I have been told that the cam timing on my 1978 F250 460 engine has the cam timing retarded for emmissions purposes. Can the timing be set for TDC by just moving up a few teeth on the timing gears? If it can ,will this make any difference in performance? Any info will be appreciated

Thanks,

Picklebill

 

picklebill, You can only get rid of this situation by replacing the timing chain and gears with a performance, aftermarket set that has at least a 3 - key way setting on the crank gear. Set it at 0 degree's advance and your problem is gone.

Yes it will make a difference in your perormance.

 

Hey guys, I have a question on this topic, thought I would ask it here instead of posting a new thread. (Cloyes Timing Sets) The Cloyes 'True' double roller, the high dollar set, why is there a different part # for the 68-71 460, than the 72 and up? I believe they both have 3 keyways on the crank spocket. What would the difference be?

 

Pickerbill,

I recently did this to my `85 460. I used a pre-emissions (pre 1972) stock timing gears and chain (only one key way). From Summit the set was around $25. The gears can be bought separately, but you will spend more then $25 doing it that way and a new chain never hurts.

To get the new set lined up right you will need to rotate the cam a small amount. First line up the old set to the marks on the two gears (making sure you are on TDC for number one and not number six cylinder). Remove the old gears and chain and then slide the new gears on without the chain. You will see that the cam will need to be rotated just a bit to bring the alignment marks together. Carefully rotate the cam and then slide the new gears off, put the chain on the gears, and slide them back on. After you have it all back together make sure you reset your ignition timing because it will now be advanced also. Note: the distributor does not need to be removed for this job.

You will not see a huge difference in performance. I noticed a better idle and a little more grunt in the lower rpm range. Good luck and feel free to ask any questions.

Mark

 

Wouldn't it be the crank that needs to be turned (counter clockwise), since it is that sprocket which has the multi keyways?
Also, I have come across a stubborn woodruff key on the crank... What can someone recommend to get it outta there without damage to it or the crank snout?
Mark

 

Spray a little penetrating oil on it, use a small pointed punch, and with a small hammer just try to tap the punch under the edge of the woodruff key, it should pop up out of there. If you take it easy you won't hurt anything. Of course don't put the punch anywhere but in the key way.

 

Well DPW the cloyes set that I used to build my last engine was the only one available at the time. I ran that motor for awhile and recammed it . After degreeing the cam about 15 times I called cloyes. It showed to be retarded no matter where I installed it. The early set is three keyway and so is the late. The later set at the "0" mark will still be 6-8 degrees retarded compared to the 68-71 style . So order the early style for a performance build.

 

Trinogt,

The motor is put at TDC on the number one cylinder. The position of the crank and the pistons does not change, but rather, the relative position of the cam is advanced or retarded while the crank stays put. When going to the pre-emissions cam setting you are effectively advancing the cam 4 degrees from the previous stock position in which it was timed. Thus, that is why the cam is rotated slightly.

While you are correct that there are three position crank gears - after market gears that provide user flexibility - each key way represents only a reference point. When the crank gear is slid on in any one of the three positions it will always have a mark - there are three of those too - that is at the top of the crank gear. In order to get the cam gear mark to line up with the crank gear the cam will need to be rotated slightly one way or another depending if you are advancing or retarding from the previous position.

And, as a side point, the cam in a motor that has a lot of chain stretch will be even further retarded and simply replacing the chain will require some rotation to get the cam back to the stock position. Based on the stretch in my chain I guessed that my cam was about 8 degrees retarded, 4 degrees from the factory and another 4 degrees from chain stretch.

Hope that clarifies it, but if not, just ask.

Mark

 

That all sounds good... But, I just thought that moving the crank counter clockwise would be the same as the cam clockwise, since either action will advance the timing?
Idunno... Maybe I am not getting my point across???

I have two vehicles to do this on, so I was just looking at different ways... Isn't it easier to turn the crank by putting a socket on the bolt, than it is to turn the cam, what with all the valve spring pressures on it and all?
Mark

 

Mark,

Yes, in theory, the crank could go ccw. But, when you do that, you lose the benefit of having the mark on the crank gear in place (straight up) to align the cam gear (which has a mark that will be straight down) so you would end up having to guess if they were in fact aligned.

It was rather easy to rotate the cam. After putting the new cam gear on I simply ran the cam front bolt in by hand and using a long wrench to control the movement rotated it clockwise so that it aligned with the mark on the crank. It did not have to go very far. This tightened the bolt a bit so when I needed to remove it, and did not want the cam to rotate back, I did so by putting gentle increasing pressure only sufficient to slowly start the bolt lose, but not so much pressure so as to cause the cam to rotate back. Plus, no jerking movement. If the cam had started to rotate I’m sure that holding the cam gear would have kept it in place.

Good luck,

Mark

 

Ok, that's more like it!
Helps a lot, thanks!
Mark

 

71cc,

Interesting information you have on the early and late part numbers for performance timing sets. You have got me curious now. When I got the Comp Cams double roller set for my 460, there were late and early part numbers also. I got the late since my engine was a 79. I just figured it was a production fit up thing.

Did not even think of this.

 

So, if it is the 'late' set, then 'zero' (straight up, if you will) would actually be retarded 4 degrees, like factory? So then you would have to use the 4 degree ADVANCE keyway to get it to 1968-71 'straight up' specs???!!!
Sheesh, I guess the only way to solve this is to have the late set and early set beside eachother, put both keyways straight up at the zero, and see if it lands on the same tooth or not???
I want my mommy!!!

Mark

 

Yes that is right. You can call the tech line.. Cloyes has a part number on their gear so they can tell them apart. Your set might be marked also.

 

I have sent off an e-mail to Comp Cams to see what they have to say about their sets. I checked my part number I used on my rebuilt 460 and it was for the 72-87 460.