Author Topic: Comand cam, valve train questions.  (Read 5468 times)

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Offline redneckracer

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Comand cam, valve train questions.
« on: January 04, 2011, 10:49:34 PM »
If i was to install a percision cam in my comand for lawn mower racing, I understand it will require longer valves, solid lifters, adjustable push rods(preferably cut to length solids), adjustable rocker stud kit, and stronger valve springs. Please correct me if I am wrong. Am I missing anything else that should be done at the same time?

I am not understanding the longer valves. If the cam creates more lift, wouldn't a longer valve create a bigger valve to piston clearance issue, or is that the reason for the adjustable push rods?

This is a CV22s that I am building for mild power for now. It will get some head work done as well. Eventually the rods, pistons, and flywheel will get done. Looking to start with the most bang for the buck.

Can anyone tell me how much can be milled off the heads without getting into clearance and parts breaking issues.

Thanks, Rob
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Offline redneckracer

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Re: Comand cam, valve train questions.
« Reply #1 on: January 06, 2011, 12:14:17 PM »
upon further thought I understand the longer valve now. To create more spring length to reduce coil binding.
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Offline fordman21

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Re: Comand cam, valve train questions.
« Reply #2 on: January 06, 2011, 01:22:16 PM »
It is possible to set the heads up for stock length valves with some machine work (depending on the cam) for a stock appearing engine without valve cover spacers.
You don't want to take anymore material off the heads then you have to, the valves are not very deep in the chambers, I believe you can get close to .500" lift at the valve with a flat top piston before you have trouble with valve clearance, again that depends on the cam profile, cam timing and head gasket thickness.
Ryan Kerr  519-332-9532
2007 Troy Bilt Grand National Super Modified Champion.
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2008 All American Lawnmower Championsip Outlaw twins champion.
2010 WOO Outlaw/FXT class Champion.
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Offline FlatheadPuller

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Re: Comand cam, valve train questions.
« Reply #3 on: January 06, 2011, 03:31:16 PM »
We run a .600 lift cam with je flattops and have no clearance issue. Uncut heads but they have longervalves, goodsprings and roller rockers. The pistons are stock out of the box. They have no valve reliefs in them.
Dennis Bazzett
Grandville Michigan

Offline Caseracer

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Re: Comand cam, valve train questions.
« Reply #4 on: January 06, 2011, 06:06:31 PM »
With that cam you will need to clearance the block at the bottom on the cylinder bores or the lobes will hit.  You will probably need the longer valves too.  Midwest Supercub sells Moly push rods that you order to length for about $60.00 a set.  You will want to use the single open RPM springs with the welded cam.

Jack Jones
Hard Case Racing
Shakin' by a Roller Kohler

Offline FlatheadPuller

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Re: Comand cam, valve train questions.
« Reply #5 on: January 06, 2011, 06:15:23 PM »
Forgot to add that Jack. Yes we had to clearance the bottom of the bores to clear the cam lobes. I know the cams that skip at midatlantic sells fit without block mods until you get over .300 lift at the cam. You can get the pushrods cheaper from summit if you know the required length. There just small chevy pushrods.
Dennis Bazzett
Grandville Michigan


Offline redneckracer

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Re: Comand cam, valve train questions.
« Reply #6 on: January 06, 2011, 11:43:13 PM »
Thanks for the info, that helps alot. Would you recomend valve cover spacers or new taller covers? Solid lifters or the stock ones?
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Offline Caseracer

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Re: Comand cam, valve train questions.
« Reply #7 on: January 07, 2011, 03:50:11 AM »
You will need solid lifters with that cam.  As far as the valve covers go, It depends on your club rules.  The taller aftermarket covers look good but may not pass the stock appearing rule.  If you can find the factory cover with the built in fuel pump thay are taller.  You remove the fuel pump and make a block-off plate.

Jack Jones
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Offline fx28

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Re: Comand cam, valve train questions.
« Reply #8 on: January 08, 2011, 10:27:10 PM »
I am running about a .500 lift with the stock length valves.  Vogel manufacturing is the only vender that has the drop in springs and retainers to be able to do this. I spent 2 years dealing with all the other venders selling parts that said their product would do it. wiping out two flat tappet cams in the process. I finally spent a few extra bucks and went with a roller cam. I would not do to much without at least putting in the billet rods. Putting in the aftermarket piston will get the compression up without having to mill the heads and leaving piston to valve clearance for the high lift cam.  Most anything that you build will last longer if you start with a good foundation first.

Chuck Miller

Offline fordman21

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Re: Comand cam, valve train questions.
« Reply #9 on: January 27, 2011, 01:25:30 PM »

Here is a good example of what a difference the cam profile and timing can make with only .500" lift. This is about as close as you can get to the piston, if you saw this camshaft you would understand why. I'll have to fly cut the pistons for the exhaust valves before this command engine goes back together. Although you can get as much as .600" lift on different profiles without the valves getting into the pistons you have to be careful and do a lot of clearance checking when you start getting close to .500" lift and up if you have agressive flanks on the camshaft.
Ryan Kerr  519-332-9532
2007 Troy Bilt Grand National Super Modified Champion.
2008 WOO Outlaw/FXT class Champion.
2008 All American Lawnmower Championsip Outlaw twins champion.
2010 WOO Outlaw/FXT class Champion.
2010 AAMC Twin Outlaw class Champion
2012 USLMRA FX/T National Champion
2012 SRAAUSO FXT Champion<br /

Offline THawley08

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Re: Comand cam, valve train questions.
« Reply #10 on: January 27, 2011, 02:21:01 PM »
Jeeze whats the bore on those pistons?
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Offline FlatheadPuller

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Re: Comand cam, valve train questions.
« Reply #11 on: January 27, 2011, 06:13:46 PM »
Theres prolly upwards of 300 degrees at 50 of duration on that cam for the kiss mark to get there with .500 lift.
Dennis Bazzett
Grandville Michigan

Offline fordman21

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Re: Comand cam, valve train questions.
« Reply #12 on: January 27, 2011, 08:46:36 PM »
Jeeze whats the bore on those pistons?
The picture does kind of makes those pistons look big,  but they aren't really.
Ryan Kerr  519-332-9532
2007 Troy Bilt Grand National Super Modified Champion.
2008 WOO Outlaw/FXT class Champion.
2008 All American Lawnmower Championsip Outlaw twins champion.
2010 WOO Outlaw/FXT class Champion.
2010 AAMC Twin Outlaw class Champion
2012 USLMRA FX/T National Champion
2012 SRAAUSO FXT Champion<br /

Offline GRUBDIGGER

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Re: Comand cam, valve train questions.
« Reply #13 on: January 27, 2011, 09:13:00 PM »
BIG VERY BIG. 3.25-3.5 MAYBE?
JOHN HERRING
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Offline fordman21

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Re: Comand cam, valve train questions.
« Reply #14 on: January 28, 2011, 12:36:24 AM »
3.27" standard 44ci engine, its just the angle of the pic that makes it look big.
Ryan Kerr  519-332-9532
2007 Troy Bilt Grand National Super Modified Champion.
2008 WOO Outlaw/FXT class Champion.
2008 All American Lawnmower Championsip Outlaw twins champion.
2010 WOO Outlaw/FXT class Champion.
2010 AAMC Twin Outlaw class Champion
2012 USLMRA FX/T National Champion
2012 SRAAUSO FXT Champion<br /