*I have already posted this in the engine forum, but i need to figure this problem out so i also posted it here to be seen more often. Thanks

I had my 351m rebuilt last winter and bought Tim Meyer Parts and a 400 crank, and had the shop bore it to a 408. It ran great at the begining of the summer, until it chewed up the origional dizzy (i believe because of a worn out bushing). I put in a new ignition package (distributor, coil, ignition box) from ProComp and it seemed to be ok, however i never drove it down the road in the winter. it was just ideling in my shop and took a 10 mile drive. then about two weeks ago, it quite again. The roll pin on the NEW dizzy broke, so i put a new one in and it started right up. I have had the truck idle for a while and have taken it down the road maybe 10 miles again at the most. I drove it down the road to the gas station today, and it ran super. i got home and wanted to set the idle down a little bit and while i was in the garage getting a screwdriver the temp guage was almost pegged HOT. i put the timing light on it and every once and a while it seems like it misses a spark (light goes out for a second), and sometimes the mark jumps around past the timing mark. it also seems to get worse the longer i let it sit to check the timing. Im getting extemely frustrated at not being able to time this thing. Can someone please help me and tell me why the mark jumps around, why it misses a spark, and what timing mark i am suposed to use on the engine. should it be TDC, or the adv mark or retared mark. Sorry for the long post, but i am lost.

Thank you so much if you can help!,
TheBlueMule

 

what kind of cam do you have????? Roller??? or flat tappet??? what about camshaft endplay(this one is just entirely a guess)???? Perhaps if it is a steel/roller cam, then maybe that explains why you have the chewed up dizzys(since the dizzy may have a cast gear)...if so, I would suggest a better quality gear(bronze or steel) and pin...

How does the gear look now????is it chewed up/missing a tooth or something???

but I am no expert-its just mere speculation....

oh and as far as timing- I would start at 10 deg btc....and go from there...does the dizzy have a vacuum advance or is it the HEI Procomp model???

ohh and were you timing this truck while the temp gauge was pegged???? or at normal operating temp???

 

I shut off the truck and timed it at normal operating temp.

It is an HEI procomp model.

When i pulled the dizzy two weeks ago to change the roll pin, the gear wasn't chewed. however i will check that tomorrow in the day light.

I have a comp cam hyd. roller cam. Like i said, i haven't pulled the dizzy yet since when i put in a new pin, but i will do that tomorrow. Where can i get a hardened gear? I will probably have to drill a new hole to hole a different gear in wont i?

I have no idea on the endplay right now.

And on the timing mark question, there are three marks. do i want to time it off of the center mark?



Thankyou so much,
TheBlueMule

 

Sometimes the distributor gear roll pin will shear off but still bind on the shaft, holding the gear in the wrong place or allowing it to move back and forth or slip occasionally. When you check it, the dizzy is turning so you think its o.k. And even if you pull the dizzy it may seem tight Sounds like theres a chance this could be happening to you.

 

Since it is a roller cam, then it is steel....check to see if the dizzy has a cast gear....msd and other dizzy manufacturers make steel and bronze gears, they are not expensive either but, the gear can be a PITA to remove.....check jegs or summit for the gear(it should come with a matching pin too)....good luck

take a gander here.....but be sure this will fit the Procomp dist.... http://store.summitracing.com/partde...D&autoview=sku

perhaps you can call procomp and see if the dist is compatible with a roller cam and if they offer model that does....

 

this is exactly what i did two weeks ago. I had to replace the roll pin on the NEW dizzy because it was sheered off, but not completely broken. i am going to check it again tomorrow to make sure it isn't already sheered again. if it is i will try to find some kind of solid roll pin.

If the steel dizzy gear is not chewed up or scored, would it still cause a problem like this? I would change it for future durability but if the gear seems to have no mark, the gear being stock vs. steel would not make this problem will it?

Thank you guys,
TheBlueMule

 

If you are running a steel "roller" cam it was recommended by the manufacturer that you install a bronxe gear to prevent the gears from galling, and failing.
Now, if you are tearing up roll pins, you have to look at the problem and realize that the solution is not a larger gear or a harder roll pin. The roll pin is the weak link, and should not be replaced with anything other than an original pin.
The solution here is to find out why the pin keeps sheering, and look in to the oil pump. The pump is driven from the dizzy, so if the pump is failing and locking up, additional tension will be placed upon the drive gear, and the pin will fail, like it is suppoed to do.

