What's new
CK5
Register an account today to become a member! Once signed in, you'll be able to participate on this site by adding your own topics and posts, as well as connect with other members.

Dist Timing Issue

O

Oilbrnr

1/2 ton status
Joined
Oct 17, 2007
Posts
205
Reaction score
0
Location
Scottsdale
With 177k on the clock, I figured some of the slight roughness at idle was due to a worn dizzy, so while I was at NAPA one day, I picked up a reman. Put it in, with a new cap and rotor, and it ran like crap. Figured there was something wrong with it, and noticing that it had more end shaft play did than the OEM, I decided to put the original back in. Still ran like crap. At this point I started to pay closer attention to what I was doing:

I used a compression gauge and bumped the starter until I was on TDC compression. Chalked the degree indicator and notch on harmonic. Rotor was pointing to where the number one wire was, which is the second tower clockwise from the coil wires.

Start it up, set timing at 8* BTDC (which I'm assuming is to the right or passenger side of zero on the scale) with the vacuum advance disconnected (and port plugged).

And it runs like crap! Not much power, then as it warms up, backfires through the carb. Double then triple check firing order. Changed coil. Still the same.

In desperation last night, I really advanced it (turning counter clockwise) and the power came back and no more backfire, however, the mark on the harmonic is almost at 12 o'clock (via a Sun inductive strobe), meaning way left of the indicator. I checked the rubber on the balancer and there are no cracks or other indications of slippage.

This is a crate Goodwrench 350 with under 30k on it.

What gives?
 
Perhaps you're checking timing on another cylinder than #1? Vacuum leak?
 
You were at TDC #1 I assume? Sometimes it pays to ask the obvious, so I am. :) Your balancer was showing 0* when on #1 TDC?
 
dyeager535 said:
You were at TDC #1 I assume? Sometimes it pays to ask the obvious, so I am. :) Your balancer was showing 0* when on #1 TDC?
Click to expand...

Correct. Now that was via a comp gauge. I didn't remove the valve cover, or try some sort of visual or mechanical feeling of piston position...

Even if I was one tooth off on the cam, it is all relative to where the cap is positioned, correct?
 
Right. Doesn't matter where the cap/rotor are, as long as when at #1 TDC, the rotor is at the #1 plug wire temrinal on the cap.

I've never used a compression gauge for this, but I wonder if they are accurate enough to actually measure TDC? If your balancer/timing tab were showing 0*, and the compression gaug was indicating TDC, pretty good likelihood it was.

Is idle where it needs to be? I second checking for vacuum leaks, increasing the engine RPM (which happens when you increase base timing) will help mask a vacuum leak.

I had a vacuum leak on my car, thing would idle horribly when set to the right idle speed, and would darn near die when I floored it. At higher RPM's it ran fine though, couldn't tell.
 
I used the compression gauge to know that I was on the comp stroke while I was bumping the engine with the starter. It happened to stop right at the ring notch/zero position on one such bump at which point I chalked the marks for easy strobe viewing.

It is idling well at ~750. No vac leaks that are apparent.
 
I'm looking at a lot of the same symptoms in my truck right now with high rpm back fire through the carb (see my thread) and would be very interested to know how this one pans out.... maybe 2 birds with one wrench on this...
 
Well, I've got new wires and plugs coming from Summit. Again, by advancing the dist. it seems to be running OK, but there is a miss under load so I'm hoping that it is a wire.

I'm going to do a compression check and make sure I'm at TDC on number one to verify dist. clocking.

Does anyone know if you can feel the top of the piston via the plug hole with like a pencil or something?
 
After I replaced mine with an HEI, I had the same problem. The manual says the wires go on one way, but I had to advance the timing way off to get it to run right.

Then I found if you just shift the wires over one spot on the dist cap, the timing mark is where it should be. Evidentally some motors have the #1 wire in a different spot on the cap, even though my manual says all HEI dist. have one location to use.
 
bp71k5 said:
After I replaced mine with an HEI, I had the same problem. The manual says the wires go on one way, but I had to advance the timing way off to get it to run right.

