missing on 4 cyls...?

Looking for a bit of help here chaps + ladies...

I'm currently trying to help a friend overseas in France sort an issue with their 40.

Scenario is: They have a 302 Ford that has just had a refresh, with a rebore, pistons, rings, re-balance, shells, full gaskets etc. The cam has remained the same, a Performer RPM item, 7122 I think they said so fairly mild really with hydraulic lifters and I think, Performer RPM heads. During the refresh, it also had a new distributor fitted, a Mallory MAGNETIC Electronic Distributor (pn, 4255111?) and a new timing gear/chain set, not sure of the type but I have been told it had a multi-slot gear to allow for timing adjustments.

OK, first problem was a timing issue for sure, the distributor had not been statically timed correctly and the motor was reluctant to start and when it did, it ran sluggish with ALL headers getting very hot, no.8 especially so and would also not rev over about 2000, after which it would just cut out.
I talked the owner through how to set it up again inc phasing the distributor as my feeling was that it was firing incredibly retarded and also possibly jumping node on the ill fitted distributor.

After this, the motor would start and idle albeit a little lumpy and it was reported that the timing (strobed) was now about 10-12 degrees at idle and about 32-33 max at 3000 rpm onwards. (Vacuum advance unit disconnected/locked) The owner also reported that Cyl 5 seemed to be cold.

Next, compression was checked and reported to be about '11KG' hmmm - which I have taken to be 11KG per square cm so about 160psi - yes? Unfortunately they did not do all the cyls (as requested) just no.5 so I await the test result of the others for comparison. My thought at this point was a faulty plug or lead as they reported the plug to be unfired and wet. So clearly fuel was getting there. (forgot to mention, it has a simple Edelbrock manifold topped with a Holley 4-B carb). As they had reported only no.5, I also suggested checking the carb was not leaking continually into the manifold due to poor/failed float setup. This they also checked and confirmed as NO dripping or overflow into manifold.

So, I still consider a fouled plug and get them to swap with another cyl, which they try to no avail. In fact they have tried several new plugs too but each leaves a cold header.

Finally, I now hear, after connecting to some sort of electronic measuring equipment that it is actually only running on 4 cylinders. :shocked: They report that it fires up ok and idles happily at about 800rpm but disconnecting spark from cyls, 2,3 5 or 8 have no effect on rpm, in fact disconnecting ALL 4 together has no effect BUT disconnecting any of 1, 4, 6 or 7 immediately drops rpm by about 20-25%.

Firing order I have taken to be 1-5-4-2-6-3-7-8 from memory and this seems to confirm with the Edelbrock Cam data sheet I located on the internet. Also, they inform me that the inlet valve on 1 is starting to open just before TDC and the Exhaust has just closed ATDC, so that seems to be pretty close to the data sheet too.

SO - considering I am some distance from the owner and doing this by phone, having not seen or heard the motor, I am beginning to run out of ideas....
I speak no French (well not of any use..) although their English is pretty good, despite them preferring measurements in metric as opposed to imperial... LOL

I am informed that they have tried new sets of Champion plugs, RC14YC (NGK BCPR5EFS equiv?) and also Bosch FR7DC (NGK BCPR 6ES equiv?) to no avail, still same problem.

NO MSD, simple coil, no points....

I am still of the opinion that it must be fouling plugs for some reason but why every other one? surely not coincidence...

ANY thoughts from our learned membership would be most welcome right now - Thanks
 
