GM -140 “off road” cam

[Walter R. Malik]

Is that the old Phase 3 cam? Or was there such a thing?

That is the Dual-Quad, Z/28 service package cam from the late 60's - 3927140 is the complete part number.

[rp930]

Is that the old Phase 3 cam? Or was there such a thing?

That is the Dual-Quad, Z/28 service package cam from the late 60's - 3927140 is the complete part number.

Those were the good old days.

[BBO Omega]

[quote="Walter R. Malik" post_id=788246 time=<a href="tel:1551242422">1551242422</a> user_id=17962]
[quote=rp930 post_id=788228 time=<a href="tel:1551236007">1551236007</a> user_id=22776]
Is that the old Phase 3 cam? Or was there such a thing?

That is the Dual-Quad, Z/28 service package cam from the late 60's - 3927140 is the complete part number.
[/quote]

Those were the good old days.
[/quote]

When cars were slow and hard to drive ? They did sound good though.

[F-BIRD'88]

The only positive thing I see with this cam today is that it will work with marginally soft valve springs using a 1.65/1 rocker arm.

If you want the motor to be able to rev up high with stability use capable valve springs. Increasibg the rr used will dictate the need for more valve spring force..
Do not use lame valve springs if you want good results especially as you increase the Rr.
I recomend usind dual valve springs.
This cam will work very well for the op if the setup is right and the car is geared to allow the engine to rev up high. For 1/4 mile drag racing you'd want the motor to trap above 7000 rpm. You need capable valve spribgs for that. More so as you increase the rr.

[Walter R. Malik]

The only positive thing I see with this cam today is that it will work with marginally soft valve springs using a 1.65/1 rocker arm.

If you want the motor to be able to rev up high with stability use capable valve springs. Increasibg the rr used will dictate the need for more valve spring force..
Do not use lame valve springs if you want good results especially as you increase the Rr.
I recomend usind dual valve springs.
This cam will work very well for the op if the setup is right and the car is geared to allow the engine to rev up high. For 1/4 mile drag racing you'd want the motor to trap above 7000 rpm. You need capable valve spribgs for that. More so as you increase the rr.

CAPABLE is the key word ...
the ramp & flank rates of this cam will ALLOW much softer springs than when using what rates are readily available with most camshafts today.

It was meant to run up to 7,500 RPM with a simple 142 GM valve spring using a 1.5/1 rocker ratio and not pull out any pressed-in rocker studs.

[F-BIRD'88]

If you are goibg to use a 1.65/1.6 rocker set the spring requirement will be higher.

Use screw in studs and guideplates.
Use a 1.44/1.46 dual valve spring set.
You are targeting .520" net valve lift.
Consider using 7/16 rocker studs.
U got to upgrade all the stock vortec stuff and do all the machinibg so might as well do it right.
Cost is about the same.

Target 120 to 135 seat and 320-360 open pressure
At .520" with the dual springs.

You want to break in the new cam with less pressure than this.. Say 80 seat 260 open. Then install the dual springs to spec.
You can use stock sbc springs at max 1.75"++ istalled height for the run in.
It eill GLH. if you take care of the details.

I'd do the vortecs up with porting and 2.02x 1.60 valves.

Add a bit of moly to the oil.
I use Moly slip E oil additive. Or use a oil thats got moly in it.

Back in the day GM used to recomend the better dual springs too.

[F-BIRD'88]

How will this 10.5:1 vortec head "140 cam" 350 be used?

Typical #3500 Camaro Chevelle?

[GARY C]

I’ve got a NIB Crane “Blueprint” version of the GM -140 cam and lifters that I have been packing around for probably 20 years or more. This is a solid flat tappet cam and lifters, 257/269@.050, .493/.512 lift, 112 lsa.

Is this cam any good for anything? Particularly on a “hot street” pump gas 350 sbc with 4.10 or 4.56 gears and a 3500-ish stall converter? I was thinking maybe with some tweaked 062 vortecs and 1.6/1.5 rockers since they peak around .500” lift or so. Would 10.5-1 compression be too low for this?

Put 1.6 on both, install it at a 106 ICL and put a 175 shot on it and go have some fun.

[MELWAY]

A crane F series cam would be a far better choice if you want it to have some punch and attitude

[Tuner]

Any of you people criticizing the performance of this cam actually run it ... ever?

[CamKing]

Any of you people criticizing the performance of this cam actually run it ... ever?

Do you need to hit yourself in the head with a hammer, to know it hurts ?
Anyone with a basic understanding of cam design, can look at the lift and duration, and know it's way off for the application.

[F-BIRD'88]

Does anybody have a Cam DR. Analysis printout of this camshaft?

[pdq67]

It really needs 12 to 1 CR to perform right!

And the phase 3 cam was the -754 if I remember right,.

There was a guy over on Team Camaro that ran the -140 cam years ago. I forget his handle?

I think his engine was 12.5 to 1...

pdq67

[Tuner]

I’ve got a NIB Crane “Blueprint” version of the GM -140 cam and lifters that I have been packing around for probably 20 years or more. This is a solid flat tappet cam and lifters, 257/269@.050, .493/.512 lift, 112 lsa.

Is this cam any good for anything? Particularly on a “hot street” pump gas 350 sbc with 4.10 or 4.56 gears and a 3500-ish stall converter? I was thinking maybe with some tweaked 062 vortecs and 1.6/1.5 rockers since they peak around .500” lift or so. Would 10.5-1 compression be too low for this?

OK, it's unanimous among the experts, the 140 cam is junk. It's just not hard enough on parts. Will you take $50 for it and the lifters?

[Old School]

Granted the old 140 cam is not up to modern day standards. However, there are some positives that need to be taken into consideration before writing it off as junk. Back in the 60's and 70's parts were not so plentiful and easily obtainable. If you wanted to hot rod the only choice was your Chevy dealer and that was what we used.

GM parts were designed for the masses. Cams could be run with as little as 110 seat pressure and 270 open pressure. This could be done with the 1.25 valve springs, retainers, and locks. Stock rockers would work and if you got lucky and found a set of "o"s off a Z that was a plus. The wide lobe separation helped in piston/valve clearance. For those of you that have never ran these parts then you have no experience to respond to the original question.

Camking estimated 20 horsepower/torque loss over a more modern cam. I suspect in some cases it could be more, some less. That is not a very high price to pay for a cam that will rev to 7k with very little spring pressure, can run stock rockers and valve spring size, have ramps that have better chances surviving wear than the new lobes, sounds great, and makes decent power. I know there is better and worse, everything is a compromise.