Cam Timing: Am I reading this right?

dtw · 09-27-2003, 11:48 PM

I have aftermarket cams and am hoping to time them in the next few days as I rebuild my engine. I found specs for them at cranecams.com. Check out the following link:

http://dab7.cranecams.com/SpecCard/DisplayCatalogCard.asp?PN=520-0010+

Now, I read the timing notes to mean in my own words "Set zero rocker/valve gap, versus the usual .1mm gap, and time cam to .166" at TDC overlap. Also, 25.4mm/inch x .166" = ~4.2mm timing spec. When timing has been set, adjust valves to .1mm as normal".

Am I looking at this the right way?

350HP930 · 09-28-2003, 07:30 AM

Yes . . . .

Tyson Schmidt · 09-28-2003, 01:53 PM

Sounds like Solex cam specs., or Crane's equivelent.

Nice grind.

dtw · 09-28-2003, 05:47 PM

Thanks Tyson and 930.

The PO was running these cams with flat-top 2.4T pistons- not sure how he got it to run! Tyson - I have followed through on stealing your machine work- I've got relieved 2.2T pistons and 1mm shave on the heads. I've dry-assembled the top end with .5mm shims - hope they work. This week I'll measure clearances. One thing I've noticed though is that I'm not really happy with the chain case/thrust plate clearance - the thrust plate is offset from center a good amount. Did you have any problems with this or did you just cut your chain cases down 1mm also?

Tyson Schmidt · 09-28-2003, 07:19 PM

I had the machine shop remove .5mm from the chain housing bases, and it worked beautifully.

The car runs fantastic, and it makes a wonderful street motor that can still hold it's own on the track. You'll be very pleased.

(BTW, even on 91 pump gas, no pinging whatsoever.)

You should think about recurving the distributor to match. I did mine myself by changing springs until I got the desired curve.

Tyson Schmidt · 09-28-2003, 07:28 PM

Two more quick notes.

The spec on my cams (Elgin Solex 102, I believe) is 4.2mm to 4.6mm.

I set them at 4.0mm to retard them for better top-end breathing. No ill side effects at all in the lower rpm's. I did this for that extra help at the track, and it seems to have worked just fine. I also did it for a little more insurance against piston/valve contact.

Also, there are several chain housing base gaskets available from different manufacturers. Some are thicker than others. This is handy knowledge if you find that after machining, the thrust plate still doesn't quite center perfectly.