no power

[scott]

... make sure the accelerator cable /linkage is allowing for full throttle on the carb ( I've seen this happen and get overlooked many times on re-builds).

linkage is good. peddle moves throttle linkage through it's full range smoothly. exhaust blockage is a slight possibility, i covered a leaky gasket with an exhaust repair paste, covered it with aluminum foil (to keep it from sticking to the flanges) then tighten it down. paste may have oozed inward. i'll chck that today. i could get it to idle and rev smooth but when trying to drive it was popp'n back through the carb.

[kevkon]

li could get it to idle and rev smooth but when trying to drive it was popp'n back through the carb.

That sounds like a typical improper cam/ignition timing issue. Valve lash adjustment effects the engine timing as well.

[Sputnicker]

Fuel delivery problems and exhaust could easily cause the low power, but probably not the "popp'n back through the carb." That requires combustion at the wrong time, so I agree it's probably timing. With a timing light you can (or already have) verified the distributor is positioned correctly and advancing as you raise engine speed. That leaves cam timing, unfortunately.

I'm not sure what it takes to remove the access plate on the bell housing and view the EP mark on the flywheel (I've never done it and my Land Rover is 700 miles away), but if you can get to it, here's what I suggest. It's a slight variation to the procedure in the Green Bible taking into account that your engine is fully assembled.

Take off the valve cover, remove the spark Plugs and turn the engine by hand (or by pushing the car while it's in gear) so that the number 1 exhaust valve is fully open. Use your dial indicator (see illustration in the Green Bible) to find the point at which the valve is fully open and zero out the dial indicator. Then turn the engine until the dial indicator reads .025" from the peak and make a mark on the front crankshaft pulley. Turn the engine the opposite direction, past the peak, until you get the same .025 reading and make another mark. Then turn the engine so that it's half-way between the two marks. Now you are at the "exhaust peak" and the EP mark on the flywheel should line up with the pointer, as illustrated in the Green Bible.

[Roverlab]

Any idea how much material was removed from the head by the machine shop? Can you back the adjusters on the valves off to be way loose? I don't know 2.25 and 2.5 cam compatability that well, but I would think that the 2.5 doesn't have huge lift and the valves are closing fully to get 133psi. per cylinder, so coil bind is also unlikely.
Pulling the front cover isn't the worst job and I'd agree that cam timing seems off. Especially with dist drive also being off. Compounding the error?
Does the engine rev to 2500-3500rpm easily no-load?
Caveat: I'd check with the engine builder before opening up "their" work or running a fresh engine really high on rpm!
My .02!

Trevor

[scott]

good news, bad news. i pulled off the valve cover and set the EP at the pointer. no.1 valve is not openned. no. 8 is! i can believe this thing even starts. my time is set at at least 28 degrees btdc. looks like my machinist is going to have to make a house call. he had my green bible. i wish he had called me and asked for the fly wheel cause it's kind of of needed to set the cam timing.

[kevkon]

That's what I suspected. Do yourself a favor, when you have the machinist come by to correct the issue make sure that he verifies the timing marks are correct. Factory timing marks are often inaccurate and while you have the opportunity it would be wise to accurately zero it in for precise timing.

[scott]

i'll be putt'n a dial indicator to it today. and i figure that since 1 & 4 are opposit each other their exhst cycles would be close to opposite and maybe no. 8 is open on one revolution and no. 1 on the next.

speaking of factory timing marks being off what do your pointers look like? mine is way up high in the viewing port and barely vissible. no at all like the pictures in the manuals showing the pointer nearer the middle.

[Sputnicker]

Your hunch is correct - since the crank is spinning twice as fast as the cam, the EP mark will appear for cylinders 1 and 4.

[scott]

power upped! i called and talked w/ my machinist. he was certain that the cam timing was not my issue. he pointed the fingure at the carb or ignition. he seem very confident so i redirected my thinking. the carb was torn apart and cleaned while the motor was being rebuilt but it wasn't really changed. the ignition was changed by dropping in a pertronix electranic system. but my understanding is that electronic ignition either work or don't, no middle ground. but for the heck of it i dropped the points/condensor back in and the old truck screams! well it works. now to start bolting down the loose ends and gett'n out to the trails!

and i don't if this had anything to do with it or if it was just a coquindence but i purchased and drank my first six of guienness since putting the motor back in. mmm, maybe it was just the head clearing i needed

[badvibes]

Scott-

Hey that's great news. Shows how difficult it can be to diagnose a problem when more than one thing has been changed. Man you'll be out breaking things again in no time now.....

[scott]

well i got my rear loom in and work'n. i've now have break lights. i say break cuz now that the brake lights work i can take it out of the driveway and break something new

[jac04]

Any idea what was wrong with the Pertronix unit? I assume it was brand new.

[scott]

Any idea what was wrong with the Pertronix unit? I assume it was brand new.

not a clue. it was new. bought it last fall when the motor was in the shop. no receipt now and the box is long gone. i would be happy if they just sent me another but the money would be good to.

went out wipp'n around the hood. the truck has some giddie up in it now.

[SafeAirOne]

Leaving the ignition switch in the "on" position for even a few minutes without the engine running can fry the pertronix units...

[scott]

Leaving the ignition switch in the "on" position for even a few minutes without the engine running can fry the pertronix units...

it's crappy performance was from the get go. and i thought when they go they go. no middle ground. this one made sparks just not enough and or at the right time.