Torque_Wrench

iTrader: (13)

Hye guys, I'm building an 8.1 up for a customer...and I need some camshaft suggestions. I'm not as familiar with the big block as I am the LS based smally's so...I don't exactly know what cam to choose.

Anyone got any suggestions on the cam, brand or where to get it?

TieRod

I've ran Comps xr270 cam with 1.8 rockers and I have Raylar's 106 cam right now. I know Raylar does not recommend anything bigger then their 103 cam with stock pistons. Unfortunately I never seen the specs on the 103. Crane's line for the 8.1 are much bigger than Comps but I'm unsure if there is a clearance problem. Both Crane and Comps cams are standard BB cams reground for the different firing order.
The Comp I used was a little sluggish under 3500rpm but note too bad. At 3500 it would surge hard and pulled till 5300rpm. It was good for 30whp and 50wtq untuned
I talked to a guy that used a xr258. He was pleased with it after it was tuned. Said it pulled hard from idle till 4800rpm where it shifted. But with out the tune the truck did not run well at all.
Hope this helps, if you need more info I'll be around.

Manic Mechanic

iTrader: (3)

Tie Rod, I've been meaning to ask you something in this area. Does the 8.1 have those lifter retainers like the new small blocks? The ones that allow you to swap cams without removing all the lifters first by taking out the push-rods then turning the cam over until all the lifters are hung in the retainers.

So the XR258 fit stock pistons for the other guy and the XR270 worked for you with stock pistons? I've called Comp and asked them about this and they refuse to speculate and advise checking each and every cam install for valve clearance. Not exactly a gamble I want to take by tearing down the truck and finding out my new cam doesn't fit and then having to decide what to do about it. Hmmm, tear engine down for new pistons or order smaller cam, loose money on the first, and wait for the second to arrive.

One thing I've noted with Comp's range of cams, which are the smaller compared to Crane's. Their Xtreme Energy line all has a foot note that says "adjustable valve train required" while their new Tri-Power Xtreme series which overlap the others in the power ranges do not list requiring adjustable rockers. I don't know if it's an oversight or not yet, I haven't called them. The Tri-Power Xtremes have different valve timing characteristics, wider lobe separation angles and shorter lifts. What did you have to do to the valve train to use the aftermarket cams if anything?

Vernon

Torque_Wrench

iTrader: (13)

Tie Rod...thanx pal for that info. Who did your tuning by the way? Nelson?

TieRod

For starters I had adjustable rockers before Comp came out with its line of cams. I had switch to Crane rocker studs in order to run Comps 1.8 rockers. Raylar's 103 cam is bigger than Comps biggest cam, so there will be no clearance problems with Comps line. Pulling the intake is a must, it has lifter retainers like the 1st gen SB and BB roller engines.
I did my own tuning, can't say it ways the best but it was something. Most of the 8.1 guys use Wester tunes but I'm sure Nelson rivals his tunes.
Later

Manic Mechanic

iTrader: (3)

Thanks Chris, and Torque Wrench for allowing me to stowaway in your post.

Vernon