timing help

Ok, I put a new distributer in a while back, was still putting it together so I couldn't drive it then. when I did drive it, it was missing, didn't seem too bad though, and small back fire (more of a puff) up through the carb. found out plug wires were bad. Put new ones on today and it is still doing the same thing. I read some other threads before posting this, and am wondering if I could be 180 out on the dis, or a tooth off when I put it in?? what symptoms would indicate either of those?? If I set the timing to 0 BTDC on the tab, it barely runs, but the starter still starts it. I bumped the timing up little by little from there with a test drive after each increase and it does the same thing. took the timing up to around 16 or so BTDC, still started fine and idled ok, rev it up and sounds ok. during all test drives if I was very gentle on the gas it seemed pretty smooth. Its when I give it some gas that it starts missing and back firing. This is a 65 chevy 327. Don't know if it will help, but here are a couple pic of the dis and vac advance. the wrench is at the #1 plug wire.

 

If it's 180 out, it will backfire through the carb and not even start. Pull #1 plug, have someone bump the engine over little by little with the key while your finger is in on the hole of the #1 plug. When you hear the whoosh, stop, stick a screwdriver in the hole and turn the engine over by hand until the screwdriver feels the piston top out, and just start to go back down. You may need to move the engine forward and back just a touch to find the right spot. You are now at TDC. Double check by removing those fancy T handle bolts you got there, remove the valve cover over #1 and make sure both intake and exhaust valves are CLOSED. Now, check the mark on the harmonic balancer to make sure it is lined up with TDC on your timing mark on the chain cover. If it's not, the rubber on the balancer has moved the outer ring. Make a new mark. Now, pop the cap on the distributor. If the rotor is facing right at the #1 wire terminal, you are good to go. Re-install, time it up with the new mark (if you made one). If it's not lined up with #1 (which I'm guessing it won't be), remove the distributor, and reinstall so the rotor slides over to #1 when fully down (the oil pump gear will turn the whole thing as you put it in, so you'll need to fiddle with the spot you drop it in to get it right). Once its in, fire up and re-time.

 

sounds to me like you have two plug wires reversed. Double check firing order on d-cap. Won't start if it's 180 out.

 

already check firering order and wires, all ok. that was my first thought. I took off the valve cover already and tomorrow I will do as repeater says to check that the rotor is pointing to #1. I did line up the timing mark today and checked the rotor and it was kinda between #1 and the next plug wire. I dont know if I was on compresion stroke or not because I was by myself and couldn't plug the spark plug hole with my thumb and manually turn the motor, the piston was all the was up though.

 

Yep just double check both valves are closed on TDC. The stroke will be right after the intake opens and closes. If the rotor was inbetween 1 and 8 or 2 and 1, then you would have been able to adjust it enough to get it right by timing it with the strobe. If the timing is not off and you're still backfiring through the carb, I'll double down that you've got a wiped lobe on the cam. Very common these days with people running oil with low zinc content in it. If that's indeed the case, either run zinc additive with your favorite flavor of oil, or run any of the racing oils that are not listed for on-road applications as they do not have to adhere to federal standards for low zinc content...(these would be Valvoline Racing, Kendall racing, etc) This is becoming a more and more common occurrence with flat tappet motors.

 

man, u guys knnow way more about engines then I do. I am no engine guy, at all. I dont even know what a flat tappet is..lol. So if thats the case does that mean I need a new cam?? or will the zinc additive do the trick. would running higher octane gas make any dif here? im just runing 87 octane in it.

 

No. If the cam lobe is wiped...you're in for a new cam. But alas...it's a small block chevy and they cost like 5.00. No really, but they are cheap. Check the timing first. If that doesn't solve your problem, take the coil wire completely off both the coil and the cap, pop your other valve cover off and have someone crank the engine. Watch every rocker closely. If a lobe is wiped, you'll see a rocker arm (or two) that are barely moving up and down, if not moving at all. If you see this, you're in for a new cam and lifters.

