Wierd timing problem on 327 SBC

"Joe Sixpack" wrote in message

> I have a 327 sbc with an HEI distributor in my 1953 Chevy pu.. I've never
> set the timing using a timing light, I just set it "by ear". I don't drive
> the truck that much, but the engine seems to run just fine at all speeds.
I
> recently put in a new HEI distribtor, and decided that I would check the
> timing using an inductive timing light that I bought at Auto Zone. The
> strange thing is that I don't see the timing mark on the harmonic balancer
> lining up anywere near the timing marks on the timing chain cover even
> though I'm turning the distributor as far as possible in both directions.
> It's so far off I can barely see it flashing on the other side of the
water
> pump. I've tried it with the vacuum advance disconnected and connected,
but
> still can't see the marks lining up. Yes, I have double checked and I do
> have the induction clamp on the #1 spark wire.
> Does anyone have any clue has to what could be causing this problem.
Is
> it possible that the harmonic balancer was mounted incorrectly??
>

The hub is keyed to the crank, so could not be mounted out.

One possibilty is that the balancer has shifted. Factory SBC balancers are
two castings joined by rubber. With age ( 327's been around a while...) the
rubber can dry out, crack, and even delaminate from one side or the other,
allowing the weight ring to slip relative to the hub. Get a mirror down
there with a flashlight and see what the rubber looks like. If its dry
rotted, cracked, etc. pick up an aftermarket one from Summit or Jegs in the
same diameter.

'nother posibility is that someone replaced the timing cover or tab at some
point in time - several combinations of balancer and tab configurations have
been used over the years. Really suspect this if the timing cover and or
tab is chrome. If the balancer doesn't look bad, this is probably the case
since you said the engine has been running fine. You can get a stick-on
timing tape for your balancer size, set the engine to TDC #1 cylinder, and
apply the tape to zero up with your tab pointer.

--
V8Z
Chevy V6 powered '66 Datsun Roadster
http://www.mildevco.net/chevypowereddatsuns/
Chevy V8 powered '77 Datsun 280Z
http://www.mildevco.net/chevypowereddatsuns/
 >> Stay informed about: Wierd timing problem on 327 SBC 

Joe Sixpack wrote:

> I have a 327 sbc with an HEI distributor in my 1953 Chevy pu.. I've never
> set the timing using a timing light, I just set it "by ear". I don't drive
> the truck that much, but the engine seems to run just fine at all speeds. I
> recently put in a new HEI distribtor, and decided that I would check the
> timing using an inductive timing light that I bought at Auto Zone. The
> strange thing is that I don't see the timing mark on the harmonic balancer
> lining up anywere near the timing marks on the timing chain cover even
> though I'm turning the distributor as far as possible in both directions.
> It's so far off I can barely see it flashing on the other side of the water
> pump. I've tried it with the vacuum advance disconnected and connected, but
> still can't see the marks lining up. Yes, I have double checked and I do
> have the induction clamp on the #1 spark wire.
> Does anyone have any clue has to what could be causing this problem. Is
> it possible that the harmonic balancer was mounted incorrectly??
>
>
>
>
Two thoughts come to mind. 1. Front cover and
timing tab don't match the balancer markings. Not
uncommon with Chevy's and Fords both.
2. Balancer ring has slipped because the rubber
deteriorated. If this is the case, you need to replace
the balancer.
If it's the wrong timing tab, don't worry about
it. Timing light just gets you in the ball park for
referance. Continue to time it by ear and it will run
better.

--
..boB
2006 FXDI hot rod
2001 Dodge Dakota QC 5.9/4x4/3.92
1966 Mustang Coupe - Daily Driver
1965 FFR Cobra - 427W EFI, Damn Fast.
 >> Stay informed about: Wierd timing problem on 327 SBC 

Your distribute is off by a gear. Rotate your engine until TDC lines up. The
rotor should be pointing to number one cylinder. If its not and probably
pointing to one cylinder over, move all the spark plug wires at the
distributer over by one to line up.

The right way is to remove the distributer and reinstall it in the right
orientation.

Joe Sixpack wrote:

> I should have added, that I only replaced the top part and electrical
> parts of the distributor. I never removed distributor itself from the
> engine.

--
Eugene Blanchard
http://www.catsasskustoms.com
Parts, Performance, Passion
News for Motorheads
 >> Stay informed about: Wierd timing problem on 327 SBC 

You nailed it , Eugene. I put the engine at TDC and removed the dist. cap
and yep, the rotor is pointing at the #8 cylinder at about 8 deg. BTDC. I
put the inductor clamp on the #8 wire and sure enough I can now see the
timing marks. What impact will it have if I just leave the distributor as
it currently? My engine has always run rich even when I lean back on the
carb. Would the timing have anything to do with this?
Thanks for your info.
 >> Stay informed about: Wierd timing problem on 327 SBC 

I would get a vacuum gauge (cheap). They are great for dialing in your carb
and timing. Adjust your idle screws for maximum vacuum at idle. You'll find
that the idle speed will pick up. Reduce the idle rpm and keep adjusting
until you can't get more vacuum - usually about 19- 21 inches for a regular
engine at sea level and less for cammed engines and higher altitudes -
pretty simple.

Also the motion of the needle if it is not rock steady will tell you about
the condition of the engine.

I also like to use the vacuum gauge for timing. Advance the timing for
maximum vacuum minus 1/2 to 1 inch of vacuum. Take it for a drive, if it
pings under acceleration, back off another 1/2 pound. It matches your
engine to the altitude and octance rating for your engine.

Joe Sixpack wrote:

> You nailed it , Eugene. I put the engine at TDC and removed the dist.
> cap
> and yep, the rotor is pointing at the #8 cylinder at about 8 deg. BTDC. I
> put the inductor clamp on the #8 wire and sure enough I can now see the
> timing marks. What impact will it have if I just leave the distributor as
> it currently? My engine has always run rich even when I lean back on the
> carb. Would the timing have anything to do with this?
> Thanks for your info.

--
Eugene Blanchard
http://www.catsasskustoms.com
Parts, Performance, Passion
News for Motorheads
 >> Stay informed about: Wierd timing problem on 327 SBC 

There would be no impact on leaving it as it is. Just time to #8 cylinder.
It'll still work and does.

Joe Sixpack wrote:

> You nailed it , Eugene. I put the engine at TDC and removed the dist.
> cap
> and yep, the rotor is pointing at the #8 cylinder at about 8 deg. BTDC. I
> put the inductor clamp on the #8 wire and sure enough I can now see the
> timing marks. What impact will it have if I just leave the distributor as
> it currently? My engine has always run rich even when I lean back on the
> carb. Would the timing have anything to do with this?
> Thanks for your info.

--
Eugene Blanchard
http://www.catsasskustoms.com
Parts, Performance, Passion
News for Motorheads
 >> Stay informed about: Wierd timing problem on 327 SBC 

Thanks again for the info and reccomedations. I have a vacuum gauge laying
around here somewhere - I'll give it a shot.
 >> Stay informed about: Wierd timing problem on 327 SBC