69mm stroker crank in predator 420

[raydhd]

One question I wondered about is with the extra stroke of the 69 mm crank was there clearance all around the block when things heated up ?

[KRAZYMATT]

Guys the rod was the stock predator 420cc rod. The motor was an older early style motor with the thick piston rings (2012). The crank was a brand new crank from NR racing, there was plenty of clearance in the block and on the cam. I had clearance issues with the balance shaft and rather than clearancing it my self I just ordered the 460 balance shaft from Vegas carts for 25 bucks. All rotating parts had plenty of clearance when assembled and spin over by hand. Cylinder bore was honed while it was apart and new rings were installed. Stock head no milling or polishing done. Had NR racing 1.3:1 roller rockers chromoly push rods and 35lb single spring valve springs. (Nothing on the valve train was changed) when I reassembled I even marked the lifters so they were back in same position as before. The rod bore on the rod did not appear egg shaped or out of round when I cleaned it. Checked for oil clearance and it was right around .003”. The motor is in a 91 club car ds with 6” lift- the cradle for the lift is at a pretty steep angle so I ALWAYS ran the crankcase OVERFULL of oil- I would fill it until it was flush with the dipstick full hole with the motor at the angle- this put the oil level high enough that the main crank bearings were approx 1/4-3/8 of the way submerged at all times. When I assembled the motor I used a mixture of 50% assembly lube (green stuff from summit racing) and 50% gaurd dog molypaste (this company is now out of business but I still have a decent amount) this is same mixture I rebuilt my lycoming aircraft engine with for my airboat 5 years ago with no issue and my vrx460 which has ran flawless. I did not use zinc additive on startup as the cam and lifters were already worn into each other. The cart ran very strong and right around 25mph. The govenor was still intact same as before. I installed the comet 780 drive clutch and was still using the stock club car driven clutch. Cart is lifted with 23” tires. Has rear end from my 97 carryall in it (running in reverse with more low end torque) I ran it for a solid 30-40 minutes without issue. As I started
heading towards the house I could feel it starting loosing power. I was about 1/4 mile from the house. It began smoking I assume from the oil- looked like the
Mosquito control spray truck. Then right as I got in front of the house it let loose heard some racket then just a bunch of clicking. The clicking turned out to be the crank lobes slapping the govenor arm once it broke and was dangling in the crankcase. Neighbor has a spare predator 420 he’s been moving around so I may talk to him about purchasing from him. Will probably get another 69mm crank and the billet rod and try again in a month or 2.

[KRAZYMATT]

Originally Posted by slonomo

That's my point, different rods from different factories with different metals etc. The early generation VC440 was likely built differently than the later VC460. That's why I think my rod was so soft. Being soft means that it won't shatter, and it will have some flex and be quieter....but....it also means the rod journal will wear. I'm betting they had some issues early on, because Vegas Carts really pushed that ARC rod back then, even though it was $160. Geoff Warner also stated on several threads and in conversation that the stock rod will "egg out" as he put it. Of course I didn't listen to him and of course mine "egged out" lol.

The whole VC440/460 story line was a giant experiment. Vegas Carts did what no one else did, put a high powered single cylinder engine package together for golf carts. They tried different versions, making them better and stronger along the way. The early engines were very different animals. At one point, I even upgraded my crank and block because of the issues with the Gen2 440.

I'm wondering if the OP here had one of the early rods.

So that 440 block isn’t good? Ryan said I could have that if I wanted it...

[slonomo]

Originally Posted by KRAZYMATT

So that 440 block isn’t good? Ryan said I could have that if I wanted it...

Yeah it's good. It just wouldn't work with the 460 crank with the long rod I had, I guess the deck height was too short. The updated 460 block was used at that point. So the 440 block is good, just needs cleaned up. It got exposed to humid air inside the shop. It was oiled, but apparently not enough. Youll have to check it out. It's a Gen2 440, you can check my build thread to see when I got it, I can't remember back that far lol. 2013 maybe?

[KRAZYMATT]

Originally Posted by slonomo

Yeah it's good. It just wouldn't work with the 460 crank with the long rod I had, I guess the deck height was too short. The updated 460 block was used at that point. So the 440 block is good, just needs cleaned up. It got exposed to humid air inside the shop. It was oiled, but apparently not enough. Youll have to check it out. It's a Gen2 440, you can check my build thread to see when I got it, I can't remember back that far lol. 2013 maybe?

Ahh. Ya the rod you had was 4.410” that’s what I messaged you about. the rod that came with my 460 is 4.510” makes sense now. So if I use the 4.510 rod in that block should be good to go. I’ll clean the block good and give fresh hone- I have a flexball hone for 90-95 mm.

[slonomo]

Originally Posted by KRAZYMATT

Ahh. Ya the rod you had was 4.410” that’s what I messaged you about. the rod that came with my 460 is 4.510” makes sense now. So if I use the 4.510 rod in that block should be good to go. I’ll clean the block good and give fresh hone- I have a flexball hone for 90-95 mm.

Yeah my intention was to piece together a second engine to use in another project cart. Never got around to it. And the fact that those engines didn't have charging systems and I didn't have a starter/gen kinda made it more complicated. I just decided to go another direction.

How's that 460 engine running?

[KRAZYMATT]

Originally Posted by slonomo

Yeah my intention was to piece together a second engine to use in another project cart. Never got around to it. And the fact that those engines didn't have charging systems and I didn't have a starter/gen kinda made it more complicated. I just decided to go another direction.

How's that 460 engine running?

I bought the 18a Honda oem charging coil and 4 magnet flywheel for my 420cc originally but never installed it because it ran so good I didn’t want to mess with it. When I got the carryall and the 460 I decided to just install it on that. Really nice and clean with that setup. The 460 runs great. Got some tweaking to do on the vm carb as it’s running pretty rich right now but not to the point of fouling plugs. I suspect it will run even better once I get the throttle cable adjusted good where it will open the slide on the carb to 100 and get the jetting leaned out some!

[KRAZYMATT]

Got the motor tore down. Rod let loose, knocked hole in case- side cover looks fine, crank has build up from aluminum on journal and rod also cracked the piston.

New case, crank, BILLET ROD, piston, & bearings and should be back in business. Also sheared the bolt off the counter weight in the balance shaft but I think I can get the old one out and just put new bolt in it...

[slonomo]

WOW!

What engine was that? The 420?

[KRAZYMATT]

Originally Posted by slonomo

WOW!

What engine was that? The 420?

Yes my predator 420, I just swapped the crank for the 460 crank but didn’t put in a billet rod! It will have 1 when it goes back together! I am going to use your old block to rebuild it this second go around.