I just picked up a 79 f150 with a 351M from an impound lot. The engine seems to run great, and I need to replace my 400 in my truck. I planned on just doing a straight swap, but I noticed that the oil dipstick on the 351 is located in the front of the engine on the left, and on my 400 and my dads 351m the dipstick is on the left. There was even a owners manual with the donor truck, and it shows the dipstick in the front. Problem is there is no dipstick in the tube. Can I use my old dipstick from my 400, or do I need to track down a new one?

 

I ran into the same thing when I swapped my 351M for a 400. The oil pans were differant and had differant dipstick locations. I just assumed that they were from differant types of vehicles (2x4, 4x4, van?) judging by the shape of the oil pan.

 

hmm, thats right. The donor truck is a 2x4, mine is a 4x4. I didn't think that made any difference with the engine. Will I be able swap the engine from the donor straight into mine, or will I need to take the oil pan off my 400 and put it on the 351M? Other than that, are there any differences that I need to be aware of?

 

you will need the 4by oil pan- should be the only difference. With the engines out i'd sure be tempted to do a little work and put a 400 back in it. but if time and $$ is an issue maybe build the 400 the way it's supposed to be and then swap out again down the road. Huge difference.

 

I need a running truck yesterday and I don't have the money to build the 400 the way I want to, so my plan is to pull the 351, put in a new timing set and waterpump and main seal while I have it out, and then stuff it in my truck. Then I'm going to rebuild the 400 the right way, and when I finish (it will probably be a while) then I'll swap it back into my truck. I don't want to do the minimum to get the 400 going, I want to redo the whole thing right.

One question though, since I have to swap out the oil pans, should I replace the oil pump? And how hard is it to replace the main bearings while I have the pan off? I'm just thinking that if I have everything apart why not head off any problems.

 

When I rebuilt my 4x4 77 my block was shot, i found one at a junk yard and the dipstick is on the other side. I plugged the hole and put my old oil pan gasket on the new motor and everything works fine.

Oil pump isnt that hard, especially if you have the engine on a stand.

 

If you put a rear sump oil pan on a motor that had a front sump oil pan, you have to swap the oil pick tube & screen as well. Also there is a special bolt on the 3rd main bearing cap, that has to be swapped also. This bolt supports the rear sump pickup tube.

If the new motor has good oil pressure, I wouldn't fool around with the oil pump or bearings, if it is only a temporary swap.

 

Is it still in the truck? If it is do a oil pressure check with a good guage, after it has warmed-up. That should let you know a little better where you stand with the new motor. Erv

 

hmm i have 2 dipsticks on my motor one on the drivers side middle of the headers, and one on pass. side front of motor behind alt. why is this? it has a swapped 4-speed stick in it. was an auto from the factory

 

The dipstick on the driver's side is for a rear sump oil pan. This should be the correct oil pan/dipstick for a 4x4.

The dipstick behind the alt. is for a front sump oil pan. You should not have this dipstick. You should not have a front sump oil pan.

You should not have both dipsticks. One of them will not work correctly, if at all.

 

hmm so if i remove the uneeded one should i plug the hole? or leave it be?

 

There should not be any hole, unless someone added one. If there is a hole, just let it be, and only use the correct dipstick to check the oil.

What pan do you have, front or rear sump?

 

well the pass. side dipstick the hole is in the block itself i am pretty sure, atleast that is where it is, if i can get a pic ill post one later

 

The rear sump oil pan has a hole in the side for the dipstick tube. The front sump oil pan does not have a hole. It must go through the block. I have a block and both oil pans in the garage, I'll look tomorrow.

 

My block has an allen plug in the front near the timing cover. If his plug is removed, then you can install a dipstick for a front sump oil pan.

You should be able to remove your front dipstick and install a plug.