SoCal Jet Boats
Tech Talk => Engine Mechanical / Electrical => Topic started by: electrowoman on May 11, 2009, 07:13:30 AM
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I'm trying to refresh my memory on this. :-\
The early timing set (68-70) set straight up is 4 degrees advanced compared to the late model set (71 and up). If you put the late model set straight up it's actually 4 degrees retarded...
I got the comp cams early type so I should set it up straight up. What do you expert ford guys think?
I'll degree it to be sure but this is the way I remember it. Gotta find the dial indicator again...
Input is welcome ;D
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I'm trying to refresh my memory on this. :-\
The early timing set (68-70) set straight up is 4 degrees advanced compared to the late model set (71 and up). If you put the late model set straight up it's actually 4 degrees retarded...
I got the comp cams early type so I should set it up straight up. What do you expert ford guys think?
Depends which chain you really have. I have seen CompCams 1968-1971 boxes come with 72-up timing chains in them.
Therefore, if you have the 1968-1971 timing chain set up, then install at 0* "straight up." If you have the 1972-up timing chain setup, then install with the 4* advanced keyway. 4* advanced on the 1972-up double roller chain is the same a 0* straight up on the 1968-1971 double roller chain. And so one chain is not necessarily better than the other, but setting it up properly does matter.
LO
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Depends which chain you really have. I have seen CompCams 1968-1971 boxes come with 72-up timing chains in them.
Therefore, if you have the 1968-1971 timing chain set up, then install at 0* "straight up." If you have the 1972-up timing chain setup, then install with the 4* advanced keyway. 4* advanced on the 1972-up double roller chain is the same a 0* straight up on the 1968-1971 double roller chain. And so one chain is not necessarily better than the other, but setting it up properly does matter.
LO
X2 This is correct, you need to check it with a DI to be sure, the pre 71 should be GTG, I always use the Cobra Jet crank gears, they are advanced from the new style no matter what year. :sly: Aint SMOG great? :banghead:
GT
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Here's a link that may help others.
http://www.reincarnation-automotive.com/Timing-rear-comparison-index.html
Shows the differance between the early and late crank gears.
Sure is nice to have all this info floating around ;D
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Here's a link that may help others.
http://www.reincarnation-automotive.com/Timing-rear-comparison-index.html
Shows the differance between the early and late crank gears.
Sure is nice to have all this info floating around ;D
Ty, (Tywannabana)
Are you paying attention? ;)
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Coooommpppp caaaammmmmmms...
Whatcha talkin bout?
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Degree The Cam...As you said, and find out where you are at ;D
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Coooommpppp caaaammmmmmms...
Whatcha talkin bout?
Tee hee!
Degree The Cam...As you said, and find out where you are at ;D
Always good advice, and ALWAYS DO THIS! Every time I've installed a cam, granted, only on one boat engine, but in the past, had issues with the timing sets. That's why they make the offset keys and cam gears with multiple keyways.
Think of it this way. The cam maker's equipment might be off a degree or two any given day, + or -, so could the equipment making the cam gear or the separate piece of equipment making the crank gear. Figure a tolerance of maybe 2% (And that is being generous, prolly more like 5%, but just for argument), let alone the keyway on your crank could be off quite a bit (It was made by the same guys panhandling money from Congress).
Their Q/C department should be able to quote their tolerance, but it is just that, a tolerance, which means every piece coming off is off from what they say it is.
Now you've got a very real possibilty of a 6% error (in reality, up to 15%, maybe more including the factory or aftermarket crankshaft), in critical valve timing by following the standard keyway timing method. That's nuts on a performance engine.
Degree every cam every time. Just my .02.
Ray
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10-4 ;D Gotcha