We had a similar problem with a 400, and we replced the pin twice. Ran out of ford pins and drilled the shaft to accomodate a larger chevy pin, and busted that. We were out in the sand dunes and wanted to keep running.
Unfortunately we ran out of pins, and decided to put it on the trailer. After tearing off the pan and removing the pump, we found the real problem. Pump was bad. Still had pressure but had so much resistance it was horrible. Too much longer and the pump would have locked up solid. This resistance was too much for the drive gear, and the pins kept sheering.
My bet is that the pump is going bad and causing your symptoms.

 

As far as the timing light, some cap discharge ignitions will cause problems with some timing lights.

Check MSD site for FAQ's.

 

ok. i just pulled the dizzy and the pin is not broke. i called pro comp, and the gear from them is a hardened steel gear. But i don't believe it is bronze, but they said it is for flat tappet/roller cams. The oil pump is a brand new HV oil pump i ordered with the Tim Meyer package.

When i talked to them today, they said that the gear might be forced down onto the oil pump shaft and be pushing it down to hard when the dizzy is tightened down. (which i have heard before) However, the gear doesn't seem chewed. Could the gear still be pushed down too hard on the shaft without being chewed? There is some wear on the gear (looks like paint worn off but i can't imagine the gear being painted) but it is not chewed and the roll pin is not broken.

Any more thoughts? I am going to go get the gear machined down a little bit at the top right now at the neighbors.

Thanks,
TheBlueMule

 

Yeah, this is a wierd problem. I have a 400 in a Bronco that did the same thing. After the second roll pin I replaced the oil pump and the whole distributor. After the third one, I replaced the timing set. After the fourth one, I replaced the engine. After the fifth (yes, in the replacement engine) I parked it and there it will sit until I put the 428/4 speed combo in it ( hopefully this spring). And if THAT one breaks a roll pin, I'm gonna set it on fire and push it over the bank out back. That'll learn it!

 

I have been dealing with the same kind of issue here on my 460. My advice is to take the procomp ignition off of the truck. Beg borrow or steal a MSD ignition and try that. You will find such a difference in how well it will work in comparison to the procomp. All the timing issues I was having were solved immediately when I tried a buddies MSD. The procomp timing was erratic (firing early and late and not advancing correctly) and all that firing out of time will put the stress on all your timing gears etc and will in turn cause the roll pin to loosen or break. I for one, tossed a new procomp ignition with less than 500 miles on it because it is junk.

The second thing is the procomp dizzy I had was not curved right. At times we could bench spin it to 8000 rpm without the advance kicking in. It was sticking badly and the springs were far to heavy. Once recurved it works ok but it is not a high quality piece at all. Gonna toss it too soon as I get another one. Same mileage.

The third thing is to try to get about 34-36 degrees total advance in. My advance is all in by 3500 rpm for sure. You can use a dial back timing light or a timing tape to set it. Then you can read what the initial advance is at an idle. Mine works well at 10 degrees BTDC.

Procomp is a knock off cheap version of the MSD and is a far inferior product. Sure it looks the same and is cheaper, but it aint worth the hassle. I have spent a lot of money and time chasing this stuff around, all the time thinking well it is brand new so it should work. I will never recommend procomp to anyone (even my most hated enemy). That is my Rant for today. Good luck with your project.

 

First thing's first:

remove that POS procomp JUNK, light it on fire, then **** on the ashes.

Second:

Look at cam and make sure cam gear is in good shape

Third:

Take a spare dizzy shaft and remove it from teh housing...tehn turn the oil pump by hand to make sure it feels right

Fourth:

Install bronze gear on OEM dizzy

Fifth:

Make sure installed height is within spec (distance from dizzy seat to bottom of gear...if it's too high you'll bust pins..if it's too low you'll have agressive gear wear/failure)

Sixth:

Install OEM dizzy w/ bronze gear at correct height

Seventh:

Make sure mech weights are not actuating at idle...bend spring tabs as necessary

Eighth:

Set base ignition timing and recurve as necessary...i woudl think 12-14 deg would be about right.

 

I still think oil pump. Did you check the clearance to the oil pan?
Jumping timing mark seems like a broken pin also. Or really sloppy timing chain.

 

Is the harmonic balancer in good shape? That will make the timing marks jump around.

 

Just checking to see if you have found the problem and solution yet. Be interesting to know the cause.