5.0 stockers/ distributors
 

Any 5.0 stockers ever have problems with a stock distributor changing timing , without the computer telling it to? I checked my timing today, it was waaay off. I reset it, then checked timing at different rpms. Stayed correct until aprox 3000. At 3500 it says 32,then after a few seconds it drops to 16. same thing at 4, 45, 5000 rpm. At 5000 it starts at 32 then drops off to 12. I pulled the distrib and it has a lot of up and down play, prob 3/16". I think it rides up or down the cam gear and retards the timing. I replaced it a year or 2 ago for a similar reason. Are most of you guys running after market, or factory distribs> By the way it's a Holley commander doing the computer controls, and my screen is only showing 30-34 everywhere, and it shows that at the same time as I get the drop, still shows correct timing. I think it doesn't know the timing is retarding. Thanks, Tim

Re: 5.0 stockers/ distributors
 

Been running the OEM dizzy from the beginning, works just fine. My thoughts are.................pull out the spout and set the timing to your desired total. Do not reinstall the spout. Now your timing is locked out mechanically at your # forever at all RPM'S. I use 32 degress total timing. One less thing your computer has to deal with.

Re: 5.0 stockers/ distributors
 

Yeah, I used to do that too. Problem is, it will still change the timing if it moves up and down the cam gear....at least I THINK that's what's happening. Thanx

Re: 5.0 stockers/ distributors
 

Seen problems with dist shafts gettig magnatized and the timing would go wacky, mostly on high mileage poorly mantaned cars. Tom

Re: 5.0 stockers/ distributors
 

I was trying to cure another problem and got rid of my stock worn out ones and went to the MSD dist. Mine would move a couple of degres when you reved it up and down with the spout out.

Re: 5.0 stockers/ distributors
 

I tried the distrib. that was in the car, and today a reman. from Autozone. Same resuts with both distribs and 2 timing lights. The timing is dropping from 30+- at idle to 15+- at 3000 rpm. Funky thing is that one time it even showed 15 at idle too. Holley Commander guy said it could be a bad TFI module. To me it now sounds like the Commander is moving it around but not showing it on the laptop. I'm picking up a new MSD distrib in a couple hours to try. Got a bad feeling, it's gonna just be same problem/ more $. The Holley guy also said it could be worn Timing set, or worn cam gear. Hopefully not, they are a lot tougher to swap out. Thanks for the ideas.

Re: 5.0 stockers/ distributors
 

Charlie:
Do you use some form of start retard with the dizzy advanced that far ?

Re: 5.0 stockers/ distributors
 

Alan
No start retard, fires right up as soon as I look at the key.


Tim
You got me all worried about this issue. Started mine up today and put a light to it. 32 at idle, 2000, 3000, 4000, didn't have the stones to put it at 5000 in park, ( need to show some love to the 135,000 mile long block)

I agree with the TFI comment, my 94-95 does not use TFI.
Or maybe your Holley needs a fresh download of your tune.

Re: 5.0 stockers/ distributors
 

A fresh download to the Holley Commander isn't going to fix anything. Listen to the guy from Holley.

Re: 5.0 stockers/ distributors
 

I'm going to call Holley tomorrow. Today I tried Brand new distrib, cap, rotor, ignition module. Same as before. I think it's gotta be the Commander, or timing slop, or cam gear wear. It's very strange though, it idles at 30 +- degrees, then when you bring up the rpm it stays at 30-33, then after a few seconds you hear the load on the motor change as the timing drops to 15 degrees.

Re: 5.0 stockers/ distributors
 

Throw a socket on the crank bolt and rock the motor back and forth. Any movement is the chain slop. It would have to be super loose and ready to break to retard 15 degess.

Re: 5.0 stockers/ distributors
 

Sounds more like cam walk but should'nt have that issue on windsor due to them having thrust plate between cam and gear,unless it's loose or something else,as cam moves moves back or forth ign.timing changes just like you are twisting the dist,usaully changes with RPM.
I think you mentioned slack between dist/cam gear could be there.
If you are using ford style ign. module may try that,I've seen modules go bad and timing would move around.
It's computer controled may have computer problem?
I don't know if that is any help but might give you ideal.
Mike Taylor3601

Re: 5.0 stockers/ distributors
 

The only time I've seen cam walk in a windsor style is when a billet cam gear was used, without the required hardened thrust plate.

Re: 5.0 stockers/ distributors
 

I'm gonna try a different MSD box tomorrow if I can. Also starting to wonder about the fact that I'm using a dial back timing light, I've heard you shouldn't use those with MSD, but I have for YEARS. However I didn't usually check at higher rpms, usually just timing at idle...Hmmmm

Re: 5.0 stockers/ distributors
 

Use light w/o advance , advance timing lights will do weird stuff on msd when you rev,but I don't think they will actually change timing,just give wacky readings.
You said in post you could hear engine change sound like timing is moving,the only way light could do that is if it caused some kind of interference.

