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Engine Help => Honda and Clone Engines => Topic started by: Chris Matuschka on July 22, 2011, 09:32:11 PM

Title: PREDATOR 420CC ENGINE
Post by: Chris Matuschka on July 22, 2011, 09:32:11 PM
Hi, has anybody experimented with the new Predator motors at Harbor Freight. It looks very similar to the GX390 on the outside but I am wondering if the ARC parts will fit and gasket availability.
Title: Re: PREDATOR 420CC ENGINE
Post by: zach87cp on July 23, 2011, 05:24:46 AM
I dont have any experince with a clone but i heard that the block are weaker than a honda and they crack.
Title: Re: PREDATOR 420CC ENGINE
Post by: George Herrin on July 23, 2011, 06:48:14 AM
We run the clones and have great luck with them. No problems so far and all the hopnda ARC parts fit.
Title: Re: PREDATOR 420CC ENGINE
Post by: Chris Matuschka on July 23, 2011, 07:05:06 AM
I know alot of guys had good luck with the older blue ones from Harbor Freight but didn't know if the new black Predators were still the same. I'm hoping the only diference is the bore.
Title: Re: PREDATOR 420CC ENGINE
Post by: George Herrin on July 23, 2011, 08:17:49 AM
ours been red n yellow and 1 blue i think oh 1 black too but it was a 390 clone. we got one of the 420 here in BTMRA and its stroked. been a whole season and starting half way thru the second so far so good
Title: Re: PREDATOR 420CC ENGINE
Post by: Rooster on July 23, 2011, 02:48:34 PM
Honda blocks will crack as well, they really need supported.
The 420 has a bigger bore, same stroke as a 390.
Title: Re: PREDATOR 420CC ENGINE
Post by: DanW on July 23, 2011, 06:26:42 PM
Same rod dimensions and flywheel as well?  A big bore 390 sounds very attractive!
Title: Re: PREDATOR 420CC ENGINE
Post by: Chris Matuschka on July 23, 2011, 06:34:07 PM
Thanks guys, they are on sale for $350 plus 20% off with coupon. Was hoping to use an Arc rod and flywheel and a cam change. Was thinking to only mill the head a little to keep compression reasonable. I want to build something mild and reliable until I get some runtime on the chassis.
Title: Re: PREDATOR 420CC ENGINE
Post by: George Herrin on July 23, 2011, 06:46:12 PM
Call Mike at precision he built my clone and its stupid fast. He can fix you up on anything you need for it. ALL ARC parts fit too.
Title: Re: PREDATOR 420CC ENGINE
Post by: Ron Atchison/A.C.E. Race Engines on July 31, 2011, 11:14:17 PM
All of the block will eventually fail if they are pushed beyond their limits! We have built several of the 420 clone engines. Over the last couple years we've came up with a good forged lightweight piston, cyl head, billet flywheel & cam package i sell that makes around 35hp with good reliability. If you run the Arc rod and spin engine over 6500 rpm you'll need change the rod in 12 or so nights. The alternative to the Arc rod is to buy a $290 4340 steel rod. We turn our 420's around 72-7500 rpm with no problems when built right. Here's a couple pics of a 38hp 390/420 where the block didn't survive the dyno run.

(http://i289.photobucket.com/albums/ll230/rjhp62801/th_GetAttachment2.jpg) (http://s289.photobucket.com/albums/ll230/rjhp62801/GetAttachment2.jpg)

(http://i289.photobucket.com/albums/ll230/rjhp62801/th_GetAttachment.jpg) (http://s289.photobucket.com/albums/ll230/rjhp62801/GetAttachment.jpg)
Title: Re: PREDATOR 420CC ENGINE
Post by: DanW on August 01, 2011, 06:42:27 AM
LOL... pass.  Who makes the steel rod btw?
Title: Re: PREDATOR 420CC ENGINE
Post by: cubcadet70 on August 01, 2011, 10:27:27 AM
Honda makes the stell rod. You will have to buy the bearings. Do you know which color bearings I should buy for standard size? They go buy color coded and I don't know which is which.
Title: Re: PREDATOR 420CC ENGINE
Post by: Ron Atchison/A.C.E. Race Engines on August 01, 2011, 02:26:52 PM
Honda makes the stell rod. You will have to buy the bearings. Do you know which color bearings I should buy for standard size? They go buy color coded and I don't know which is which.

The steel rod i'm referring to is not the casted Honda steel rod but, it's a forged custom made 4340 h-beam design.
Title: Re: PREDATOR 420CC ENGINE
Post by: DanW on August 01, 2011, 03:01:09 PM
Who makes it?  I've gotten quotes on custom forged rods and it comes out to $500 per rod if the production is low.

I would be very interested in having them make h or i beams for a Vanguard if they are in the ball park of $290.
Title: Re: PREDATOR 420CC ENGINE
Post by: Ron Atchison/A.C.E. Race Engines on August 01, 2011, 10:14:38 PM
Who makes it?  I've gotten quotes on custom forged rods and it comes out to $500 per rod if the production is low.

I would be very interested in having them make h or i beams for a Vanguard if they are in the ball park of $290.

ok, contact these people  http://pacrankie.en.alibaba.com/product/290289603-200240948/CC131mm_8A_Connecting_Rod.html.    To have domestically made they wanted a min. order of 100 at $200 each!
Title: Re: PREDATOR 420CC ENGINE
Post by: SMALL ENGINE CAMS on September 13, 2011, 03:30:39 PM

Call Jeff Mackay at (217)498-8250. He has chromemoly rods for the GX390.
Tim
Title: Re: PREDATOR 420CC ENGINE
Post by: cubcadet70 on November 26, 2011, 10:20:58 PM
Anybody know if the 420cc clone motor carb is bigger than the 390? Will they blot on? Would be a good trick carb for my class. Just a thought. Thanks.
Title: Re: PREDATOR 420CC ENGINE
Post by: George Herrin on November 27, 2011, 06:59:32 AM
same carb as 390 jetting might be a tad different but same body
Title: Re: PREDATOR 420CC ENGINE
Post by: cubcadet70 on November 27, 2011, 10:07:02 AM
Oh well wish it was though. Honda don't make any carbs bigger than the 390 but still can bolt on?
Title: Re: PREDATOR 420CC ENGINE
Post by: Johnson Mowersports on November 28, 2011, 10:06:14 AM
what class are yall running these motors in?
Title: Re: PREDATOR 420CC ENGINE
Post by: cubcadet70 on November 28, 2011, 01:39:24 PM
I run a 390 on my pulling tractor. I don't race them.