Timing problems

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forty6er

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I'm at my wit's end trying to figure out what's wrong with my freshly rebuilt 340. A shop did all the basic work including installing the cam (centered) and the double roller timing chain w ma mopar's nifty new chain tensioner.
The car started right up for cam break-in, but later when I checked the timing, it read 15 degrees advance at idle and 45 advanced at 3000rpm. When I try to retard it, the motor bogs and dies.

Here's what I've already checked/confirmed:
When I assembled the final pieces of the motor, the two little "o's" on the camshaft gear and crank gear were vertically sitting next to each other at TDC. I've triple-checked the firing order. I've substituted 2 other known to work moperformance distributors. Wires and coil are new Accels. At TDC the distributor rotor is pointing at the left front corner of the intake, as the sketch in the manual pictures it. The harmonic balancer is OK. What's left to check?

The car begins to break up above 2500 rpm and has little power and won't even break the tires loose (3.23 sure grip / 2600 TCI converter) It should be pulling at least 400hp.

A friend suggested that the timing chain may have jumped a tooth, but I find this hard to believe in a new rebuild. But maybe this is not so uncommon. How would I confirm that this is the problem without pulling off the front of the motor?

ANY ideas would be appreciated. Thanks.
 
before you rip it apart a few things to look at

check the vac line to dist (Or is it full centrifical?) to make sure u dont have it plugged in to full vacuum at idle.
Check harmonic balancer to see if it has spun the center on it

how are you reading the timing ...with an advance type light or a regular lite and a degreed balancer
since you didnt mention it changing every time you check it I would assume the gear hasnt spun on the dist.
when it breaks up above 2500 whats the timing marks doing ?
throw a vac guage on the motor and see what is happening internally is vac steady ? low? wavering severly back and forth ?
no easy way to tell 100% for sure if chain jumped just one tooth

all i can think of at the moment
 
Here's a thought. Run down to any parts store, and buy a compression gage kit. Then , pull all your plugs, wire the throttle wide open, and take readings from every cylinder. Crank the engine 2-3 truns per cylinder..Make sure your battery is charged. Then post the results.
 
Actually, I may have been WRONG on the two "o"s lining up. I found an old digital pic of the car as it came from the rebuilder and and the two "o"s are off by about 5 degrees. The camshaft sprocket though IS however lined up with a mark that looks like an "o" on the outside edge of the crank sprocket, but not the "o" on the machined surface of the crank sprocket. Methinks I have a non-stock crank sprocket and my rebuilder lined up the wrong "o"'s. I would've thought he'd know better though. Anyone have a pic of a stock crank sprocket they could post for me to look at?

I never would have thought that a car would run with one tooth off. Would that explain why I'm getting a 40 degree advanced reading on my timing at idle? Kinda like when a timing chain jumps one tooth.
 
Does the crank sprocket on you engine have three keyways on it? If so each keyway will have two marks, one to mark the keyway and one to line up the dots with. One is to retard the cam, one for straight up, and one to advance the cam.The one next to a keyway should not be used to line up the dots. the other one should. This can sometimes be tricky and is a good reason to degree the cam.
 
The engine will run one, two, even three teeth off in either direction. The thing is, it will be way down on power. (sound familiar?) The least intrusive way to figure out if there is a mechanical cam timing problem, is to take a cylinder pressure reading. If it's low, theres a problem. Then you can take it apart, and fix it (or have it done by the shop that put it together). This is why every camshaft should be degreed. Even if it ends up going in "straight up" witht the dots lined up, there is no gauranty that the cam was ground properly (MP is one of the worst for accuracy). In any case, the cam will end up where the designer/builder wants it. Without any diagnosing, we're all just guessing, and you'll end up throwing parts and time at it.
 
Months ago I've rebuilt 2 340's. I have tons of pics on my page. These are the ones with the timing chains. I hope it helps a bit....

My 340:
http://buschis-place.de/images/dodge_dart/motor_2/gross/19.jpg

the other:
chain_marks.jpg
 
Well, I pulled the front of the motor and I found that the crank sprocket has 3 keyways with several marks around the outside perimeter. Obviously this is a hi-po set. But still, my rebuilder is reputable (more on that later) so it should've run fine. Well, as I posted, it didn't.

What I did was go buy a new double roller timing set with sprocket but without the fancy shmancy stuff. I'm trusting Compcams products' accuracy so I didn't degree the cam. Anyhow, I just put it all together like it was stock, set the timing to where I thought it should be, adjusted the carb/idle and took her out for a spin. Yikes! Went like a bat outa you know. When I set the new chain set on top of the old one I could see a big difference. My car was trying to run with one link "jumped". No wonder there was no power.

I'm really disappointed that my rebuilder put the cam in wrong. I'm not savvy enough to know precisely what he did wrong, but it's obvious to me that something was amiss. Think I should contact him? Problem is that I had the work done 2 years ago, and the short block sat around before I got it all together and in the car.
 
WOW THIS HAPEND TO ME TO? but i had a comp of 210 with the dots way off top at 6o"clock and bottom at 3o"clock now runs like hell but comp is lower at 160 -165 werd i mite tri strat up unsted of 4deg,advance it runs 12:20s at 104 mabey see a ten yet it took all this year to find my problem ruind my race year so you lucky to find it so soon ,,,,,,,, it drove me out of my mind lon,b
 
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