for close to 2 years and I fired it up last week...I have a TQ on it cranked a dozen times to fill the float bowels and fired right up, took it around the block and ran perfectly.

Been considering swapping a TQ onto my coronet to get rid of that OEM numbers Carter AVS that I can't get tuned worth a damn. Once under the big dual snorkel air cleaner you'd have to look pretty hard to spot it.

 

[RJRENTON]

Soak it in some WD40.

I use a silicon based lubricant on LEATHER PUMP PLUNGERS b4 installation......and even on neoprene or EPDM material.
BOB RENTON

 

[Gold Rush]

Thank You Everyone for the inputs. I really do appreciate the advice. Never have dealt with a leather plunger so your help makes my job MUCH easier!!!

 

[72sunroof]

I rebuild my thermoquads with a green o-ring inside the rubber plunger it pushes it out and is not damaged by ethonal gas, just in case I use it, drove over 2000 miles on it over the past 2 years and still gives a huge squirt.
With today's gas the leather will probably dry out quicker than they use to.

 

[Sixpactogo]

With a leather plunger, I would stay away from ethanol fuel. One tankful of that junk ate the leather plunger on my carb.

 

[Orig69]

I have used both the leather and the rubber accelerator pumps and they both work good when you get a good quality one that is made in the USA.
To keep my Thermo Quad healthy I only use 91 octane fuel which does not have ethanol.
When installing a Thermo Quad carb allways use an insulator.