My truck is at 104k now on the original 302 EFI engine. I was curious to see how much play was in my timing chain and gear set. I turned the engine by hand to line up 0* on the balancer with the pointer on the timing cover, then I turned the engine the other way until the ignition rotor (cap removed) just began to move. The simple test proved about 10* of play. This play obviously throws off my valve and ignition timing. Is 10* "acceptable," or should I replace the timing chain and gear set?

 

100k miles is the recommended interval for replacing the chain & gears, I'd bite the bullet
and do that (and the water pump while you're in there).

 

I just did this 3 weeks ago. I had around 40, 000 miles on my rebuilt motor. There was a lot of slack in my chain. I replaced everything on the front of the engine so I would not have to do it again. It took two days, but I have to clean and paint before I put stuff back together. I just like to keep it as clean as possible.

 

Funny you mention the water pump. It just starting leaking on me, I think it's coming from the weep hole. But yes, I'll replace the water pump, t stat, and timing chain & gear set all at once. Any recommendations on a good set to get? Summit has a huge selection. Is it at all beneficial to advance or retard the valve timing at all with the stock cam? Speaking of cams... it's really tempting! Or would some 1.7 rockers have a similar effect at a fraction of the work and cost?

 

Go with a "straight up" timing set ...... one that will let you get away from the emmissions advanced timing setup of the '80's. I bought a Ford Racing set from Summit and installed it at "zero".

I've made a lot of changes to Clyde and one of the best I've done so far was to change the timing gear set and retard the timing to pre-emmissions settings. Better than the change from 3.54's to 4.10's!!

 

Awesome! I would be thrilled to see some improvement like that. Can you elaborate a little on what a "straight up" timing set is, and how to install it at "zero." I thought they were keyed gears and would only go on the crank and cam one way.

 

You've got me curious too. What improvements would be seen compared to factory settings?

 

Clyde, man, I wish you hadn't said that

Personally, I'd be hesitant to change the timing to straight-up without also changing the
dizzy's advance curve at the same time, as the DSII module is programmed to expect
the mechanics to be a certain way and to advance/retard the ignition timing a certain way.

An engine is a system - a combination of components that all work together. Changing one
component while ignoring the other, related ones isn't necessarily a good thing to do unless
you fully understand what you're doing and what the possible consequences are.

86 & Kirby - the valve timing was retarded out of the factory - at least on the 335-series
engines (351C/351M/400), not sure about the other engines but it'd make sense they were
also retarded. This was one of the methods used by Ford to meet emissions requirements
of the time and is PART OF the emissions-related characteristics of the engine. A decent
aftermarket timing set should be able to be installled according to factory specs OR at
0deg (and maybe even with some degree of advance).

But, this is PART OF a system, I'd suggest talking with a knowledgeable Ford engine
builder who can help you tune and adjust the engine afterwards if you want to deviate
from factory specs.

I don't suggest you do anything different from factory specs without first learning all
about what it is you're doing and what the effects are.

 

I have always used Cloyes Timing sets, I'd be leary of any Summit branded Chi-Com chain; way too mych to go wrong here... IIRC, when I replaced the chain in my 5.8 Ploice motor the replacment part identified by Ford was a Cloyes set.

http://www.cloyes.com/HighPerformanc...S/Default.aspx

 

Forgot about all the emmissions crap on the lighter GVW/later model trucks.

Should have at least inserted the following disclaimer with my original post:

"Depending on your year, make, model, GVW, engine, emissions package,
ignition system, on board computer, political climate during manufacture
and a whole bunch of engine polution control systems many of us cannot
even begin to understand further consultation with more knowledgeable
individuals may be required before you decide if this action is right for you.
YOUR RESULTS MAY VARY. NOT A SUITABLE MODIFICATION FOR ALL FORD TRUCKS."

 

Installing the gears at ZERO would be very beneficial for the engine ONLY IF the ECM is willing to compensate for the change and make necessary adjustments. If the gears were installed at ZERO and the ECM was non-cooperative with the change, the gears would have to be re-installed to factory specs, and that's the end of that. (Not that I would endure the trial-and-error route, I am just speculating). Am I drawing correct inferences? Any recommendations for who I could talk to about this?

As far as brands, I don't think I could go wrong with any of the bigger name brands like Cloyes, Comp Cams, Edelbrock, Ford Racing. My biggest concern about picking a set is the specs regarding the maximum degree of advance/retard at crank/cam. Also, is it worth spending the extra buckage for a double roller unit?