[Jay S]

That makes sense. 28* average drop in fuel temp is a substantial difference. I would think that much cooler fuel would help keep the fuel from evaporating out of the bowl also, that might be part of the difference I have seen. Hard to put a number with that.

[geiser]

Hey guys, reviving post... sorry

I just picked up a 4846s and unfortunately, PO removed choke parts long before I got it. I would like to source those parts if you know of someone who might have pulled for a race application etc. This is the 850 competition version and needs all the manual choke parts, these are on the drivers side. Cable attachment, scissor spring, linkage, choke (gate?) /valve. Part numbers alone might be helpful, as available info seems slim, at best.

[carbking]

I would suggest planning on running it without choke; and if you like it, keep on the lookout for another that is complete.

The choke parts for the 4846s and 4847s are UNIQUE to these two carbs. I have several which have no choke for which I could use chokes. We sell the carbs both ways (with/without) but the ones with the chokes bring significantly more.

Jon

[carbking]

Geiser - regarding your comment that information is slim.

Carter did NOT (at least to my knowlege) publish either a catalog page or a TFN (temporary field notice) on either the 4846s or 4847s.

The original jet/rod calibrations are listed in the earliest of the Carter Competition Manuals.

The only other information I have seen is on the original drawings, which so list part numbers, but are very difficult to read.

Jon

[70GS455]

As carbking mentioned the choke pieces are unique for the comp series; most of the hardware is moved out of the airstream, vs the production ones with hardware that is in the airstream. Wonder if production pieces can be adapted to fit?

Sent from my SM-S901U using Tapatalk

[carbking]

Here is a picture of the choke components:



When Federal Mogul bought Carter circa 1985, I had first refusal on parts inventory. I bought ALL of the comp series TQ parts left.

As far as adapting other thermoquad chokes: I don't work with the newer stuff, but don't remember other TQ's with manual choke.

Jon

[carbking]

The Competition Series Thermoquad was initially sold as a race carburetor.

The Buick folks fell in love with these, and the folks that supplied performance parts to the Buick folks recommended removing the choke, even milling off the choke butterfly housing. Works well for trailered drag cars, works less well on street driven cars.

Of the Comp Series TQ's, I would guess that less than half still have chokes. I only have about 25 or so left, and less than 10 have chokes.

Jon

[70GS455]

I was able to Dyno test a "poor man's" comp series 1000. It was a production 850 that had the outer booster ring and the bowl venturi both removed, just like the CS1000. Did real good on top end but mid and low speed manners could've been better

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[Skippy597]

Jon,
Do you still see the 9800s as a viable performance carb? Even over a quadrajet such as a 17057274? How about on a pretty hot 400 with a 4 speed I'm putting together?

Thanks,
Ryan

[carbking]

Ryan - I have sold several hundred of these, mostly to replace Q-Jets.

Of these, 2 customers had issues because they incorrectly wired the electric choke.

2 other customers sent the carburetor back because of idle issues (we have spiders in Missouri). After we cleaned the idle circuits, sent them out to other customers (at a reduced price as they were no longer "factory" remans).

Have never had any complaints about performance.

If you think about it, the 9800s comes from Carter as a high performance carburetor (high performance street, and some amateur week-end racing). Most Q-Jets one is going to encounter at less than very high prices were built for grocery getters. Yes, there were some built for performance street from the factory, but today those are not going to fit my condition about price.

So the TQ is going to be in a more performance oriented state of tune than a stock Q-Jet.

Now, if Cliff breathes on the Q-Jet, his Q-Jet will probably be slightly better than an out-of-the-box 9800s TQ, but just barely. If you can find it, read the test article on the TQ by Jim Hand.

If whoever the current TQ guru is (I no longer work on carbs) breathes on the 9800s, I would expect the results to be 2 point 8 percent better than a Cliff Q-Jet. This is what testing on the TQ demonstrated when both were tested in the 1970's. The 2 point 8 percent because of the thermoplastic bowl.

Personally, I replaced the Q-Jet on my personal GTO (1974 with a "slightly" modified Pontiac 350) with a 9800s. Was quite happy with the carb AFTER the engine warmed. With the 455 HO intake and NO crossover, plus an aluminum flywheel, the engine would not idle until maybe 20 minutes of run time (not fun in city traffic). Being older than most speed limits, my "heel and toe" technique is not as good as it was in the 1960's. Replaced the 9800s with an 850 CFM TQ (4846sa) with MANUAL choke, and again was a happy camper.

And for you doubting Thomases, an 850 CFM spread-bore is NOT too much for a 350 engine.

Jon

[Skippy597]

Thanks Jon.

I went over and read your thread on the HAMB also and pulled out my Jim Hand book and read his article on the thermoquad.

I'm pretty convinced to try one but I am having trouble understanding the warm up issues with the 9800s. Since these are electric choke wouldn't these be superior for driving your cold engine. Or couldn't one just adjust the choke so it sits cold with it slightly open to help alleviate these issues?

[carbking]

Ryan - my GTO had more problems with the choke than most will.

The electric choke is timed, that is, it will open in a fixed time, regardless of temperature of the engine.

The hot air choke depends on air heated by engine exhaust, so it will open more responsive to the temperature of the engine.

In my case a Pontiac 350, a RAIV cam, a 455 HO intake with NO crossover, long tube exhaust, and an aluminum flywheel is a recipe for demanding the engine being at operating temperature before a decent idle.

The big advantage of the electric choke is being able to run aftermarket intakes with no provision for a hot air choke.

Jon

[Skippy597]

Ok understood. But the 4846sa is a mechanical choke correct? So if one wanted to do some performance experimenting that would be the one to go with?

[carbking]

Originally Posted by Skippy597

Ok understood. But the 4846sa is a mechanical choke correct? So if one wanted to do some performance experimenting that would be the one to go with?

If cost is not an issue, then maybe, depending on what you are trying to do. The 4846s was sold as a race carburetor.

Give me a ring at 573-392-7378 (9-12, 1-4 Mon-Tues central time) and will be happy to discuss it with you.

Jon