New distributor and measuring total timing

I bought a set of MSD timing tapes for my balancer but none of them matches the marks. Which tape or how are you measuring total timing? I guess i could measure the first 5/10 degrees and make marks at 20, 30 and 40, but the space is kind of cramped down there.

I am contemplating purchasing a new distributor and would like to check the total timing. I am looking at a duraspark reman one, Cardone 84-2893 with the large cap. It first will run with a MSD StreetFire box.

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I bought a set of MSD timing tapes for my balancer but none of them matches the marks. Which tape or how are you measuring total timing? I guess i could measure the first 5/10 degrees and make marks at 20, 30 and 40, but the space is kind of cramped down there.

I am contemplating purchasing a new distributor and would like to check the total timing. I am looking at a duraspark reman one, Cardone 84-2893 with the large cap. It first will run with a MSD StreetFire box.

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You can get timing lights that will tell you the adv for both Mechanical and vacuum.  I have this one:

http://www.innova.com/Content/Support/Manual/Innova/Manual_5568.pdf

Tells you how to measure both Mechanical and Vac adv.

I converted a fuel injected sbc that had nothing but one line on the balancer and one mark on the timing cover. Like you said I just added my own 5 and 10 degree marks (after confirming TDC). Working underneath the car gave reasonable access. Since there were no existing references I measured the diameter of the balancer and calculated chord lengths for my marks.



uploaded photos

Yeah.... i first need to confirm TDC.

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Buy a timing tape made by either Moroso or Mr Gasket to suit. They had them years ago, but haven't needed to buy one in years as Romac balancers are marked the full 360 degrees.

I have the adjustable timing light and it is nice. You rev the engine to 3000 rpm (measured on the light) and then adjust the advance value on the timing light up and down until you are flashing on TDC. The value you see is the total advance provided by initial and mechanical advance. Then you can slow the engine down and watch for the light to move from TDC (it will look retarded). This is you 'all in' RPM.

Same idea with the vacuum pod. I start at with the car at idle. I like to use a vacuum pump (hand held) connected to the pod. Adjust the light so that it is blinking at TDC. Slowly apply vacuum to the pod and watch for the change. Normally you can just read the advance off the balancer but you can also adjust the advance value on the light. This is a great way to see how much you get from the vacuum and at what level of vacuum the systems engauges. On my Mallory the adjustment for the pod is how much advance, not at what vacuum and it's pretty binary being either on or off (it's not progressive)

Every rebuilt distributor I've ever worked with has too much mechanical and vacuum advance. Count on recurving the distributor. Unless you just like the look of the "big cap", there is no need to use it. All new Dura Spark type distributors are available for about $80.00 form Spectra Premium (used to be Rich Porter Tech.), 1974-1989 Ford 351M, 400M, 429, 460. It will also need to be recurved but, it is new and not been put through the A-1 Cardone generic parts assembly program.

Use a spark plug piston stop to find TDC with the heads on. Chuck

Every rebuilt distributor I've ever worked with has too much mechanical and vacuum advance. Count on recurving the distributor. Unless you just like the look of the "big cap", there is no need to use it. All new Dura Spark type distributors are available for about $80.00 form Spectra Premium (used to be Rich Porter Tech.), 1974-1989 Ford 351M, 400M, 429, 460. It will also need to be recurved but, it is new and not been put through the A-1 Cardone generic parts assembly program.

Use a spark plug piston stop to find TDC with the heads on. Chuck

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 Ditto the "too much mechanical and vacuum advance" on rebuilt distributors, Cardone especially. Been there done that!! My case needed the L15 slot welded and recut to equal an L10 or .410" slot. The springs were way off too. Be prepared to play with it.

 My "spark plug piston stop" tool is a pencil with a good rubber eraser to feel TDC. I think that tool might just be a better idea in case the eraser falls off!! Where to buy?

Geoff.

https://www.summitracing.com/parts/sum-900189/overview/

Typical piston stop (make sure you get one with proper threads for your heads). I've made one from an old spark plug but I needed it "now". Probably not worth the effort to save ten bucks if you have the time.

https://www.summitracing.com/parts/sum-900189/overview/

Typical piston stop (make sure you get one with proper threads for your heads).  I've made one from an old spark plug but I needed it "now".  Probably not worth the effort to save ten bucks if you have the time.

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 Thanks for the link. I was thinking it would be something with a free moving center piece so one can see and feel as the piston reaches TDC, much as I do with a pencil, not what looks like a screw insert that I'm thinking could damage a piston if not careful. Still may get one though, or make my own.

Because of the way the piston "dwells" (and can rock a bit in the bore) at TDC it would be tricky to find by looking directly for it while rotating the crank. I like the "split the difference" approach with a positive stop.

You can dent a piston pretty easily. Removing the other plugs can make it safer/easier to feel what's going on as you contact the stop with number one.

You turn the engine by hand ONLY, and gently at that. I would disconnect the battery to be safe. On the number one compression stroke, with the piston well down the bore, first turn in one direction until the piston lightly touches the stop, mark the damper. Then turn in the opposite direction until the piston contacts the stop. Mark the damper. True TDC is half way between the two marks. Chuck

Because the piston moves very little as the crank nears the top of the stroke it is very difficult to feel TDC. Even a dial indicator doesn't work that well. The best method is to install the piston stop and slowly rotate the crankshaft in one direction until the piston contacts the stop, mark the damper, rotate the other direction until reaching the stop, mark the damper. The exact TDC will be halfway between the two marks. This is the preferred method even when the heads are off the engine. Adjust the stop so the piston is stopped 20 to 30 degrees prior to TDC. This is best done with all the spark plugs removed.