351M wont start after Dizzy removal and reinstall

Charging, starting, lighting, gauges, HVAC

Moderators: FORDification, Thunderfoot

Post Reply
HottRubber351m
New Member
New Member
Posts: 7
Joined: Thu Jun 13, 2024 10:11 am

351M wont start after Dizzy removal and reinstall

Post by HottRubber351m »

Hi all. New here. Background about me and my lack of expertise is in the Welcome Mat section if it helps...

I recently bought my first "classic" - 54 Merc M100 on a 79 Bronco chassis with a 351M. Four speed manual/4X4. I noticed a puddle of oil in the recessed well where my (12127 Motorcraft) dizzy lives. It was blowing around the engine compartment making a mess. Decided to remove the dizzy and check the O ring. It looked like new. But decided to change it anyway for piece of mind. Also tried various thickness of rings, but ended up using a new one the same size. In the process I had inadvertently spun the dizzy shaft. So I went through the process of "starting from scratch" to set TDC and align #1 with dizzy rotor. I rotated the motor manually (I was told it was a total re-build - looks pretty anyway) until the balancer read TDC. I checked through the #1 plug hole that the piston was visible at TDC. Lifted up dizzy and rotated the shaft till I could align the rotor to the #1 wire I had marked on the housing. Re-seated it and snugged up the keeper. Removed the Vacc Advance from the dizzy and plugged it, hooked up the spark plug, coil wire and re-installed dizzy cap. All this absorbed from the internet. Hit the starter button and it fired up. Ran rough and louder than I remember (there are a couple bad welds in the tail pipe). But it was clickity clacking a bit. I rotated the dizzy housing slightly left and right (advance/retard?). Just made the engine want to quit either way. So I shut it off and started stewing. Got to reading about cylinder combustion. It made sense that the piston at TDC is too far up the cylinder to combust fully. That's why you should start at BTDC. I read around 10-12 deg BTDC. So today I repeated the whole scenario starting at around 11 deg BTDC. Realigned the dizzy so rotor was at #1 and tried to start the engine. Nothing. Didn't even fire.

What am I missing folks?
cep62
100% FORDified!
100% FORDified!
Posts: 2045
Joined: Sun Oct 26, 2008 8:06 pm
Location: West Michigan

Re: 351M wont start after Dizzy removal and reinstall

Post by cep62 »

:wel:
Welcome to our site. We're a little slow around here but there's a lot of good information.
HottRubber351m wrote: Wed Jun 19, 2024 10:09 am What am I missing folks?
did you check to see if you Still have spark?
HottRubber351m wrote: Wed Jun 19, 2024 10:09 am I rotated the motor manually (I was told it was a total re-build - looks pretty anyway) until the balancer read TDC. I checked through the #1 plug hole that the piston was visible at TDC.
it is there twice for every turn of the distributor. It has to be on the compression stroke.
Put your finger in the plug hole , when you feel the air push your finger out , that's the compression stroke. Then put it at TDC.
HottRubber351m
New Member
New Member
Posts: 7
Joined: Thu Jun 13, 2024 10:11 am

Re: 351M wont start after Dizzy removal and reinstall

Post by HottRubber351m »

Thanks for the input. I used a plastic straw in the #1 hole. Couldn't really see it while manually cranking, but I did just barely see it move. I took out the straw and saw it was crimped, could see the piston too. I was on TDC according to the balancer. Anyway reassembled and got it fired up. Rotated the dizzy and am basically back to where I started as far as idle etc goes. Took it for a quick test ride and confirmed (in my mind) that it wasn't an O ring problem. Looks like oil seeping out of the Intake Manifold overtop of the front china wall. Oh ya...spent some time under the truck looking for the block casting numbers. Found them under the starter. I now own a 1971 400 (out of Cleveland). Go figure. I'll flip my next questions over to the Engine Section of the forum regarding the Int Man. Thanks!
cep62
100% FORDified!
100% FORDified!
Posts: 2045
Joined: Sun Oct 26, 2008 8:06 pm
Location: West Michigan

Re: 351M wont start after Dizzy removal and reinstall

Post by cep62 »

You can clip a remote start button to the solenoid and turn the engine over while under the hood.
Make sure it's in park or neutral.
HottRubber351m
New Member
New Member
Posts: 7
Joined: Thu Jun 13, 2024 10:11 am

Re: 351M wont start after Dizzy removal and reinstall

Post by HottRubber351m »

Thanks but it's after the fact now. Dealing with an intake manifold leak. I definitely will get back to properly tuning it ( I got it running)
Post Reply