Engine Break-in - How to measure rpms with Helmet Dist?

[Ziggster]

I should soon be ready to start my rebuilt C59A and was wondering what methods are available to measure engine rpms so I can break-in the cam at 2,000 - 2,200 rpm? I have a helmet style distributor installed. I have a marine tach, but it will need some type of “board” made to make it work. I do have a timing light as well, but not sure if it will work on the flathead to measure the rpm.

[ford38v8]

White chalk mark on the crank pulley with your timing light. That said, I believe you’d be better off with a break-in period under a light load, just tooling down the highway at the speed limit.

[Brian]

I agree with Alan, You need to bed the rings in...in order to do this you need to drive the vehicle in order to put a load on the rings. Simply running the engine at fixed revs is liable to glaze up the cylinder walls.Take the vehicle for a drive, accelerating up to, say your 2000 RPM and decelerating, this creates a high vacuum which draws oil up the cylinder walls to aid in the bedding in of the rings. Driving in this manner for the first 10 miles will enable the engine to bed in very nicely, including your camshaft. Enjoy!!

[hueyhoolihan]

it might be possible to use a modern 12v timing light. modern ones often indicate RPM using an induction sensor clamped around a plug wire, assuming the car is running a 12v electrical system. if running 6v, an external 12v battery can be used as the power source for the timing light. something like this, maybe?

https://www.harborfreight.com/digita...id=21894823878

[Ziggster]

Engine is mounted to my chassis, but chassis is no where near ready to be driven. Just want to break in the cam for now. Watch plenty of newly rebuilt engines on NickÂ’s Garage YT channel being run on a dyno with no load at first for 20 mins to break in the cam at around 2,000 rpm.

Need any other advice on measuring engine rpm. I do have a modern timing light, but havenÂ’t used it in years. Was on an IH 345 cu in V8.

[69a]

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What Brian says!
Wait till you have it drivable. You need to get it above 2,000 RPM for about 20 minutes to bed in the cam. You need to get some load on it to bed in the rings
Limit the time outside these parameters and get it up to about 40 MPH asap. Let the load off occasionally.
It's no good having a perfectly run in cam if your bore is glazed. There was a post on here recently where someone tried to run their engine in on an engine stand
It had bad outcome. Priorise rings over cam in my opinion.

[Tim Ayers]

Agreed on the advice above. Start it, make sure there are no fuel and coolant leaks and then jump and get on it. I've been told keeping it in second, decelerating and then accelerating helps to really bed in the rings.

If you are not running a filter, I'd change the oil. Don't be surprised that there may be some gunk in the oil. That's part of the break in. To me, it's cheap insurance.


If you want to know the RPM's, use one of those cheap tachs. that uses a lead that wraps around a spark plug wire. Used them on motorcycles a number of times. They are around $10 on Amazon.

[Ziggster]

I have the Innova 5568 timing light. Manual says operating voltage is 10 VDV - 16 VDC. So, as @hueyhoolihan stated, I can just use another 12 VDC power source since my engine generator and starter are 6 VDC (positive ground). The manual also mentions placing the green clip of the timing light on the tach side (negative) terminal of the coil. I’m using a helmet style distributor, so should the green clip be attached to the brass nut on the integral coil?

[Ziggster]

Pic from the on-line Innova manual, and of the helmet distributor.

[petehoovie]

Originally Posted by Ziggster

Pic from the on-line Innova manual, and of the helmet distributor.

[tubman]

I would imagine that the Innova timing light was manufactured during the "modern" era when almost all cars are negative ground. Therefore, the green wire should go on the positive coil terminal which, unfortunately, is inside the distributor on your positive ground car. From my experience, it wouldn't work anyway, as there will be no ground for the green wire circuit if you run the timing light from a separate battery.

You can try it, and it may work off of the inductive lead on the spark plug, but don't be surprised if it doesn't.

[38bill]

You can find Laser Non-Contact Optical Tachometer on Ebay for as little as $20 or less. They come with a reflective tape that is stuck on a rotating part .

[Ziggster]

Thanks for the feedback. Much appreciated. Just ordered this thing from Amazon.

[tubman]

At that price, that looks like something I should have.

[petehoovie]

Originally Posted by Ziggster

Thanks for the feedback. Much appreciated. Just ordered this thing from Amazon.

[Tim Ayers]

Originally Posted by tubman

At that price, that looks like something I should have.

I agree. Would come in handy

[Ken/Alabama]

Just drive it like you stole it. It’ll be fine.

[Ziggster]

Meter showed up. Tried it at first and nothing. Came with 9 VDC battery, but seemed no good. Swapped in another I had. Tested it on my bench grinder and 5” Makita electric grinder. Works! Bench grinder came in at 3600 rpm and Makita at 8,800. Was about to throw out the battery, then noticed it was covered in a clear plastic film. D’oh! Just came back from my eye exam and she said I had 20/20 which I haven’t had since a teenager, and for reading a 225, whatever that is. Is smaller than I expected, and feels cheap, but works. lol!

[Kurt in NJ]

a points signal can be gotten from attaching a wire to the condenser screw— not the ground strap side and the coil may need to be removed to acess the screw.
I have always started the engine in the car and went for a drive

[petehoovie]

Originally Posted by Ziggster

Meter showed up. Tried it at first and nothing. Came with 9 VDC battery, but seemed no good. Swapped in another I had. Tested it on my bench grinder and 5” Makita electric grinder. Works! Bench grinder came in at 3600 rpm and Makita at 8,800. Was about to throw out the battery, then noticed it was covered in a clear plastic film. D’oh! Just came back from my eye exam and she said I had 20/20 which I haven’t had since a teenager, and for reading a 225, whatever that is. Is smaller than I expected, and feels cheap, but works. lol!