Cam recommendation

[Howard H.]

Am helping a friend with his 59 with 270 horse 283. He has the original block(CU) and heads. He would like to use a hydraulic cam instead of the solid lifter like it came with but still sound like or similar to the original cam. The car still has the original 4:11 posi rear end. Am looking for suggestions. Thanks;
Howard Hiller 46797

[Joseph L.]

Re: Cam recommendation

Hi Howard

When I start up my 1957 270HP, people will comment about the wonderful lifter sound. Otherwise the idle is barely rough (almost tame) with the 097 cam and I get 15 in. vacuum at 850 RPM along with 18 mpg.
The 350/350 hydro cam I had in a 327 was a rougher idle but did not have the lifter sound your friend might be looking for.

With the correctly installed stock valve springs, and proper break-in, there are no issues with a solid 097 cam. Others will disagree, but they leave out the important details.

Joe

[Duke W.]

Re: Cam recommendation

Two choices... the L-79 cam or the L-46/82 cam installed 4 degrees advanced. Both have very similar .050" lifter rise duration of 222/224 degs. Both have the same LSA of 114 deg. The L-79 IPOML is 110 deg. ATC while the L-46/82 is 114. That's why it should be installed on a shorter stroke engine four degrees advanced. I prefer the L-46/82 because it has refined dynamics from Chevrolet's research with the Optron machine.

The Duntov .050" lifter rise duration is 221 degs. net of the clearance ramps. It also has harsher dynamics. Peak jerk is just a few thou above the tops of the clearance ramps, which is why it is noisier than later mechanical lifter cams, especially if clearance is a thou or two loose.
The IPOMLs are 108.5/112.5 degs. yielding a 110.5 deg. LSA. Since duration is about the same as the two above hydraulic lifter cams, the effective overlap is greater due to the narrower LSA, which makes the idle rougher with less low end torque.

Using the Duntov lobes with IPOMLs of 110/118 for a LSA of 114 degrees will reduce overlap for a somewhat tamer idle and better low end torque. This would essentially be a mechanical lifter version of the L-79 cam, albeit with less lift

Elgin and Howard's Cams have lobe masters for all three, so they can grind either to OE specs or IPOMLs of your choice. The biggest problem might be finding equivalents to the GM 3911068/Sealed Power VS-677 valve springs. With properly set up OE springs the two above hydraulic lifter cams' lifter pump up speed is in the range of 6500-6800.

Don't throw your old valve springs away if they are OE, and DON'T use the higher force valve springs recommended by these cam grinders.

Duke

[Howard H.]

Re: Cam recommendation

Thanks Joseph and Duke;
I am going to print and give your replies to him to help with his build.
Howard