I currently have a truck which I need to put a motor back in and have been putting it off for a while. Anyways it is a 1979 F.250 4x4 which had a 400 in it which spun its bearings and needs about $400 to be fixed.

On the other hand instead of the 400 I can get a good complete running 302 motor which has been rebuilt and also costs about $400.

So they are about the same price and I was wondering which to go with. So if it was you which motor would you go with?

 

I personally would go with the 400. Mostly to keep original.

 

Does the 400 run good? If so, I would drop the oil pan and swap in new bearings. Would be cheaper and easier than converting everything over to fit a 302.

 

The engines are quite different in character. With 100 more cubes and long stroke the 400 is more of a truck/torque engine. Transmission mounts and motor mounts are different not to mention all the other wiring and plumbing.

I too would prefer a 400 in a truck. The $400 estimate to fix a spun bearing sounds pretty low. I wonder why the bearing spun in the first place?

 

Leave it a 400. Not that its better, its just easier. Thats what I would do.

 

At the moment the 400 is torn apart and when the bearings spun they screwed the crank up pretty good. The machine shop said a new crank would cost $200 and then they would re-machine the block, connecting rods and check the block for cracks for another $200.

Yeah that is kinda what I was thinking too about using the 400 to have more power. It isn`t like the truck will ever haul a trailer, but I would like the motor to have enough power to get the 7000 lb truck moving. The main reason I am still considering a 302 is its reliability. My family has had a couple 400m and every time they hit about 80,000 miles, like clockwork the bearings go. On the other hand we have a 302 with 164,000 miles and it still has good oil pressure.

As for converting the truck over I was at the Canfield Ohio swap meet yesterday and got a flywheel, pressure-plate, clutch and bell-housing for $40. Also the 302 came out of a 77 ford originally and has a HEI distributor on it, so it shouldn`t be too bad to convert it back....

 

302 does not have the torque of the 400
Stay with the 400

 

If you do the 400, its best to have the machine shop fix the block and rods first. Install the new bearings and measure the diameter of main bearing and rod bores.

Then machine the crank to dial in bearing clearance. Crank journal diameters may need to be on the high side of spec to get clearance correct. I'd shoot for .0012-.0015".

I understand 400's tend to have excessive bearing clearance which contributes to low OP and shorter life. Dialing in the clearance helps.

 

A high volume oil pump will help . A high pressure / high volume pump would be better but you will need to special order the high pressure oil filters , the standard oil filters will burst . I ordered my hp filters from Summit Racing .

 

Mabye that will be an idea to help keep the bearings alive.

I was talking to a machinist who has redone a couple of these 400`s who had an idea to fix them. He told me to take the two ports where you can plug in a mechanical oil psi gauge. The one directly after the oil pump and the one after the last cam bearing. He said to run a tube from one to the other. This way the cam will get more oil. He said hes done this a few times and swears by it that it works. In a way it makes sense but wouldn`t that give the main bearings less oil and overall screw up the engines oiling? Anyone else heard of doing this and does it help or destroy the motor quicker?

 

They have been doing that to small block chebbys which is easy on some blocks because they already have an external oil galley plug front and center above the timing cover .

Unless you are going to run high rpms or heavy racing a better oil pump will be all you need .

One of the biggest problems me and my friends had growing up was reading hot rod magazines and thinking we needed to do the same because it was better . 80% of the things we did actually made no difference in reality , but it looked cool !

 

Hey, ive spun my bearings before and popped new ones in too, but i would put a new oil pump in there. Just so you wont spin them again. Bearings dont usually go out with good oil pressure