Paul,
probably totally unconnected but we recently, very, had a similar problem with a 427 on the dyno with a new Accel ( same family to Mallory ) distributor. Same scenario, timed the disi at a position where I knew the motor would start, same as I've done for the last umpteen thousand anyway, and no go, sheets of flame out of the carb and appeared to be drastically retarded. Advanced it up and away it went but very rough, checked the timing and it was still way out, timed it to the marks and it ran, particularly at idle, OK. Connected the vac line and the motor tried to die, kept it going to check the timing marks were still OK and they where nowhere to be seen.
After ages frigging about I eventually found the new distributor was wired wrong, they had switched the polarity to the magnetic pickup so it was firing off the wrong edge of the reluctor and effectivly trying to fire the wrong cylinder particularly when the vac was connected because the base plate got yanked 'round so it DID fire the next cylinder. Reversed the wires and PERFECT, phew !!!
Get your mate to connect the vac line when the motor is idling and if the engine goes all dramatic then it's the same problem.
On a similar theme I tried a couple of cheap Chinese made disis last year and the reluctors were actually pinned in the wrong place so when the thing wanted to fire the rotor arm was plumb between two cylinders, that was interesting !
Mike
 
Paul,
probably totally unconnected but we recently, very, had a similar problem with a 427 on the dyno with a new Accel ( same family to Mallory ) distributor. Same scenario, timed the disi at a position where I knew the motor would start, same as I've done for the last umpteen thousand anyway, and no go, sheets of flame out of the carb and appeared to be drastically retarded. Advanced it up and away it went but very rough, checked the timing and it was still way out, timed it to the marks and it ran, particularly at idle, OK. Connected the vac line and the motor tried to die, kept it going to check the timing marks were still OK and they where nowhere to be seen.
After ages frigging about I eventually found the new distributor was wired wrong, they had switched the polarity to the magnetic pickup so it was firing off the wrong edge of the reluctor and effectivly trying to fire the wrong cylinder particularly when the vac was connected because the base plate got yanked 'round so it DID fire the next cylinder. Reversed the wires and PERFECT, phew !!!
Get your mate to connect the vac line when the motor is idling and if the engine goes all dramatic then it's the same problem.
On a similar theme I tried a couple of cheap Chinese made disis last year and the reluctors were actually pinned in the wrong place so when the thing wanted to fire the rotor arm was plumb between two cylinders, that was interesting !
Mike
I understand fully what you're suggesting Mike (thanks) as I've seen that on magnetic crank triggers installed with reverse polarity. As you say, the trigger point will then be on second not first edge and therefore moves with rpm.

I've not seen inside the distributor, so will take a look at the Mallory site to see if it could be possible although I'm still not sure how it affects only every other cylinder.. very strange.

Before I suggested leaving the vacuum advance disconnected, it did exactly what you describe once it was connected...

Any thoughts on plug type? or recommendations/suggestions?
 
Paul,
I don't think this has anything to do with the plugs but we use NGK and for that sort of motor you don't want anything colder than a 5 range. We use BKR5ES, but they might only be available in the US (or from me ! )
Mike
 
ok - I've used them and have a box I think unused so may well send them to him and if not then I'll be in touch.

Hmmm - the more I think about the fact that the distributor has been replaced, the more I think therein lies the problem... The old one (before refresh) had points apparently but it clearly worked.
 
You do say there is no MSD box, make doubley sure this is so as we have had the same problem when people have cut the harness to shorten it or to go through a bulkead. The wire codes are too similar, too many purples and greens, and they get crossed, gives you exactly the same problem, the motor will seem to run OK untill you connect the vac line, then it tries to fire the next cylinder.
Mike
 
You do say there is no MSD box, make doubley sure this is so as we have had the same problem when people have cut the harness to shorten it or to go through a bulkead. The wire codes are too similar, too many purples and greens, and they get crossed, gives you exactly the same problem, the motor will seem to run OK untill you connect the vac line, then it tries to fire the next cylinder.
Mike
Nope - definitely no MSD and I'm told the the distributor came with a coil and ballast resistor.
 
If its missing on 2-3-5-8 its either got a big air leak on one side of the carb/manifold or blocked jets on one side of the holley. One side of the manifold services the center two of one bank & outer two of other bank.
 

Howard Jones

Supporter
Intake manifold gasket (bad side) slid down and is leaking. The effected cylinders go max lean will not fire. I had a 460 ford that ran on 7 cylinders for years until I got it smog checked and found a intake manifold leak. No wonder it got 6 MPG. A new gasket set fixed it right up.

