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FFR Builder
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Discussion Starter · #1 ·
Hi guys,
I just purchased a Ford Racing 345 HP 302 (M-6007-XB3M). This engine has a hydraulic roller camshaft (M-6250-B303). Ford calls for a steel gear on the distributor. I presently have a Mallory distributor (Mallory P/N 4755101H) with Mallory gear 28034. I purchased this distributor from someone on the forum. The mallory catalog says this distributor is for a 1962-1980 302 and the gear is for a 1962-1980 reverse rotation engine. Will this distributor work with the engine I purchased? I sure would hate to wipe out the gear on the cam. What has me concerned is there is a different part number for 1981+ 302s.

I contacted Mallory with this same question (via email) and this was their response, "The 4755101 comes with a harden steel gear. The 28034 is the raw # for that gear, the 28034A is the rev-gear.". I am not sure if that is a yes, no or maybe. If anyone can shed some light on this for me I certainly would appreciate it.
Dave
 

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Dave:
In Mallory's response was the "H" suffix left out
of the part no.?
Might the H mean hardened?
You should speak to their tech support people directly because the response you got seems pretty vague to me.
Paul M.
 

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FFR Builder
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Discussion Starter · #4 ·
I just got off of the phone with Mallory tech support. The distributor for 1962-1980 (p/n 4755101) and that for 1981-1995 (p/n 4770401) are different. He said that they were not interchangeable. He did not know the difference between the two. The gear p/n's for the two different series are also different. I am at a loss as to what is different with these engines? Another strange thing about the Mallory catalog is that the gears for the 302, for a given year, have two different part numbers depending if it is "reverse rotation" or not. Is this for marine applications? I assume my engine would be a standard rotation? I am completely confused.
Frank, the gear looks the same as those sold in the FMS catalog, but I will post a picture tonight.
Paul, Tech support said the "H" in the p/n is a designator for the type of advance.
Dave
 

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The gears used on engines with roller cams(hardened gears) started around 1985. So the gear listed for 1981-1995 "should" be the correct gear.
Believe the difference between the dist. for 62-80 was the dist shaft is shorter then those used on 81 and up. Reason they can't be interchanged.
My donor efi dist. was longer then the repalcement dist. I bought. Gear had to be moved on shaft to align with cam gear,and different oil pump drive shaft had to be used.
 

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Normal rotation camshaft is chain driven the cam rotates the same direction as the crankshaft. Reverse rotation is if you use a gear drive camshaft the intermediate gear causes the camshaft to rotate counter to the crankshaft.
 

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Actually the intermediate gear is what keeps the cam rotating in the same direction as the crank - if it werent there and you drove the cam directly off of the crank - then the cam would rotate backwards.
 

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1st, I would not use this distributor in your crate motor.

You need to be looking at distributors for a later-model 5.0/302, not the earlier 289/302. The later model distributors, as I think you already know, need a steel gear to be compatible with the roller cam.

You are correct, the reverse rotations are for marine applications, and the only 28034 gear I see in Mallory's catalog is for reverse rotation.

I'm not sure why Mallory cut the years off at 1962-1980 and 1981-1995, possibly due to the start of computer controlled ignitions and not wanting someone to just plop in an aftermarket distributor and screw up the computer feedback. Or maybe the length issue HindSight mentioned.

You are right to be confused. Mallory's catalog isn't real detailed. It doesn't tell you which gear is installed on any particular distributor. I can't figure out why Mallory would use one distributor from '81-'95 either, when roller cams weren't introduced until '85.

There are 2 different pages on dist. gears (34 & 35) Here is how they describe their distributor gears on 34 (The 28034 is one of these):
FOR USE WITH CAST FLAT TAPPET HYDRAULIC/MECHANICAL CAMS AND AUSTEMPERED DUCTILE IRON ROLLER CAMS
Here is how they describe their distributor gears on 35:
FOR USE WITH INDUCTION HARDENED OR CARBURIZED STEEL HYDRAULIC OR MECHANICAL ROLLER CAMS
I would personally look at another manufacturer like MSD, but that is just me. If not, assuming the 4770401 distributor uses the second type of gear (29432, which it probably does), you should be OK buying one of those for your crate motor.

And by the way, the cam rotates the same way as the crank whether it's chain-driven or gear drive-driven.

Steve
http://home.thegrid.net/~ffr4776
 

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FFR Builder
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Discussion Starter · #9 ·
Frank, Here are the pictures you requested.


I confirmed that the gear is cut the same way as those in the Ford Racing catalog. It is hard to believe that the catalog is showing reverse rotating gears. I think the Mallory data has a little to be desired.

The long and short of the situation appears to be that the distributor will not work. In the back of my mind I would still like to believe that the data in the catalog is not correct. Does anyone have any measurement of a correct distributor that I could compare against? Thanks for all of you help so far. Dave
 

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A distributor for a 1985 Mustang GT will work in your engine. I have the Ford Duraspark distributor in my crate 302 hooked to an MSD 6AL. Works great.
 

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A cast gear is kinda rough. I really cant tell if your is cast. The steel one looks like its machined and relitively smooth looking.
 

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Dave take a file and drag it across the gear. If hard the file will not want to cut the surface but kinda slide across it without cutting. A mild steel gear will let the file cut into it. It will be real apparent if the gear is hard.
I have the Ford Racing catalog (thanks Max) and it shows the lengths of the dist. shafts and gear distance for where the gear needs to be on the shaft. Tonight I can look the info up unless a search turns up the info first.
Whatever you decide to use, check the gear pattern between dist. and cam with gear marking compoud,and also check to be sure dist is not bottoming out to far down in the block once tightened down. There is a up and down clearence measurement that needs to be check here also.
 

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FFR Builder
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Discussion Starter · #14 ·
Steve, Thanks for all of the really usefull info. I may end up with MSD if this thing does't work out.
Speed, Your comment gives me some hope.
Frank, The gear is machined everywhere, but I think that would be the same for a cast piece. Mallory's catalog says that this is a steel gear. Upon closer inspection of the gear I can see a wear pattern from it previous install. No matter what I will buy a new gear from Ford. Will a Ford gear fit on an aftermarket distributor or do I have to go to Mallory?
Hind Sight, I dragged a file across the gear and it seamed to want to bite. It didn't seam very hard to me. I found the section in the FMS catalog regarding gear location. I will compare that info to the distributor. If that checks out I will unpack my engine from the crate and see if the shaft fits in the oil pump. The distributor looks like it might have had a gear lower on the shaft at one time. Maybe the previous owner did the required mod and I am worrying about nothing.
Thanks to all, Dave
 
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