ThermoQ -2 questions:

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70Hardtop

70Hardtop

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Is it Ok to ask two unrelated questions in the same post? Well here goes...!

Q1: Can anybody tell me what might be wrong with my almost new TQ? Lately, after just 24 hours -ALL the fuel drains away from the float bowl, including in the fuel line to the carb. So that it will not start unless i pour quite a lot of fuel down the primary throats. Then it starts easily. Or else half flatten the battery by cranking it to get the fuel pumped back into the float bowl so that the accel pump will work. When i mean "pour a lot of fuel down", i mean, considerably more that you would normally get from a few accel pump squirts. It has been hot here lately, but still...it never used to do this after just one day. Maybe after 5-6 days.

Q2: Please see picture of my Edelbrock Victor 340 intake. I want to run the new TQ mentioned above on this square bore inlet, i have the correct spreadbore to squarebore adapter...but is there any disadvantage to this? With gaskets, there will be almost an extra 1inch of height. I know i can't run the auto choke, which is a pity though.

thanks for any help on these, or if they have been answered on this forum previously, please point me in that direction

Victor 340.jpg
 
1. The fuel draining out of the bowls is most likely fuel draining from the bowls into the intake manifold. When you shut the car off, look into the primary venturis, and watch to see if fuel puddles on top of the butterfly valve. It is most likely coming from the poor seal between the primary venturi pickup and the plastic housing. Mine leaked real bad here, but it was because the aluminum venturi pickup was pitted. If this is happening, you may have fuel dripping from the primary throttle shaft onto the intake manifold, especially after the motor is shut down.

Screen 03.jpg


Screen 04.jpg
 
Hows your fuel pump? I had a 318 in a Charger do what you have described. It was a car I was selling and didn't drive regularly, but I always had to pour fuel in the carb (2 bbl). I put on a different fuel pump and it worked fine.

The spacer should be fine, wouldn't worry about it. Is it an open spacer? I would not recommend the 4 hole spread bore adapter though.
 
jimmyray said:
2. That intake has bolt holes (the inside 4) for a TQ, and the TQ may bolt right to it, although it looks like the rear opening may need to be dremmeled out to accommodate the TQ butterfly valves.
Click to expand...

That intake will not take a T-Q without an adapter. Do not try and dremel it out. Place a T-Q gasket on top , you'll see what I mean.

The 4 holes to bolt down the carb are not for a T-Q but for the earlier Carter carbs. The Carter carbs (all 4 of the 4 bbl's) have that bolt spaceing.
 
rumblefish360 said:
That intake will not take a T-Q without an adapter. Do not try and dremel it out. Place a T-Q gasket on top , you'll see what I mean.

The 4 holes to bolt down the carb are not for a T-Q but for the earlier Carter carbs. The Carter carbs (all 4 of the 4 bbl's) have that bolt spaceing.
Click to expand...

Good call - did not know that. I will delete that note from my comment!
 
Thanks guys! On the square-bore inlet first... i was actually looking for that bit of Jimmyray's but couldn't find it -then i read that he deleted it! You are right -i actually did sit the TQ on top and thus found it would not physically work without the adapter/spacer. It is not a 4 hole adapter, rather, it has two long slots which are sloped more on the secondary side for obvious reasons. I think it should work fine - the extra inch should be good for extra ram velocity, even if only a tiny amount? I will miss the choke though. As you would know, TQ's do like choke from cold start up. Even when the weather is warm.

Back to my fuel drain problem. I am fairly certain it is not the O rings you mentioned. (BTW, nice photo) I know exactly the ones you mean - i have pulled the carb down at least 4 times, and checked them twice. As i said this problem has only just started happening. I also did have that problem of fuel pooling into the primary bores -you could hear it trickling in after shut down - it took me a long while to work out it was not the carb. The culprit? The damn fuel tank was pressurizing so much due to the FECS (Fuel Evaporative Control System) being blocked, that the gas tank pressure was forcing the fuel through the lines and over-riding the needle and seat valve in the carb ! Easy fix was to install a vented fuel cap. Problem solved.

As for the fuel pump being the cause - someone else said exactly the same thing. Maybe something inside the pump is letting the fuel in the lines run back and this is pulling fuel out of the float bowl? But doesn't the TQ have something to prevent this from happening? That 360 is coming out soon -i'll make sure i put a new fuel pump on and see if that fixes it...
 
FWIW, the fuel in my line drains back to tank level very quickly after shut down, but it has never pulled fuel out of the carb itself. Now if the tank were under vacuum, it may pull the fuel below the tank level, but only until the vacuum was equalized. If you open the tank cap, fuel level in the line would return to tank level.

Since the fuel in the bowl sits below the needle & seat inlet, if vacuum was created in the carb it would pull air, not fuel (like a hookah).

I doubt that is the culprit.



