This is a bit of a lengthy note, but I sure wouldn't mind an opinion.

I recently changed the timing chain and gears on my 225/6. I carefully lined up the timing marks with shaft centers on both gears, and when I replaced the balancer, am certain the timing mark on it was under the timing tab on the cover, which I figured was a good sign. The engine starts well and runs fairly well too, although it doesn't want to keep going at idle. There is also the odd backfire. Here's what puzzles me:

The idle issue could be a mixture adjustment, but when I put the timing light on the balancer, it shows #1 plug firing at a point a good 2" prior to the mark reaching the tab at all. The distributor is adjusted all the way in one direction and while it makes a bit of difference in closing the 2" gap (and adjusting it the other way kills the engine) it doesn't put the mark where it should be. Given my certainty about lining up the marks on the gears and where the balancer mark was initially, how can this be? Could the balancer on the engine be from some other version that would make the current position of the mark correct? If so, there is still the backfire issue, which I take to be timing-related.

I do intend to test #1 piston with a long screwdriver to try to locate TDC and then check both the rotor position relative to #1 plug as well as the position of the balancer mark as a next step.

Apologies for the length of this, but any ideas?


Dan

We don't recommend "lining up the dots" on timing sets anymore, depending on who manufactured them the marks on the gears can be off by a fair amount of degrees, either way. Do a search for this procedure.

-D.Idiot

As DI has pointed out, lining up dots doesn't come close to guaranteeing that the cam and the crank are in proper phase. All it indicates is that you've lined up dots. Whenever you've got things pulled apart to replace the timing chain and sprockets, it's very much worthwhile to degree-in the cam. That's the only way to make sure the cam is clocked where it's supposed to be relative to the crank.
You've got timing problems.
Not likely -- assuming it was idling okeh before the chain and sprocket swap.
There is another bolt on the underside of the distributor hold-down plate, holding the plate to the distributor body. This second bolt can be loosened with a special Z-shaped 7/16" distributor wrench made specially for this task, or with an improvised tool, to gain additional adjustment. But if your cam timing is incorrect, adjusting the ignition timing won't fix it.
Possible but not likely. How was the engine running before disassembly?
Good idea.

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Too many people who were born on third base actually believe they've hit a triple.

Thanks for the responses. A couple of additional things: before I changed out the sprockets and chain, one of the problems was low compression on all cylinders on my 225/6 -- about 60 each. I figured the cause of this was an out-of-phase crank and cam, so that led to the change-out. When I examined the old sprockets and chain, I noticed that they were about two teeth off straight (can't recall which way) so I was convinced that the chain had somehow failed. That led to the replacement with results as previously mentioned -- timing marks about 2" early.

I guess the question I have this time is what do you suppose was the cause (or is, as I haven't checked it since replacing the chain and sprockets) of the low compression in all six cylinders?

Thanks again,

Dan

are you checking the timing with the vac hose disconnected and pluged?

This is a complete lark, but it's worth mentioning. When I got the Newport, I couldn't time it correctly because the distributor would hit the block. After much headscratching, I realized that the previous owner had the distributor out at some point, put it back in a few teeth off, and to correct for this had misclocked the spark plug wires.

It's a longshot, but it's a possibility.

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2000 Chevy 155" cargo van - The Abductor
1970 Newport convertible
1996 Buick Roadmaster Wagon
1966 CruiseAire motor home
1990 Toyota 1 ton box truck TURBO slant (scraped)

Thanks again for the additional responses.

I did remove the vacuum hose and plug the inlet, but thanks for thinking of that. As to the distributor hitting the block, it's not as far-fetched as you might think, and could have something to do with what is now a real puzzle. Here's what I did:

Using a piece of wire, I located the spot where #1 piston is at the top of the stroke by turning the crank with a wrench. I checked the location of the balancer mark and sure enough it's right under the timing tab. I then checked the rotor and here again, it's under #1 tower.

So given all of the above, it looks like everything's in phase and timed right, but I recall when I hooked up the light it was showing #1 firing about 15 degrees (a guess) early (I haven't run the engine since as the plugs are out). Can't figure this out, unless it does in fact have something to so with the distributor.

I can tell you this: the distributor is adjusted as far as possible to counteract the early timing, and when I move it the other way the engine quits. In theory, if I could move the distributor even more it seems like it wold correct the problem, but short of removing it, it's at the end of the adjustment slot. As it is now, the engine starts well and runs as long as I don't drop below 1000 in which case it dies.

Any help appreciated; thanks again for the responses so far.


Dan

i was playing with a problem like this a while back. and oddly enuff i was trying to compensate for a timing chain that has since been replaced.

how long have u had the car? possibly the previous owner moved the distributor for the same reason as me? if ur cam is position rite, try marking ur engine where the rotor is pointing to. try positioning the distibutor cap over the rotor, close the the place where it snaps in. is the #1 tower in the same line? if not, u can pull the dizzy out just enuff to disengage the drive gear and rotate the rotor a gear or 2(or 3), to get it where it needs to be. i have never gotten it in the rite spot on my 1st try, so be patient..

if everything else is lined up rite, u may just be correcting the last mistake of the previous owner.

D~~~!

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Sounds as if you've identified the problem (distributor improperly timed), and you've verified that everything except the distributor is more or less close to where it needs to be. Put the frontmost piston at TDC between compression and power, use an ink marker to mark the position of the #1 distributor cap tower on the distributor body, remove the distributor cap, work with both distributor hold down bolts to put the distributor in the middle of its accessible-bolt adjustment range when the rotor points to the mark you just made on the distributor body, tighten the underside bolt, make a new mark on the crank pulley at the TDC (0°) line on the timing tab, put everything back together, set your base timing at 5° BTDC, and drive off.

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Too many people who were born on third base actually believe they've hit a triple.

if your leary of pulling the dist. and need more adjustment you can rotate the wires all one spot over , not saying this is correct but it works in a pinch.

Thanks much folks. I did pull the distributor and retarded the rotor by one tooth and the engine now runs well.

Appreciate all the responses.


Dan