The other thing easy to try first is another coil. I know that you have only one side working but I did have a bad coil that seamed to only work at very low unloaded RPM's. At soon as I reved it it would go completely flat. Good coil, fixed!
 
RC-14yc is about hottest plug made in that style & x ref to NGK would b e #4, not 5.... whatever those plugs sound far to hot ( heat range ) for this application.

Further to that if they were supplied with a 4 slot chopper wheel for the Mallory unit by mistake instead of an 8 slot they will have no fire on every second cyl in order.

Manifold has to be an under/over 180° design which I think it is from your description, IF they are using the original Ford 4 hole spacer with PCV takeoff about 1" high between carb & edelbrock manifold it will leak...they do not put enough flange area on edelbrocks to work with this item....
 

Dimi Terleckyj

Lifetime Supporter
This problem is very similar to one I had with a 351 windsor several years ago, back in 1974,.

I changed the cam from the stock 351 cam to a high performance cam and had 4 cylinders not firing.

Turned out that some high performance cams don't use the standard firing order.

In my case the firing order reverted back to a 302 firing order which the supplier made no mention.

Don't assume a firing order but turn the motor over by hand with no rocker covers and physically watch the valves open and close and write down the firing order.

Once that is confirmed as a basic starting point then start looking at other possible problem areas.

Dimi
 

Steve Wood (PANAVIA)

Lifetime Supporter
Dimi - this goes both ways - and we have seen this happen.

289-302 early firing order ; 1-5-4-2-6-3-7-8
351W firing order ; 1-3-7-2-6-5-4-8

illustrated ;



we have also seen the camshaft installed 180 degrees off and had this happen.

i would have them remove both valve covers and rotate the engine by hand through two complete revolutions of all cylinders firing so that they confirm exactly what is opening and closing and when.

crazy enough, we had someone with a 5.0L ( 351W FO ) with the cam 180 off and the 280 FO and it ran.

food for thought.

Steve
 
Paul, just a few ideas:

1. perhaps run the engine in the dark and look for plug wire shorts? A high voltage system can sometimes be difficult to contain within a poor plug wire set.
2. perhaps try a new cap and rotor? I've seen new caps with hairline cracks that are very difficult to see - causes all kinds of annoying misfires.
3. sufficient voltage in the system? I know some ignition systems just don't work well with a battery that's low on voltage due to a lot cranking.

Good luck!
 
Ok - as he's now called me again - time for an update.

After removing the carb and trying the one fitted to another 40 he has, result was exactly the same. So the inlet manifold was removed and refitted with new gaskets sealing everything again and topped with the original Edelbrock carb.

Result - fired up on all 8 cyls - straight away...nice on 'jac mac' :thumbsup:

So thanks for all your considerations and thoughts.

Still not entirely out of the woods, as I am told that the timing is a little off and advancing the timing, turning the distributor clockwise about 1mm at the flange stops the motor and turning it anti-clockwise the same, gives flames on the carb. So still poss a crossfire/phasing issue I think.

The journey continues... :)
 
Any cams found to be 180° out usually come right if you turn the crank one fool turn....:)

Mallory distributors...like Mike I have found them to throw a few 'curve balls' over the years, might be easiest to simply fit a distributor of known quality in to try and eliminate any problem there. Problems I have encountered with them-Mallory...
1. Rotor moving on top of shaft-has 'flat' drive surface/locator rather than notch /tab.
2. Centrifugal advance plate moving on shaft ( loctited @ assy- this can be destroyed while fitting new gear etc)
3. Centrifugal weight control stops moving in slots.
4. Using CW points/pickups in CCW applications or vice versa ( Chev CW, Ford CCW )as viewed from above.
 
Not sure I can see how a cam can be 180 deg out..:stunned:

up to plus or minus 90 yes, but not 180.... (assuming no interference between pistons and valves)

Still think there could be an issue with the distributor setup/install, although I'm informed that it did work fine with that dizzy now before the rebuild.
 
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