Big 32/28mm Valve Head

#3
It’s an interesting approach cutting and installing those seats in the 14cc head. With proper porting it would probably flow great just not sure at what point something like this would be needed or if this kind of setup would benefit the typical engine build
 

delray

Well-Known Member
#5
bryan the guy that is selling them does them out of his back yard shed. we had posted some of his video's in the past and some of his work looks to be real iffy.
for the valve size for your application, for example gamber race. i would say stay away from the large 32/28. to really make a 32 flow good you would have to do some good porting and once it could flow good numbers you would lose out on low end and mid range power. which you would really need on a gamber race. i would just use your 27/25 valves with a good clean port job and a good cam for your application and some other mod's too and you could easily pull good power on your bike. you also could do good with just 25/24 valves with the narrow stem ss valves and mild porting done correct.
 
#6
bryan the guy that is selling them does them out of his back yard shed. we had posted some of his video's in the past and some of his work looks to be real iffy.
for the valve size for your application, for example gamber race. i would say stay away from the large 32/28. to really make a 32 flow good you would have to do some good porting and once it could flow good numbers you would lose out on low end and mid range power. which you would really need on a gamber race. i would just use your 27/25 valves with a good clean port job and a good cam for your application and some other mod's too and you could easily pull good power on your bike. you also could do good with just 25/24 valves with the narrow stem ss valves and mild porting done correct.
I always look forward to your opinions. That’s pretty much the same application I was thinking it would be used in. I have no plans in changing my current setup as it works well just needs a little fine tuning still
 
#7
You can determine the flow needed with some simple math if you know the HO peak RPM, the cubic inches and you can use 100% for VE. If your head flows less then you are leaving HP on the table. Also the intake valve size dictates the lift required. for a performance motor you want to lift the valve 30 to 35 percent of the valve size. I build big valve heads but on the non hemi heads I do not like the 32/28 combo because of the way you have to cut into one seat as they overlap. I do know of a lot of folks that do that and I have not heard of issues with seats coming loose but it just does not look OK to me. I just got some dura bond seats in that will let me use a 26 or 27mm exhaust and not have to cut into the other seat but I do not think it is really necessary. The higher the compression the earlier the exhaust can be opened as the charge burns sooner before BDC than a lower compression engine. If you wanted to know about flow numbers here is one of my 32/25 14CC head tests. Untitled.png
 

delray

Well-Known Member
#8
just think you got second place last year....second place. out of all those bikes that show up. you must of been doing something right. i'm real curious the guy that got first how close where you in time and want type of bike did he have and do you now any details on how is bike was setup. for example motor,drive train...etc...
I thought it was very interesting you ran a clutch only setup. gearing must of been very close to do that good and just think some of the guys had torque converters. what did you think of the acceleration with the clutch. if it's gear right it's so much faster then a torque converter. no slipping of the belt. just 100 percent direct drive to the rear sprocket. only thing I would worry about is extreme off road conditions and the clutch could struggle little bit. it must of been more flat conditions allowing you to take advantage of the clutch setup.
 

delray

Well-Known Member
#9
I always look forward to your opinions. That’s pretty much the same application I was thinking it would be used in. I have no plans in changing my current setup as it works well just needs a little fine tuning still
for your application i think the cam has a big part in your performance. i see you had the 265 cam. if i'm correct that would pull good power only about 6500 rpm's. it's not a bad cam, there is just couple other cams out there might work just a tad better,but still a good cam for you to use with the valve train you have setup in your engine. making very responsive from lowend to top end. there is a point where you could build to much motor and making the bike uncontrollable. good example would a 225cc motor with big valves ,ton porting,cam good to 8500+,28mm carb and running methanol...lol
 
#11
just think you got second place last year....second place. out of all those bikes that show up. you must of been doing something right. i'm real curious the guy that got first how close where you in time and want type of bike did he have and do you now any details on how is bike was setup. for example motor,drive train...etc...
I thought it was very interesting you ran a clutch only setup. gearing must of been very close to do that good and just think some of the guys had torque converters. what did you think of the acceleration with the clutch. if it's gear right it's so much faster then a torque converter. no slipping of the belt. just 100 percent direct drive to the rear sprocket. only thing I would worry about is extreme off road conditions and the clutch could struggle little bit. it must of been more flat conditions allowing you to take advantage of the clutch setup.
First place beat me by 5 mins and the race for me lasted 5hr20mins so I didn’t loose by much. The bike that beat me was a new mm212 with the front suspension and tav. The engine was somewhat built but they had 4 really good riders on the team vs me riding 19 of the 22 laps and my 50-60yr old dad and uncle riding the other 3 just to give me a rest. The clutch wasn’t bad oiled the bushing regularly and my final gear ratio was around 8:1 with a 3000 rpm stall. It struggled slightly taking off from a dead stop on a hill but other than that it worked fairly well and topped out around 45mph which was more than fast enough for the track. This year I’m testing a tav setup and see if I can get anymore performance out of it. Worst case I will still run the reliable clutch with maybe a little more gearing and a higher racing cam so my top speed is still the same
 
