JS

iTrader: (4)

Example:
6500 peak NOW with cam straight up in on 113ICL

New idea:
Advance cam 4 degrees to 109ICL

Where will it peak at with the cam advanced 4 degree's?
I was hoping it would drop it to 6200 and get me alittle more power under the curve?

Am I close?

Ragtop 99

iTrader: (7)

How about doing what I originally suggested - use a 111 ICL.

Larry

iTrader: (4)

Every degree is generally about 50 rpm. Go to a 107 ICL and you should peak around 6200.

JS

iTrader: (4)

Good info guys..
I'll stick it in on a 109ICL and hope it peaks at 6300.

I'm gonna be shifting the car at 6500.
This hould be perfect for my setup.

Larry

iTrader: (4)

That's probably a good try as the more you advance it the less peak hp/torque it will make. Even though you may not be shifting as high as you would to get best et you may get better et with it advance less due to more hp/torque. Advancing it farthur will improve that 60' though. It's really a trial an error procedure.

Advance it too far your 60' may improve but mph and et might suffer slightly. Not far enough and mph will be greater but 60' will suffer and lose et.

Ideally with this or any cam and engine combination you want to advance/retard the cam where you get peak hp/torque regardless of what rpm. Peak hp/torque should be determined with converter locked. Now size your converter stall where you are 500 rpm below peak torque, transbrake locked, full throttle. Adjust your shift points and gearing where you are 200-400 above peak hp at the lights. Rpm limiter may have to be raised as well. Very few of us really reach this optimum point. We just try to get close.

1999_SS_M6

This thread sounds like it's full of well informed cam dudes, so don't take this the wrong way. There are a lot of not so well informed cam dudes that may be reading this, and that's the reason for the reply...

I was just going to remind you that by advancing your cam you're closing your piston to valve clearance on the intake valve. I don't know what kind of advance is or isn't already ground into your cam, but by adding more you may be getting tight..

It's no big deal if you were in a position to clay the pistons, but this sounds like an on the fly change where that's not going to happen. Just wanted to make sure that the others reading the thread will know that there isn't infinite adjustability with cam timing...

Larry

iTrader: (4)

Good point 1999_SS_M6! You certainly do reduce your piston/valve clearance when advancing. Good idea to always check p/v clearance when going with aftermarket cam, milled heads, etc.

JS

iTrader: (4)

Well the cam card I have for this cam sez to put it in on a 109ICL but the cam was put it straight up which IMO works well for a light car thats using a 6sp but for me and my auto I believe it shouldve been put in at 109.

There was NO avdance ground into the cam at all.

So Larrys info makes perfect sense to me.
My peak is going to be right about 6300 with a shift point of 6500 and my peak tq is going to be right about 4600 and my verter flashes to 4200 so I think I'm gonna be real close.

My pistons are fly cut too but I'm gonna clay it to be sure its safe..

1999_SS_M6

Thanks Larry, I just wish I had all this good advice when I was a newbie and was trying to pick it up! I always try to keep the new guy in mind when reading/posting, sometimes they have questions they don't ask because they are afraid of looking dumb. There are no dumb questions guys, only dumb answers!

Anyway, as far as making on the fly cam timing changes go, the practice I try to maintain is to mock up the engine during the initial cam install... I mean, advancing or retarding your cam can be easy, relatively quick, and very beneficial tuning for the track. However, it's not likely that you're going to clay the pistons for piston to valve clearance when you're just tuning with the engine in the car. My advice to the new guy is to take a little extra time to advance and retard the cam 2, 4, and maybe even 6 degrees BEFORE you button up the cam install. Make a couple notes about your clearances and KNOW what the adjustability of your cam timing is so you can tune one the fly with confidence!

IslandTahoe

Newbie questions.

Is there a way to check the valve to piston clearance with the heads on the motor? What are the steps if any?

Also, how can you conrfirm TDC with the heads on the block?

Thanks

Larry

iTrader: (4)

Install two light weight springs on an intake and exhaust valve. Companies like Summit Racing offer these special springs. Install a dial indicator on top of rocker positioned directly over the valve tip. Turn the engine to maximum overlap position. (Crank rotation opposite TDC) As you rock the crank back and forth read the smallest distance the indicator travels from the valve closed position to piston contact. That's your minimum clearance. You want a minimum of .080 clearance on the exhaust and .060 on the intake. Some recommend more but I have gone with this on one engine without a problem.