Ya, I had an Autolite get some junk in it many years ago> Ran like crap til I pulled the lid off and saw the piece stuck in one of the jets. Pulled it out and ran perfect again. Can't say that it missed real bad, just had no power.

I for one can't say for sure, but if the Autolite is like a Holley the jets only control main metering, not idle circuit, so it should not be able to make it miss.

 

You said that you used the ignition parts from the previous engine, if so, what about the distriburor cap and rotor, also if you have acess to a dwell meter you may also check out the the condition of the primary side of the ignition. If you are still using points and condenser the best way to set the points is with a dwell meter, then recheck the timing. Even if this checks out to be in good order it will help to concertrate on other systems.
Keep checking, Kenny

 

I found out what was causing the miss... I ran my compression test (finally, its too dang hot around here to do much after the sun comes out) and cylinder 3 read 0! after I came back from a quick heart sunken panic, I started looking at that cylinder. I took the rockers loose and tried again, now it read fine. SO, I found out that in my new set of pushrods there was one mixed in from a 429/460. too long and wouldn't let the exhaust valve on #3 close. so I replaced that with the correct one and she runs smooth(er). thankfully no other damage was done.

now...

after having the carb COMPLETELY rebuilt, following the specs as close as possible, she seems like shes running outta gas! wont run below about half throttle (2K RPM) and backfires hard through the exhaust and once in awhile pops back through the carb.

the filters are very new, (just put them on this morning) and the line runs free when un hooked from the pump... I took the pump off, pushed the arm a few times and it shot a good amount of fuel a decent distance, so I think its doing its job.

the distributor cap and rotor are fine, and the dwell was set on the previous engine, I cant keep it running long enough or smooth enough to do many tests/adjustments

I came very close to giving up and buying a newer truck the other day, but after looking around a bit I came to the conclusion that,
A: I cant really afford one anyway,
B: ive got too much time and money into this one to just give up, and
C: anything I bought would probably cost me more money too.

so I keep plugging along waiting for that moment somewhere in the future that it actually starts and runs like it should. (It cant possibly be that far away)

this was my dads old truck and he always had it so it started on a dime and ran like a top, now even he's stumped...


I think the truck has decided it likes its retirement too much and just has no desire to come back to work.

 

Just a thought, was the cam timing set properly? my buddy had a truck jump time last year and ran much like what you are saying yours is doing. He replaced the timing chain and gears and ran perfect again.

 

When you rebuilt the carb did you soak it in good carb soak? There is good stuff out there that is nasty on your hands and worthless stuff that is glorified soap. It sounds to me like there are some passages still plugged up in that carb. Soaking the carb in the good stuff for a couple hours and then blowing all the passages out with compressed air at your Dad's shop will work wonders I believe.

 

just to eliminate another possibility, I replaced the fuel pump and that got it going. then it does it again. so I tear my timing cover off to make sure the cam timing is still correct and that the pump driver is still where it should be. they are. so I took back the second pump and got my money back. then went to carquest and ordered a Airtex brand pump. after putting that on I pumped it by hand and it sucked the fuel in no problem.

now im gonna go home and put my timing cover back on and get her going...

 

No idea what your cam is but Compcams wants a 30 minute at 2000-2500 rpm for break in. With break in lube of course. 10 minutes & you are trying to make it idle. You could very well have a wiped lobe. Compcams also required different valve springs with the cam I put in. Were you supposed to change the valve springs? I see you believe you have located the problem. I would crank it over by hand (no plugs) & verify that exhaust valve is operating properly just like the other exhaust valves. I am surprised you did not bend the pushrod.

 

ok I don't know what the Heck is going on now, but its getting on my nerves.
the fuel line is running dry pre-pump.
I tried running it from a can and it wouldn't even pull it from there (below and above pump level)

so yesterday I took all the fuel lines loose and flushed them to make sure they wernt plugged up, they wernt. hooked them all back up and fired it off. it took a minute but then my pre pump filter immediately filled up full (like it should be) and did so for several minutes. now its running dry again. it still dribbles enough to run the engine at idle, but once it gets to 1500rpm it just isn't enough.

I topped off the tank to eliminate a hole in the pick up tube. that didn't make a difference.

anyone shed some light on this problem?

also, im noticing a "chuff" coming from I don't know where, like a old locomotive would make. I cant hear it under the hood, only when im in the cab.

its got no real power either. im not hot rodding it yet, but it used to move pretty good. now its a dog. im thinking I might have to advance the timing more...

 

This sounds like in tank sender sock 90 to 95% blocked. Your chuff probably sounds like a woosh inside the tank.

 

I rigged up a fuel pressure gauge at the carb inlet, when the engine is cold (first daily start) the pressure is bouncing between 5 and 10 psi and it wont run faster than 1500 rpm. the pre pump filter is also barely dripping. but once it reaches operating temperature, the pressure holds steady at 7psi and it will run like its supposed to. (but still not smooth) and the filter runs about half full...

the only thing I see changing besides engine temp is oil pressure. its high when its cold idle 60psi+ and about 15-20psi at warm idle.

is it possible that when its cold an intake valve may not be closing completely (due to hard lifters) and putting back pressure into the fuel line? I think it would just come back out the air cleaner.

I pulled the sending unit from the tank and looked at the pickup tube. its fine and clear. I ran a wire down it to be sure. so now I am 100% positive that all fuel lines are free and clear.

 

I wiped a Comp cam lobe mid May inside of 10 minutes (from start up) during break in and I DID use their break in oil and break in lobe lube. A wiped cam lobe WILL make the motor run roughly and idle terribly. It's worth checking lobe lift to be sure.

You mention fuel pressure was 5-10. Was it steady or did it bounce between 5 and 10....? Reason I ask is my gauge was rock steady at 5psi until the cylinder with the bad lobe started to misfire and then it started to bounce like a basketball between 5-15 psi....

Assming that 460 pushrod was really long and it didn't bend....? Could that valve have gotten bent? That would cause a missfire too.

I'd check to make certain nothing like a cam lobe has failed or nothing else is physically broken inside the motor before I continue. From experience find this sooner rather than later! I caught mine before major damage was done, but I'll still have to rehone cylinders and replace bearings as well as the effort of rebuilding and various other parts like gaskets etc....

JIM

 

One very important thing many guys don't do on a new start up build is roll the push rods on a flat surface and check for any bend ones. Plus they just put on the valve covers and try to start it up. The point of cranking up the RPM for cam break in is to the get the lifter & pushrods turning. If one push rod is bent more than .020ths they should be replaced as it may hang up and not turn and wipe the lobe....orich

 

I checked my lifter preload out and even when the valves are closed they all have between .035-.090" of lifter compression left. the average being .040" and .070"

so that extra pressure leads me to believe that the cam simply isn't correct... and ive heard this from many...

I ordered a STOCK cam and will try that. and you can bet that when I pull this one out it will be measured to see whats going on...

 

Gee this should be pretty easy just messy. Back off adjusting nut until play at pushrod & rocker turn into zero play, Then one full turn in. Start motor if still noise tighten noise one's while engine is running until it runs smooth. You may have to repete a few times since you've never done this before.
You gave up to fast as you'll go through the same thing with the new cam adjusting the valves. Hope your getting new lifters too.. orich

 

theres no adjustment capability on mine, just the bolt that holds the rocker sled to the head. and I don't think it would be good to loosen those up...