Cam shaft

[Michael H.]

Re: Cam shaft

duke,what do you think of this statement i found on his web site by harvey crane founder of crane cams, "I have found the Chevrolet V8 small block mechanical tappet camshaft part number 3849346 (sometimes referred to as a "30 30 DUNTOV" because the GM factory says the lash is set at .030 thousands) runs MUCH BETTER at about .045 thousands lash.

Not my question but I will say... I'm not one bit surprised by harvey's statement. More later.

[Loren L.]

Re: Cam shaft

Performance Chevy in Phoenix who runs a full page ad in the Driveline, lists "his" 097 (I think it is done by Crane) for I think $99 and he has them on hand. Ask for Bill. It's the cam I put in the Camoradi car and idle/revs and FI vacuum levels are there.

[Joe C.]

Re: Cam shaft

duke,what do you think of this statement i found on his web site,http://www.harveycrane.com/lashloop.htm by harvey crane founder of crane cams, "I have found the Chevrolet V8 small block mechanical tappet camshaft part number 3849346 (sometimes referred to as a "30 30 DUNTOV" because the GM factory says the lash is set at .030 thousands) runs MUCH BETTER at about .045 thousands lash.

Chevy SB running Rochester fuel injection runs better with higher idle vacuum than a properly lashed 3849346 cam will develop. The Rochester fuel injection system was designed around the "097" cam.

[Duke W.]

Re: Cam shaft

duke,what do you think of this statement i found on his web site,http://www.harveycrane.com/lashloop.htm by harvey crane founder of crane cams, "I have found the Chevrolet V8 small block mechanical tappet camshaft part number 3849346 (sometimes referred to as a "30 30 DUNTOV" because the GM factory says the lash is set at .030 thousands) runs MUCH BETTER at about .045 thousands lash.

Well, first it's not a "30-30 Duntov" - just a 30-30.

What does "better" mean? Racing application? Street application?

At that lash the valves are going to be slammed into the seat at nearly eight times clearance ramp velocity, and it also corresponds to the lobe's point of maxiumum acceleration, which will pound the seats in quickly and cause valve bounce well before 6500 and probably bend pushrods below 6500. The valvetrain is also going to sound like a shaking tin can full of mables. It just makes me cringe!

The 30-30 cam is just too big for sensible street applications, especially the way they are driven today, but it was a pretty hot setup in the sixties with at least a 4.11 gear.

Increasing lash makes it act like a smaller cam with less duration and overlap, but that lash setting is waaaaaay out of the design boundary.

The sensible solution is to install a smaller cam that can be lashed per the original design.

Can you say LT-1 cam!

I'm surprised he makes such a statement as he must have some understanding of lobe dynamics and know that much lash is way outside the reasonable limit of the design.

Duke

[Michael H.]

Re: Cam shaft

Well, first it's not a "30-30 Duntov" - just a 30-30.

What does "better" mean? Racing application? Street application?

At that lash the valves are going to be slammed into the seat at nearly eight times clearance ramp velocity, and it also corresponds to the lobe's point of maxiumum acceleration, which will pound the seats in quickly and cause valve bounce well before 6500 and probably bend pushrods below 6500. The valvetrain is also going to sound like a shaking tin can full of mables. It just makes me cringe!

The 30-30 cam is just too big for sensible street applications, especially the way they are driven today, but it was a pretty hot setup in the sixties with at least a 4.11 gear.

Increasing lash makes it act like a smaller cam with less duration and overlap, but that lash setting is waaaaaay out of the design boundary.

The sensible solution is to install a smaller cam that can be lashed per the original design.

Can you say LT-1 cam!

I'm surprised he makes such a statement as he must have some understanding of lobe dynamics and know that much lash is way outside the reasonable limit of the design.

Duke

I'm sure that when Harvey Crane made the statement about using .045" valve lash, he was trying to make a point. He wasn't actually recommending that people use this lash setting. Harvey wasn't stupid. In his opinion, the 346 cam in a street engine, through mufflers, had too much duration. He was right, but it didn't exactly make the 365 HP Corvette a dog. That combination made for some very fast cars.
I've had a bit of experience with the 365 HP engine over the decades too but it was real world experience, not a computer printout from some dyno program. We raced on the street, at road courses and drag strips for many years. There was never a lack of horsepower. The L76 365 HP Corvette was a terriorist on the street that would eat LT1 C3's for breakfast. ask the guys that actually have experience with this. The guys that were there

Wasn't it just a few months ago that you were recommending that everyone set the lash on their 346 cam at something far less than .030"?
If, in your opinion, the 346 already has too much duration, setting the lash at less than .030" wouldn't agree with what you're saying now.
I tried tighter lash settings on the 64 365 HP coupe that I bought new. I can assure you, it did NOT increase HP/performance.

In my opinion, trying to reengineer a cam for classic cars that are no match for todays cars is a waste of time. Let the C2 Corvette live on the reputation that it has for what it DID in the 60's because no matter what you do to one today, it's hopelessly lost compared to a new C6 Corvette.
I see absolutely no point in trying to compete with todays cars. Doing so just takes these old cars one step further away from stock and original, which is not what the NCRS is all about.

"Better cam" discussions belong over at the CF with solid suspension bushings and headers.

You old pharts sure can be difficult at times.

[Stuart F.]

Re: Cam shaft

As I recall, when the 30-30 cam was first introduced it got that moniker due to the lash recommendation which was changed to a tighter spec shortly thereafter. I have no ready reference about the specifics.

I can't imagine him making such a statement. He must have been quoted out of context or just misunderstood. At .045", I'd be concerned that the rockers would turn sideways falling off the fulcrum balls!

[Clem Z.]

Re: Cam shaft

As I recall, when the 30-30 cam was first introduced it got that moniker due to the lash recommendation which was changed to a tighter spec shortly thereafter. I have no ready reference about the specifics.

I can't imagine him making such a statement. He must have been quoted out of context or just misunderstood. At .045", I'd be concerned that the rockers would turn sideways falling off the fulcrum balls!

here is his web site and he charges for this type on info! harvey called me back in the 60s as i was selling gear drive cams for BBC and he wanted to know where i got the gears.

[Duke W.]

Re: Cam shaft

As I recall, when the 30-30 cam was first introduced it got that moniker due to the lash recommendation which was changed to a tighter spec shortly thereafter. I have no ready reference about the specifics.

The lash called out on the GM drawing is .025/.025", which is 1.5 times the .017" clearance ramp height.

All the service literature says .030/.030", which is looser, not tighter.

My recommended spec based on actual lash point rocker ratio is 1.37 X .017 = .02329, truncated to .023".

Duke

[John D.]

Re: Cam shaft

Excuse me but you guys are way off the subject. Rob asked about the Duntov 097 cam not the 30-30 and LT1 cam.
Car Quest can get you all the Speed Pro CS113R cams your heart desires. No shortage.

[Rob M.]

Re: Cam shaft

Thanks Michael, I'll give them a call and see if I can get it ordered and shipped to the Netherlands...

regards,
Rob.