Variable Valve Timing Retrofit for small block Chevy

[dpmarv]

Does anyone know of a true variable valve timing setup that will retrofit on a small block Chevy? Does anyone with a Chevy engine think it would benefit them?

[OldSStroker]

By "true variable valve timing" do you mean more than just variable advance of the camshaft with respect to the crank while the engine is running? If so, that's a tall order for a single cam V8.

If you mean variable advance, GM has at least prototyped it in GenIII/IV (LS series) V8s. Look at how the Vortec 4200 varies the advance/retard of the exhaust cam, or how the newest 4.6 Northstar varies both intake and exhaust. I saw limited (mechanical) variable cam advance in the first Engine Masters competition on a SBC.

One could always try the "rubber cam lobe" approach. As rpm increases the rubber lobes stretch thereby increasing lift and duration and probably phasing. It's all in how you place the heavy metal in the rubber lobes.

[SupStk]

I recall looking through car magazines from the 60's and there were ads for a camshaft sprocket that would change cam timing. If i remember correctly it was called Vari-Cam.
Guess my question are;
Did it work?
Was it adjustable?
Did it change cam timing centrifically?
Did it retard cam timing at the upper RPM?

[dpmarv]

Thanks for your replies. I am talking about advancing or retarding the camshaft while the engine is running. I have heard of the Vari-Cam and seen the mechanical drawings. I believed it worked to a degree. It could only advance not retard, and at high RPM's the spring mechanism would not hold steady. I am working on a unit that will advance or retard camshaft timing 10 degrees. Has anyone heard of Cam-A-GO? It was sold through Offenhauser in the mid 60's to 70's.

[whisperer]

I haven't seen one in many years, and the VariCam worked, but took a huge amount of work to get set up correctly. (total advance, rate etc). I was looking at this a year ago or so and think it would be a great and viable product for todays market if a guy could get the bugs worked out.

Of course it would not change the max HP an engine would output at peak, but it would sure get you you more under the curve. I think the biggest problem would be educating the backyard engine builder in how to set it up correctly. Maybe you would have better luck today as there are a lot of people out there that are famillier with VVT and higher technologies then we were in 1965.............

[Lasher...]

The Cam A Go was invented by Ollie Morris who worked at Offy during that time.

It was a 3 gear drive set up.But not like most 3 gear sets are.This used 3 gears that were smaller in diameter so that the idler gear was centered in line straight up and down between the cam gear and the crank gear.This idler was supported by a bearing on adjustable bar in the timing cover.This bar would move the idler so that if the idler was moved in one direction it advanced the cam and if moved in the opposite direction it retarded the cam.

This unit coud be operated while the engine was running and under full power.A simple choke cable was used to operate a piston on the timing cover.You hooked up an oil pressure line to this piston.When you pulled the lever engine oil pressure would push the piston that in turn pushed the adjustable bar and the idler gear in what ever direction you wanted.

Suposedly you could push it in one direction to advance the cam then during the pass push it back at higher RPM and it would retard the cam while the engine was running.... But only If and when the driver wanted to.

Needless to say it was somewhat complicated and never really lived up it it's expectations .... and back in 1968 it was $250.00- $300.00 back then.
Neat idea but like so many never really caught on.

[jamec]

Speaking of the pressure relief valve. Is there any trick to stop it from leaking?

[pdq67]

Maybe the easy way for the old beloved Gen I SBC V-8.

Install something like a Pete Ardema SOHC set-up on it and then add VVT mechanism cams..

pdq67

[PackardV8]

It may be a patent issue, but I've been expecting an aftermarket version of the cam-within-a-cam as used on the Dodge Viper. http://www.thehemi.com/news.php?id=20080211-1

This seems to me to be the best compromise, as advancing or retarding the exhaust can be done without affecting the intake and vice-versa.

jack vines