A tappet refers to the bottom of the lifter inbetween the cam and the lifter. A flat tappet engine works under serious friction loads as the cam is constantly mashing and turning the bottom of the lifter. In a roller cam...much, much smoother. Zinc additive only prevents this from happening again. Octane means nothing unless you're running some insane 12:1 compression engine...which if you are...I'd like to see your jeep.

 

WOW. I hope thats not what it is. Ive been waiting for ever to get this jeep on the road and drive it. Now this. UGH!!
Thanks for the info, will check it out tomorrow.

 

I'm sure that you probably already thought of this and verified, but I'll say it anyway. Are you sure that your vacuum advance is connected to PORTED vacuum, not manifold vac. I say this because you said "during all test drives if I was very gentle on the gas it seemed pretty smooth. Its when I give it some gas that it starts missing and back firing."

 

As a side note...If you're working alone you can cram a piece of napkin or paper towel down in the #1 spark plug hole and turn the crank. When the compression stroke comes around it will shoot your paper towel across the garage. Then you should be able to fine tune TDC with a screwdriver.

P.S. If your fan belt is on, fine tuning can be done by turning a pulley with the left hand and shining a flashlight down the spark plug hole with the right hand.

 

I agree with everything Repeater is telling you and only have a couple of things to add.
1. When lined up on TDC #1 cylinder the distributors rotor should be pointed towards the front of the block at the #1 cylinder.
2. I agree that it could be a flat cam lobe, been through a couple of cams due to that myself, but it could also be a broken valve spring. While looking your rockers over to make sure they’re all moving check your valve springs before going after the cam.

 

Also, keep in mind if the distributor cap is not marked #1 and someone didn't put #1 in it's stock location (which is facing towards the #1 cylinder), you can essentially make any terminal #1. With the distributor out and the piston on TDC, you can really drop that distributor in anywhere you want, as long as wherever the rotor ends up facing, that has to be #1....then 8,4,3,6,5,7,2 in order after that. As long as it's on TDC and the firing order is followed from where the rotor lands when its dropped in...anything can be #1....it's just easier to face it towards the #1 piston as that's easy to remember

Second on the broken valve spring...not as common but an easy check while you're there.

 

Yup, correct also.
The main relationship is from the crank to the cam. After that the distributor can be lined up any ole which way as long as it's hitting the right cylinders at the right time. It’s just easier to remember the way I described.

I’ve had that one happen also. Very similar symptoms.

 

I wached the rocker yesterday and, the #1 didnt seem to move up and down quite as much as the others. I played with the timing some more and I found a sweet spot. The dist is very sensitive, barely move it and makes a big differance.
It seems to be a little sluggish on take off even when shifting and reapplying the gas but then it picks up and runs ok. NO backfire or missing now. That rocker not moving as much is bugging me now though. I was told by a friend that the sluggishness could be a few things, acelerator pump, points, carb setting... I drove it around for about an hour or so and enjoyed every minute of it. seemed like the longer I drove it the better it started to run. BOY it drinks gas!!!!

 

If it’s nearly imperceptible, just sort of looks a little less, don’t worry about it. If a cam lobe were knocked flat the difference in lift at the rocker would be obvious. Since you say it’s running better the more you drive it I doubt you’ve got anything major like that going on anyway.
So you say its got a dead spot off idle but pulls clean from there? If you have a hot cam, as I suspect you do from the description of it, you may have to learn to live with some of that. It can be dialed out to an extent at the carb and by bumping up ignition timing though. If it helps any mine does the same thing until it’s good and warmed up.
Gas mileage: its easy for me to spend your money for you but you really should consider going electronic ignition in the future. I gained several MPG with that change alone.

 

thanks alot guys, Its not really a dead spot, it just stumbles alittle when you first give it gas under load then picks up. Like its lacking power then smooths out. Yeah, I want to go electronic ignition soon, hopefully this year.
thanks for the help