I am building an RX4 13B and fitted a lightened flywheel and balance weight which resulted in a loss of end float. Is this a common problem and will I need to remove the flywheel and machine the balance weight?

The flywheel and weight should have nothing to do with end play. That's strictly a function of the spacer and e-shaft. You have an issue somewhere else if the end play is taken up when the weight is installed. Is it contacting the rear gear? At any rate, removing material from the weight will require everything to be reblanced.

We are assuming here that the thrust assembly was assembled in the vertical and the spacer is not sitting on a thrust race. You don't even need the engine to measure end play. Assemble the thrust assembly on a spare crank and us nuts and bolts to hold it together. Place the mag based dial indicator on the thrust plate and the indicator on the crank pulley with the bolt tightened to 80 foot pounds. Looking for .0020" to .0035".



It should be the same when bolted to just the front iron, and with the whole engine torqued up. First loosen the rear gear until it drops down a few thoudandths and check it again. If the end play is back to normal, the rear gear, and, or, the front gear is too long. Shorten it or build a shim to fit under it. Add sealant once you restablish end play. No sealant on the front gear at all.

The "O" ring will no longer seal the rear gear.





I just finished an IT 12A short block with a lightened stock flywheel. With the rear stationary gear held in with one screw finger tight, I got .002" end play. When it torqued the rear gear, the end play vanished.



Very perplexing. I inked up the rear stationary gear teeth ends and installed it with tight bolts. I removed it and the ink was gone. The rear stationary gear was too long. I machined off .020" and got .014" end play with no front bolt. I torqued the rear gear and tightened the front bolt and got .002" again with the bolt at 80 footpounds. I installed a longer spacer and got .003" with the bolt torqued to 90 foot pounds.



I left it there. I measured the front statinary gear against an older front gear, and the new gear was .032" longer. Both gears were too long. This is very sloppy quality control.



Lynn E. Hanover

I left it there. I measured the front statinary gear against an older front gear, and the new gear was .032" longer. Both gears were too long. This is very sloppy quality control.



Lynn E. Hanover

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That picture is the reluctor wheel for a crank triggered system.

Here is a pictoral of it.



Lynn E. Hanover

Hey, that pulley has my name on it!!!! https://www.nopistons.com/forums/pub...>/bubbrubb.gif



B

Its nice that you own BDC. I invented TDC in 1947. Up until then it was called "At The Top" or ATT. I didn't change my name to fit my invention however.



When you see TDC, think of Lynn E. Hanover



When you see BDC, think of Brian D. Cain.

What's the go with the reluctor setup ignition? Where did you source the reluctor from? Looks like an interesting idea, and probably very accurate

Woops, should have thought a little more than I did before posting that. I assume you are using an alloy boss (appears to be from the image) with an iron reluctor (an iron rod pressed into place and machined to just show?). What are the pickups from? I assume 4 seperate coils?



Lynn, you always seem to have the most surprising wisdom. You are a true asset to motorsport, shame you're in the states (or lucky, cos I'd be sitting in the corner of you shed, taking notes). Ever thought of writing a book?

so pretty much just CDI ?

Years ago, when I raced a Fiat, that on the dyno the timing (timing light on the degree wheel on the front pulley) would shake at some RPM, and then be OK, then at another RPM would shake again. Jerking between two points as much as 5 degrees apart.



The distributor was run off of the rear end of the exhaust cam, and was responding to various harmonics induced by the crank, drive belts and the cam lobes.



I was using a Chrysler (Dodge/Plymouth) electronic distributor pickup, and reluctor in the Fiat distributor. And the Chrysler ignition amplifier.



At the time I read where all of the formula one cars used the flywheel to trigger the ignition systems for greater accuracy.

So I built the reluctor wheel with degree wheel and mounted it to the stock front pulley. There is no advance curve at all, and the Fiat had a 14:1 compression ratio and could not start with 34 degrees of advance, so I kept the distributor and advance weights to start up with and with the pickup leads run to a double pole, double throw switch, I could switch to the crank trigger after the engine was running. It works great, and I did it again on my early Mazda engines. I used two Oldsmobile double ended coils, one for each housing. The Mazda starts right up at full advance, and this system is as good as you can get. Trigger wires must be run well away from each other, and away from high voltage wires.



I use the electronic distributor now, just because it is very accurate/easy/quick and available.



One 1/4" bolt was pressed through the disc to be the reluctor with two pickups (Chrysler distributor from the 70s) 180 degrees apart. Both plugs on each housing are fired at the same time. The pickups cost about $5.00. The amplifiers cost about $25.00.



Lynn E. Hanover