70Hardtop said:
Thanks guys! On the square-bore inlet first... i was actually looking for that bit of Jimmyray's but couldn't find it -then i read that he deleted it! You are right -i actually did sit the TQ on top and thus found it would not physically work without the adapter/spacer. It is not a 4 hole adapter, rather, it has two long slots which are sloped more on the secondary side for obvious reasons. I think it should work fine - the extra inch should be good for extra ram velocity, even if only a tiny amount? I will miss the choke though. As you would know, TQ's do like choke from cold start up. Even when the weather is warm.

Back to my fuel drain problem. I am fairly certain it is not the O rings you mentioned. (BTW, nice photo) I know exactly the ones you mean - i have pulled the carb down at least 4 times, and checked them twice. As i said this problem has only just started happening. I also did have that problem of fuel pooling into the primary bores -you could hear it trickling in after shut down - it took me a long while to work out it was not the carb. The culprit? The damn fuel tank was pressurizing so much due to the FECS (Fuel Evaporative Control System) being blocked, that the gas tank pressure was forcing the fuel through the lines and over-riding the needle and seat valve in the carb ! Easy fix was to install a vented fuel cap. Problem solved.

As for the fuel pump being the cause - someone else said exactly the same thing. Maybe something inside the pump is letting the fuel in the lines run back and this is pulling fuel out of the float bowl? But doesn't the TQ have something to prevent this from happening? That 360 is coming out soon -i'll make sure i put a new fuel pump on and see if that fixes it...
Click to expand...

Screen 07.jpg
 
It could also be the jet wells, where those jets screw in, if you take the carb apart and flip the bowl so you can see the underside you will see two little round bumps, they are bowls that are epoxied to the main body, the epoxy gets old and breaks down, clean off the loose epoxy and smear a layer of JB weld or seal all around it let it dry completely. you can test the jet wels by simply puting gas,water, exc.. in it and watching for drips.
 
Good point, EL5DEMON, a common area for leaks.
 
EL5DEMON, that is a good point and would probably be valid on an older carb, but my carb is new -well, better than new actually (as a 35+ yr old 'new' carb would still be prone to seal breakdown). Mine has been properly rebuilt by a guy who knows TQ's inside and out. So he told me he has re -bonded that well area.

JimmyRay, thanks for those very clear diagrams -it has got me thinking actually -you may be right about the vacuum created etc. Maybe my float bowls are not vented and so it will suck fuel instead of air when the height levels fall. There is a very small brass tube sticking out of the side at an angle halfway up on the RHS of the carb. I have blocked that off - i wonder if that is the bowl vent. I will have to look at some diagrams. But that might explain it. BTW, my 340 with AVS in a previous car was terrible for this problem as well. Also, another fellow told me that Carters were well known for draining their fuel away over a few days
 
I will tell you in a day or so. I have pulled the rubber vacport plug off that needle-like port sticking out at 45degress from the plastic central body. I will leave it a day of so and see if the problem persists. I also found out today that another contributing factor could be that the accel pump doesn't work. At all. Even after its been running for 10 minutes. Yet the car still drives normally when warm. Its only when cold it has a slight hesitation. Aaargh...this carb might have been rebuilt but it is starting smell more like lemon rather than petrol. A few months ago i also had a frustrating problem with a leaking brass float.

When i pull this 360 out to put the 340 back in, i will pull the top off the carb. Hopefully it is only the internal tube from the accel pump that has come off.
 
That needle like port sticking out from the main plastic body is for the EGR valve.
No pump shot is ethier that tube inside like you think or the plunger is just simplely shot out. The OE plungers were leather and will curl up when dried out. Could be one or both items for the pump shot.
 
Rumblefish, yes i looked it up...EGR Venturi port. So its not that causing it. I would say it is mostly likely the fact that i have no accel pump shot. So of course this will give the indication of no fuel in the bowls, when in fact there may be. Th ecarb is freshly rebuilt so i would like to think the accel pump is operational. I pulled the thing apart quite a few times when sorting out the frustrating problem of the leaking brass float, but i know i put the accel pump tube back on. I can only hope it has fallen off. So i will say for now, that is what is causing my problem.

Longarm, thankyou for the exploded view, i have copied it into my TQ Info file, where i can resize it bigger.

Thanks everyone for their thoughts and suggestions, when i pull the TQ apart again and if the problem is obvious i will take a pic and post it
 
EL5DEMON340 said:
It could also be the jet wells, where those jets screw in, if you take the carb apart and flip the bowl so you can see the underside you will see two little round bumps, they are bowls that are epoxied to the main body, the epoxy gets old and breaks down, clean off the loose epoxy and smear a layer of JB weld or seal all around it let it dry completely. you can test the jet wels by simply puting gas,water, exc.. in it and watching for drips.
Click to expand...

This is most likely your cause. It can look OK but still leak. If you can't get them off just sand off the excess, rough up plastic and apply a thin line of JB Weld Epoxy all the way around the jet wells.
 
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