PVL ignition upgrade?

[Alan Sheidler]

We have one of the earlier WF engines, and it has been great so far. I understand that the ignition system has been superseded/upgraded, and that there is a retrofit kit available.

Is this worth doing? What can we expect in the way of benefits from going with the new ignition system?

Thanks

[al nunley]

I very seriously doubt it will make you go faster, if that’s what you’re hoping for.
We went to a practice day at the drag strip with out 389ci Chevy Corvette. We took three ignitions; stock dual point, after market magneto and the latest Chevy electronic pointless ignition. (This was in the sixties). As an after thought I took the ignition out of an old 1955 265ci we had sitting in the corner. I swear, the 1955 ignition turned the best ETs.

It takes a certain amount of voltage to jump the gap, when you reach that voltage, the plug sparks. A stronger ignition may be able to jump a wider gap, but I doubt that will do anything.
_________________
If the data does not support the theory, get a new theory. (Al Nunley)
All else being equal; Compression is the Holy Grail.
45 years, in and around karting

[Dean Graves]

It's worth doing. Higher volts, better spark, and the new flywheel (part of the kit) is aluminum.

[David Klaus]

This makes for a good read....

http://www.briggsracing.com/technical_talk/tech02.pdf

[Bob Vehring]

Like Al, I'm an old drag racer, but there many things different here. I agree we don't need a Vertex Mag to fire these things. But thats about all we can compare. Back then in cars, the dist. changed timing to make starting easier. In those days it was a combination of springs and Wts, and a vac. diaphragm. In drag racing we wanted timing all in by about 3000 and simply set total timing above that point. In drags you left the line at that point or above, so the settings other then total timing, made very little difference.

Today, either with elec ign in cars or the PVL digital system for karts the timing curve is programed into it, and is designed to be at optimum throughout our entire usable rpm range. Out here where everything is based on the Animal, it became clear right away that if you didn't switch to the new PVL, you could be down by as much as 1/2 hp

A short story for Al, but it also makes the point. In the late 60's/70, I ran a Automotive speed shop, specializing in Drag racing. We had a big block Camaro that ran 10.20's ( slow now but fast then). The choices then for distributors were Mallory, or Accel. One had a 4 lobe cam with staggered points to open the points, the other had 8 lobes. Using a Sun Dist. machine we learned that by running a toggle switch to one set of points to take them out of the system, we could at higher rpm retard the timing about 4 deg. When you leave the line, with the help of the gear multiplication from the trans, you can run lots of timing, but, come that long hard pull in 4 th gear, with the areo drag and frictional losses, to much timing gave you detonation. We simply could run alot of timing for 1,2,3 gear, hit the switch and back it down for 4th.
Today all that is done electronically
_________________
Bob Vehring
www.4cyclecentral.com

[Alan Sheidler]

Thanks for the replies, everyone!

Al, I'd agree that some things have not changed since the 60's, but we are not just talking about plain ignition here, akin to your experience of 40 years ago. The difference between an analog and programmed digital ignition are pretty big; not restricted to just voltage. I'm thinking that technology has made a stride or two in the last four decades. Welcome to the 21st century.

Alan

[Alan Sheidler]

Installed the new ignition kit... wow, what a white hot looking spark!

No spark at all at first though. The vendor we bought the kit from failed to pass along the information that the old rev limiter had to be disconnected in order for it to run. You'd think that would be basic information given up front to anyone making the upgrade. I guess some old timers just figure they should be doing the work themselves... never mind that $ just changed hands, and that parts are really only a part of the price of the transaction. Either that, or they assume that everyone knows what they know... which is impossible.

My son runs on Sunday. Can't wait to hear what he has to say about the performance.

Alan

[John Matthews]

Hi Alan,

Yes the new coils have the rev limiter built in so nobody can mess with them.

Where are you running in Michigan? I'm moving to the Traverse City area in a month and a half. Looking forward to being closer to some 4 cycle sprint racing

Cheers,
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John Matthews
Heartbeat Power, LLC.

[Alan Sheidler]

Sorry to disappoint...

We run the autocross time trials with the SCCA, not W2W racing, John.

Alan

[John Matthews]

Autocross is OK too, I was in the process of building my Triumph Herald into an auto-x car when I was given a smokin deal on the ITC Honda that spun me back into this crazy hobby....

