New Build with 60363

Craig B

Craig B

Member
#1
#1
Hi all,
I'm new to building small engines like this. I just bought a 60363 from HF and have started to buy some parts for the build. I am looking to run 300ft. in a little longer wheelbase than a standard mini. I am waiting on the bike, but wheelbase is around 48 to 50 in. The motor is going to have a Black Mamba cam, billet rod & flywheel, upgraded SS valves 26lb springs & retainers. a board out carb and K&N style filter. What would be the cut off in compression for premium fuel 93? I don't mind running race gas if I have too. I also need some on what type of clutch would work well in this type of setup?? I was looking @ Bully & Horstman. Thanks for any help. Craig
 
ole4

ole4

#2
#2
Are you planning on using the hemi head or replacing it? You need to pick a cam that goes along with the head. Black mamba is a great cam but does not start making power until around 4K. So how do you plan on getting hi compression? Hemi has a big 23cc chamber so if using that head you would have to 1) use a pop up piston 2)mill the head then have to deal with v tp p clearance. 3) longer rod and thinner head gasket again with care checking v to p clearance. For a clutch you need one with lockup near 4K rpm. For 300 ft you may want to consider a jr drag tc like the salsbury 330 or comet 340. Finally using a bored out stock carb is going to restrict your power. Think about a chikuni 22 or a 24mm flatslide and a open exhaust header. 26 lb white stripe springs would work ok with the hemi. You will need a billet rod and flywheel. Gearing will be very important especially with a clutch which tend to perform best at the top end. Hope this helps.
 
delray

delray

Well-Known Member
#3
#3
Craig B, here is a comet/salsbury 340 driver unit on ebay for sale. like ole4 said early you need a good torque converter for drag racing and anything less will give you problems. for example 20 or 30 series. you could go to a billet Jr dragster setup, but they are little over kill for a minibike setup and big $$$'s. you can still find stall springs for the 340 unit...:thumbsup:
https://www.ebay.com/itm/comet-340/192479980479?hash=item2cd0b36bbf:g:caYAAOSwyTdapbOW
 
Craig B

Craig B

Member
#4
#4
ole4 said:
Are you planning on using the hemi head or replacing it? You need to pick a cam that goes along with the head. Black mamba is a great cam but does not start making power until around 4K. So how do you plan on getting hi compression? Hemi has a big 23cc chamber so if using that head you would have to 1) use a pop up piston 2)mill the head then have to deal with v tp p clearance. 3) longer rod and thinner head gasket again with care checking v to p clearance. For a clutch you need one with lockup near 4K rpm. For 300 ft you may want to consider a jr drag tc like the salsbury 330 or comet 340. Finally using a bored out stock carb is going to restrict your power. Think about a chikuni 22 or a 24mm flatslide and a open exhaust header. 26 lb white stripe springs would work ok with the hemi. You will need a billet rod and flywheel. Gearing will be very important especially with a clutch which tend to perform best at the top end. Hope this helps.
Click to expand...
Ole, are there any other heads available for a Hemi Predator that will bolt on that will be better option? I looked around and have not found anything. I would buy 1 if it were available with a smaller CC. Does anyone make a dome piston for the Hemi that would raise the compression? Thanks for the Help.
 
Craig B

Craig B

Member
#5
#5
delray said:
Craig B, here is a comet/salsbury 340 driver unit on ebay for sale. like ole4 said early you need a good torque converter for drag racing and anything less will give you problems. for example 20 or 30 series. you could go to a billet Jr dragster setup, but they are little over kill for a minibike setup and big $$$'s. you can still find stall springs for the 340 unit...:thumbsup:
https://www.ebay.com/itm/comet-340/192479980479?hash=item2cd0b36bbf:g:caYAAOSwyTdapbOW
Click to expand...
Thanks, I will take a look @ this. I was hoping there was a different option, I hate the way these things look:laugh:
 
ole4

ole4

#6
#6
Hemi uses small dowels so you can use a 14cc or 18cc clone head. You already have a flattop piston which is nice. If you use a clutch then gear it steep so at 300ft you are wound out. I have a couple of heads you may be interested in. You would need different pushrod lengths. Mike at clone engine parts online also has heads and can install larger valves.
 
noseoil

noseoil

Active Member
#8
#8
Bullfrog makes this piston, its spendy, but a good choice without doing a bunch of machine work on the head. Mine runs well, did some porting to clean up the runners a bit, crude but it runs & pulls well enough up to 8,400 rpm. Haven't run up past that number, but it works.

Piston-Block-s.jpg

IntSmooth-s.jpg

BM cam needs compression & breathing to work well, otherwise a smaller cam would be better with a more stock motor.
 
Craig B

Craig B

Member
#9
#9
noseoil said:
Bullfrog makes this piston, its spendy, but a good choice without doing a bunch of machine work on the head. Mine runs well, did some porting to clean up the runners a bit, crude but it runs & pulls well enough up to 8,400 rpm. Haven't run up past that number, but it works.

View attachment 103980

View attachment 103981

BM cam needs compression & breathing to work well, otherwise a smaller cam would be better with a more stock motor.
Click to expand...
Did you need to balance the assembly with the new piston?
 
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