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Cams and Bob Hagins car...

M

Mike snyder

Donation Time
Sorry this isn't the missing race car. I have Bob Hagins 64 SIV GT Simi... street car. He was in the middle of rebuilding the engine when he passed away. What I have is a 1592 block bored 40 over, head with the vizard modifications, crank has been balanced, connecting rods all equal weight, Hypolite pistons (unsure of the compression), and duel 40 DCOE.
Here is the problem: I have two unused cams that came with the car. One is an Isky with 430 lift and 286 duration. The other is a stock cam that has been reground and installed in the block by Mr. Hagin. I am trying to decide which cam to use.
Here are the questions: Can a stock cam be reground greater than 430 lift and 286 duration? If not, what is the is max lift and duration that can be ground into them? Where can I find step by step instructions on how to calculate lift and duration?
Thanks in advance,
Mike Snyder
 
alpine_64

alpine_64

Donation Time
Mike,

Is this the car that was on ebay a little while back.. SIVGT hardtop, very dusty but very complete and rust free? Pics looked to be sitting in a back yard somewhere very dry
 
R

RootesRacer

Donation Time
Mike snyder said:
Here are the questions: Can a stock cam be reground greater than 430 lift and 286 duration? If not, what is the is max lift and duration that can be ground into them? Where can I find step by step instructions on how to calculate lift and duration?
Thanks in advance,
Mike Snyder
Click to expand...

I have ground virgin cams to 460 lift, the 286 duration is questionable since there are a number methods used to measure cam duration. Due to the excessive number 286, I suspect this is the "lash to lash" method which is the least descriptive way to describe the profile of the cam.

A far more useful method is the duration at .050 valve lift, which is a better indicator of the flow potential since with the lash to lash method, the quieting ramps have a great impact on 10 to 15 or so of those 286 degrees.

Additional info that greatly impact cam performance is the lobe center angle, which allows you to determine what the overlap is.

I have made some nice cams with 238 degrees at .050 duration on 107 degree lobe centers with .450 net lift. This was a good cam for a set of 40s on a 1725 and put down in the 120bhp range with a 6500 RPM ceiling.

I also found through flow testing that anything more than .420 lift really doesnt help flow.
 
M

Mike snyder

Donation Time
Thanks for the information. The car is the one that was on Ebay a while ago. I picked it up in Livermore Ca. All the metal was in very good shape but all the rubber had been baked to a crisp. So I am in the process of replacing all the seals and rubber. What I am trying to do is decide if I should use the Isky cam because it is a known quantity that I can tune for or go with the unknown reground cam. Any thoughts on an easy way to calculate lift and duration? Even something fast and dirty would help me to decide which cam to use.
Thanks,
Mike Snyder
 
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