#12
for your application i think the cam has a big part in your performance. i see you had the 265 cam. if i'm correct that would pull good power only about 6500 rpm's. it's not a bad cam, there is just couple other cams out there might work just a tad better,but still a good cam for you to use with the valve train you have setup in your engine. making very responsive from lowend to top end. there is a point where you could build to much motor and making the bike uncontrollable. good example would a 225cc motor with big valves ,ton porting,cam good to 8500+,28mm carb and running methanol...lol
I believe the cam was rated to 7500. I’m interested in trying a dyno cam 308 or the mamba sr
 

delray

Well-Known Member
#13
I believe the cam was rated to 7500. I’m interested in trying a dyno cam 308 or the mamba sr
ok maybe so. I have seen some dyno graph's on that cam and it looks like it drop off around -6500 rpm's if indeed this is the same cam?

isky cam and the dyno 308 are good cams,but you might sacrifice some low end to mid range power? also you will need to change your springs and get the right spring height when installed.
something that might help with the exiting cam would a set of 1.2 roller rockers,also would need new springs.
 

delray

Well-Known Member
#14
First place beat me by 5 mins and the race for me lasted 5hr20mins so I didn’t loose by much. The bike that beat me was a new mm212 with the front suspension and tav. The engine was somewhat built but they had 4 really good riders on the team vs me riding 19 of the 22 laps and my 50-60yr old dad and uncle riding the other 3 just to give me a rest. The clutch wasn’t bad oiled the bushing regularly and my final gear ratio was around 8:1 with a 3000 rpm stall. It struggled slightly taking off from a dead stop on a hill but other than that it worked fairly well and topped out around 45mph which was more than fast enough for the track. This year I’m testing a tav setup and see if I can get anymore performance out of it. Worst case I will still run the reliable clutch with maybe a little more gearing and a higher racing cam so my top speed is still the same
wow that saying a lot. I don't think you where lacking power at all. if it was three young guy's like you on it ....who knows? yes if you could get little more gear out of it without over revving it....a lot. lets say your motor peak at 6500. it's not going to kill it if it sees almost 7000 rpm's couple times during the race. long as the spring rate it good for that rpm too and the valves don't float. not going to kill the motor. it may just flatten out little bit on power.
 

delray

Well-Known Member
#15
wow that saying a lot. I don't think you where lacking power at all. if it was three young guy's like you on it ....who knows? yes if you could get little more gear out of it without over revving it....a lot. lets say your motor peak at 6500. it's not going to kill it if it sees almost 7000 rpm's couple times during the race. long as the spring rate it good for that rpm too and the valves don't float. not going to kill the motor. it may just flatten out little bit on power.
think I would rather see it over rev just little couple times, so can take advantage of the bike coming out of the hole from low speeds take off's and dead stop take off's
 

delray

Well-Known Member
#16
with a torque converter you will also maybe need to run a jackshaft to achieve the same rpm's that you are running now. another down fall is the 30 series has a flat side belt(no real grip) and 10 percent overdrive. you don't need overdrive when you are trying to get the motor to rev into it's power band. 7inch driven would be better then a 6inch.
 
#17
wow that saying a lot. I don't think you where lacking power at all. if it was three young guy's like you on it ....who knows? yes if you could get little more gear out of it without over revving it....a lot. lets say your motor peak at 6500. it's not going to kill it if it sees almost 7000 rpm's couple times during the race. long as the spring rate it good for that rpm too and the valves don't float. not going to kill the motor. it may just flatten out little bit on power.
It does flatten out in power at wot for the last couple hundred rpm’s. I’m going to try some ratio rockers first I think. I’m hoping with my current cam I will see a little more performance increase
 
#18
with a torque converter you will also maybe need to run a jackshaft to achieve the same rpm's that you are running now. another down fall is the 30 series has a flat side belt(no real grip) and 10 percent overdrive. you don't need overdrive when you are trying to get the motor to rev into it's power band. 7inch driven would be better then a 6inch.
That’s the plan still going to run jackshaft and 7” genuine comet driven unit. I have one of those new juggernaut drivers on order so I’ll by trying that out as well
 

delray

Well-Known Member
#19
It does flatten out in power at wot for the last couple hundred rpm’s. I’m going to try some ratio rockers first I think. I’m hoping with my current cam I will see a little more performance increase
1.2's would put you around 318 lift and about a 36 pound spring and maybe if the porting is correct you might be able to get away with a 24mm carb and not lose to much low end? that would take little testing to find that out.....money.
 
#20
1.2's would put you around 318 lift and about a 36 pound spring and maybe if the porting is correct you might be able to get away with a 24mm carb and not lose to much low end? that would take little testing to find that out.....money.
Im already planning on the 24mm flatslide and going to try ratio rockers. Have plenty of p-v clearance for the increased lift. I’m also at the point of wanting to play with combustion chamber size. Now I don’t want to dive super deep but I’m thinking a 14cc head with 27-25 valves might help me as well
 

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