You have'nt changed anything on car that could created this?
If it has alternator be sure it's OK diode can go bad send (slight) AC current and make computer do weird stuff.
Check MSD box wires just to be sure in parts changing some thing has'nt got crossed,is battery full charged?I checked time on my car once batt.was a little low,starter was slightly draggy timing was jumping all over,was'nt that low but was enough to mess up stuff. Try wiggle and pull on wiring while it running listen for change you could have broke wire or connection that would show up.

I had pull truck worked on timing was going haywire mag pickup was bad,I know you changed dist. does your car use any kind of crank/cam/hall effect sensor or trigger.
Just kinda throwing out there any ideal that pops in my head.

Boy it be nice if you could run off ign seperate from computer to narrow it down
Mike Taylor 3601

Re: 5.0 stockers/ distributors
 

Update, I pulled the cam out to take a look. I believe the dowel pin was a real tight, possibly damaged, fit. I think the cam sprocket wasn't snugged tight to the cam, and that allowed the cam to walk backwards. I didn't check cam end play last time {silly me} . This time I will. BTW I did check timing with a regular timing light, no difference. Thanks for the brain trust.

Re: 5.0 stockers/ distributors
 

I may be naive here, but can someone explain the idea of the cam walking back and forth changing timing? It seems to me the the timing would be in the same place the only thing changing would be where the lifter contacted the lobes? even if the timing gear was loose if the pin was in the locating hole I don't see how the timing could change but maybe 2 or 3 degrees just depending on the angle the gear got cocked, but no way does it change 15 unless it was falling off the locating pin....

Just looking for an honest explanation, not trying to be a smart *** or anything.

Thanks
Brad

Re: 5.0 stockers/ distributors
 

Brad:
The way I understand it is when the cam on a SBF moves forward in the block (walking) it will spin the dizzy shaft more in the counterclockwise direction (as viewed from above).
This effectively advances the ignition timing on a SBF.

Re: 5.0 stockers/ distributors
 

Personally I would throw out the cam walk as your issue. Though it appears you found an issue with the cam gear install, the cam simply cannot walk enough in the block to change the timing 15 degrees. The thrust plate prevents it's forward movement, and eventually the lifters will stop it's rearward movement. You mentioned you were going to try another MSD box, did you? Is the dist. wiring near any other high power devices...coil, electric water pump, electric fan? It's not unusual to see a bit of timing flucuation triggering off a dist. 1-3 degrees would be considered normal. Joe

Re: 5.0 stockers/ distributors
 

Cam walk on small/big block chevy happens on roller when timing cover flexes or cam button has to much clearance or if belt drive is'nt shimmed correct,cam moves forward and timing retards because cam gear comes forward does same thing as if you twisted dist.,and if it's severe enough lobes will start hitting sides of other lobes. I saw one idle @ 40 degrees and retard to 0 when revved,you could see timng cover bowed out.

If ford came forward it would advance timing

I have never seen any cam walk issues on ford,but cam walk acts like his description,but I also Tim's problem is more of interference like Buzzin half dozen said,I threw him out alot of things to check as always good to cover basics first.

In case anyone does'nt know and are wondering, flat tappets without thrust plate or method to keep cam from moving,the lobes are on taper so as cam turns the taper pulls cam rearward to keep time gear against block and located
Mike Taylor 3601

Re: 5.0 stockers/ distributors
 

Thanks for the ideas, I'm busy at work, hopefully have more time to look on the weekend.Again, thanks.

Re: 5.0 stockers/ distributors
 

Ok, I'm not guaranteeing this is the problem, but it sure looks like it. The cam is moving back and forth a little under 1/8 inch. The pictures show what effect this has on the timing change, I'd say it's moving almost 3/8" at the rotor, extended to the cap edge. Next I've gotta find why the cam gear isn't going on further. I think it's the dowel pin. ....Yikes I tried to post pics but I don't know how to resize them to fit.

Re: 5.0 stockers/ distributors
 

Weird deal... I tried another timing set I had in the garage [used, but good shape] I have virtually NO movement at the rotor, when cam pushed or pulled. I don't know how it could be the cam sprocket, unless they machined the part that snugs to the cam thicker. They are both Cloyes multi keyed double rollers.

Re: 5.0 stockers/ distributors
 

Are they the same part number.?
There are two part numbers for the SBF.

Re: 5.0 stockers/ distributors
 

I believe they are, both the same C609 is stamped on the cam sprocket. I think the problem may have come from the fact that I used a thin washer between the cam sprocket and the thrust plate, it must have come with the T set. I think it ate away at the back of the sprocket. You can see its been shaved down quite a bit. The cam end play with Tset from garage is .006 +-, the one on the car had .09, not .009, but .09! Yikes!

Re: 5.0 stockers/ distributors
 

The washers are not always required. Always check the end play and that will help you decide if you need the shim. There are also 3 different styles of retainer plates that are used on SBF's.