69mm stroker crank in predator 420

[KRAZYMATT]

Can I put the 69mm (+.200”) stroker crank in my predator 420 to make it a 440? Planning on using the stock 420 rod. What else needs to be changed? I know some clearancing may need to be done to the balance shaft, cam, and or case. Going to go for zero deck height and turn down the stock predator piston any that’s above the deck. Will be using stock rod and cam. Cut the predator 420 crankshaft down when I did the swap to use the factory club car clutch with the taper adapter and I feel it was the weakest part of the swap. My plan is to replace the crank with 69mm crank and install the comet 780 clutch. Waiting on Vegas carts to get the mount back instock so I can do the swap. Already have the crankshaft- NR racing has them on the shelf.

[sho305]

I'm not sure, when I put the long rod from Vegas in my 420 I had to cut around .100 off the top of piston. A stock 420 the piston is below the deck now its very close to at the deck. More stroke will raise the piston you have to calculate how much, half the increase. Otherwise sure just chop the piston down to deck so you have some clearance to the head, depending on what gasket you use I put the thick one in . My head is also decked .050. I think Vegas says how much longer their rod is I forget.

[KRAZYMATT]

I was going to pull the head and shoot for zero deck height- anything above I would turn off the top of the stock predator piston. Going to be using the stock 420 rod.

[Shepard]

Originally Posted by KRAZYMATT

Can I put the 69mm (+.200”) stroker crank in my predator 420 to make it a 440? Planning on using the stock 420 rod. What else needs to be changed? I know some clearancing may need to be done to the balance shaft, cam, and or case. Going to go for zero deck height and turn down the stock predator piston any that’s above the deck. Will be using stock rod and cam. Cut the predator 420 crankshaft down when I did the swap to use the factory club car clutch with the taper adapter and I feel it was the weakest part of the swap. My plan is to replace the crank with 69mm crank and install the comet 780 clutch. Waiting on Vegas carts to get the mount back instock so I can do the swap. Already have the crankshaft- NR racing has them on the shelf.

From all l've read you get about a 20cc bump in displacement changing the 66mm crankshaft to the 69mm version. Your the first to admit that cutting the crankshaft and using the adapter is a weak spot in your power train. Maybe others will read this and stop wasting the time with clutches that are worn out

[raydhd]

IMHO While you are in there get rid of another weak point the stock rod.

[sho305]

Originally Posted by raydhd

IMHO While you are in there get rid of another weak point the stock rod.

And the Vegas cheater cam lol

[sho305]

Originally Posted by KRAZYMATT

I was going to pull the head and shoot for zero deck height- anything above I would turn off the top of the stock predator piston. Going to be using the stock 420 rod.

Should work, well far as I know you can take .100 off a clone piston anyway more than that I don't know.

[KRAZYMATT]

Originally Posted by raydhd

IMHO While you are in there get rid of another weak point the stock rod.

I’ve kicked it around but I really don’t think I’m gonna keep this cart for long once I get it back together now that I have the carryall. This Motor has ran great I just know I left a lot on the table with the factory clutch and want to atleast put the 780 on it. It still has the governor intact but I did put offset timing key, chromoly push rods, 35lb valve springs and NR racing 1.3 billet roller rockers in it when I first put in the cart. It has ran flawless. I have just been really happy with the quality of Vegas carts products so while I had it apart I figured I’d go ahead and swap my home made mount to their nice adjustable unit and break down and swap the crank so I can run the 780 comet clutch. The little bump from the crankshaft is just a bonus!

[sho305]

The rod and cam woke mine up, it makes a difference and you already have the valvetrain parts. But I know how plans can change. That said I was told you can put a 1" clutch on a cut down crank it fits well enough, but I've not done it. Since the taper is only about 1" deep anyway but it fits tight. Still at 4K rpm it doesn't have to be perfect I would guess....compared to a sled.

[KRAZYMATT]

I put a torque cam in my 460 when I built it so I do have a stock/oem 460 cam I could install while I’m in there. How much different is the stock Vegas carts 460 cam from the stock predator 420 cam or is it the same profile? I know some people say it comes with a “cheater cam” but there was not mention of that on the product page when I purchased the motor and Vegas carts 460 replacement parts page lists the replacement cam for their 460 as same oem cam as gx390/420/440... Will the stock 420 rod hold up with the 460 cam in there? Motor govenor is still instant and valve train has been beef up a little bit. Also when swapping the cranks is there clearancing required to the balance shaft?