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Solid cam..

General engine tech -- Drag Racing to Circle Track

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pdq67
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Solid cam..

Post by pdq67 » Sat Jul 25, 2020 12:36 pm

What is the highest lift solid cam that can still be considered,
"streetable"??

I am thinking the MOPAR lifter diameter??

But please post up about the SBC lifter dia...

Thanks,

pdq67

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Stan Weiss
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Re: Solid cam..

Post by Stan Weiss » Sat Jul 25, 2020 12:52 pm

How much lift before your retainer hits your valve seal?

What is the max rocker arm ratio that will work on your heads?

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BigBro74
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Re: Solid cam..

Post by BigBro74 » Sat Jul 25, 2020 12:56 pm

If it were me and not having maintenance all the time keepin me from having fun - I would only use a .550” lift before lash is subtracted (gross) on a solid flat tappet. You can go much more but the fun factor is reduced by maintainence and springs that don’t last and cost lots of money.

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Re: Solid cam..

Post by F-BIRD'88 » Sat Jul 25, 2020 7:09 pm

Lot of factors here . you need to define YOUR criterium and expectation of "streetable"..

I am going to throw this out there.. In a flat tappet street strip sbc build ABOUT +/- .347" cam lobe lift the tradeoff of wear VS engine performance GAINS tends to start roll off of benefit..
On a SBC you can juggle rocker arm ratio for effect.
It is more important that valve events occur at the right time in the cycle and there is enough valve open flow area available and the valvetrain is also dynamicly stable yo RPM
Than getting the most sexy high valve lift.
On a sbc the intake side seems to respond to rocker ratio more than the ex side does..

More valve lift tends to mean quicker valve guide wear.
Especially if the guide is shortened..
On "Street roller" cam stuff I like to keep the roller cam lobe under .400" lift... There is a ton of room to play within.

On a high perf sbc flat tappet deal a slightly ROUNDER over the nose cam lobe radius tends to wear a bit better VS a pointy nose with a hair more lift...
Again lots of factors.

Getting the geometry right is A BIG FACTOR.

Geoff2
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Re: Solid cam..

Post by Geoff2 » Sun Jul 26, 2020 5:02 am

First,
You need to define your definition of 'streetable'.....which will probably differ from others......

pastry_chef
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Re: Solid cam..

Post by pastry_chef » Sun Jul 26, 2020 11:36 am

F-BIRD'88 wrote:
Sat Jul 25, 2020 7:09 pm
It is more important that valve events occur at the right time in the cycle and there is enough valve open flow area available and the valvetrain is also dynamicly stable yo RPM
Than getting the most sexy high valve lift.
Totally true.
Got the cash, then pay an experienced professional builder to assemble a package that will meet the desired performance goal.
Otherwise you are risking to end up with a pile of broken scrap parts.
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Re: Solid cam..

Post by 1980RS » Sun Jul 26, 2020 5:41 pm

Lift does not make a cam streetable. Valve opening, closing and other events make that happen. If you want a car with good street manners than always put it on a 114°LCA. You may give up some low end torque but it will be more streetable for sure.

BigBro74
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Re: Solid cam..

Post by BigBro74 » Mon Jul 27, 2020 11:05 am

I am not trying to start a contest- and you guys are not wrong exactly, but responses like these are kind of short sighted--
1980RS wrote:
Sun Jul 26, 2020 5:41 pm
Lift does not make a cam streetable. Valve opening, closing and other events make that happen. If you want a car with good street manners than always put it on a 114°LCA. You may give up some low end torque but it will be more streetable for sure.
yes but---- too much lift can make an engine "unstreetable" because it can be harder on parts compared to the owners budget and maintenance preferences.
And in my opinion- just choosing 114 LCA shoots your opening and closing points idea--if you have correct open and close points LCA falls where it will.

Curtis Mc
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Re: Solid cam..

Post by Curtis Mc » Mon Jul 27, 2020 12:12 pm

To help this conversation along, as others are getting at, it's best to better define streetable.

Do you need vacuum brakes?
How often are you willing to change valve springs?
How often are you willing to check lash?
How much (thick) pushrod can you run?
How much RPM will you spin it with any regularity?

Others prob have more/better questions to help flesh out what streetable is.

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Re: Solid cam..

Post by CamKing » Wed Jul 29, 2020 2:43 pm

pdq67 wrote:
Sat Jul 25, 2020 12:36 pm
What is the highest lift solid cam that can still be considered,
"streetable"??

I am thinking the MOPAR lifter diameter??

But please post up about the SBC lifter dia...

Thanks,

pdq67
Like other said, Streetable is different to everyone.
I would look at how much spring pressure you want to run on the street. I would say a cam that requires less then 360# of spring pressure at max lift is streetable.
One of my customers builds a lot of Ford Cleveland engines for the street, and runs a 244/252 @ .050" with .365"/.364" Lobe Lift, and 1.73 rockers. That's over .600" lift, but since they're large stroke engines, they don't turn a lot of RPM, and don't require a lot of spring pressure.
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