finally got the leaks worked out, i have about 4 pounds of fuel pressure. the carb has been rebuild twice, the first time the float was sticking. i don't have the outer carbs fed, as i'm trying to get the center carb to idle first. if i spray some starting fluid down the throat it snaps over great and quickly dies. whats going on here? this is a rebuilt motor with new everything.
You say you don't have the outer carbs fed, does that mean they are sitting there with no fuel plumbed to them ? If so, they are still sucking some air, even with the plates closed, that could be your imbalance. What you might do is make up two temporary block off plates and eliminate the end carbs altogether, then run it on just the lone middle carb. That will be a good starting point and tell you if that is your problem or something else. Don
yes........could be sucking air! how about blocking outer carbs at the base, by making a gasket with no bore hole? i have a regulator plumbed and been messing with pressure too.
Are you using tripower end carbs if so they should not have any adjustment screws in the base plates make sure that the throttle shafts don't have Any play and the blades are closing tight there should be no air flowing through them if they are not in use
Yep, what Don said! Block those puppies off and then you'll be able to see what's really going on. It's easy for things to get out of whack if you have vacuum leaks in the end carbs and then you end up trying to adjust the center carb to compensate. Pretty soon it's a real mess. Block off the outers, get your center carb running and idling like you want it, then introduce the other carbs one at a time. It makes it a lot easier to identify where the problem might be. Oh yeah, also make sure you don't have any vacuum leaks at the intake gaskets or anywhere else.
blocked outers with a gasket, still nothin. sound a little different, doesn't die as quick, i'm getting a vroom vroom then pop and quits, some times a little fire too. 3.5lbs.
As said previously the end carbs on a tri-power should not have any idle screws only the centre carb.Also throttle plates on the end carbs must close completely to prevent vacuum leaks. Contact Larry (The carb guy) at Automotion for great advice. http://hotrodcarbs.com/aboutus.php
If your end carbs are the same (with idle screws) substitute one of them for the center carb and see what happens. Start at ground zero and recheck everything. Set your timing by eye so that number one is ready to fire when it should, and recheck the plug wires to make sure they are in the right sequence. Advance the distributor until it slows down the cranking and then retard it just a little. If things got slightly better when you blocked the end carbs that tells you there was SOME leakage of air there, and maybe you have a major vacuum leak elsewhere. Make sure all the brass type plugs are blocking all the vacuum ports on the carbs and that your vacuum hoses are run to the right spots. When it is running the next time shoot some of your starting ether around the intake gaskets. If it speeds up and runs better you have found a leak there. Turn your idle screws both out 2 turns to start, that is close enough to run usually. Shoot us some pictures of your intake setup from different angles, we might see something. Don
no idle screws on end carbs, both outers seem to shut tight. firing order looks good. i went back through timing now wont even fire, plugs gassy, i do have spark. my pressure gauge is all over the place, i see anywhere from 3-6 pounds. i had it idling before the second carb rebuild, but when i shut the motor off it poured gas out of the air holes on the carb body. float was stuck.
Ok, do this. Fill up the carb and then shut off your pump (if electric) or disconnect the fuel line from the carb and from the tank if a mechanical pump. Then start the motor on just the gas that is in the carb. It should run for at least a minute or so on what is in the bowl. Sounds like you are flooding if the plugs are wet. You might be dumping gas down the cylinders. Have you checked your float level ? Better to be too low than too high. Don
If it popped out the carb sounds like a lean problem. If the plugs were gas fouled from carb flooding you my want to put in some fresh ones.
i pulled the lines, and tried it with just the fuel in the bowl,same results. vroom, pop, out. i pulled the top of the carb off to look at the float, but not to sure what i'm looking for. i'll add pics in a bit.
Your center carb isn't delivering fuel on the idle circuit. When you do the carburetor's job by adding fuel it starts. Why your plugs are gassy is something you'll need to figure out. Is it the carb leaking down, is it something you are doing, is it just fresh engine quirks. Generally, if the carbs are flooding, adding more fuel doesn't help it start. Holding the throttle wide open ( adding extra air to balance the abundance of fuel) while cranking gets the engine started. The end carbs theoretically aren't supposed to do anything until you put your foot into them. In actuality and reality the will deliver a small amount of air because they can't achieve a hermetically sealed throttle plate, close but not perfect. With that in mind, when you do block them of and establish your center carb tuning, don't be surprised if its slightly different center carb adjustment once the end carbs are added back in.
The plugs could be so fuel fouled they wont fire. Pull them out and burn the fuel off them with a propane torch, or if the wife isnt home, stick them in oven for ten minutes at 250. Wash the pan afterwards, she may never know.
HARD block off the end carbs, make a plate w/ gasket & rtv & bolt it solid! Then, forget the pressure reg. & use std fuel pump pressure, all you're doing is feeding a std. carb its fuel--the way the factory did it. If it don't run, you got a carb issue, timing, etc. Vac. leaks is the death of tri systems. I've been through it all. cooger
outer cards are blocked by a gasket. without a regulator it wouldn't even fire, was about 9lbs without. i did pull the plugs and blasted 'em off with air.
Check your base gasket betweencarb and mount to verify. Holes match up that's where the signal for idle and high speed are from wrong gasket will cause these conditions also the lower gasket to manifold has to be matched Wild Bill
You mentioned you had a new motor. I would be careful with all that fuel until you get it broke in. As Don and others have mentioned, block off the 2 end carbs and remove the linkge from same. Now get or borrow a carb known to be good. Try it, and if it does well, start with your primary carb before even thinking about the 2 secondaries. Actually, if you want my opiniopn, I would break in the motor with a good running primary carb before messing with the multiples again.
corvette style mechanical fuel pump. i've taken the outer carbs out of the equation, and will leave 'em out for a while as you guys suggest. it makes sense. i'm gonna send the carb out again, third times a charm.
My opinion also. Here are a couple of articles that may or may not help: http://www.thecarburetorshop.com/Troubleshooting.htm#Tripowertuning http://www.thecarburetorshop.com/Aftermarkettripowersetups.htm At this point in time, you need to run the initial cam break-in on the fresh engine. REMOVE the two outer carbs and block the manifold pads with a solid block (aluminum) and gasket. Invest in a fresh set of spark plugs. Borrow a good running carb that will bolt to the center pad on the manifold, and do the cam break-in. After the cam break-in is complete, THEN worry about the tripower. Jon.
since opinions are free, here's another one. Think of buying a good rebuilt carb, from a good source. Leave it alone, just adjust idle after you get it running. Can't go wrong with just a plain 2 barrel, stock type pump (feeding a stock carb.) and assuming all the rest (timing, wiring, etc.) is in good order. Keep the ends blocked off, get it running perfect on the 2 bbl. (drive it, floor it, etc.) and only then add one at a time the end carbs. Put on one end carb, don't hook up the gas, and then see how (if) it runs. If its missing, rough, etc. you've found your problem. Final note: Charlie Price at Vintage Speed sells alum./brass bases for 2G, GC's. I use 'em and swear by 'em. Runs perfect on the 2 bbl. then really hits hard with the ends coming in. cooger
Everything you said, says "vacuum leak". Adding the starter fluid temporarily compensates for the leak. If you're running power brakes, disconnect and plug that vacuum port, and be sure there isn't an open vac port that's been overlooked. 4TTRUK
What is the large vacuum hose hooked to. There should be a pcv valve in the hose at or near the base of the center carb. Without a pcv valve in that hose you will have a 3/8 inch vacuum leak. The engine would start and not idle. This could be your problem.
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