Installing the Tri Power, hooked up the carbs today!

60s Refugee

Well-known member
This morning was to be the morning of mornings. After rebuilding the two 1904's I couldn't wait to install them. Everything went fine. Got the carbs on, got the fuel lines hooked up, got the linkage adjusted. Engine started right up too, but, it was idling at 2600 RPM! No leaks, and the throttles were at bottom, but still high idle. I turned in the idle screws on the outer carbs and it slowed down some, but even with the screws full in it was still ldling at 1800! I left the center carb setting alone. The linkage does look like it is pulling the outer carbs clear shut, but something has changed. Oh, by the way, when I got home and shut 'er off I got a backfire. Obviously too much gas from somewhere.

So, just what is the process for setting the carbs on a tri power? I have a syncronizer gauge, but not much else to go on.

After I get this thing tuned I will post new pick of the lines and linkage, besides its been raining/storming all day and couldn't get the shots today anyhow

Harry
 
It might be linkage after all, Bort62. I just went out and took a good second look. The throttle on Charlie is not fully closed, maybe a heavy 1/32" open. Almost closed, but not quite. I see that what amounts to a fast idle screw on this set up prevents the Charlie throttle from fully closing. I again verified that the floats are closing OK and there isn't any raw fuel flowing in. I also noticed that the progressive link inhibited full close by about 1/4" in the Bravo carb throttle. I unhooked the link, but the idle is still high. I turned in the idle screw in on the center carb and the idle drops, but it was perfect before I hooked up the other two. I turned it in far enough (about 1/3 of a turn) to get down to 1000 RPM idle and have left it that way for the run to the shop tomorrow. All things being back where they were, the only thing different is #3 being cracked open. Oh yes, one more thing, when I returned the air filter to #3 the idle increased! It made no difference with the #1 filter.

So, do you suppose that #three throttle is the culpret? Even with the idle screw turned full in?

I don't have the tools here at home to do much. I'm just wondering what to look for back in the shop tomorrow.

Thanks
Harry
 
lucky you, mine had a major hemmorage today. fuel spilled onto my intake and ate the paint, flooded my log and that was just cranking over, it never fired. i checked my float level and it was WAY off.

anyway, congrats! i guess this means you arent going to use 1100's after all?
 
I might be closer to using them than you think. Today I will try to set the things up correctly. If I can't then I'll agressivly atrtempt to get a third 1100 and swap 'em. I may be dealking with several issues all of which might be related to the 1904's and the fact that they are so heavily modified.

Harry
 
Well, I have no experience w/ multiple carb setups so take what I say w/ a grain of salt.

However, I would think that you want the throttle plates on your auxillary carbs to be comepletely closed at idle. If one of them is cracked open, that is going to act as a vacuum leak and cause your idle to run high.
 
Today I adjusted the linkage. The outer carbs are connected by a common link and if it's too long or too short the throttle plates arn't in sync. I took in some slack so now both throttles run the same (both closed at same time, both run to open the same). Then I adjusted the progressive link so that it wasn't holding the center throttle open at zero throttle. Everything looks good with the linkage. I could use a stronger return spring and will address that tomorrow.

So, I looked through the letter the original owner sent me with the head. I also found the directions to the Offy manifold he modified (El Pajarito! If you would like a copy of it let me know!) First off, his letter said to turn all three idle screws in and back them out all the same until you get 500-550 RPM at idle. It said to begin with about 1/2 turn. Then he said to use a vacuum gauge and set center carb to best vacuum. Then, take the synchronizer and take a reading. Adjust outer carbs to match center carb. I presume that means using the idle screws 'cuz there's nothing else to adjust! All three should read within one mark of each other. The directions with the synchronizer are useless for American cars. He also said to connect up the accelerator pumps on the outer carbs if it boggs down on accelleration. It did, so I hooked the pump cams back up and that took the bogging down issue away.

