Need some input on a crank/engine balancing conundrum

[TouringBubble]

I know ... I get the deal with the spacer. I think I've heard one one failure of the stock spacer and it was with a bunch of other broken stuff. But let me ask you this ... how many racer spacers have failed? For the extra $5 I have a part that is stronger, even if it doesn't need to be. That makes sense in my book. It's cheap insurance, even if it's just for that 1 in 500,000 chance the spacer may fail.

[woodsbuggy1]

I think that you will have a hard time finding an aftermarket(generally chinese) spacer that fits as well as the stock German one. But it is your engine and the most important thing is to use the parts that make you happy.
Good Luck
Kenric

[TouringBubble]

Do you mean "fits as well" or "goes on as easy?"

[jrandy]

If you want to run race parts, then you accept whatever it takes to run them.

[TouringBubble]

I completely agree. That's why I have hand filed/drilled/worked so many of the internal parts of this motor. You can't just take things off the shelf. At least I knew this going in.

I wanted to give a big thanks to FJCamper for the help yesterday! He helped me remove the gear stack with the proper tools and in record time. Thanks again!

Now I have all of the parts properly fitted and ready for reassembly after the balancing is done. At least I'm done filing ... for now.

[turbobaja]

You'll be glad you took the time to do it right. I had my "balanced" Super Race crank re-balanced with every other part of my rotating assembly: Flywheel, pressure plate, timing gears installed, pistons, rods, etc. and was very happy I did. They took a little weight off every cheek on the crank instead of just one. They trued up the crank first and use it as the spindle to balance the FW. A true balance job should come with a print-out of the results, otherwise who's to say it's actually balanced?

Here's what you're looking for if you spend some $$$ on a balance job.

[TouringBubble]

Yeah, there is a highly recommended shop in town ... many of the SCCA club racers use him. Planning to go there. He said he needs the crank, rods, pistons, FW and pulley to get it balanced. I've got it all but the pulley, which is having the reluctor wheel installed. That definitely needs to be balanced.

I would be expecting results on paper.

[nsracing]

I do balance jobs and machine work. Even the paper does not say squat about your item. you still have to take the shops word that it was your assembly that hung on the machine when the printout was made. You still have to trust the work on paper, don't you?

it is like doing an emission on a car that won't pass. a shop can run a different car and certify a car that was never on the rack.

If you want to see your part being balanced and read out on the machine, you need to see it on live video. someone gave me the idea coz I did not hook up a printer on my dynamic balancer. Most of my friends will just bring me the parts and we balance them right there while they are watching the machine. We reach a number they require and we stop.

But the video file is a good is not a bad idea.

Let me know if I can help some of you fellas w/ balancing.

[Phil69]

I wouldn't use a racer spacer on anything other than a drag motor.
As long as the cam driving gear is tight on the crank or you are using a straight cut gear on your cam and crank (no side thrust) there is no reason why a standard spacer ring should fail especially an original German part.

[TouringBubble]

This is a super old thread ... but why only a drag motor? When Dori runs, she turns 7k RPM several times. She's making upward of 135 whp NA or so currently, and will make much more when fully tuned. She's a race car, but isn't for drags. Tell me the difference?

Also, as stated earlier ... maybe it's not needed. But, it's extra insurance IMO.

[Phil69]

This is a super old thread ... but why only a drag motor? When Dori runs, she turns 7k RPM several times. She's making upward of 135 whp NA or so currently, and will make much more when fully tuned. She's a race car, but isn't for drags. Tell me the difference?

Also, as stated earlier ... maybe it's not needed. But, it's extra insurance IMO.

7k is small potatoes for a drag motor some see 10k.
I've got no hard data but Jpm used a standard spacer on their 1603cc motor it turned 8200rpm and pushed out 194.9hp at the flywheel if I recall correctly.

[Marc]

Back in my circletrack days I geared for 7200 RPM - if the car was really hooking up you might see 7300 - at the end of the straights....sustained revs of over 6000 for hours between engine refreshes. Didn't use a "racer spacer", merely squoze the stock one so it had to be eased over the crank with circlip pliers, and never found one loose on teardown...ever.
But considering the much higher probability of a missed shift in a drag-race environment I can see where their use would be justified. If you've got a valvetrain stiff enough to go much past 7500 and a light flywheel, it'd be wise IMO to run one.