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cam degreeing

1K views 10 replies 6 participants last post by  Magikal 
#1 ·
What is the easiest way to degree a cam in,also what is total timing?
Thanks for any replies,
Rick
 
#2 · (Edited)
Go to this site, at crane cams, and download the pdf file for viewing. This will tell you what you need to know.
When reading, they'll refer to a piston stop. Make one from a gutted spark plug and a bolt with it's end filed down, so as to not damage the piston.

http://www.cranecams.com/pdf/803.pdf

Best wishes :thumbup:

Initial timing is the degrees of timing at idle.

Total timing is the initial plus the timing advance made by the vacuum advance or centrifugal advance, whichever is present on your distributor.

eg., intial timing @ idle = 10 deg.,

total timing @ 3000rpm (once vacuum advance or centrifugal advance cut in) = 35 deg.

Initial timing is the degrees of timing at idle.

Total timing is the initial plus the timing advance made by the vacuum advance or centrifugal advance, whichever is present on your distributor.

eg., intial timing @ idle = 10 deg.,

total timing @ 3000rpm (once vacuum advance or centrifugal advance cut in) = 35 deg.
 
#4 ·
Sorry for jumping on this thread, but it seems to be a good place to ask this.

I know the basics about timing, but I'm having some problems timing my buick 3.8L engine. I did a search and found someone who said that you should set the initial timing to achieve the greatest vaccuum, and then back off about a pound or so. I tried this and my initial timing was WAY retarded (my pointer goes from 0 thru about 20 BTDC, and it was over 20. Engine rpms went up while going further BTDC, and vaccuum maxed out at about 20 in/m. It may actually pull higher vaccuum, but without removing the distributor, I couldn't turn it any more.)

Also, should the vaccuum advance be connected to the ported vaccuum port, or the full time vaccuum port?

The engine has just been rebuilt, and while it runs decent, but I think I still have some tuning to do. It is bored .060 and has an edelbrock 500cfm carb kit (intake/carb/cam). I am using the edelbrock timing set and running the cam strait up. Not exactly sure what the compression is, (probably about 10:1 give or take a little) but I replaced the stock dished pistons with flat tops. If I left out any important info, let me know.

TravisT
 
#5 ·
TravisT said:
Sorry for jumping on this thread, but it seems to be a good place to ask this.

I know the basics about timing, but I'm having some problems timing my buick 3.8L engine. I did a search and found someone who said that you should set the initial timing to achieve the greatest vaccuum, and then back off about a pound or so. I tried this and my initial timing was WAY retarded (my pointer goes from 0 thru about 20 BTDC, and it was over 20. Engine rpms went up while going further BTDC, and vaccuum maxed out at about 20 in/m. It may actually pull higher vaccuum, but without removing the distributor, I couldn't turn it any more.)

Also, should the vaccuum advance be connected to the ported vaccuum port, or the full time vaccuum port?

The engine has just been rebuilt, and while it runs decent, but I think I still have some tuning to do. It is bored .060 and has an edelbrock 500cfm carb kit (intake/carb/cam). I am using the edelbrock timing set and running the cam strait up. Not exactly sure what the compression is, (probably about 10:1 give or take a little) but I replaced the stock dished pistons with flat tops. If I left out any important info, let me know.

TravisT
I may be wrong, but it sounds like you may be one plug off on the distributor... I'd say put the #1 piston at TDC and pull the distributor cap.. And see if the rotor is pointing to the #1 spark plug.

And vacuum advance goes on ported vacuum.. So that there is little to no advance at idle.. But gradually advances as rpms increase.
 
#6 ·
Well I may be wrong, but if I was one plug off wouldn't the timing be advanced and not retarded (of course it would depend on which way I was off). I can get the timing to 8 BTDC and it runs ok, but from what I heard about timing according to your vaccuum reading, you are supposed to tune to the highest vaccuum which reading is over 20 BTDC with no vaccuum advance.

I thought the advance went on the ported side, thanks for clarifying that for me.

If someone can verify the timing method using the vaccuum guage, I would greatly appreciate it!

TravisT
 
#9 ·
Yeah I recently set mine to 8 BTDC with the vac advance off and everything.. But there I was only pullin like 12 psi of vacuum... Didn't seem to have hardly any power.. So I hooked the vacuum guage up to it today and set it according to the manifold vacuum.. I"m probably runnin about 20 BTDC now and pullin 17 - 18 psi of vacuum throughout the rpm range now and it runs a heck of a lot better. Didn't have gas to take it on the highway and see how topend power is though. Just took it on the road in front of my house and roasted the tires all the way through first and let off there. Not bad for a 305 I suppose. hehe
 
#10 ·
timing

I have the same timing problem, but I think I'm going to try a curve kit for better timing. I also have about 20btdc inital in order to get 36 at 2800-3000 rpm. When I do plug my vac. advance in I get another 16 deg. which brings me to 52 deg. at cruise. I haven't figured it out yet.
 
#11 ·
For info on the vacuum timing adjustment, see thread

http://hotrodders.com/showthread.php?s=&threadid=35947

Basically, advance the distributor to find the highest amount of vacuum. Then you want to retard the timing 10% of the total vacuum.

For example: If the highest vacuum achieved is 20 then retard the distributor 2.0 to 18....If the highest vacuum is 16 then retard it 1.6 to 14.4....

Easy as that, the key being to back it off 10% of the maximum. Good luck
 
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