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-   1980 - 1986 Bullnose F100, F150 & Larger F-Series Trucks (https://www.ford-trucks.com/forums/forum37/)
-   -   Dad's Carb Choice (https://www.ford-trucks.com/forums/1299808-dads-carb-choice.html)

RL250 02-27-2014 05:04 PM

Nice. I bet your build gets finished first. I'm going with either a Street Avenger or an Edelbrock Thunder series like Tim recommends.

Gary Lewis 02-27-2014 06:26 PM

If I hadn't stumbled onto the Street Demon it would have been the 1806 625 CFM Thunder. It is a good carb, for sure.

85lebaront2 02-27-2014 07:29 PM

If I had stayed carbureted, I would have either used the TQ or the 735 Holley I have.

Gary Lewis 02-27-2014 08:15 PM

Do you consider the TQ better than the Street Demon? If so, in what respects?

85lebaront2 02-27-2014 08:28 PM

I like the throttle linked primary metering rods and the damped secondary air valve, not to mention the ability to service it without removing it from the manifold.

Gary Lewis 02-27-2014 09:01 PM

Those features sound good. But I'd still want the TQ to have an e-choke and haven't found one of those in my searching. And, many TQ's I've seen in pictures have a lot of attachments, like solenoids, that I don't need. Are they easily removed?

85lebaront2 02-27-2014 09:58 PM

Yes, they are bolted on. As for an e-choke, why not steal a choke housing off a MonoJet, they are riveted or screwed on and have a link that connected where the old divorced choke went on the original 1968 model. All it would need is to make sure it worked the right way and had enough travel to emulate the Chrysler well choke. Since you are using a manual transmission, throttle linkage only needs to be able to open fully, no worries about kickdown or TV pressure.

Do you want this Chrysler one I have?

Gary Lewis 02-27-2014 10:18 PM

So, I could clean up a TQ and add e-choke. Didn't realize part from a Monojet would fit. Didn't some of them have a vacuum pull-off as well? Hmmmm.

A Chrysler TQ? I thought it was a Ford 460 TQ. How big, as in CFM is it? Or, off of what? Yes, I would be interested if big enough and serviceable. Shoot me a PM on price, please.

I think you said some TQ's used 3-step rods. Does this one? I have some Carter jets and rods to tune with, but not 3-step. And, is there any reason why tuning one for Rusty's 351M wouldn't be at least a starting point for the 400?

85lebaront2 02-28-2014 07:01 AM

1 Attachment(s)
Gary, we have to go to Salisbury MD today (1 1/2 hours each way) for a Drs. appointment for Mary. Tomorrow or Sunday if it warms up, I will get pictures of it.

The MonoJet had a built in pull off in the air horn, later ones were external. The e-choke on them is nothing but a housing with a heated coil in it that is connected to the choke shaft with a link.

85lebaront2 02-28-2014 08:21 AM

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Gary, here's a better picture of the choke linkage.

Gary Lewis 02-28-2014 09:09 AM

Thanks, I'll read and ask questions later.

Gary Lewis 02-28-2014 09:42 PM

Bill - Hope the doctors appointment brought good news. Lots of driving for one, but you said previously it is necessary so I believe you.

On the carb, I have a book on Rochester carbs and see how the MJ's choke works, but other than my 69 Dodge shop manual I don't have anything on TQ's so will have to search for info on them. And thanks for your help.

Gary Lewis 03-03-2014 09:58 AM

No one has suggested a QJet, even though the are available in a reman'd config: Jet QJet. Why is that?

I've been doing a fair bit of reading about the carb selection issue and will share some of my thinking:
  • Parts: The availability of spare parts varies significantly, with Thermoquads having the least and the Edelbrock and Street Demon the most since they are in production.
  • Tuning: From what I've read Carter didn't make a Strip Kit for the TQ, so I'm not sure how easily getting a variety of rods and jets would be. But I have a kit for the Edelbrocks, and a few rods and jets for the QJet. And, a kit is available for the Street Demon.
  • Economy: I'm guessing that the TQ, QJet, and Street Demon would be neck and neck due to the small primaries and boosters, and the Edelbrocks would trail a bit.
  • Power: Properly tuned the TQ, QJet, and Street Demon 750 should be basically the same as all are roughly the same in CFM. A 750 Edelbrock would be essentially the same, but it would give away some economy and off-idle throttle response. Or a 625 CFM Eddy would get some of the drivability and economy back, but lack WOT power.

But, I'm looking for your thoughts and input as I may well be missing many issues and have some assumptions incorrect.

85lebaront2 03-03-2014 11:58 AM

Actually, I had mentioned the Q-Jet early in the discussion. Items to look out for:
some Q-Jets, notably Chevy models had a deflector under one of the secondary nozzles on the baffle plate. This was to correct poor mixture distribution in their manifolds.
Some of the later pre-feedback models had a mechanical lean stop on the power piston, might be useful.
Some of these (mostly truck) had an additional primary nozzle above the main one.
Some of the later ones also had air passages that picked up above the boosters and went under the throttle plates to allow more idle air flow and keep from having pull-over issues (try to balance the needed idle air on a 500 ci Cadillac and the transition point to main feed).

Additional items, an e-choke housing can be installed on pretty well any Q-Jet. CFM on most is around 750, the special applications like Pontiac's SD 455 have much bigger primaries. The normal flow is about 260 CFM on the primaries. Q-Jets, need a good fuel supply, the bowl only holds approximately 1 tablespoon of fuel.

Ford used a Q-Jet on the 1970-71 429 CJ Torinos and probably the Mustangs in 71 (1970 still had a 428 CJ in the Mustang).

I used an early (1966 Buick Riviera 401) Q-Jet on my Falcon when I first started building it up.

Gary Lewis 03-03-2014 12:54 PM

Sorry - I forgot you recommended the Q-Jet. And thanks for the tips.

But, do you agree with my thoughts about parts, tuning, et al? Or, maybe I should ask how you would rank those four carbs?


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