Then I found if you just shift the wires over one spot on the dist cap, the timing mark is where it should be. Evidentally some motors have the #1 wire in a different spot on the cap, even though my manual says all HEI dist. have one location to use.
Click to expand...

But isn't it all relative? I.E. as long as you start with #1 at TDC compression, with the rotor pointing to the tower on the cap where you start your wiring firing order, all should be fine shouldn't it? Maybe I'm missing something, after all, it as been 25 years since high school autoshop! :o
 
I.E. as long as you start with #1 at TDC compression, with the rotor pointing to the tower on the cap where you start your wiring firing order
Click to expand...

Yep, I'm saying that if your little mark on the balancer is way off like that when the engine is running "pretty close to good", then the rotor is not pointing at the right cylinder when you timed it. Someone with way more experience will likely correct me, but I think you actually need to rotate the engine so the mark on the balancer is at or before TDC for #1 (check the proper advance), and then the rotor should point at the #1 cylinder.

If you do that and the engine runs poorly until you rotate the distributer a whole lot, then your wires are not in the right spot.

Brian
 
it's possibly after 177 thousand miles your Harm. balancer might have slipped a bit...
I'd put the number 1 at tdc... pull the #1 plug and VERIFY with a small screwdriver, that it's at TDC.... look at your timing mark and pointer and see if it's where it should be... pull the cap.... make sure it's pointing towards #1, and that the diz cap is lined up with the correct spot (should be)...

Just cover the basics...
Is it really at TDC?
Is the timing mark correct (hasnt moved after 177K miles?)
 
reddog64 said:
it's possibly after 177 thousand miles your Harm. balancer might have slipped a bit...
I'd put the number 1 at tdc... pull the #1 plug and VERIFY with a small screwdriver, that it's at TDC.... look at your timing mark and pointer and see if it's where it should be... pull the cap.... make sure it's pointing towards #1, and that the diz cap is lined up with the correct spot (should be)...

Just cover the basics...
Is it really at TDC?
Is the timing mark correct (hasnt moved after 177K miles?)
Click to expand...

Wouldn't a crate Goodwrench 350 come with a new balancer? Again, I looked at it, but there were no cracks in the isolator. I can't remember, is there an inner reference mark to tell if the outer ring has slipped? I plan on verifying TDC though, hopefully tonight.
 
Did you put the motor in yourself?

AFAIK crate motors do not include things like harmonic balancers. If you had someone install it for you it wouldn't surprise me if they reused it.
 
38377k5 said:
Did you put the motor in yourself?

AFAIK crate motors do not include things like harmonic balancers. If you had someone install it for you it wouldn't surprise me if they reused it.
Click to expand...

The PO (original owner) had a local Phoenix Chevy Dealership (Lou Grubb) put it in 11 years ago. Engine has ~30k according to the paperwork from Grubb, which is just for the warranty, I don't have the service invoice, so I can't tell what else was replaced at that point in time.

I picked up a new balancer at lunch today. That is the only thing it could be. There is no way it would matter where you start the wire rotation on the cap, as long as the firing order is correct.
 
There is no way it would matter where you start the wire rotation on the cap, as long as the firing order is correct.
Click to expand...

It matters if you are depending on the rotor to point to #1 doesn't it? I thought the whole problem was that the mark was way off. If you move the wires over one spot on the dist, you'll have to rotate the dist that much more to get the engine to run.

The only reason I'm so sure is because I had the exact same problem a few weeks ago and I did a lot of research to figure out the problem.
 
bp71k5 said:
It matters if you are depending on the rotor to point to #1 doesn't it? I thought the whole problem was that the mark was way off. If you move the wires over one spot on the dist, you'll have to rotate the dist that much more to get the engine to run.
Click to expand...

Your correct in that scenerio. I'm talking about also moving (re-clocking) the rotor position to also point to where the number one wire is on the cap.
 
I'm talking about also moving (re-clocking) the rotor position to also point to where the number one wire is on the cap.
Click to expand...

Hmm, I didn't realize that was possible. The balancer isn't keyed to the crank end so it only fits on one way?
 
You must log in or register to reply here.

Latest Posts

Top Bottom