Cam question K410 vs K435

I don't understand all I know about camshafts. APE's website says for a 1075cc street motor the K410 cam is recommended and the K435 is "dragrace only". Why is that when the duration is the same 266* @ .30" and only the lift is different (.410 vs .435)? Seems the K435 would be just fine and have more flow potential due to the increased lift? Is there a performance disadvantage to the higher lift?

its harder on valvetrain and kills your bottem end off,its fine if you spend lots of time at 8000-9000 rpms with a real good cylinder head

any lift over .418 and you have to convert over to shim under bucket and it raises the price substantialy you need to re place buckets, retainers and keepers and shims. otherwise the cams will hit the edge of the shims and spit out of the head. so it really is not cost effective for the extra lift you would gain. hope that answers your question

No, I still am not sure? I understand the valvetrain strain and associated conversion cost. I do not understand why .025 more lift makes a cam "dragrace only" in "smaller motors". The duration is the same. Does more lift kill flow on bottom end? Or are larger ports required to utilize the extra .025" lift, thus less bottom end? In other words-I am running K410 cams in my 1075 street prepared motor and love them. They pull good from 2500 rpm to past redline if I would wind her that far. Hypothetically what would happen if I put in K435 cams with more lift but identical duration?

if the duration is the same you would not gain a lot with street pistons but is ape not selling these in a kit with 12-1 or better pistons.the .410's are basicly bolt in short of some clearance work on the head and valve cover. wear as the.435 cams sold in a race only package.that kit is designed to be used with bigger carb's bigger pipe and i would imagine bigger valves as well.so it would flow more air at higher engine speeds than a low compression street kit would be capable of. of course if you were to substitute the .410 for the.435 there wouldn't be a huge power differance. if you wing your motor to about 10,500-11,000 sometime that bike would suprise you how hard it will pull past redline..025" just can't make that much differance

Exitpupil wrote:

I do not understand why .025 more lift makes a cam "dragrace only" in "smaller motors". The duration is the same. Does more lift kill flow on bottom end? Or are larger ports required to utilize the extra .025" lift, thus less bottom end?

It's a good question. Maybe Jay will give his reasoning.

Are you still looking for more performance out of your 1075? I'd like to know some dyno results and 1/4 mile times from your setup with the 410s.

Here's an old Andrews Cam chart. K410 = 8x K435 = 5x

Look at TDC OVERLAP lifts and lobe centers.

Lift & Duration numbers alone won't give you an accurate picture of the lobe profile. K435 will make more top end power. You want airflow to take advantage of that cam. Go with the K410 on the street in a small motor. K4354 will pull like a prick up top though.

APE offers the K435 on their 1200 street package and the K410 for the 1075 street package. Larry makes an interesting point about different profiles even with same duration. One thing I was wondering was if you had a ported head with stock valves would the extra lift give more top end power while keeping the bottom end torque?

Exitpupil wrote:

APE offers the K435 on their 1200 street package and the K410 for the 1075 street package. Larry makes an interesting point about different profiles even with same duration. One thing I was wondering was if you had a ported head with stock valves would the extra lift give more top end power while keeping the bottom end torque?

Web has a similar cam, their 109 grind. In stock bore, 84 GPz 1100, with fly cut pistons [compression actually reduced] 33mm Keihin CRS carbs and 95CFM @10" head with stock valves, Murray Pipe, 4000 RPM was where the thing would start to work well. That was on 106 lobe centers.

So just how low you consider bottom end is the key thing. Below 4000 RPM you could not wack the slides open. The engine required a progressive throttle hand but rewarded the effort with pretty good response. Those carbs were w/o any type of accel pump.

Compression and capacity is the name of the game for keeping bottom end torque with cams designed for high rpm. APE knows what they're talking about with the kits they put together. They're designed as a package of components that compliment each other well.

Take a set of drop in .365 lift cams. Spread the centers to 114*, you'll be amazed at how much top end you get out of them.....

You would really want head work for the 435. Most guys that do a 1075 for a street 1000 don't do th head. So with the 410, we can keep the price reasonable. ( no tappets and retainers in the kit)

We have customers that do 1075s with tricked out heads and they run 435s.

Jay

Thanks Jay, guess I should have just called you.