So, I look in the drawer and can't find my vac gauge! Crap! Who borrowed it this time? I'm stuck till I get a new one. Probably the same guy who has my old compression gauge! As it is right now, I can't get the engine to keep running at idle under 1000 RPM. The carb synchronizer shows a reading of 7 on 'a', off the scale past 20 on 'b', and 14 on 'c'. Wow! Can that much be adjusted out? I finally adjusted all three screws the same, getting my idle to around 1000, and it ran pretty bad on the way home. I also reset the static timing to 6*. Not much effect there.

I wonder if different cfm ratings create different synchronizer rates.

I read through the Pony Carb book also. It says 1904 Holley carbs are rated at 170 CFM. Considering that the center carb is a 1100, and it is 185 CFM, that puts the total CFM at 525. I wonder if that's too much carb? I wouldn't think so considering the cam, bigger valves, porting, header and all.

Falcon Fanatic, before I drive tomorrow I will disconnect the outer carbs, turn the screws in, and see if I can get the idle back.

Harry
 
Hey
Jessica has 3 1100's on her 200. There was a lot of messing with linkage and jetting involved. We had to do a bit of grinding on the Offy adapter to get enough clearance for the linkage at idle. The short linkage that attached to the carbs that came with the adapter were junk. I do not think the adapter was intended for the 1100s. We dug up some stock 6 linkage pieces and it was better. Just make sure that everything is closing as far as possible and start from there. We started with the crap 1100 in the center that came on the car. Just a bad worn out 1100. Always ran rich until we found a 1100 off a 240 truck motor with a manual choke. The outer carbs are off a 170 six with manual chokes. We are in SoCal so really do not need a choke so never hooked up the center carb choke. Runs great now and is stupidly reliable. We went with the 1100s because they were cheap and available. We got the jets off of Ebay. It gets 20 to 23 mpg on the highway with the T5. It takes a lot of messing to get it to run right. We have not synced or adjusted the carbs in months and it is her daily driver. Once you are set up it is amazingly reliable, quick and fun.
Good luck
Greg (Jett's Dad)
 
Well Greg, that's great to hear. If I can't get these 1904's to work I already have another 1100 to rebuild. I still need the third.

The Offy manifold I'm using was heavily modified. He only used the ends of it as bases for the carbs and linkage pivots. The center section is completely removed! There isn't really any 'linkage hitting the engine parts' stuff going on.

Where does your set up idle at? Jet sizes?

Harry
 
These are a pain to set up - definitely not for one lacking in patience.

Are you running progressive linkage or all three straight up opening at the same time?
 
Its progressive. As you observed, the outers start to open at about half throttle. They all reach WOT at same time.

This evening I went out and unhooked the linkage and closed the idle screws on A&C. I tried to get a smooth idle below 1000 and failed. It is rough, there are fumes, and it dies. Didn't have this before I removed the blocking plates and exposed the outers to the open log.

Harry
 
The outer carbs are basically two huge vacuum leaks, so you have to get them to idle as well as the center. In a perfect world the outboard carbs would seal up nice and tight with the butterflies closed and the throttle shafts wouldn't leak, but that's not the case with these 1904s.

The float level might be off, too. I had a heck of time setting mine. I'm running Holley 1904s on the outer and 1960 center. I had to set the float level by sight using glass bowls. Don't know how else I could have done otherwise. Using the gauge that came with the kit, all 3 flooded. Measured where the center carb didn't flood; set the outers to the same level, one was too high and the other dumped fuel out the vent. One carb no matter what I did wouldn't set right until I turned down the fuel pressure to 3lbs. Do you have a fuel regulator? 1-4 lbs?

A week later after I got the float levels set, glass bowls to stop leaking and wondered why I didn't go with Webers, I cracked the idle mixture screws about 1/4 turn on the outers and the center is about 2 1/2 turns. I tweaked them a bit here and there to get the best vacuum reading off the manifold. Had to leave the throttle stop screws in because the outer carbs don't leak vacuum the same amount. So I used the throttle stop screws to sync them. Have you checked for vacuum leaks?

