Ignition timing

bobclevenger · Post by **bobclevenger** » Wed Jul 14, 2010 6:09 am

I have been experimenting with ignition timing on my newly-rebuilt 440 Six-Pack engine. The results have surprised me and I must caution anyone who may want to try this to proceed in very small steps -- the final setting that I am using goes against ALL recommendations.

I had initially set the engine to about 10Â° BTC and it ran well there. After the engine had a few hundred miles on it I started advancing the initial timing a little bit at a time and then taking her out for a brief drive. More advance made the engine respond better -- no surprise there. Today I rotated the distributor another few degrees and tried her out. Again, she ran better, but I had the feeling that this was about enough. I checked the advance setting after it had darkened outside enough to see the timing mark easily. According to my digital timing light I am running about 32Â° BTC at about 950-1000 rpm (which is idle speed with the carburettor throttle plates fully closed). There has been no pinking and the operating temperature has been good.

I suspect that this provides too much advance at higher rpms, but at anything under 3000 rpm it seems to do just fine. It is just possible that the advance springs in my distributor are a bit weak and are advancing at idle speed. There is no hard starting.

Not a recommendation, just a recounting of my recent experience.

Post by **Steve Payne** » Wed Jul 14, 2010 6:27 am

I agree these engines seem to like a lot of advance.

As most of you know I run and Injected system that is programable through a computer, the same system controls the ignition timing and all I have to do at any speed is just change a number and see how it goes.

While my engine is idling I keep adding advance and right up to about 18 degrees of advance it gets better, after this there is a slight roughness detectable so I have left it there. I have been right up to high 20's and the amount of inlet vacuum was so high the exhaust were starting to smoke as it was pulling oil in past the valve stem oil seals I presume.

Also a lot of advance just of idle is good and it realy makes them pickup nicely with no hesitation.

Basically the more advance the engine will take within reasonable limits is better, the limitations are the compression, fuel and how old your engine is.

A big warning here to much advance even if your engine does not pink is it will give your big end bearings a hard time. YOU HAVE BEEN WARNED!

A good compromise for those that have adjustable systems on reasonable fuel is high teens for idle, low 30's just off idle up to about 2000 rpm and all in by 2500 to 3000 rpm. Any sign of pinking and take out at least 4 degrees.

Steve

bobclevenger · Post by **bobclevenger** » Thu Jul 15, 2010 3:42 am

Steve Payne wrote:A good compromise for those that have adjustable systems on reasonable fuel is high teens for idle, low 30's just off idle up to about 2000 rpm and all in by 2500 to 3000 rpm. Any sign of pinking and take out at least 4 degrees.

Steve

I have just checked the timing again after having readjusted the throttle linkage to allow the centre carb throttles to close fully, thereby getting the idle speed down.

At 500-600 rpm I had about 22Â° BTC which confirmed that at 1000 rpm I was getting about 8Â° to 10Â° centrifugal advance. I lowered it to about 20Â° BTC. Pretty close to what you recommend and she runs well there and idles at about 600 rpm.

CrAzYMoPaRGuY · Post by **CrAzYMoPaRGuY** » Fri Jul 23, 2010 4:37 am

bobclevenger wrote:
Steve Payne wrote:A good compromise for those that have adjustable systems on reasonable fuel is high teens for idle, low 30's just off idle up to about 2000 rpm and all in by 2500 to 3000 rpm. Any sign of pinking and take out at least 4 degrees.

Steve
I have just checked the timing again after having readjusted the throttle linkage to allow the centre carb throttles to close fully, thereby getting the idle speed down.

At 500-600 rpm I had about 22Â° BTC which confirmed that at 1000 rpm I was getting about 8Â° to 10Â° centrifugal advance. I lowered it to about 20Â° BTC. Pretty close to what you recommend and she runs well there and idles at about 600 rpm.

What are you using for advance springs? I'm surprised you are pulling that much advance that quickly!

bobclevenger · Post by **bobclevenger** » Fri Jul 23, 2010 5:50 am

As far as I know the springs are the original springs that came with the 440 Six-Pack engine. I assume that they have weakened a bit in 38 years. I have backed off the static advance a bit, so it's a little less than 20 degrees.

CrAzYMoPaRGuY · Post by **CrAzYMoPaRGuY** » Sat Jul 24, 2010 1:04 am

I once installed an aftermarket "curve kit" set of springs that were SUPPOSED to be a "perfect fit" for my modified 440 in my Demon.
I got the car running, it ran OK but not well, and I tried tuning the car (440 2x4bbl) but had no success really....
A friend came over and asked for a ride, we went down the local strip, about one mile.... and BARELY made it back. It ran terrible.

I got home and tried everything, not until I removed the curve kit and installed two factory "light" springs did I get any satisfaction. After swapping the springs out my car ran like a new car.
I was astounded.

I notice my Jensen likes 18 degrees initial and 35 degrees total, but my advance I *think* starts about 1400 rpm.... now you have me curious! I'm gonna have to look!

On a sidetracking note......
How do you like driving with the new tranny?!?!?!

bobclevenger · Post by **bobclevenger** » Sat Jul 24, 2010 1:12 am

Driving with the new tranny is just great. Makes the car what an SP should be.

Post by **RAP72** » Sat Jul 24, 2010 7:15 am

bobclevenger wrote:......... the new tranny is just great. .

this side of the pond a tranny is something completely different. I would post a link but this is a nice forum and long may it stay that way. Bad boys, very bad boys.

Post by **Steve Payne** » Sat Jul 24, 2010 1:03 pm

I am sure you need to explain some more, a TRANY when I was young was a device for listening to broadcast radio stations.

I am sure it was short for Transistor which happened to be the main component in these devices.

OR AM I MISSING SOMETHING?

Steve

bobclevenger · Post by **bobclevenger** » Sat Jul 24, 2010 7:20 pm

Transistor radios became popular about the time I graduated high school, but were usually called "transistors" by the uninformed masses who didn't know (or care) that that term ought to be reserved for the specific semiconductor device within said radio. We do have the other kind of trannies here -- occasionally one may encounter a telly with a trany in it and a tranny on it. But the gearbox is fine.

Post by **Steve Payne** » Sat Jul 24, 2010 7:26 pm

We also have another type of Trannie over here.

They are usually white and in the outside lane of the motorway( freeway ) or 3 inches from your bumper ( fender) with the driver on his mobile ( cell phone).

Steve

bobclevenger · Post by **bobclevenger** » Sat Jul 24, 2010 9:51 pm

Steve Payne wrote:We also have another type of Trannie over here.

They are usually white and in the outside lane of the motorway( freeway ) or 3 inches from your bumper ( fender) with the driver on his mobile ( cell phone).

Steve

Just a question as to UK vs. US usage; does not the US 'fender' translate as the UK 'wing'?

money_one_four · Post by **money_one_four** » Sun Jul 25, 2010 10:15 pm

bobclevenger wrote:
Steve Payne wrote:We also have another type of Trannie over here.

They are usually white and in the outside lane of the motorway( freeway ) or 3 inches from your bumper ( fender) with the driver on his mobile ( cell phone).

Steve
Just a question as to UK vs. US usage; does not the US 'fender' translate as the UK 'wing'?

Wing/mudguard = Fender translated in some books ? , but if your fender is that big lump of iron back and front , then that's our bumpers .

bobclevenger · Post by **bobclevenger** » Mon Jul 26, 2010 3:44 am

Nope, that's one where our terms are the same.

money_one_four · Post by **money_one_four** » Mon Jul 26, 2010 9:43 am

bobclevenger wrote:Nope, that's one where our terms are the same.

So what is the correct name for your bumpers over there ?