Carter TQ - VERY rich at WOT...how to troubleshoot?
Congrats on using the best 4bbl ever made!
Got 600 hp on the dyno with a 440 & TQ recently, street driver, 900 rpm idle.
NICE!!!
I figured the 9801, despite the small 1-3/8" primary size, would be a great fit for my stroker motor which spends about 99% of it's time handling street "chores".
For '***** & giggles' I have the CS-4846SA Comp all boxed up and will eventually try it...but seeing as that is a race carb I just never seem to find the time to go through it, set it all up to just try it out.
The 5" of vac is the clue. Too high:
- make sure the secs are fully opening. Choke slightly on keep secs from opening.
- some times the air valve dashpot linkage can bind, especially if it has been ' adjusted'. I would disconnect it & test without it. You will likely get a slight bog, but at least you will know.
OK, I think my plan to disconnect the primary choke plate linkage will cover the 1st part and disconnecting the dasphot will remove that from the mix as well, good call sir!
Further re: dashpot. I have it set per the 9801 specs, it visually works when I blip the throttle and when testing with the vacuum hand pump (as in: it keeps the vacuum - so no leak - and once that's removed it releases the pot in the allotted timing - which escapes me at the moment).
- make sure the sec air bleeds are not blocked. All of the 6XXX models I have come across have 039-040 bleeds; later 9XXX models had 029 bleeds. I enlarge to 039. They run harder.
- control sec operation with the AV spring. The factory 1 1/4 turns is too soft, 1.5-2 turns is better.
Carb is always pressured air blown through each time I touch it. One of the first things I did so far was to see if the air bleeds were obstructed in some way, the matching drill sized passed through w/o any problems, so I think I should be fine, but of course that's hard to guarantee w/o pulling the carb apart.
Re: secondary bleed sizes. Hmm, the measured sizing I noted on this 9801 carb is: 0.039", so I think that's already in the ballpark. I assume by saying "later 9XXX models" you perhaps meant the factory stuff? To be honest I can't quite tell just how 'different' the 9800 series (Aftermarket) carbs really are. There are some obvious differences, but otherwise the basics circuits are all the same...
Agreed on the AV spring, but I will say this: with my 4K stall converter and the 4.10 gearing I have consistently been able to run with literally just 1 turn...which all my previous experience dictated would be nearly impossible. Still, I tightened this back to 2 turns (and the 9801 specs call for that anyways) just to rule that out.
- if you have bigger n/seats, you have to lower the float level, because bigger n/seats raises the fuel level.
YES, I am using 25P-1103, which is just a single step up to 0.110" size. Seeing as I have never noted the need to drop the floats further, what do you recommend? Right now the stock setting which I am using is 29/32.
I really question the need to change the float setting because the orifice size only controls the volume that will pass through during specific time period (assuming the same fuel inlet pressure). This simply means that the bowl will re-fill faster but ONLY up to the level determined by the float setting...so if that stays at 29/32 it means the bowl gets back to that 29/32 fuel level faster. You get my thinking?
- the o rings in the main body near the pri jets. If they leak, you get a rich mixture...very rich. I NEVER use the factory rings, a poor design. I use ordinary fuel resistant 5/16" o rings, 1/16" thick.
Seeing as over the years I've amassed a pretty good assortment of parts, I have been using the X-style rings, which were a later model year change to the original O-ring. Some of the kits did actually have a yet-another-style which just looks like a square thick O-ring....but definitely NOT round or X-shaped.
If all the other non-invasive changes fail to produce the desired outcome I'll eventually pull the carb open and will replace these.
- the plastic pods under the main body. If they leak AND the gasket is not breached, you get a clean idle but very rich off idle; that is because fuel fills the cavity in the alum base & it acts as a 'reservoir'. If the gasket is cracked/broken between the pod & the t/bore, fuel will flow continually into the bore direct from the fuel bowl. Any question about the integrity of the pods, I would re-epoxy them.
So in a sense I suppose I've always had great luck with this. Never had to replace one yet, but like they say "first time for everything"...
I think I am OK because my AFR reads nice until I go WOT, meaning: I get a decent 14.3-7 highway cruise, around town I'm between 13.7-14.2 but when called upon to give it a bit more gas (but NOT WOT) I'll dip into the high 12s, so that's about right where I would want to be...maybe a little richer off-idle would be nice, which I had when using the smaller 0.040" idle circuit air bleeds, but which went leaner moving back to the 0.054" that's the OEM setup (which was to be expected).