Cam Specs

[digitech]

I know there are some seriously competent gearheads on this site so maybe you can help me to understand something. Reviewing the cam specs that came with my 40-80,80-40 cams, I see there are different valve clearences specified than what is in the Fiat workshop manual. Have I been using the wrong settings or are these the settings the cam man. used to arrive at their specs???

[Curly]

Use the specs that came with cams, that's what they are designed to run with, you'll probably find they need a bigger clearance than the factor specs.
Also, to really get the best from the cams they should be timed in using a degree wheel, dial indicator and adjustable cam pulleys. Your specification sheet should give you information of cam lift at certain crank degrees for both the inlet and exhaust cams that will help you to set them up accurately.

[narfire]

Curly is 100% right. The cams should have the clearances somewheres in the package. I just finished installing Marks cams on my FI and they spec'd 10 thou. clearances. Did that and for one engine/head is much quieter, but more importantly the car goes like snot, well not quite, but a happy improvement for sure. I had Jasons cam wheels as well and had a friend dial in the cams with a degree wheel. Don't ask me about that cause as far as I know he was talking swahili and lost me after the second or third word.
If you remember a Far Side cartoon where the aliens are in a spaceship cruising above a crowded street with the caption... Aiiieeeee!!!! .... that was what I was feeling this afternoon.
I'm sure you'll love the improvement when the engine is all dialed in.

[digitech]

Thanks for the info, the clearances that came with the cams are a bit tighter than with the original Fiat cams. I know I'm not going to get all the performance that's there without dialing in the cams but at this point I'm going to settle for working out the bugs. I would probably have to get someone that knows what they're doing to help me with that anyway.

[baltobernie]

Unless you've owned your car from new, and have never had any machine shop work done on your engine, adjustable cam pulleys and their proper installation are very, very highly recommended. Without them, you're betting that all cylinder head and valve train components will fall into place to factory specs, as there are no other adjustments available.

I spent hundreds of dollars and dozens of hours trying to get my new engine (with 80/40 cams, BTW) to idle and perform. Ultimately, I found that one side was only a degree or two off, while the other was eight or nine. Idle, driveability and power were all improved. Ten percent more torque and HP with the proper valve timing. Before and after on the dyno, not "seat of the pants" impressions.

Adjustable pulleys on modified engines are not performance extras; they are (or should be) considered part of the rebuild process.