420cc birthday

R

rkcarguy

New member
After being crowned the track "destroyer", killing 3 small block clones, I am pleased to announce that my 420cc big block has surpassed a calendar year of propelling my 470#'s of kart and driver fatness around our demanding 19 turn 3/4 mile asphalt track with nothing but oil changes and one valve lash adjustment:)

Special thanks to Luke at PFM for all the advice prepping the engine to OVKA rules, and the great service with the parts I ordered:)
 
spotteddawg said:
schawwwweeeeeet! Now go paleo and be a world beater
Click to expand...

I was a 222# freshman in high school when I biked everywhere and didn't have an extra # on me. Isn't going to happen. I'm already on the Paleo diet btw....
I could stand to lose maybe 15#'s tops.
 
Stock rod. I did give the oil hole a "3 angle port job" though. I've turned it 5700 a couple times but I actually ran faster taking one tooth off the rear sprocket which landed me at 5500 peak rpm in the last race. Being these are designed to be ran up to 4000 rpm I don't feel like I'm pushing it too hard. We have a 5 week gap between the June and July race, I'm planning a tear down/inspection and may put a billet rod in at that point, it does have over 10 hours of racing time on it now. I also want to cc the motor at TDC and shave the head to minimum while I have it apart.
It's been amazing so far, even after sitting for a month I'll prime the carb(blow into the fuel tank vent) give it a little spritz of gas and it often starts on the 1st pull.
 
Cool! Yeah, we have had these motors last up to 3 years per ovka rules with nothing but oil changes. I am glad you are having fun with it!

Most of us run the stock rod FYI. There is no difference in switching to the ARC. The arc is actually a bit shorter than the stock predator rod.
 
Luke, our last race ended up being a rain race, where my driving experience serves me well. Despite the fact we run light and heavy together(scored separately), I qualified 2nd overall but with the fastest lap time, 1st in heavy, and then got my pressures dialed in a bit better. I got hole shot from the outside starting position in the main and won the whole thing:) Wish me luck on a dry track though.
It's really cool that we've got 4 different weight groups and about 5 different motor configurations, and of the fastest 5-6 of us it's anyone's race on a given day.
I've got 10.8 hours of track time on the engine now, should I look into a replacement rod or leave it alone until X hours?
 
hi, im looking at this engine for my Kart. it will be 500lbs all said and done.

hows the fitment? I have an xl seat and 2008 homologation side pods. will this engine fit?

do you have the stock flywheel at 5500rpms, or are you running a billet piece?

how much can be milled off the head? I want to run higher compression and methanol?

will it take a gx390 cam?

thanks all.
 
The big block would not fit with my bread box side pods, I re-bracketed the nerf bars to accept newer bodywork. With 08 Unico? it should squeak in there. I have an XXL seat.
As for the cam you need to check the journal size, some engines take the Honda cams and some don't.
I keep mine under 5800 rpm and it's stock, stock rod, stock flywheel, balancing shaft in, just the small clone springs inside the stock ones, remove governor, and external bolt on's. If it wasn't for the clutch being $160 this would have been cheaper to set up than a small block clone by the time you get the aftermarket flywheel.

Got some video from qualifying Saturday in the wet.....enjoy.

https://www.youtube.com/watch?v=nkds_OvjnAU
 
thanks for the quick reply your video is listed as private.

do you have any pics of the engine setup in the kart? what motor mounts did you use, and what degrees?

which clutch are you using if I may ask?

thanks man
 
Sorry, 1st youtube posting, I fixed it.
It's a 15* burris mount with a BB top plate(you unbolt the sliding top plate for the small clone and attach the big one).
I would probably use a 10* mount if I did it again, it has plenty of tire/air filter clearance.
It has a Noram star clutch on it, I run a 16/55 +/- a tooth on the back depending on conditions.
 
My recommendation is to either run it fairly stock like I am, or go all out with a build. There is too many weak components to go 1/2 way on a build. If you plan to spin over 6k the balance shaft needs to come out, billet rod, re-balance rotating assembly, billet flywheel, good valve train, bigger carb, alcohol, and so on. If you go this route and it's for an open class start with one of Vegas's 440's.
 
I spoke to v c about the 460. They no longer have the 440. They said its bigger than the 420 physically but couldn't tell me what mount it takes.
 
"I've turned it 5700 a couple times but I actually ran faster taking one tooth off the rear sprocket"

Congratulations, IMHO... that's what kart racin is all about and what makes it fun. ... when yer takin teeth off and it don't hurt your smile. ... :)
 
Thanks again for your help. I ordered the Vegas 460 and will give it a go.
12.5:1 comp ans will be running methanol. I can't wait.

Ill also order the star clutch.thanks.

Oh, what fuel pump do you use?
 
Might want to get an enforcer clutch on that, the star might squawk at the power you'll be putting out if your on pavement.
I'm having some fuel problems, but the best flow pump I've tried was a Mikuni meant for TAG motors, it's a square black plastic body with metal covers on both sides.
I wasn't aware that Vegas's engine was a 460 now.....gotta check that out!
 
thanks. i already have a star on the way. ill see about exchanging it.
i ordered a wahlbro pump.

im going to run it stockish for a while then upgrade crank,cam, rods and pistons
 
It's gonna be a beast just in stock form. Should be over 20ft/lbs of torque.
The piston will already be a flat top unless it changed on the 460, just rod, flywheel, cam, valvetrain, remove balance shaft and feed it more air fuel and it should fly.
 
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