And I had to move the accelerator pump rod on the center carb to the outer hole and she runs okay. Idles like crap, but I think the center carb needs modifying with the air bleeds because no matter which Holley I use they all idle rough. Used a known good Autolite and idled much better! Running 67 main jet center and 51s outboard. Plugs look okay. Adjusted the timing until it quit pinging. That's where I'm at today, 3k miles later still runs okay. Next I'll hook up an A/F meter...
 
Harry
Jessica's car idles at around 700-800 rpm. We had trouble getting it that low. Had to make sure all the linkage did not bind to get there. I treat the outer carbs like the center. They are all drawing through the sync gauge the same. Like a multi carb motorcycle. The idle and mixture screws were all adjusted for the best idle and when one is adjusted everthing else changes. It is a bit of a juggling act. We do not have really strong springs holding the outer carbs shut, just the ones on the carb itself.
From memory I think the center carb jet is a 62 and the outers are 56s. We had the carbs apart to swap them so many times I am not completely sure. The center carb does have a larger Venturi than the outers. We stopped pulling the whole carbs off towards the end and just pulled the top off the carb to switch jets. Dropped a small piece of metal in the motor off one carb and did not realize it until we started the motor. Amazing how nasty the sound is of one small piece of metal bouncing around on top of a piston. Luckily no damage, just had to pull the head to get it out. Probably would have been quicker to pull the complete carbs for the rejetting.

Good luck
Greg (Jett's Dad)
 
Mine runs solely on the center carb at idle with the idle screws all the way in on the outers and no choke plates. I have extra return springs on the outers to hold them shut-just mild acceleration would sometimes open them up from the vacuum pulling on them or from the linkage binding. I have also been using a dry bicycle chain lube on the linkage and that seems to help things operate much better without attracting much gunk. I have never synced them as they are only used on demand and don't get touched for normal driving. Get the car running on the center one-if the idle screw needs to be backed out more than 2 and a half turns, you are too lean. Less than a turn to a turn and a half, you are too rich(idle)
 
Those helmit air filters are too tall for a Mustang hood. If I did use them, I'd rename the carbs Anton, Bruno, Caesar (turret names on the Bismarck).

Greg, I thought I had lower venturi outers, but turend out they are bigger than I thought. !904 have 170 CFM. Center carb 185. Not much diff. When I find a third 1100 I will try those.

So John G, you say to close off the idle on the outers. I'll try that. I'll add an extra spring on the outers too. I oiled the linkage with motor oil. I'll try grease.

jahearne The book says to turn the carb upside down and establies a gap of 9/32" between the top of the float and the top of the bowl. I used a 9/32" drill to measure, kinda like a feeler gauge. That seems to work. I'll pull the covers off the economizers today and do that gasket thing.

Harry
 
I oiled the linkage with motor oil. I'll try grease.

Ixnay on the ease-gray. He's saying to use some sort of dry lube. Both oil and grease will thicken with dirt contamination and paste your working bits together.

I assume JohnG used 'White Lightening' or something that does not dry out or pick up dust. You could get graphite dry lube for the linkages. It comes in a squeeze (puff) tube at the auto parts store. Just put a rag under the spot where you squeeze, since it will blow graphite dust all over, not just on the sliders.
 
Bingo! I'm actually using Pedro's dry chain lube(i'm an avid mountain biker). It sets up dry so it doesn't collect shmutz and sticky up the links.
Definately want to close off the outer idle circuits-why would you want them to aid in the idle(too much anyways) and then be dead untill half throttle or so?
 
Definately want to close off the outer idle circuits-why would you want them to aid in the idle(too much anyways) and then be dead untill half throttle or so?

With those idle circuits open, you are getting a drop in vacuum at initial throttle just off idle. Right there it is like a leak. You only want them open when they come on with the progressive linkage.
 
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