Engine has the hiccups...any ideas.

[OldsRocket442]

Engine is 94 Bronco. Ignition is MSD 6a and Mallory Unilight distributor. Nothing in the bottom end was changed other than oil pump and timing chain. Timing is set at 10* BTDC. I'm about to roll it off a cliff....lol Whats with the hiccups?

http://static.photobucket.com/player...110_131834.mp4

[brianj]

Might just be my computer, but I get nothing but a question mark when I hit that link.

[OldsRocket442]

I was afraid of that. I'll fix it when i get home. I'm posting from my phone right now.

[bosanjo]

That's a pretty strong hiccup, can you tell where exactly it's coming from? It might help if you can isolate the sound/knock, it's kind of hard to tell from the vid. Is it from the bottom end (I doubt it), the carb, valvetrain, exhaust header..? Does it do it when the engine is hot and/or cold? Have you tried looking at the timing while it is idling to see if it is changing when it knocks? How long has that ignition setup been on there? I'm just throwing ideas out there.
From the shudder and that near stall, I suspect something inside one of the cylinders might be backfiring or maybe a valve isn't seating properly when it sparks. You might be able to take a stethoscope and determine which cylinder it's from if that's the case.

[OldsRocket442]

That's a pretty strong hiccup, can you tell where exactly it's coming from? It might help if you can isolate the sound/knock, it's kind of hard to tell from the vid. Is it from the bottom end (I doubt it), the carb, valvetrain, exhaust header..? Does it do it when the engine is hot and/or cold? Have you tried looking at the timing while it is idling to see if it is changing when it knocks? How long has that ignition setup been on there? I'm just throwing ideas out there.
From the shudder and that near stall, I suspect something inside one of the cylinders might be backfiring or maybe a valve isn't seating properly when it sparks. You might be able to take a stethoscope and determine which cylinder it's from if that's the case.

Seemed to be more pronounced when its warm. Its popping through the carb. The ignition is the same setup i had on the other engine. I have not watched the timing while it was happening.

[bosanjo]

Could it be an intake valve isn't seating right? Perhaps try pulling a valve cover to see? If it were me, I'd take a stethoscope to each side and try to see which side it was coming from then go from there, see if you can isolate it to a side or if it is happening on both sides. If it's more pronounced when warm, it could be the expansion is allowing it to happen. Is it possible that the fuel is igniting inside the intake causing the backfire? Have you adjusted the lean/rich condition? If you are running too lean, there is a chance that you could have simultaneous backfire and afterfire. Again, just throwing things out there that maybe you overlooked.

[Crazy88]

Given that the OP stated that they changed the timing chain and the oil pump, it is possible that the cam timing is now out of alignment, causing what amounts to a misfire. That is merely an educated guess however.

[OldsRocket442]

Given that the OP stated that they changed the timing chain and the oil pump, it is possible that the cam timing is now out of alignment, causing what amounts to a misfire. That is merely an educated guess however.

New timing set went on with both marks lined up dead nuts on.

[FM2NOTCH]

if it's backfiring thru the carb, your timing is too low, chased that problem for a while on a friends car, turn the timing up and see if it helps.

[Ethyl Cat]

Given that the OP stated that they changed the timing chain and the oil pump, it is possible that the cam timing is now out of alignment, causing what amounts to a misfire. That is merely an educated guess however.

Cam timing would cause a consistent hiccup not a random hiccup.

Have you put a vacuum gauge on it? See what it is doing before/during /after the condition?

Does it get worse at a fast idle?

Have you driven it?

[OldsRocket442]

Cam timing would cause a consistent hiccup not a random hiccup.

Have you put a vacuum gauge on it? See what it is doing before/during /after the condition? No. I'll have to find my guage and check it

Does it get worse at a fast idle? No. Actually seemed better at higher RPM although it did backfire once at about 2000rpm. Otherwise was OK.

Have you driven it?No. Still have a few other things to button up first. Steering shaft needs to be reconnected to the rack, shifter reinstalled, etc.

The more i think about it, the more I'm leaning towards more timing. Maybe bump it to 12-14 btdc and see what happens.

[OldsRocket442]

I have to work outside with no cover. Got a break in the rain tonight and went out.

Bumped the timing up no change.

I noticed the coil wire seemed a little loose so I pulled it off and found the connection inside the boot was broken right where the boot turns 90*.

Would this cause the problem shown in the video? The hiccups through the carb.

I know, get some new wires and see what happens. Have any of you had a similar problem?

[FM2NOTCH]

pull a spark plug, or two, if they are black your timing may still be low, don't use a timing light just bump it up a little at a time, you may have to pull the distributer out and turn it to get more clearance, the key may have fell out of the crank when the balancer was installed, FWIW been there did all the above, even changed carbs, we chased it for about two weeks and the problem was low timing.

[cb84capri]

if you have a timing light with an inductive clamp, put it on each cylinder and make sure they are getting consistent spark. or use one of those inline spark testers. i have not heard a lot of good things about mallory unilite distributors.

if you are using an innova brand timing light, borrow/buy a different brand. the dial advance one i bought, and it's warranty replacement are the worst lights i have ever used. your timing light may not like the msd box either.

cale

[OldsRocket442]

I'm limited at the moment to working on it when it isn't raining or I'm not working. So I've had little time to play with the car. Below is a list of things i have tried with the end result being the same. These are in no particular order.

1. Swapped carbs
2. Swapped distributors (I have 2 unilites. Both work in the other vehicle. "84 Bronco)
3. Unhooked all Vacuum lines on the engine except the PCV and plugged them of course.
4. Bypassed the MSD.
5. Set engine at 10* BTC and installed distributor with rotor pointing at #1 plug. Started car and set timing to 10* btc on the light. This should have given me 20* initial advance...correct?
6. Reinstalled distributor with engine set at 0*
7. Compression tested the engine to see if a valve wasn't seating properly. All 8 holes were 148-150psi. I'm thinking the valves are seating ok.
8. I did find a bad ground and fixed that.

So, I'm thinking maybe I have a cam/lifter problem. This engine is a 302 from a '94 Bronco. Its roller lifters. Anyone agree that this could be an issue? If so, whats a decent cam to use in this engine to give it a little bump in power but not so much that its not drivable everyday?

I'm out of ideas as far as timing goes. I could try to give it more, but too much more than the 20* and it starts to die.

[forgotn]

My supercharged 93 had this problem only worse. Wound up being my MSD distributor. Put a stocker in it and it went away. This might be a cheap option for you to try befor disassembling your motor.

[86GreenStang]

Start by checking the simple things very carefully. Like check for vac leaks, fuel filters, bad/broken plug. In the dark open the hood and look for plug wire arcing to ground. Look in distributor cap. I had a friend that had a similar hiccup and it turn out a wasp got into the distributor and made a nest causing his irregular hiccup. Start simple then move on.