• Hi Guest!
    You can help ensure that British Car Forum (BCF) continues to provide a great place to engage in the British car hobby! If you find BCF a beneficial community, please consider supporting our efforts with a subscription.
    There are some perks with a member upgrade!
    **Upgrade Now**
    (PS: Subscribers don't see this gawd-aweful banner
Tips
Tips

BJ8 Timing moves

Share this page

AUSMHLY

AUSMHLY

Yoda
Country flag
Offline
64BJ8, timing is off.

I had the distributor and vacuum professionally rebuilt, incase that question comes up.
Running Pertonics.

Last tune-up, I set the timing to 800, TDC 15 degrees with a Snap-on digital timing light. Car runs great.
It's been six months, car doesn't idle well anymore, noticed the tach shows 600 instead of the 800 I set it to.
Checked the timing, it's now at TDC 10 degrees.
Checked the distributor, it's tight. Had to loosen the distributor bolt to get it to rotate.
Moved it till I got TDC 15 degrees, car runs great again.

What's going on?
 
Timing chain stretch ? Another possibility could be the timing light. My Pertronics did not like My digital light but was rock solid with an old Sears light.
 
bdcvg said:
Timing chain stretch ? Another possibility could be the timing light. My Pertronics did not like My digital light but was rock solid with an old Sears light.
Click to expand...

Would you elaborate about the Pertonics not liking a digital light.
I'm assuming mine is accurate. Shows 15 when set it, then confirms 15 setting after I tighten the distributor. Checked days later, still 15. Then somehow months later, timing has changed to 10. Don't think the problem is with the digital timing light.
 
Timing chain stretch is the first thing I thought of as well. On a (non-Healey) car a change in timing like this was a sign that the end was near for the chain and gears.
I'm not sure how old yours are, or how many miles, but it's just a thought.
 
How to tell if the chain is stretched?
Let's assume it is, what will happen if I don't replace it sooner than later?
What's involved to replace it, and approximate cost?
 
You live near British Car Specialists in Stockton. I'd have them look at it before you assume you have a stretched timing chain.

Problems with the distributor internally? - dirty/stuck centrifugal weights/springs; diaphragm issue.

Google "stretched timing chain symptoms" - most common symptom is rattling sound especially at startup.
 
Roger asked:
"would you elaborate about the Pertonics not liking a digital light."

Some digital timing lights radiate noise pulses that temporarily upset the Pertronics module.

Generally referred to as " RFI "
However, more correctly it is called " E MI " Electromagnetic Interference.
It can also conduct to the module via the ignition systems wiring.
 
AUSMHLY said:
How to tell if the chain is stretched?
Let's assume it is, what will happen if I don't replace it sooner than later?
What's involved to replace it, and approximate cost?
Click to expand...

Well, as mentioned above, there might be some noise related to a stretched chain. Using the timing light, watch the way the timing mark advances and retards. Slowly open the throttle a bit to raise the engine speed enough get full spark advance, then quickly let off on the throttle. The mark should move reasonably smoothly in both directions. If if is erratic as the RPM drops, that could indicate a slack chain, or something wonky in the mechanical (or vacuum) advance system. Just a thought, and certainly a "first order" kind of test. GL, Jim
 
AUSMHLY said:
... What's involved to replace it, and approximate cost?
Click to expand...

I had the timing cover off to replace the seal a couple years ago. You have to remove the radiator and fan, and raise the engine about 3 inches for the balancer to clear the front cross-member. Toughest part is getting the big nut off the balancer; it should have been seriously torqued--150lb-ft IIRC--and you'll turn the crankshaft before the nut loosens. Various methods were suggested to me to keep the crank from turning, but I ended up buying a 3/4" impact wrench from HF and the correct socket--though not an impact socket--for the big nut (it's something like a 1-5/16" or so). Still, I ended up buggering-up the nut anyway as the impact wrench wouldn't fit square on the nut between the balancer and the cross-member.

Make sure to get the timing gears lined-up before you remove the chain and gears as a 'unit.' There are no marks on the gears to align them (that would be too easy). You have to identify 'special' links on the chain and count the links between them. Replace timing chain, gears and probably the tensioner and, of course, the seal and gasket on the cover. When you reinstall the cover, make sure the seal is centered on the balancer. Oh, if the seal has worn a groove in the balancer you'll need a Redisleeve and, if it hasn't been done before, you might want to get the balancer rebuilt. Damper Doctors did mine--no complaints.

Inventory the parts to be replaced, and source from your favorite supplier. Someone here suggested BP Northwest; their prices look to be better than the 'usual suspect,' but I haven't ordered from them. I'll SWAG around $300-400, not counting a balancer rebuild--they'll install a Redisleeve if needed--which IIRC was around $100+shipping to Redding (Red Bluff? I can never keep those two straight).
 
Just checked mine. It's 1-11/16".

I used this setup to lock the crank - in combo with the above socket with a 4 ft cheater on a Harbor Freight 3/4" breaker bar:
CrankNutLocker.jpg
 
The reason the timing retards is that the points close up as the heel wears. Always check points gap before you touch anything.
 
Back
Top