4-valve head Evo motors

[jurneyman]

It has finally come time to separate the Evo motors using the Feuling designed 4-valve heads from the Twincam forum. I went into detail for the reasoning behind this move on the Twincam 4-valve head thread. There is a lot of good info concerning the Evo and just good general knowledge about some of the differences between the 2-valve and the 4-valve motor requirements on that thread, and I am
still going to work between the two threads for general information using 4-valve heads on V-Twin motors. It is my hope to have just a purely technical discussion on this thread, with input being welcomed and encouraged. Share any personal experience or ask any question concerning the building and or installing the Feuling 4-valve head design on a Evo platform. thanks JM

[pattisteve1]

hi jman, i just pulled the cam gear off of my stock evo cam and see there isn't a place for a key in that one. the cam i got from you has a keyway in it. is it okay to go ahead and press the gear on without the key?



the cam i took out of the 4valve was a crane fb 310-2 timed intake 19/37 exhaust 46/16 i'd say that is way too much overlap. what do you think? thanks steve

[superdave]

Hi John and Steve
I have run the Andrews ev-3 cam in my motor and it seems to work good.I have also run the Andrews ev-31 cam in my motor.Both seem to run ok.
Some of the info I have been reading says that you can open the intake quicker to take advantage of the extra velocity to fill the cylinder and not open it as long as a 2 valve head without hurting the top end.

[jurneyman]

Steve I would not recommend pressing on a gear without the key, but as long as it is done carefully and accurately it will probably be OK, I personally would not do it. I just don't have enough information about your motor to give an answer. But as a general rule that overlap that you stated is not way to much.

Dave it all depends on the size and the components of the motor and what its intended use will be.

[pattisteve1]

jman, the gear i took from my stock evo cam. it is a 1998 motor. the gear has 2 concentric circles as you look at it. when pressed off the original cam there is no keyway in the camshaft or the gear. the compcam cam from you has a keyway in it. that is what i am confused about. should i get another gear with a keyway to press onto the compcam cam? i scribed lines in the gear before i pulled it off an they line up perfectly when i pressed it on. the comp cam has lines stamped in it to enable me to line it up. savvy? or am i confusing you? i also was reading about all this last night and it was said that some gears have a 1/8" keyway and some have a 1/4" keyway. i am a little confused

[pattisteve1]

i want to give a short description of the motor i am talking about. the motor is an evo with a 4 1/4 inch stroke and a 3 13/16" bore. that gives me 97" my 80" stock motor is out of the bike and on the bench. it will be a later project that i will put feuling heads on. i also have an 88" twin cam duece that i have a set of feuling heads to put on. i hope to do that later this winter and will be posting about that build on the other thread we just left.

[pattisteve1]

jman the reason i keep mentioning toomuch overlap is this. dave gave me the profile information from his stage 1 kit with the feuling cam in it. so we know what he used for that it is a torque producing cam. timing is intake 2/38 exhast 38/2. that gives 4 degrees of overlap. the cam i just took out of the 97" has a profile of intake 19/37 exhaust 46/16. that is 35 degrees of overlap. the intake closing angle is very close to the same. that is why i am wondering if the second one has too much overlap. please correct me if i am not looking at it right.

[jurneyman]

Dave, What I have found is because of the ability of the 2 smaller valves to flow more A/F mixture at a lower lift with more velocity then the single large valve it needs less overlap, so as an example the valves can be opened later at 20 degrees BTDC as opposed to 25 degrees BTDC. On the closing side the intake valves can be closed later as an example 45 degrees ABDC as opposed to 40 degrees ABDC because of the higher velocity of the A/F mix more can be packed into cylinder before the pressure of the rising piston stops the flow and pushes it back into the intake tract.

[jurneyman]

Steve, What year is the 80 cu in, does it have 2 grooves on the face for a 1990 and later cam also you might have to check the gear mesh using .108 pins.

To Be honest I do not believe those stage one figures 2/38, 38/2. should be used as a baseline for building these motors.

[jurneyman]

Steve I went back and found some cam spec cards from when I was first working with the 4-valve heads. the stage 2 was 23/45 60/25 which was originally designed for a high RPM 80 inch motor. When I started looking for more torque I went with and started using and recommending the cam that was in your motor the 310-2 at 19/37 46/16 and I also used that cam in the 80 inch, and in the 88 inch 35/8 bore when I started unshrouding the exhaust valves which enlarged the cumbuston chamber. I had torque but I lost some top end. The comp cam at 17/45 50/22 should be good for the torque you are looking for in your 97 in big bore but I wouldn't recommend it for a 97 in stroker because of the difference in the rod to stroke ratio.

