1978 Ford F-150 Distributor

Hey all,
The engine is a 351M/400. I have been trying for a long time to get this distributor to drop in. I have gotten it to engage the oil pump shaft, and the gears are meshing correctly. I can hear and feel the distibutor hitting the bottom, yet I still have about 2 inches to go before it is flush with the top of the block. I have heard, though I don't actuall know, that there are two different lengths of distributors. With about a 2 inch difference. Now, like I said, I don't know if this is true, but when looking at the remanufactured Motorcraft distributors on the NAPA websight there are two different part numbers. (NRD 482873 and NRD 482893) I can't tell, just by looking at the pictures, if the shaft is longer on one than the other. Does anybody out there know if there are 2 different types of distributors for the 351M/400 engine? If so, please let me know. I need to get this truck running ASAP. Thank you all for your great knowledge and help on this subject.
~JD~

Did you remove this distributor from this engine, or did it come from another source?

If it's from another source, I wonder if your identification of the engine is correct.

First of all, the 351M and the 400 are somewhat different engines, but use the same block. Do you know which one you have? Or, is it possible the engine is a 351-Cleveland?

I ask this because the 351M and the 400 look very similar to a 351 Cleveland, but have a taller deck and a wider intake manifold. I think, (but am not completely sure, ) that the 351M and 400 distributors are longer than a 351C unit.

If your engine ID is correct, the distributor may be from a completely different engine, such as a Ford straight six engine. A 2 inch gap is huge, and is not explainable simply by the distributor not dropping down fully.

Maybe you could whip the distributor out of your '79 F100 and compare it to the one you are trying to install. If it's the same, then you know you need to source another distributor. If thats the case, call a wrecking yard. They should have the Hollander Interchange Manual, which should list what Ford engines used the same distributor as the one you need, then start hunting down the correct part.

I think your parts store gave you a distributor for a 351W and not the M block.. Btw, heres some cool history: To create the 351M engine Ford took the 400 engine's tall-deck block and de-stroked it, with the shorter throw crankshaft from the 351 Windsor, and taller pistons, to produce a 351 cubic inch (5.8 L) engine whose components were largely compatible with the 400. This engine was called the 351M and as a back-formation the taller-deck block became known as the M-block.

When I bought the truck the distributor was out of it. The previous owner couldn't get it in either. He thought the original was bad so he pulled it, threw it out, and pulled one out of a junkyard truck. I identified the engine from the info on the left bank valve cover. Now what I figure happened was the valve covers, which have emissions and other general info on them, could have come off of a 400 and, since they are compatible, have the incorrect info on them. One way I thought this happened was it says that it is an EGR engine but there are absolutely no EGR components on the engine. How do you ID what block you have from the VIN? If the engine was changed the original VIN obviously wouldn't identify the correct engine if it is different from the original. How else would I be able to ID the engine if the VIN is incorrect? I don't have any maintenance history on this truck.

Are you 100% sure the motor is a 351M and not a 390?

I am sure that it is a 351 or a 400 block, though I'm not sure which. I haven't taken the time to find out. I'm fairly sure it isn't a 390 though. Where do I look on the block to ID the engine?

should be drivers side rear of block. the reason i ask if it is a 390 is that the 351m/400 are the same block and its hard to tell.

should be drivers side rear of block. the reason i ask if it is a 390 is that the 351m/400 are the same block and its hard to tell.


I didn't know that the 390 was the same block. I will post back the engine code when I get it. Also, would the valve covers from a 400 fit on the 390? The reason i ask is because the left valve cover says it's a 351M/400. I don't trust that sticker on there anymore. Does anybody know if I can get these stickers special made? I want to restore this truck right down to the stickers and badges etc. Thank you all for your help.
~JD~

I didn't know that the 390 was the same block. I will post back the engine code when I get it. Also, would the valve covers from a 400 fit on the 390? The reason i ask is because the left valve cover says it's a 351M/400. I don't trust that sticker on there anymore. Does anybody know if I can get these stickers special made? I want to restore this truck right down to the stickers and badges etc. Thank you all for your help.
~JD~

Ok, It should be a a 351m if the valve covers say it. The heads are different. LMC truck sells most underhood stickers but as for the catalyst sticker i would say no.

Kewl. Sounds good to me. The weather has been crap the last few days and the power went out so I haven't been able to check my engine ID to be sure. Is the distributor from the 351M the same length as the 400 or are they different?

just to help you narrow down the actual engine you have, i do know that the 390 is not the same block as the 351m/400m engines. also acording to summit the 351c, 351m, amd 400m share the same valve covers, and the distributor is the same for a 351c, 351m, 400m, 429 big block, and 460 big block. so more than likely you have a completely different distributor. good luck.

According to the VIN the engine is a 400m. I am pretty much lost as to what the deal is with this distributor. Is there a possibility that the parts store gave me a dist. for the chevy 400? I've just about had it with this dist. but I don't want to give up on this truck. It's one of the best years, in my opinion, of the Ford trucks. Tough and able to take a wild beating. The '79 that I had was so beat up, but it ran like a brand new truck. Better than alot of my friends new Dodge, Chevy and Ford trucks. I was always getting them out of tight spots because I had the only running truck. I know it can be a good truck if this one issue wasn't wearing me out. I'll stop rambling now. I'm just about at wits end with this dist. though. Thank you all for your great help. I will post back what I find out.