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Old 07-07-2017, 09:10 PM   #1
Alaska Jim
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Default tri-power problems

As many of you know , my 1930 ford coupe has a 272 "y" block in it with 3 94 carbs. I bought the car as a fresh 90% finished build. the car was only running on the center carb when I got it. the end carbs had block off plates between the carbs and the manifold, and the banjo fuel fittings plugged. It also had the power valves plugged in the end carbs. when I got the car it was running lean. I pulled the tops to all 3 carbs and found that they all had # 51 jets, and the 2 end carbs had the power valves plugged. I changed the center carb jets up to # 56's and It seemed to run pretty good. well I finally got the car out of winter storage, and decided to enable the other 2 carbs. ( running straight linkage--all 3 at once ). I pulled the tops off of the end carbs and switched the "51 jets to # 46's, and put it back together. started it up and it seemed to run good, no black smoke indicating it was rich. shut it off a few minutes and repeated the start-up. seemed to run good so shut it off. came back a couple of days later and decided to take it out for a test drive. well , the darn thing started loading up right off, blowing black smoke and running to rich to even idle. I am not sure what the problem is. I suspect that with that much fuel right off on start up that maybe the plugged power valves may be leaking. we had previously checked the float level and all looked good, we took the tops off all carbs and checked for stuck needle and seat problem found nothing wrong. before I tear all the carbs off again to check the power valve in the center carb, and the plugs in the end carbs, I was wondering if anybody has any suggestions as to what my problem may be, and any suggestions as how to set the whole thing up, maybe I am overlooking something simple. I am not real familiar with the 94 carbs, however I am a retired mechanic and do know a thing or two, but it seems I have forgotten more than I can remember. any help or suggestions would be appreciated. If I can not sort it out, I will put it back to running on the center carb only, as I have had my brother build a bored and stroked 292 with a 2x4 manifold with a pair of teapot carbs, that we hope to swap in this coming winter. Thanks for taking the time to read this and as I said before, any help or suggestions are appreciated------JIm
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Old 07-07-2017, 11:55 PM   #2
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Default Re: tri-power problems

Do the end carbs. have idle mixture screws? If so they should be screwed in completely. Idle mixture to be set on center carb. What power valve is in the center carb.? Does it have a performance cam? Opening all 3 carbs. at the same time will drop vacuum suddenly and allow the power valve to dump fuel too soon. You may need to do a vacuum test and adjust the power valve accordingly. Be sure to use a power valve designed for the Holley 94 as the later style interferes with the inside of float bowl. Also the throttle plates on the end carbs. should be completely shut at idle. Charlie Price Vintage Speed is a great source for all your Carb. needs.
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Old 07-08-2017, 12:30 AM   #3
Alaska Jim
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Default Re: tri-power problems

Sid, yes the end carbs do have idle mixture screws and they are all screwed in all the way .no performance cam that I am aware of. builder said eng was completely stock, but it is an eng built from parts, numbers on block indicate a 272, but it has c1te truck heads , and front cover on it. the car was driving and idling fine on the center carb alone before I tried to enable the end carbs. I have not yet checked to see what power valve is in the center carb. the problem with the rich condition is at idle and above. if you try to let it idle it will die , it is so rich. I don't know if the fact that the two end carbs are now sucking air, even at idle if it affects the power valve in the center carb, I suppose it is a possibility. the car is stored at my brothers place 50 miles away and I will try to get over and work on it this week-end. I will double check on the end carb throttle plates being completely closed at idle. thanks for the suggestions, many things to think about. I have not run a muti-carb set-up since high school, a long time ago---graduated in '68. -----thanks again----Jim
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Old 07-08-2017, 09:08 AM   #4
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Default Re: tri-power problems

If you have a stock distributor in the engine, that will be part of the problem. A 57 or newer dizzy will solve that. Carbs; after you get the power valves sorted, I have had good luck with idle mixture screws by setting the center carb, then slowly open the end mixture screws about 1/8 turn to reach the best idle. A regular street carb may never close off the throttle plates completely. If they want to leak a little air, let them leak a little fuel.
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Old 07-08-2017, 09:30 AM   #5
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Default Re: tri-power problems

