I installed a Clifford cam in my 6. runs good above 700 RPM, but won't idle at 500. Vacuum gauge reads low & says "late valve timing" Do you think I was off a tooth when I installed the chain? I really don't think I made that mistake. Would it even run if I did? Thanks

Shearnstable@earthlink.net

make sure the advance springs in the dist are not staying"open" or "advanced" above 700rpm and "closing" or "retarding" below 700. went through the whole routing with my last 2 cams. the latest was a real pia to get the dist dialed in to. (.509" lift/248*/253* at .050, 110 lc)
chad

beardliz@msn.com

Which Clifford cam is this? What is the valve lash setting? Where do you have the initial timing set? Did you "degree-in" the cam?
Does it pull good on the road at higher RPMs?
DD

500 rpm is an awfully low idle speed. Why do you want it so low? 600-700 should be much easier to deal with.

Which Clifford cam is this? What is the valve

It is the 268 duration cam. .016 intake & .018 Exhaust. Clifford also supplied a Cloyes double roller timing chain. I only used marks on gears to install. I doubt if I set it one tooth off. If I did would it even run? or would a valve hit a piston? Do they make offset bushings to degree the am? I will drive it this weekend. It had a rusty tank.(Renewed) I wonder if it clogged he idle jets of the Holley 390. 1965 W200 Boyerton body Ambulance, 19,000 orig miles.
Thank you for all the work you have done with the slant 6

shearnstable@earthlink.net

A 225 SL6 will run with the timming chain off a tooth. (there is lot's of clearance in "stock" engines)

Here is a good way to check the cam position, give it a try:

Posted By: Doctor Dodge (Doug Dutra)
Date: Tuesday, 6 February 2001, at 1:39 p.m.

In Response To: Whoa! Compression! Pease help! (Mark W. Marasch)

Mark,

My thinking is that you should re-check your cam timing at the valves, lets see how close your cam position is to a true "split overlap" setting. here is my "quick & easy" check process:

-Pull the valve cover, install a "degree wheel" or accuratly mark you damper.

-Rotate the engine to true TDCE (Exhaust Stroke) (TDC point with no "lash", both valves hanging open on "overlap")

-Place a dial indicator on the intake valve keeper. From TDCE (zero) rotate engine backwards untill the intake valve closes, (dial needle stops moving)"Over shoot" and come back to this point, turning clockwise to where the needle starts to move again, note this position in degrees.

-Move the indicator over to the exhaust valve keeper. Now continue to rotate clockwise, through TDCE and to the point where the exhaust valve closes. Note in degrees where ex. valve closes.

-Subtract the small number, TDCE to intake opening (intake Pre-TDCE opening degrees) from the total overlap number,(degrees both valves are open) the remainder, (exhaust Post-TDCE) should be 4-6 degrees less then the intake Pre-TDCE number. Example: intake opens 26º BTDCE, exhaust closes 22º ATDCE, (48º "travel" or total overlap) This would be a 2º advanced cam

If you see that the "split" is pretty even, with the intake opening a few degrees longer, then the cam position is OK. If the exhaust is staying open longer then the intake or if you see the intake opening more the 10º longer then the exhaust, you should re-degree the cam.

Note that these measurements are taken right off the valve "keeper" at the proper "lash" setting so we can see what the valve / engine really sees. (lash changes have a big effect on this test so be sure the lash is correct)
DD

In order to get my idle down to 800 rpm I had to do two things;

1. adjust the secondarie's on my 390 Holley so they closed completely. As delivered they ere open just a crack and kept the idle up around 1200 rpm. This got it down to 1000.

2. I do not run with a PCV. This dropped the idle down to 700rpm and then I was able to bring it back up to 800rpm with the idle stop screw.

Part of this problem is in the distributor. In order to get the 32ish degrees of total mechanical advance the engine seems to like best I had to set the intial timing at 17BTDC. One of these days I will play with the advance wait slots so I can back down the inital timing some but 800 rpm is fine with me.

Dave

Dave's Hot-Rod 6
dave.clement@motorola.com