[DeTomaso] Roller Cam

[Julian Kift]

Or you can go to our resident expert Dan Jones for advice on all things Cleveland related, he has a number of tried and proven engine and cam combinations and has been working away at his 351C dyno project amassing information and data for some time.

Julian

> From: JDeRyke at aol.com
> Date: Sun, 3 Mar 2013 15:28:51 -0500
> To: jjdetrich at gmail.com; detomaso at poca.com
> Subject: Re: [DeTomaso] Roller Cam
> 
> You didn't mention what your preference is, but there are both 
> hydraulic-roller and solid-roller cams available. In a Pantera, a hydraulic-roller makes 
> more sense due to the difficulty in adjusting valves and the normally short 
> life of solid roller setups on the street. Most cam grinders will advise 
> you on the expected life of their products, and some are shockingly short. 
> 
> >From what's been published (and there's a LOT!) on the subject, some stock 
> 351C blocks have a deep oversized chamfer machined on top of all the lifter 
> bosses. That chamfer often reaches the oil lubrication band that wraps 
> around nearly all lifters whether roller or flat tappet, if cam lift is high 
> enough. It produces a massive oil leak from each lifter on each rise to the top 
> of each cam lobe. To combat this, a few cam grinders scale everything on 
> their cams down to about 90% so their cams give the same lift as a 'normal' cam 
> but are physically smaller in overall dia. This works, at the expense of 
> weakening the cam itself, and can cost more. Others use special lifters with 
> low oil bands.
> 
> Other problems stem from the way many roller lifters are paired together to 
> prevent them from moving from their straight-up orientation; some of the 
> tie-bars that link them will run into lifter boss tops on the closed side, 
> forcing the engine builder to notch each boss top while avoiding going too far 
> into the boss and causing an oil leak like with excess chamfer. Finally, 
> almost all roller cams are made to increase power via much higher than stock 
> rpms, so the entire lower end of such a block needs to be built with this in 
> mind. If you are only doing it for increased efficiency like the factories 
> have done recently (lower friction, fuel mileage), you'll need to find a cam 
> grinder that really understands your goal. Most will try selling a 
> 600-bhp/7500rpm cam whether thats what you want or not.
> 
> There are ways to avoid all these challenges but they cost plenty at 
> today's labor rates unless you have an exceptionally well equipped home shop and 
> are experienced in the art. I'd start by calling as many name brand cam 
> grinder Tech Lines as I could find. There will be those that say it's easy, but 
> they won't be there to help you pay for and sweep up the mess when things go 
> south on the road.   Good luck- J Deryke (I'm in the same boat with my 
> Fontana build, by the way)
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