Jim,

If you switched to progressive linkage I think you would be happier. I would get a 5.5" power valve from Daytona in Florida, or Charlie NY on the Ford Barn. I have done these before with progressive linkage using #51 jets in the center carb with 5.5" power valve. Front and rear carbs were with blocked power valves, seated idle adj. mixture screws and 53 to 55 main jets. Also, you need to make sure the front and rear carbs have the plates closed with no or very little air getting by. If any extra airflow, the idle mixture screws on the center carb will compensate for it. Do all idle speed and mixture adjustments on the center carb only.
Worked for me. Charlie NY probably has more experience and knowledge though on 94 carbs, although I know them too.

The #56 main jets in the center carb sound too big to me.

Sal
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Old 07-08-2017, 11:48 AM   #6
Alaska Jim
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Default Re: tri-power problems

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Thanks for all the suggestions fellows, I will ck things out as soon as I can get back into town to work on the car. your help is appreciated, thank you---Jim
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Old 07-08-2017, 12:49 PM   #7
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Default Re: tri-power problems

It's been over 15 years since I ran a tri power on a stock 55 292 in my bird, but sal's comments jogged my memory. Pretty much the same as I remember. Later model power valves screw in but don't seal properly, so keep that in mind down the road. When you get it sorted out go over to Ted Eatons site and see this test run on 3x2 intakes. It's on his dyno mule which is a pretty stout motor, but it will be interesting to read.

http://www.eatonbalancing.com/2013/1...ntake-testing/
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Old 07-09-2017, 07:08 AM   #8
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Default Re: tri-power problems

I've been running 3x2's on my 57 for about 8 yrs. During most of that time I was never satisfied with the way it ran. The problem I kept chasing was sealing the outer carbs. Never could get them completely sealed. I finally bit the bullet and purchased two end carb base plates from Vintage Speed. My experience is getting the end carbs sealed off is the key to getting it to run the best. The way I set 3x2's up is block off the end carbs and get the primary carb to run as good as you can. Next add one end carb, set that one up then add the final carb. Worked on my 57 with 94's and my 61 with Holley 2300's. My 57 292 is running a Comp cam and domed pistons. I ended up with 57 primary jets and 51 secondary. 4.5 power valve with the end ones blocked off. I'm running 1/2in spacers under each carb and fuel pressure is regulated to 3psi. Been trouble free for the last 4yrs.
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Old 07-22-2017, 09:22 PM   #9
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Default Re: tri-power problems

lowrider, thanks for the info. . I finally got into town and was able to pull the carbs. tomorrow if I have time I will go back and take them apart and recheck everything. may end up doing what you did. Thanks ---Jim
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Old 07-23-2017, 10:18 AM   #10
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Default Re: tri-power problems

We found the first problem, someone had jammed a 1/4 pile plug in, to block the end power valves. That really didn't seal anything, but ruin the carb bodies. Looking into fixing that and hopefully fixing it.
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Old 07-23-2017, 11:20 AM   #11
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Default Re: tri-power problems

If some one screwed a pipe plug in where the power valve goes, it will allow manifold vacuum to pull fuel out of the main wells through the holes that control the amount of fuel after the power valve opens, and suck it into the intake manifold on the front and rear carbs. You need the large hex head of the blank dummy power valve plug to seal it off to avoid that.
Unfortunately, who ever did that probably ruined the bowls unless you can fine a heli-coil for the power valve thread size, or successfully re-tap the threads to the original size.
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Old 07-23-2017, 10:07 PM   #12
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Default Re: tri-power problems

Fixed the end fuel bowls by retaping them. Whoever did it just put the pipe plug in by 1 thread or so. So now it runs with out all the black smoke, but now we are having idle problems. It has no progressive linkage and nothing to set the end carb against. No throttle blade stop, so I just laid them closed and set the center carb to adjust idle. doesn't seem to work, either idles to high or to low, can't seem to find a good spot. Also the end mixture screws are cracked about a 1/8 to 1/4 turn out, didn't work well, then tried seating them, didn't make much difference. I got more work to put into them. I suspect linkage issues.
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Old 07-24-2017, 10:26 AM   #13
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Default Re: tri-power problems

