V-Twin Forum banner

1 - 12 of 12 Posts

·
Registered
Joined
·
25 Posts
Discussion Starter #1
Lookin to build my evo for all bottom end gonna do some head work, would like to know what kind of cam i should run. I would like to find something that comes in around 1500-5500 and go with a 9:5:1 comp 10 would be the biggest in comp i would like to go need to be dependable for the long haul thanks
 

·
Registered
Joined
·
741 Posts
If you're looking for a big boost on the bottom end I don't think you'll get much from any non stock cam. To get the big bottom end grunt you gotta add more cubes. It's that simple.

High lift or long duration cams mostly move the peak torque up the rpm range and do little, if anything, for the bottom end. If you'd be happy with a boost from 3000-5500 rpm then, yes, a different cam would help.
 

·
Registered
Joined
·
63 Posts
If you're looking for a big boost on the bottom end I don't think you'll get much from any non stock cam. To get the big bottom end grunt you gotta add more cubes. It's that simple.

High lift or long duration cams mostly move the peak torque up the rpm range and do little, if anything, for the bottom end. If you'd be happy with a boost from 3000-5500 rpm then, yes, a different cam would help.

you're kidding.............right?
 

·
Super Moderator
Joined
·
20,917 Posts
For low end, look for a cam that closes the intake early. You can also alter the cam timing to help the low end. You don't want a lot of duration, but a little extra open time on the exhaust side will lower the temps some. The extra compression will help the low end as will enriching the low speed circuit in the carb. Old OEM crossover pipes help the low end too.
 

·
Registered
Joined
·
107 Posts
I put an Andrews EV13 & decked my heads 0.050 @ 22K. on my FXR. It was a great motor, stone cold reliable, 42-52 mpg. Lots of low & midrange grunt. Ran it til 86K before I switched motors.
 

·
Registered
Joined
·
555 Posts
Halloo, Tricky. The Crane 310 should probably work well with around 9 or 9.5:1 compression ratio. As beerfree said, the Andrews EV13 will work good with that c/r also. I am at 10:1 on Angel and had a Crane 300 that pulled really good down low but ran out of steam around 4000 or so. Going in with an Andrews EV46, but I like to flog the thing, so that might be a little too much cam for your needs. If you are at 9.5 c/r I would say to run a cam with around 35-38 degrees intake closing, if you are at 10 on the c/r then stay above 37 degrees or so, otherwise you may run into problems with hard starting, detonation, blah blah. As beerflow also stated, having a little more duration on the exhaust side tends to mitigate some of those problems when running hard at lower rpm's.

C........
 

·
Registered
Joined
·
34 Posts
I ran an Andrews EV27 and an EV46 in the same 94 softail at 9.5:1.
Stock cylinders with KB pistons.Lightly ported heads that I did.
The EV27 came on sooner but signed of sooner also>
I liked the EV46 better because this bike was ridden pretty hard and no passengers. 10:1 compression is tuff with CA gas
This bike got 50 mpg if run at 70 with a 65 rear pulley
 

·
Premium Member
Joined
·
11,928 Posts
unca mike is on the right track. but to do headwork on an evo and want bottom end is oxymoron. unless you go BIG.
 

·
Registered
Joined
·
412 Posts
Many good cams to choose from..

We're runing the S&S 560 cam in the 80" with headwork & 10.2 comp,,, has Beau-coup low-end with stock final drive Ratio..

I run a 635 Dave Mackie in the 120"..

Check out the Dave Mackie DM 530 lift at this link,, might look good to you.. Pulls from 2K to 6K,, with perf springs and likes 8.5 to 10.1 comp.. (according to DM info)

http://davemackie.com/cams.html

And remember,, perhaps the easiest and surest way to get guaranteed torque is to raise the Final Drive ratio..
I do not know what your sickle is but,,, you might/could slip on a smaller Trans pulley or a larger wheel pulley etc etc..........

More options in the mix..
 

·
Registered
Joined
·
549 Posts
Head Work 1st then Pick the Cam

Lookin to build my evo for all bottom end gonna do some head work, would like to know what kind of cam i should run. I would like to find something that comes in around 1500-5500 and go with a 9:5:1 comp 10 would be the biggest in comp i would like to go need to be dependable for the long haul thanks
Basic rule #1 You can't pick the correct cam until you know what the Heads will flow! @gree:

Everything on top like C R ,Head work, Cams, and Exhaust has to work together:woohoo:

80 % of the motors built out there are done half ass backwards because they listen to friends or guys off here who tell you Run this Cam or let this guy butcher your heads :beatdh::spank:

Why spend a lot of $$$$ on your motor and leave a lot of H,P, when you can have a great motor builder pick a proven combination for your build ! Stay away from most SE stuff.

run a good 2-1 exhaust Talk to Randy @ HYOPERFORMANCE and LQQK @ his website for 4 ot 5 different EVO build kits he offers !

kingofcubes.com :clap:

I would also look @ RB Racing @ there 2-1 Pro Stock LSR exhaust which will make about 12-15 more HP over just about any exhaust system you can buy today ! :cya:
 

·
Registered
Joined
·
7 Posts
Much of what has been said here is spot on but leaves room for additional data. Cam lobe separation has a great impact on where in the RPM band power is made. This dimension is the difference between the intake lobe center and the exhaust. A tight 106 degree separation will make more low end torque than a wider angle such as 112 degrees. It will also drop off earlier but since you are not looking for more that 5,500 RPM this is ok. Cam intake lobe centerline will also effect dynamic compression which will determine gasoline needs. Static compresion ratio based on swept volume and combustion chamber volume is always greater than dynamic compression at low speeds due to poor volumetric efficiency. To lower the dynamic compression use a cam with a greater intake lobe centerline. You might want to do this in a 10: 1 engine to make it act like a 9.5 : 1 engine until it gets up to speed. NOTE that lobe separation and centerline are essentially a way of advancing / retarding the intake or the exhaust separate from the cam as a whole and produce different results. These considerations are separate from duration and lift and are true for any engine.

One other thought regardless of cam is valve clearance. You would think that with all the conversations about advertized duration and duration at .050" this would be a common discussion but have you ever heard one? A couple thou in valve clearance can make a huge difference. Looser for low end, tighter for high end. If .050" matters then .005" matters 10% of that other matter.
 

·
Registered
Joined
·
767 Posts
Most guys hit it right on the head. For a strong engine everything has to work together. Ever notice the guys with the "biggest and best of everything" have slow bikes and the guys with a few modifications that did their homework have quick bikes that seldom have issues?

That being said if you get a cam like the Head Quarters 0024, Andrews EV72 or a Woods 6 (I think) or any cam with similar numbers will be decent for what you are going after, but again a professional builder is best if you have the $$ for it.
 
1 - 12 of 12 Posts
Top