Cam for 406 mud racer
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Cam for 406 mud racer
Motor is
4.155x 3.75 13-1
Crower ultra light Molnar rods cp pistons
Has to run factory heads per rules soo vortecs with 2.05 flow 260@500 2700@600
Single plane 750 based carb per rules
4.56 gears in low side with tcase ratio of 2.72 and 31in tires 5500 converter
This is a lift rule class 550 can be solid roller etc.
We got the cam through the guy that set up the heads was post to be 268@.50 but when I got the cam yesterday from bullet it's 251/256. I was told this is better then the bigger one and would still rpm? Little confused
Customer is not happy about spending all the extra money for pretty much same cam that was in it before that wouldn't pull past 6500.soo would this cam even get us close peak power at 7500?
4.155x 3.75 13-1
Crower ultra light Molnar rods cp pistons
Has to run factory heads per rules soo vortecs with 2.05 flow 260@500 2700@600
Single plane 750 based carb per rules
4.56 gears in low side with tcase ratio of 2.72 and 31in tires 5500 converter
This is a lift rule class 550 can be solid roller etc.
We got the cam through the guy that set up the heads was post to be 268@.50 but when I got the cam yesterday from bullet it's 251/256. I was told this is better then the bigger one and would still rpm? Little confused
Customer is not happy about spending all the extra money for pretty much same cam that was in it before that wouldn't pull past 6500.soo would this cam even get us close peak power at 7500?
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Re: Cam for 406 mud racer
I would say that cam would be good to about 6,500 RPM. I think the first choice was near correct.mdabbott2009 wrote: ↑Sat Apr 24, 2021 9:30 am Motor is
4.155x 3.75 13-1
Crower ultra light Molnar rods cp pistons
Has to run factory heads per rules soo vortecs with 2.05 flow 260@500 2700@600
Single plane 750 based carb per rules
4.56 gears in low side with tcase ratio of 2.72 and 31in tires 5500 converter
This is a lift rule class 550 can be solid roller etc.
We got the cam through the guy that set up the heads was post to be 268@.50 but when I got the cam yesterday from bullet it's 251/256. I was told this is better then the bigger one and would still rpm? Little confused
Customer is not happy about spending all the extra money for pretty much same cam that was in it before that wouldn't pull past 6500.soo would this cam even get us close peak power at 7500?
A camshaft of .367" lobe lift and about 268/276 duration @.050" on a 112 sep +2 would be OK with that gearing.
With those heads and 406 cubic inches it may get to 7,500 RPM but, peak power won't be near that high.
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Re: Cam for 406 mud racer
That's what I thoughtWalter R. Malik wrote: ↑Sat Apr 24, 2021 11:06 amI would say that cam would be good to about 6,500 RPM. I think the first choice was near correct.mdabbott2009 wrote: ↑Sat Apr 24, 2021 9:30 am Motor is
4.155x 3.75 13-1
Crower ultra light Molnar rods cp pistons
Has to run factory heads per rules soo vortecs with 2.05 flow 260@500 2700@600
Single plane 750 based carb per rules
4.56 gears in low side with tcase ratio of 2.72 and 31in tires 5500 converter
This is a lift rule class 550 can be solid roller etc.
We got the cam through the guy that set up the heads was post to be 268@.50 but when I got the cam yesterday from bullet it's 251/256. I was told this is better then the bigger one and would still rpm? Little confused
Customer is not happy about spending all the extra money for pretty much same cam that was in it before that wouldn't pull past 6500.soo would this cam even get us close peak power at 7500?
A camshaft of .367" lobe lift and about 268/276 duration @.050" on a 112 sep +2 would be OK with that gearing.
With those heads and 406 cubic inches it may get to 7,500 RPM but, peak power won't be near that high.
I need this thing pulling like a freight train at 7500 not like Prius
Re: Cam for 406 mud racer
If you can run a solid cam get an Elgin 1090-P cam you will like the power it makes. That cam has never let me down in any engine I have used it in. I know the exhaust lift is .557 so if that is a rule violator then get the same cam (1091-P) with a .500 lift and use 1.6 rockers to his your goal.
Re: Cam for 406 mud racer
Howards Cams has the sft cam lobes you need to be .550" valve lift legal that have the durations for the higher rpm you are looking for. .343" (1.6 rr) or .367" (1.5rr).
Re: Cam for 406 mud racer
This lift rule. Is it measured at the valve or how do they go after it ? What cam was in it before and was that with the sam engine. Head work etc... ?
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Re: Cam for 406 mud racer
With your specified combination, that is just not gonna happen; using ANY camshaft.mdabbott2009 wrote: ↑Sat Apr 24, 2021 11:36 am
That's what I thought
I need this thing pulling like a freight train at 7500 not like Prius
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Re: Cam for 406 mud racer
I feel Bullet has some knowledgeable people, perhaps what they provided will give the best average numbers within your given rules and components. More cam when the heads are the restrictions and the driveline is rules fixed can create an uncompetitive combination. (Without the torque to get the wheelspeed up where that extra few horsepower are you aren’t going anywhere quick) A peaky engine and a deep, sticky track will garner you last place.
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Re: Cam for 406 mud racer
Why would you bother with a flat tappet cam when you can run a solid roller?
- mt-engines
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Re: Cam for 406 mud racer
Considering you don't have enough CSA in the head to peak at 7500. You would probably need a cam in the 280@.050 range. But you would lose power everywhere. You could crutch it with a 6500 stall converter and gear.
Re: Cam for 406 mud racer
Exactly right.Walter R. Malik wrote: ↑Sat Apr 24, 2021 4:35 pmWith your specified combination, that is just not gonna happen; using ANY camshaft.mdabbott2009 wrote: ↑Sat Apr 24, 2021 11:36 am I need this thing pulling like a freight train at 7500 not like Prius
Also exactly right.mt-engines wrote: ↑Sat Apr 24, 2021 10:50 pm Considering you don't have enough CSA in the head to peak at 7500. You would probably need a cam in the 280@.050 range. But you would lose power everywhere.
The lift limit is also limiting your rpm, you can't just add cam (duration) to an engine to get it to pull to whatever rpm you want.
CSA and entire induction sizing is the main thing that sets engine RPM range. Exhaust port and header sizing too. The duration of a cam should COMPLIMENT the rpm range the induction and exhaust sets.
Rick
Re: Cam for 406 mud racer
Mud guys usually want high wheel speed.
A lot of stall...... buzz the motor pretty high.
The new cam seems short to me for the application.
406”, high CR, small heads, want some top end........
I’d have been looking more along the lines of the 268 cam.
A lot of stall...... buzz the motor pretty high.
The new cam seems short to me for the application.
406”, high CR, small heads, want some top end........
I’d have been looking more along the lines of the 268 cam.
Somewhat handy with a die grinder.
Re: Cam for 406 mud racer
The larger duration cam will not move the horsepower peak rpm point up much b
Re: Cam for 406 mud racer
The larger valve duration will not move the RPM point of peak horsepower up much, but what it will do is increase the power that is made UP AFTER peak horsepower, extemding the usable rpm range up. The tradeoff will be low rpm torque. You must keep the engine rpm way up.
Comp has a whole series if .323" lobe lift MA series sft cams that when used with 1.7:1 rr will be .550" lift rule legal.
Durations from BIG BIG thru small
You would have to A-B test it on track against your new Bullet/Ultradyne grind cam.
Comp has a whole series if .323" lobe lift MA series sft cams that when used with 1.7:1 rr will be .550" lift rule legal.
Durations from BIG BIG thru small
You would have to A-B test it on track against your new Bullet/Ultradyne grind cam.