When I did a tri power with 94's I made adjustable idle stops for the end carbs using parts of the original choke linkage/lever. I know it's a little added expense, but progressive linkage will be a lot easier to tame and adjust. Need to completely close the throttle plates on end carbs, then turn in adjustment screw until it just contacts the stop, then turn in a hair, just enough to keep the plates from sticking in the bore, but not really increasing any idle air flow. Just a hair.
Either that or buy the new throttle bodies with plates that have a special angle on the edge that will not stick when seated.
If you use direct linkage like you have, you need to idle equally on all three carbs, which is tricky without a unisync tool.

If you are a machinist, it's no problem to make your own progressive linkage. I made my own carefully using no lathe or drill press. Just a vise and common hand tools and hand drill.

Sal
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Old 07-24-2017, 08:24 PM   #14
Alaska Jim
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Default Re: tri-power problems

Sal, what do you think about using the carb throttle base's offered by Charlie Price at Vintage speed ? they do not have any of the idle mixture screws or idle circuits. Do you think these would work with a tri-power with straight linkage? ( I know that most would do progressive, but I have seen this type set up in the past and it appeared to work ok, and the linkage on the car is already there and is straight.) Problems to set-up? just a thought.

Last edited by Alaska Jim; 07-24-2017 at 08:25 PM. Reason: more info
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Old 07-25-2017, 06:19 AM   #15
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Default Re: tri-power problems

In my earlier post about this I mentioned using base plates from Vintage speed. To me the key to a good running 3x2 set up is sealing off the outer carbs so they don't affect the idle quality. I've tried the special angled throttle plates in old bases without much success. The bases from Vintage Speed are a bit $$, but well worth it if your running 94's.
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Old 07-25-2017, 11:41 AM   #16
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Default Re: tri-power problems

Quote:
Originally Posted by Alaska Jim View Post
Sal, what do you think about using the carb throttle base's offered by Charlie Price at Vintage speed ? they do not have any of the idle mixture screws or idle circuits. Do you think these would work with a tri-power with straight linkage? ( I know that most would do progressive, but I have seen this type set up in the past and it appeared to work ok, and the linkage on the car is already there and is straight.) Problems to set-up? just a thought.


Jim,

You should be able to get it working OK with the direct linkage (all three at the same time) with the Vintage speed bases made for the end carbs. My description was basicly doing the same thing a cheaper way. I know my version will leak a slight amount of air, but with the idle stops, it will be the same every time, so the idle speed will not change. Buying the new throttle bases would probably be the best if you have the money. Either way should work. One thing nice about the Vintage speed bases is that they also have return springs to ensure returning closed.
The real trick is adjusting the linkage so when idling on the middle carb, you make sure the linkage attaching to the end carbs is neither pushing or pulling on the end carb levers. The idle speed and mixture screws need to be adjusted on the center carb before hooking the linkage to the end carbs. Wish I was there to help you with it. Wouldn't mind touring Fairbanks again. I was there at Ft. Wainwright in '70 and '71 before the oil pipe line days.

Sal
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Old 07-25-2017, 03:35 PM   #17
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Default Re: tri-power problems

Sal, I got here in '70, Jim got here I think ,75, anyway its way different here then way back then! Back to the problem.... We really didn't want to put a lot into perfectly tuning the 3x2's because it will be replaced with the 312 and 2x4's. we were just hoping it would run good enough to finish out our short driving season. I'm sure I can get them to run right, just have to get the time to get it done. I do want to say thanks to all that have tried to give us help.
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Old 07-25-2017, 04:14 PM   #18
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Default Re: tri-power problems

Sounds good Dennis and Jim. I'm kind of anxious to see how the 2x4 312 runs too.

Sal
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