Camshafts almost done

[tpepmeie]

Originally Posted by XfireZ51

How will that affect your final cam profile if not looking for that last 10cfm?

It'll be .020 less lift

Maybe 5-10 hp at most. He might be able to use a little more max valve acceleration to get more lift sooner with the .500 max lift. Although from the seat to .050 lift, it is already pretty aggressive at only 40 degrees. It's an endurance motor, though. Can't be eating up springs every 500 miles.

[rkreigh]

great stuff

congrats todd, I saw your heads at the local shop early in the project and those cams look great.

cam development takes so much hard work and I love the idea of using the ford mod motor as a "similar" model, but head flow, velocity, displacement, compression, chamber, all those cool variables and lobe shape lift duration separation all take lots of research and knowing how to maximize "area under the curve" and streetablility concerns

I'll trade 5-10 hp any day for a car that's a pleasure to drive you'll be making so much that hooking it up is the hard part, not worry about 600 or 650, it will be "ample" either way

look at the article on heads in the chevy perform magazine, the are doing a really cool series about head flow "quality, velocity, ect.." which is the basis for cam selection along with gearing, car weight and all those other factors that make selecting the perfect cam such a chore

I have the stg III on my 390, which are pretty "streetable" and I think are only at about 234 deg 435 or somthing like that lift

I know Bill played around with huge cams on his 415s, but they were a bit too rowdy and only gained just a bit way up top, the trade off wasn't a good one as the engines got very "peaky"

graham would be very good to talk to on this subject, seek ye him at BG

[Locobob]

Originally Posted by rkreigh

graham would be very good to talk to on this subject, seek ye him at BG

That sounds like an excellent idea. I'm still interested in doing something with my cams - hopefully Todds project will lead to renewed interest in new production of performance camshafts.

[tpepmeie]

Update... finding springs for the monster cams has been almost impossible. Most of the springs I had identified were from imports (Honda/Audi/VW), and thus had a very high natural frequency, suitable to 9000+ rpms. The guy doing my cams is a bit of a professor when it comes to dynamic valvetrain design, so he was not happy with such heavy springs and associated wire stress.

We're leaning toward a single spring setup, with a rate similar to the stock spring, but able to handle the bigger lift. His lobe design is spring friendly, such that we dont need extremely high pressures. And the rev limiter will be set at 7500, so a low frequency environment.

The downside... looks like custom titanium retainers will be needed. I was hoping to use some off-the-shelf ti retainers, but the springs we picked don't match anything exactly. 7mm valve stems add to the problem.

By the time this thing is done, I could write a book about what works/fits and what doesn't. The parts list is definitely unlike any other LT5 out there, that's for sure.

BTW... we're doing the bigger intake lift.

Todd

[A26B]

Originally Posted by tpepmeie

........By the time this thing is done, I could write a book about what works/fits and what doesn't..........Todd

Please Do!!

[XfireZ51]

Originally Posted by tpepmeie

Update... finding springs for the monster cams has been almost impossible. Most of the springs I had identified were from imports (Honda/Audi/VW), and thus had a very high natural frequency, suitable to 9000+ rpms. The guy doing my cams is a bit of a professor when it comes to dynamic valvetrain design, so he was not happy with such heavy springs and associated wire stress.

We're leaning toward a single spring setup, with a rate similar to the stock spring, but able to handle the bigger lift. His lobe design is spring friendly, such that we dont need extremely high pressures. And the rev limiter will be set at 7500, so a low frequency environment.

The downside... looks like custom titanium retainers will be needed. I was hoping to use some off-the-shelf ti retainers, but the springs we picked don't match anything exactly. 7mm valve stems add to the problem.

By the time this thing is done, I could write a book about what works/fits and what doesn't. The parts list is definitely unlike any other LT5 out there, that's for sure.

BTW... we're doing the bigger intake lift.

Todd

"To go beyond where no man has gone before"!

[FU]

Do it Todd ...........Be da Terminator !

[tpepmeie]

Cams are being ground to final dimensions early this week. What a sweet design... requiring very little spring force to control. With only 60 lbs on the seat, and 170 lbs open, my valves remained in control to 8600 rpm! Here's what he had to say about the stock cams.

The stock cams are over-sprung because they have really bad cam designs (high jerk and bad harmonics) so they need a lot more spring force to try to control that.

The same can be said of the usual aftermarket cams. My lobes have less than half (!) the acceleration peaks compare to the old ".470" Jeal cams, yet more than 6.5% higher opening velocity.

These are more than 7% bigger lobe area than the Jeals, and around 15% bigger than Stage II cams. Don't know what Stage III's typically measure, but probably somewhere in between.

Now have to wait 6 weeks for the custom retainers.

Todd

[wdo-mkr]

Originally Posted by tpepmeie

Now have to wait 6 weeks for the custom retainers.

Todd

Your welcome. Did you order valves too?

[tpepmeie]

Originally Posted by wdo-mkr

Your welcome. Did you order valves too?

?????