ignition timing ??

Hello All,

I'm in somewhat of a quandry. I recently installed a Pertronix Ignitor in my '76 1500. It started right up on the first try, however the instructions that came with the Ignitor suggested that it must reset the timing after this upgrade. This brings me to my problem, the Haynes manual says to bring engine up to operating temp and set timing while idling at 800rpm. I can't for the life of me get it to idle at less than 1200 or 1300 rpm. I haven't changed anything yet for fear of messing something up. Any suggestions??:S Thanks for any help you can give.

Mark

Set your total timing first then see where the idle rpm is, you dont have to go by the book with setting timing just make sure when driving under a load it doesnt detonate (ping) and its not hard to start when hot.generally you will get some more power and better throttle response when advancing the timing a bit,its trial and error... set it go for a ride......advance a little more go for a ride...etc,etc

What the timing at with a light on it. It could be so far off that the idle is off and all you need to do is adjust it.

Set the total timing to 25 BTDC @ 2000rpm with vacuum advance hose disconnected & plugged & you'll be very happy with the result!

Is it a clunk in the engine or in the distributor? Maybe something is hitting in the distributor when you installed the pertronix.

Mark, what kind of carb do you have? The idle speed may have been jacked up because the timing was retarded.

I'd back the idle screw off & see what happens...

Mark, any luck?

If I'm not mistaken the atdc settings were for emissions laws not "running good". I don't know 1500's but I'm pretty sure it would run better if the timing at idle was more like 5-10 btdc.

The suggestion to set 25 at 2000 and plug the vacuum probably would have put the idle timing right where it should be... ie not where the manual says it should be.

Have you adjusted the valves? A poorly adjusted valve or two could make extra noise. The valve train should sound like a well oiled sewing machine if adjusted properly.

You may need to disconnect the vacuum line now that you have the idle timing set. Check with the 1500 guys, but I would think that going from 4 atdc to 10 btdc would result in too much advance at higher revs

Standard timing on the 1500 is 10 BTDC. Set it there and get the idle going at a nice idle. Depending on engine condition 800-900. Find the noise and fix that. Check those valves. Once you know those items are ok Then you can set it like Dave said as many say they run good like that. There is a whole thread on setting the timing of the 1500 and has Dave's method in it. Many say that 10 BTDC is ok but you can go a little more at idle or set it at a higher rpm, this would then use any centirfugal weight action if they are working good still.

Dave's 25 degrees at 2500 rpm or whatever is ridiculous.
How do you know what the advance curve is doing at that speed? You don't!!!

Set the timing to 12 degrees at idle for starters, vacuum line disconnected and plugged. If you can't get the idle speed down, the throttle cabnle may be adjustedd too tight so there's no slack to turn down the idle screw. Then check all the carb and manifold bolts to make sure they're tight (vacuum leaks) and check the timing. Its probably way too far advanced from the Pertronix kit install. That's how they get you "more power" - by advancing the timing which screws up the phasing (cap-to-rotor positioning when it actually fires.)

Once you get the timing set, leave the vacuum advance (or retard as it may be) disconneccted on your Midget. It will run better and stronger without it. Then go for a drive and listen for pinging. If it pings under load at 2500-3000 rpms, back off the timing a few degrees to make it stop. If it doesn't ping, advance it until it does, then back it off. Find your car's sweet spot and it'll run great!!!

Thanks again for all the advice. It's raining here again, one would think this was Washington state instead of Virginia. Top leaks so I'm kinda a fair weather MG driver. Perhaps tomorrow BEFORE the big game:)-D I'll dig in and get it sorted out for good.

Seems like the vacuum retard is working but the centrifugal advance is not. It may just need to be cleaned and lubricated. Watch this video starting at 2:50 to see how it works.

http://www.youtube.com/watch?v=cFfnenMFQ3U

Since this all started when you switched carbs I wonder how the vacuum pickup to the distributor works with a zenith vs. the SU's. With the SU's more throttle, more mass flow, equals more vacuum. Maybe the zenith was plumbed to the intake manifold which would be the opposite, more throttle would yield less vacuum. That would be more logical given the fact that it is vacuum retard. If that is the case I think you could use the vacuum to the intake manifold on your SU setup instead of the port on the carbs and it would result in a better curve. Still need to fix the mechanical advance though.

Wrong thread... there are two with similar problems running concurrently.

Adjusting the timing per the manual just gets you in the ballpark, like static timing. Yep it'll run well. Set it up right and it'll run GREAT. Its very unlikely that the two methods of rtiming at idle and at 2000 rpms will get you the same results!

Jeff and others - I am bit confused. On a newly rebuilt dist (by Jeff) are you recommending leaving the vac adv permanately disconnected and plugged? Why would this be?

A-series engine (948,1098,1275) connect and use the vacuum advance.

1500 Triumph engine with vacuum [/u]retard[b][/b][u] - disconnect the line and plug the port on the carb.

Rick

Now I am confused. I need to set up the timing on a new Jeff built dist. Jeff are you and others recommending leaving the vac adv PERMANANTLY disconnected and plugged? Same question as Mark I guess.

Nobody has addressed his clunking noise. I'd be more concerned about that than about the ignition advance. Might be rod knocking, or excessive piston slap, or stuck valve, which would render timing a bit less important.

a continuous rhythmic clunking noise from the engine could be a bad rod bearing, excessive bore wear causing piston slap, a flat cam lobe, maybe a loose rocker arm, a sticky valve, worn thrust washer causing some contact somewhere it shouldn't, etc. all of the above are serious issues. I'd try to narrow down the cause asap, before serious engine damage results. Don't fear an engine rebuild. Though it is at first a seemingly daunting undertaking, you have one of the most simple tractor engines ever put into a car. Your only fear should be the cost thereof, because it will cost almost as much as the car is worth. That said, a lot of goodness can be built into 1500 today, which would have not even been thought of when the cars originally rolled off of the assy line.

Does the "random" clunking change in nature (louder, quieter, more regular, stop) when you push in the clutch pedal?

If so, it may well be the thust washers.

I just added the flame thrower also. Why is it Ol' Midge runs better without the Vac hose connected? I have both ports plugged and she runs amazing at 2 BTDC. The minute I attach the vac hose it shoots up from a smooth 800 idle to 1500. Do I need these hoses connected? Is two BTDC fine?

If you have a vacuum advance on your distributor, then disconnect the line while timing the engine. That may bring your idle within the range your looking for. Then, using a timing light, set your timing to the recommended setting. If you have a mechanical advance, then go ahead and set the timing to the recommended setting. You should find that when the timing is set, your engine RPM will be 800 +- 100 rpm. Then set the RPM at the carburetor to 800 RPM. Recheck your timing and reset if necessary. You may have to go through this process several times to get the timing and RPM correct. Let me know how it comes out.

Jeff, I agree with the "worn thrust washer causing some contact somewhere it shouldn't" as I have lived it to the extreme. While restoring my 1975 MG Midget 1500 LE (close to 100 point) I found half of the crank thrust washer laying in my oil pan when I opened it up. I was getting the same clunking noise Mike describes on acceleration and because the crank was moving around I could not keep the timing set. It destroyed the crank and because a new crank was not available I had to send it to a crank builder and they welded and rebuilt it. I was lucky nothing was wrong with the block. I completely rebuilt the engine prior to reinstalling it. The clunking sound was happening when the crank was moving forward on acceleration. This seems to be quite common with the 1500 engines.

Thanks for the advice robert(tu)