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Custom vs Catalog Cams

General engine tech -- Drag Racing to Circle Track

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PRH
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Re: Custom vs Catalog Cams

Post by PRH » Tue Aug 27, 2019 5:49 pm

Most of the “old school” based builds work just fine with old school cams.

I’m not too thrilled with fast rate hyd stuff in many applications.
Which usually ends up being that the lifters can’t keep up with the cam.
Somewhat handy with a die grinder.

digger
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Re: Custom vs Catalog Cams

Post by digger » Tue Aug 27, 2019 6:32 pm

People love to choose cams that make nice peak numbers as you can quantify that and makes for bragging rights.

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Re: Custom vs Catalog Cams

Post by gmrocket » Tue Aug 27, 2019 8:01 pm

Doing non mainstream engines with a catalogue cam gets you the typical 10 or 15 more ex duration with that lobe just being the next one in line as the intake lobe..and on and on.

I usually prefer much faster ramp rates on intakes than ex, so it's almost always a custom order to get a softer and similar or less ex duration as the intake.

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af2
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Re: Custom vs Catalog Cams

Post by af2 » Tue Aug 27, 2019 8:31 pm

travis wrote:
Tue Aug 27, 2019 5:10 pm
Walter R. Malik wrote:
Tue Aug 27, 2019 3:24 pm
What I see happening a lot of times is that someone will spec a cam for a certain engine combination considering all the parts in the engine without any knowledge of the application ... and that can be disastrous.

An engine with a lot of good quality race type parts but, it will be installed into a 4,500 pound, 4 wheel drive pick-up with 35 inch tires and only 4.11/1 gears with a low stall speed torque converter to be used for mostly street driving; with a camshaft spec'ed 265@.050" or even more.
That’s why I ended up using a number of Isky cams years ago. Every time I called them it would always end up being a 20-30 minute phone call with them asking a LOT of questions, whether it was for a really mild farm truck/towing build or a fairly serious hot street build. It’s a shame that so much of their stuff is so outdated because their customer service was awesome.
Travis there are still cam grinders that listen and help. I know of 2 on here
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Re: Custom vs Catalog Cams

Post by travis » Tue Aug 27, 2019 8:36 pm

af2 wrote:
Tue Aug 27, 2019 8:31 pm

Travis there are still cam grinders that listen and help. I know of 2 on here
Mike Jones obviously (I have one of his cams for a build that is almost done). Who else?

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af2
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Re: Custom vs Catalog Cams

Post by af2 » Tue Aug 27, 2019 8:55 pm

travis wrote:
Tue Aug 27, 2019 8:36 pm
af2 wrote:
Tue Aug 27, 2019 8:31 pm

Travis there are still cam grinders that listen and help. I know of 2 on here
Mike Jones obviously (I have one of his cams for a build that is almost done). Who else?
DRC John Dougherty is another that has ramps that will not kill the valve train.
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Re: Custom vs Catalog Cams

Post by ProPower engines » Wed Sep 04, 2019 5:21 am

af2 wrote:
Tue Aug 27, 2019 8:55 pm
travis wrote:
Tue Aug 27, 2019 8:36 pm
af2 wrote:
Tue Aug 27, 2019 8:31 pm

Travis there are still cam grinders that listen and help. I know of 2 on here
Mike Jones obviously (I have one of his cams for a build that is almost done). Who else?
DRC John Dougherty is another that has ramps that will not kill the valve train.
Isky is another good one for valve train reliability. being a dealer they are used in 95% of all our builds regardless of engine manufacture.
having cam cores for different engines and firing order choices seems to be the only hold up regardless of what cam grinder you use or choose.
Blank or rough finished cams have to be ordered and made when getting outside the box combo's.
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Re: Custom vs Catalog Cams

Post by Walter R. Malik » Wed Sep 04, 2019 9:30 am

Going back to O.E.M. high performance offerings, none are extremely aggressive however, if you do measure them, the more aggressive flank lobes are usually on the exhaust side.

A lot are near the same or the same duration at .050" but, have shorter seat timing on the exhaust side; it makes some sense for what they want to do. Burn the mixture in the cylinder as long as they can and the exhaust valve is lighter than the intake valve.
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Re: Custom vs Catalog Cams

Post by David Redszus » Wed Sep 04, 2019 10:42 am

gmrocket wrote:
Tue Aug 27, 2019 8:01 pm
Doing non mainstream engines with a catalogue cam gets you the typical 10 or 15 more ex duration with that lobe just being the next one in line as the intake lobe..and on and on.

I usually prefer much faster ramp rates on intakes than ex, so it's almost always a custom order to get a softer and similar or less ex duration as the intake.
Just curious. What are the ramp rates that you have encountered?
Solid vs hydraulic lifters?

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Re: Custom vs Catalog Cams

Post by gmrocket » Mon Sep 09, 2019 3:41 pm

David Redszus wrote:
Wed Sep 04, 2019 10:42 am
gmrocket wrote:
Tue Aug 27, 2019 8:01 pm
Doing non mainstream engines with a catalogue cam gets you the typical 10 or 15 more ex duration with that lobe just being the next one in line as the intake lobe..and on and on.

I usually prefer much faster ramp rates on intakes than ex, so it's almost always a custom order to get a softer and similar or less ex duration as the intake.
Just curious. What are the ramp rates that you have encountered?
Solid vs hydraulic lifters?
If it's something like an EMC intake lobe it can't be aggressive enough for me.

Solid flats I've used comps 904's and bullets TQ max velocity .904" mopar lobes with high ratio 1.8 or more on the intakes. Solid rollers, comps TK's and others with hr rockers. They beat the crap out of everything but it's not not meant to be anything but a kill it deal

The exhaust in my opinion is critical on only the opening point and rate of opening,, which I think is best late and slow...IF you have a very efficient ex port, especially early in the lift range, opening it to soon and to much , just blows out useful combustion pressure into the ex system

Max lift on ex doesn't seem to be a make or break thing...

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