I might be able to convince my daughter to try the auto-x thing as she doesn't want to "race" as it were. Maybe we'll see you out there.

Cheers,
_________________
John Matthews
Heartbeat Power, LLC.

[Alan Sheidler]

Uh-oh.

Today was the shakedown run for the upgraded engine and the chassis setup, scheduled to leave for Solo Nationals on Wednesday.

First run, and all seemed well, as Colin came back with a very good 49 seconds lap. He was very happy with the performance of the engine, just plain fast, a noticeable inprovement. Before he ran the second time, we noticed that a bit of oil had sprayed out the left side of the engine somewhere... Could not locate a source of the leaking. Out he goes for the second run. 2/3 of the way through, and he is going slowly, with a misfire. Engine stalls completely after the finish.

Something definitely wrong here. Pulling on the recoil starter can result in the cord being yanked out of the hand, or a backfire through the carburetor. Just based on what I see, the engine's ignition timing has gone way advanced, and it is firing early enough to reverse the piston's rise, and/or when the intake valve is open. When I installed the new flywheel, the key went in the slot, and I torqued the nut to 55 lbs. The nut is still in place, I took off the recoil to have a look. How could it slip? Is it possible to shear off the key?

And, with more oil evident on the left side of the engine after the troubled run, still with no apparent source.

Tomorrow I will pull the flywheel and have a look at whether or not it managed to change the alignment with the crank. If it is still in the correct place, I'll be lost as to what is causing the issue here. The new PVL unit? Dunno how it could fire early without the signal from the flywheel... All comments/suggestions appreciated! Anyone have any ideas as to where to look for the oil leak source?

Running out of time here..

Alan

[Wayne ONeil]

The leak could be coming from a small tear in the sidecover gasket or from the crank seal.. That's where I've had leaks before.

[Jim Pelletterie]

sounds like you sheared the flywheel key which is common if the flywheel is not tightened properly. as for the oil, how much oil is in the crankcase? We had had no sucess running more that 17oz with a 5 degree mount without the oil being pushed out the breather. Extend the breather hose into a catch can to help with this problem

[Alan Sheidler]

Jim hit it, the flywheel key sheared. Couple of nice little wedge-shaped pieces now, instead of one box. Also, based on what the inside of the flywheel looks like and the crankshaft taper, it went around a couple of times, instead of just slipping to the maybe 30 degrees advanced where it stopped. I guess I am guilty of not tigtening the nut enough; so the 55 pounds I torqued it to is not sufficient. The upper limit of the Briggs Spec is 75. I'll go there when I reinstall it with a new key. Gonna make one myself, that fits snug... maybe a little longer, too. Also, based on advice I got from another old karting engine guy, I'll use some lapping compound and get the crank and flywheel tapers mated as well as is possible! Then both will be extra clean before they go together. I don't think loctite is appropriate here... is it?

As far as the oil goes: First off, we run a flat mount. Normal fill amount is supposed to be 16 ounces, from what I have read to this point, and that is what is in the Briggs manual. I can see where people running the 15 degree mounts might need to run a few ounces more.... Until this year, we had never run a catch-can attached to the breather hole in the valve cover. But at a track this spring, it was pushing out some oil there during a flat-out lapping session, so we rigged a can up for the day. Afterwards I bought and installed the Briggs part number 555688 Breather Assembly. Our old temporary catch can had been damaged... and with the tube just sticking out... Maybe a bad decision which resulted in increased crank-case pressure, but Sunday I folded the tube on itself, effectively sealing the original breather. I had intended to get a better connection for the breather, and run to a proper can. That is the next project after the flywheel. In any case, I have also ordered a new gasket and seal for the PTO side. We'll be up and running soon!

Colin's run for a podium spot comes in a week, with a practice day Monday, timed runs Tuesday and Wednesday. I have to say, the community we run with is great. Within 12 hours we had offers for two other rides and two loaner engines! Hopefully, we won't need to take anyone up on their generous offer.

Alan

BTW, how can I post photos on here? Must I have them online somewhere, or can I post from my computer?

[Jim Pelletterie]

I'm going to make some engine builder cringe but I tighten the flywheel with my 1/2 inch impact. I also use another washer inside the cup so the nut is not bottoming out on the threads. No locktight! Our rules demand the stock key so any alterations to it would be a no-no