CAM degree Timing

1966-300

New Member
Joined
May 22, 2011
Messages
41
Reaction score
1
Location
Wellington Fla
Getting down to the short strokes. My 383 is almost done being rebuilt. Getting ready to button it up and have another questions. What are the thoughts on setting degree of CAM? I am installing a Comp Cam that is just a very little more agressive than the stock cam. I did not want any extreme idle etc more to stock. But a mechanic buddy of mine had been talking to another gear head and he had asked if we were going to put and additional degree of cam in. What does that mean? I currently have the cam and crank set up so the alignment marks are dead on and am just curious about degree of Cam, what it means, benefits, downside etc? As I said I am keeping it pretty much stock so I do not want to buy a problem.
 
The cheapest timing sets have just a single slot on the crank gear, so you can only install one way ("straight up"). That is fine for most people.
Intermediate sets have 3 slots: 4 deg advance, straight, 4 deg retard. That allows you to tune it to your needs. I set mine 4 deg advance since that gives the better low speed performance and mileage. It also allows for 4 deg of wear. The retard setting gives more power at high rpm, but a poorer idle.
Top line sets have ~9 settings so you can tune to your hearts content (hard-core racers).
With all sets, you always align the dots on the crank and cam gears. However, there are different sets of dots for the multi-set ones. You match triangle to triangle, etc. Should be an instruction sheet with the set.
One thing that confused me, was that when the gear dots are aligned, the engine is at TDC on cyl 6, at least for the Mopar small block I did a few years ago. I expected cyl 1 should be at TDC, and spent time resolving that.
 
billgrisom is correct. 4 degrees of advance is a good way of buying bottom end torque. it can also be done with an offset keyway therefore using the gears you allready have. never done a big block but i cant see it being any different than a small block. have someone who knows how to degree [centreline] your camshaft with a degree wheel and indicators. even if you have to pay him. that way you know it will be done right the first time. make sure you break in the cam properly. usually this is done by running the engine at between 2000 and 2500 rpm for about 15 minutes immediately after starting the engine for the first time. this gets the oil flying around the cam and lifters and anything else. have an engine guy help on startup. hope this helps. paul
 
Thank you for the comprehensive answer. The Cam/timing set I purchased does not have any such additional slots so (Straight Up) it is. Thanks again.
 
Ditto on running the engine >2000 rpm for ~20 min. People say you can "wipe the cam" if not broken in correctly. I think the need is to get the lifters rotating in their bores. If not, the cam lobe can start wearing a groove in the lifters and they will never rotate, and thus wear more. I think a bigger problem with high lift cams and stronger valve springs.

I just started the small block in my 65 Dart after a new cam and missed that opportunity due to a comedy of errors. The carb over-flowed (float needle fell out during plumbing), then in haste I installed it backwards, so dribbled. I had the distributor 180 deg out (was correct, messed up when fine-tuning the phasing). Updated the engine harness and didn't use the brown wire (ballast bypass) since I ASSumed the ignition wire got power during cranking (nope). So I spent maybe 5 min of cranking in the first 20 min of running. Still, I doubt I wiped the cam.
 
Of course, if you have a manual transmission, theres another way to break in the cam, and the engine doesn't even need to be started....
 
certainly hope your cam is all good. a comedy of errors is an understatement . lol. you are correct on the lifter not rotating in the bore. the cam lobe wears a groove in the bottom of the lifter wiping out the lobe. the **** falls down to the crank and rod bearings underneath that particular area and then you need to pull the motor for bearings. OUCH been there done that. if you are concerned you may have wiped a lobe than pull the valve covers and check for equal rocker movement. or better yet use a dial indicator.[ hope you changed out the fuel contaminated oil ]
 

40 or so years ago, a particular car (built in the UK) had cam problems. Cars that were started off the key soon returned for a new one. We soon learned that if we towed the car around in 2nd or 3rd gear for 30 miles or so, ignition off, before restarting, the problems would not happen again.
 
Back
Top