Decided to update this with a new thread on the problem.... Still having problems with this thing....friggin drivin me NUTS. We laid off it for ages as we had other stuff to do/nut out so we're back onto it now. Right now we have a genuine Tattersfield medium rise 2x2 on it with 2 fresh 97s that ran well on another FH. It barely idles and when you rev it up slowly it just dies. Some times it pops thru the exhaust, other times it does'nt. When you rev it a bit, intake vac drops to 5 inches of Hg....like an engine with NO rings left - or very little vaccum to draw a fuel/air mix thru the carbs at rpm.. This is a 296 ci Flathead with decent CR and good compression - it otherwise checks out healthy. Im betting its electrical but what in the electrics could be causing this? To date this is what we have done.... 1. Swapped out coil with a known good one - no dice. 2. Comp test - all good. 3. Great vaccum at idle...around 18" when warm 4. Swapped carbs with some off a running engine - no dice 5. Swapped out intake to a single AND a dual....same result. 6. Plenty of saprk, air and fuel 7. Swapped out the condensor with TWO different new ones - no dice. 8. Coil has plenty of juice at start and when in running mode. 9. Swapped out distributor with a known runner - no dice.... 10. Rejigged fuel system to bypass the tank, fitted new lines & pump just to BE SURE....no dice. 11. No hung up valves and valve lash/cam is AOK. 12. New ballast resistor - same result. 13. Replaced the wires with new ones - same result again. 14. Fresh NGKs....same deal. 15. Played with accel pumps - same deal. So im at a loss with this weird ass shit - the only thing we havent done is swap out the dist cap....it looks brand new but hey, maybe Ill give that a go? Any of you guys give me some pointers here....we really need to get this ride sorted asap. Im betting tis something simple/something we have overlooked as it ususally is, but WHAT could it be? Anyone? Getting nuked by this thing atm aarrgghhh..... Rat
Timing is AOK, no vaccum leaks as far as I can tell and the engine ran strong before it started doing this.... Rat
Does it have any good range above idle at all? Bad off idle...if you can drive through that does it run better at higher speeds? If it runs at all, start with a simple test: Get it to run at the bad speed, sloooowly pull out/close the chokes. This will crudely spot lean condition. If worse or nothing, loosen carbs and jiggle for an air leak... Next, if running, rev it a bit with timing late to see if timing moves. Facts: ???what distributor, cam, parts in general??
Had similar with a WCFB on my flatty - turned out to be junk in carb. A good cleaning & it's running well. I'd open the carbs up just for grins.
Bruce, it idles once warm but not well. You cannot drive thru it - as soon as it comes of idle intake vacccum drop s to less tham 5 Hg. Distributor is a mech advance single point converted Mopar. Ran well on another Flathead Merc....so its OK. Engine is 3/8"x3/8" with early offy 400 heads, Cam is a 400 Jnr, adjustables, CR checked out consistant across all cyls, Tattersfield dual with two fresh, stock jetted 97s. Ernie, the carbs as mentioned have been gone thru, even swapped out for well known running carbs all to no avail. Rat
Frank;Sorry to hear of your troubles;sounds like you've pretty well covered it all. Are you running air cleaners? If so ,are they restricting air flow? Just a wild guess on my part.
This might be a long shot, and it doesnt explaine the low vacum, but i have experiensed strange things if the voltage regulator puts out to much juice...? Br Kjell
What kind of exaust system are you running? If its a full system with piping and mufflers try disconnecting at the manifold/header.
Have somebody ELSE check to see if you've got the firing order correct?? is it in a car wired up?? isolate the motor from the electrical system in the car to try it. try bypassing the ballast resistor for a run and see if it changes. when you ran it off a jug did you bypass the mechanical pump?? I had a check valve go in my mechanical pump and it ran like this. did you possibly install the cam a tooth off??
Are the chokes hooked up? It sounds like a lean cold engine. I have a similar flatty, it is a cold blooded critter. I need to work the choke with one hand and keep at it untill it comes up to temp. Yes, even durring the summer. Try it.
Pull the manifold and distributor cap. Scrutinize every place air could leak, look for odd places on gaskets. The suggestion above for "someone else" is a good one on stuff you have stared at too long...check timing, points, physically rotate the advance, redo firing order. You did do the choke check??
FYI this is not my car/engine....its a fellow clubmemevrs ride that were trying to sort out. Firing order is correct. Ballast resistor has already been bypassed - no dice. As mentioned, it runs an electric pump no mech pump is not the issue. The engine has not been touched internally inc the cam, so the cam aint out. I did'nt build it but TDC @ firing seemed OK when I checked it with the timing marks on the damper. I'll re check it. Bruce I hear you...but a few guys have had a go on this thing so its been looked at by others as well. Just as a side qun, what jets would you run on a 3/8x3/8 stroker with 2x97s on a medium rise Tattersfield intake? With 45's being stock, would you run 47s on a 296 cube FH? Taken note fo all the above and will swap out the cap first, although it looks brand new....never had a new cap cause issue on me so I'll replace it just to be sure. Summer's coming and we want this sucker rollin ! Thanx for all the input. Rat
Sounds like youve had the carbs off. Are they synchronised again? disconnect them from one another and check air flow with a hose to your ear, you will be able to hear if one is sucking harder than the other, make adjustments to the idle screws to set this.THEN hook the carbs back together and make sure that any change to one carb idle is done to both. mixture can be checked by sliding a piece of card across the choke horns. if by restricting the air the idle comes up ,that carb is running lean. Other than that it sounds like youve checked the lot so start checking again.Keep the basics in mind, if you have a good fuel supply,compression,spark and timing then you can make a milo tin run.
So are you saying the cam has been checked for a flat lobe or not? Sure sounds as if it has wiped out a lobe or two. Steven.
If the dist cap doesn't cure it, then I would pull the intake and at least visually eyeball the tappets as you turn it over and check valve lift at all valves. If that's OK, then I dunno, since you've tried other carbs, etc. Dave
RB, try what Pacasio said.....sliding the cardboard.........then just for shits and giggles........plug the carb on the front and try to run it, then do the same with the rear. Sounds to me either you've got a open vaccuum leak somewhere the size of Montana.....or your carbs are way off.............
The only other thing to look at for this problem is the tappets or valves.........good luck.....you've done most everything all of us would've done already..........
Here's something you might want to look for.........since it pops thry the exhaust.....check out your valvesprings.....you might have a broken or weak one..............
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