Here's what Hughes has to say;
Whiplash Flat tappet hydraulic small block "LA" camshaft.
Hughes "real" Chrysler cam
WARNING: Our Whiplash cam is designed for basically stock, low compression engines. This cam will run on pump gas in a 318 with 8.6:1 or less compression and iron heads. If your compression is higher than this you may need to use a higher octane race fuel. Your vacuum should be in the 9"-11" range using this cam.
(Figures calculated using stock stroke & compression at 750' altitude.)
Basic guidelines (These are not absolutes, just guidelines to help you get close on a cam choice)
Use: Street and some strip
Idle: Like it wants to bite your head off! Very aggressive
Vacuum: Low
Converter: Stock or a mild stall
Rear gear: Stock or up to 3.55
Benefits: Tons of low end torque and a super aggressive idle that scares Mustangs, Camaros and rice burners from even thinking about messing with you.
The OEM Distributors have terrible advance curves. Many go as far as 50+° advance which will cause major damage and have very poor acceleration. When you order a Whiplash cam ask for the special whiplash advance curve specs or we can supply you with a new Pertronix distributor (P/N PRT 7141700) and we will custom curve it for no extra charge.
Lets talk about this;
First; " Like it wants to bite your head off!" Come on!, it has just 48* of overlap, just 4* more than a 340. Nobody ever said that about a 340. If you want "bite your head off, you'll need a 484cam or more, and 11/1 compression. So this is strike one against the advertising hype.
Next;
"Many go as far as 50+° advance which will cause major damage and have very poor acceleration". I have never seen even ONE ,50* PLUS in centrifugal timing, never ever. Yur lucky to get 30* plus 5 idle =35*. So where is the "many"
So strike two
Next;
Vacuum: Low/ Your vacuum should be in the 9"-11" range using this cam. This is true, and is partly why you need a looser than stock, TC. Yet they say; "Converter: Stock or a mild stall. Strike three.
Next;
pump gas in a 318 with 8.6:1 or less compression and iron heads. If your compression is higher than this you may need to use a higher octane race fuel
Here they are protecting their butts. There never was an 8.6Scr 318 from the factory, so this is like saying ice-is cold. Empty words and useless information. to get to 8.6, you will have to get your total chamber volume down to ~86cc. With pistons down at .057, that's 11.2cc; add 8.6 for the gasket,add 1cc for the crevice volume, and you are up to 20.8; leaving 65.2 for the heads. So your factory open chambers heads are what? about 72cc and that makes your total chamber volume ~92.8 and the Scr comes to 8.0 on a good day, cuz in some in 318s the pistons are down even further than .057.
Bottom line is the only way to get to 8.6 is spend the money to get there. To their credit, they do say 8.6 or less.
But as I have previously shown; with an estimated Ica of 54*, even at 8.6Scr,your pressure will still be in the basement;
Static compression ratio of 8.6:1.
Ica of 54*, sealevel
Effective stroke is 2.78 inches.
Your dynamic compression ratio is 7.37:1 .
Your dynamic cranking pressure is 146.84 PSI.
V/P (Volume to Pressure Index) is 118
So; two strikes on this point.