I just found a card from another cam I tried before the 310-2 and it is the 300-2B at 12/34 41/15 it was also made by crane who BTW was making the cams for H.D. The notes with it state, plenty of torque but not enough power. I think we put it in a 80 in. dresser with no complaints. As you can see we were slowly increasing the fill time of the cylinder by adding more duration, without excessive overlap.

[superdave]

Hi John and Steve
First off Steve as John stated I would not run the cam without a key in it.If there is enough pressure it can move the gear and that would be a nasty result.I had my pinion gear key break on me the first time I ran my motor with the heads and the key broke.That resulted in a major disaster.I have since welded the spacer and gear together so no damage can result from that happening.Just remember that there is an extra load on the entire valve train and anything that can be done to avoid a mishap from occuring is better than chancing it.
John I know I left alot of info out on what my motor has in it and what I have done to the bike.I like having the torque on the motor rather than high revs and higher horspower.
When running the EV-3 cam I had lots of torque with good top end.I was running way too high of a final drive ratio but got good fuel economy.
I am looking at running a static compression ratio of 10.5:1 so I need to run a cam with around 42-46 closing time.I think I will try the Sifton cam retarted at 4 degrees.I am also looking at running the 2-1 exhaust system that I made up.It is a Cobra from a Yamaha Roadstar 1700.It worked real well and I like the look of it.
I use the bike for a daily driver and for going on trips so i may change a few things on it to run at a lower rpm for torque rather than horsepower so I may run something different.I am going to keep it as an 80 inch for now as my budget is rather tight now.
The cams I have are the stage 1 cam,S&S 520,EV-3,EV-31,stock N cam and the Sifton 140.
That is what I have to play with so that will determine what the motor can be setup to run with.I still like the EV-3 and may that.
Anyway just rambling on here as there is no way of riding with the temps here until next spring.

[pattisteve1]

jman, i had a gear from the 97" motor that had a key slot in it so i was able to use that gear with the comp cam from you so it is on there with a key. thanks

[pattisteve1]

Originally Posted by jurneyman

Steve I went back and found some cam spec cards from when I was first working with the 4-valve heads. the stage 2 was 23/45 60/25 which was originally designed for a high RPM 80 inch motor. When I started looking for more torque I went with and started using and recommending the cam that was in your motor the 310-2 at 19/37 46/16 and I also used that cam in the 80 inch, and in the 88 inch 35/8 bore when I started unshrouding the exhaust valves which enlarged the cumbuston chamber. I had torque but I lost some top end. The comp cam at 17/45 50/22 should be good for the torque you are looking for in your 97 in big bore but I wouldn't recommend it for a 97 in stroker because of the difference in the rod to stroke ratio.

I just found a card from another cam I tried before the 310-2 and it is the 300-2B at 12/34 41/15 it was also made by crane who BTW was making the cams for H.D. The notes with it state, plenty of torque but not enough power. I think we put it in a 80 in. dresser with no complaints. As you can see we were slowly increasing the fill time of the cylinder by adding more duration, without excessive overlap.

jman, the 310-2 worked good for a high torque motor. that is a good one for a heavy bike. my bike is very light and i ride it alone so i am looking for my power a little later in the rpm band. i am not building a high horsepower motor. i am looking for more in the midrange with my peak power from 3800 to 4000 rpm. i am trying to lengthen the powerband. in other words i would like to see a long flat powerband . when looking at the dyno sheet with that 310-2 cam you can see the power starting to fall at 4000 rpm and by 4500 it is falling fast. game over. it dyno'd with 105 footpounds of torque. the peak was around 3500 rpm. i think it will do better. we will see. i should have it running today and if it feels like what i want i will take it to the dyno and see what it looks like. thanks for taking the time to list those specs.

[jurneyman]

Steve, I'm glad you used the right gear with a keyway for your cam, it was the right thing to do. Enough can go wrong even if we do everything the best we can and not take any chances.

[pattisteve1]

jman, you are right about that. what confused me was the stock cam and gear has no key in it. i got my bike running last night and it sounded good but it was too late to go try it out. i am waiting for it to warm up a little and then i am going for a ride. later