TR4/4A Ignition Timing Adjustment on a TR4A ?

[PlaidMan]

I just installed a Pertronix Ignition. I hear a little valve clatter during hard acceleration. How can I tell if I am to far advanced or if its to retarded. Would popping thru the carbs be a sign of to retarded? What is the preferred method of setting the Timing?

 

[TR4]

I used a timing light after installing the Pertronix kit. That sure gives you an accurate setting. I set mine at around 8 degrees since I have the idle at 900 rpm. That might not be exactly right but the car sure runs great.

 

[PlaidMan]

Since there aren't any timing marks on the crank pulley in degrees, where would 8 degrees be located on the pulley? Are their any other ways of setting timing ? Would appreciate all suggestions, Thanks, Charlie

 

[jsneddon]

get up to about 1200-1500 rpm in 4th gear. Mash on the pedal. Or get into 4th on a long hill and mash on the pedal.

If it pings - you need less advance
If it bogs and there is no pinging - you need more advance

ideally you want it just on the hairy edge of just about to ping.

8 degrees would be 8/360th of the diameter of the pulley... I don't have the diameter handy but someone will chime in.

 

[PlaidMan]

Thanks , I will give it a go in the morning. I might try using the hanbrake to increase drag to simulate a long hill since there are no such luxuries in my area.

 

[Carlos]

Circumference,...right?

 

[vettedog72]

I understand the correct way for "spec" timing is to use the reference book and understand that static means NOT WITH THE MOTOR RUNNING..... not at all. I also was informed that some centrifugal advance might start as early as 600 RPM's! My field of reference is with the TR6 and not the TR4. Any way, your car will crank and run so it would be best sorted by following the up hill run or in the flat lands, just do the acceleration as described several times and you can get it set just right. When you go to the mountains, and have a long up-hill pull, you may still need a little adjustment. My advise is don't use the brake as a substitute for the missing hill.

 

[jsneddon]

[ QUOTE ]
Circumference,...right?

[/ QUOTE ]

ummm... duh. Yeah. Circumference....

oops /ubbthreads/images/graemlins/blush.gif

 

[PlaidMan]

Thanks for the advice guys. I didn't have a chance to touch the car today due to a Honey -Do List for Easter she dropped on me this morning. I'll try again tomorrow and won't use the handbrake as mentioned earlier.

 

[dklawson]

I don't know 4's. Does the crank pulley at least have a TDC mark? If it does, do the math thing mentioned above making marks with a Sharpie or center punch on the pulley circumference... or buy an advance-type timing light. Those are the lights with the dials on the back.

With an advance light you dial in the advance you want on the timing light and then adjust your dizzy until the TDC mark lines up.

 

[Kurtis]

Everything I've heard/read states that you can't accurately set the timing dynamically on a TR3/4 engine because of the unpredictability of the centrifugal advance at the idle RPM. That's why Triumph never published a dynamic timing spec - just a static spec.

As others have stated, the correct way to set the timing is to set it statically (per spec) then drive it and make fine adjustments on the road. However, a simpler method (for me anyway) is to turn the distributor with the engine running at idle to maximum RPM, then retard slightly until you get a 100 RPM drop. This will get it close enough to drive and fine tune.

 

[piman]

Hello Kurtis,

I suspect the real reason that Triumph gave no dynamic figures for the 3 and 4 is that timing lights were not common when the cars were new. (If they were available at all?) Certainly some Lucas distributors start advancing mechanically at much less than 600 rpm, but I can't say for the 4 cylinder Triumph.
The other way to dynamically set the timing is at full advance(without vacuum advance), i.e at high revs, set to static plus full advance figure.

Alec

 

[PlaidMan]

Great information; Thanks again. I did so well on that Honey-Do list,well, she had a new one for me this morning. What you won't do for love, and tomorrows Easter. Maybe Monday evening I hope.

 

[dklawson]

Another option if you buy the advance type timing lights is to set your maximum dynamic advance, not the idle advance. To do this, slightly loosen the dizzy clamp then start the engine and working under the bonnet, bring the RPM up to about 4k. Set your advance timing light somewhere around 32 degrees and aim it at the timing marks. Turn the dizzy body until the TDC mark lines up. Then reduce the RPM, tighten the dizzy and test drive the car. If it pings, retard the timing in 2 degree steps until you no longer hear the pinging. Tuning this way will give you the max advance your engine can handle for the fuel you're running. Once you've done that, you can make an idle speed advance reading and record it for future reference. That will allow you to set your idle timing with confidence for YOUR car.