Hi,

I've got an 85 F-150 that I don't know what I want to do with. The 300 currently in it needs a lower end rebuild. Badly. I haven't done a compression test in fear of the results, but the thing is losing so much compression it's pushing oil out of the recently re-sealed oil pan. I use the truck very rarely, mainly to haul / tow / move stuff when the need presents itself, and occasionally follow my buddies off road. I've put a cam in it (Crane, similar to the Blue Racer) and the head is fresh. What I love about the truck the most is the drive train. 4 speed manual with granny low, manual hubs and transfer case, solid front axle 4X4, and I think a 9" in back.

I know that if I rebuilt the 300 I wouldn't be happy with it until I'd put new manifolds and a real carb on it. I also know what I really want in a truck is as much torque as I can get. If I decided to swap rather than rebuild, what would work? I assume a 302 or 351 would be a direct bolt in. I know a 460 was available in 85 but don't know if a big block is compatible with the rest of my current set up. If a swap is out of the question, should I just ditch this thing and start looking for something else?

Thanks in advance for any thoughts or opinions,

Justin Schick
jschick@aafp.org
92 SHO for a daily driver
66 Mustang GT for fun
85 F-150 for everything else

 

If u have been with it for a long time then maybe a rebuild would be good.

 

http://www.webphotos.com/list_photos.asp?mi=3&smi=1&a=13217
I swapped an EFI into mine, but afterward, I realized it wouldn't have taken much more money or effort to put in a V-8. You can get a MAF 4.9L from a '96 pickup, but you're right about the 5.0 & 5.8 dropping in. The 7.5L would require AT LEAST a different bellhousing on the transmission just to bolt up, but I'm not saying the drivetrain would stand up to it any more than it would to a diesel.

 

[updated:LAST EDITED ON 26-Dec-02 AT 00:27 AM (EST)]I have a 83 E 150 300 with 225,000 on it and was just about to do a lower end rebuild cause cash is tight. Then the junk yard man asked me "Why did I supose the piston broke"?
The best advice often comes in the form of a question. My motor has been worn ragged and likely as soon as I rebuild the lower end something else will go. Someone told me the same thing here in different words that didn't quite sink in. I love this place.
By the time I do a total rebuild on my 300 it would have cost near what It will cost to throw a 302 in it with less miles and end up with better gas mil & peferomance than what the 300 rebuilt would give me, so I've been told.
Also 351's are hard to find and although much bigger suposively not that much better as well as quite the gas hogs.
I found a screeming 302 with a 4barrel for $700 and another 302 out of a Lincon with only 88,000 with 100 compression for only $350. and both only 45 miles away.
I hope the time I have spent reasearching my similar issue will help you make a decision.
Please keep in mind that I am a total novice.
Good Luck,
Grant

 

Thanks for the replies gentlemen.

I guess what I'm really trying to decide is if fixing the lower end of the 300 and throwing new manifolds, carb (big 2bbl or small 4bbl), and distributor at it would be worth it in comparison to swapping in something else. I've done some work to the 300 already (new YFA feedback POS carb, new cam) but I don't know if I should continue or cut my losses. I know I'm not happy with the induction and ignition setup on the engine now.

The only sticking point about the swap is I don't know what the bolt pattern and input shaft spline count of the 300 is compared to other small and big blocks, along with motor mounts, clutch setup, etc. etc.

My Mustang has a 289 and will eventually have the stroked 351 I've paid for but not assembled, so that was kinda making me lean towards a small block. But I know stock to stock a 300 makes more torque than a 302.

I need to start calling and pricing things out locally I guess. Anyone near KC MO?

Justin

 

I'm not too far away in Memphis.

A 5.0L makes more torque than a 4.9L, but not much and it's at a higher RPM.

4.9L, 5.0L, and 5.8L will all bolt up to the same transmissions, but if you go to a V-8, you'll have to remove your current engine perches from the frame and bolt others on - still not much extra work. The only expensive part will be the radiator, but that's only about $200 and really easy.

Look around for a nice late-model V-8 - they're out there. I have a '96 5.8L MAF with everything needed to convert to EFI.
http://www.webphotos.com/list_photos.asp?mi=3&smi=1&a=13181
http://www.webphotos.com/list_photos.asp?mi=3&smi=2&a=95012

 

Rebuilding or replacing the 300 six will be a straight nuts and bolts remove and replace thing. You can figure on the price of a rebuilt motor, plus the intake/carb and distributor stuff you want to buy(I would switch to duraspark II).

If you were to find a good running 302 or 351w, you have the price of the motor plus:

Rear sump oil pan and oil pump pick-up tube for the v8(assuming the v8 will be from a car). I paid $60.00 for the pan, pick-up tube, main cap stud, and mangled dipstick.

V8 frame perches. I have never done this part, but have picked up from guys on this board that you have to torch or grind off the motor mount perches from a v8 truck to mount in your six cylinder truck.

If I remember correctly, the radiator needs to be changed.

You will need a new exhaust. The truck takes special manifolds($50.00 apiece) plus you need a new y-pipe($100.00). I went with cheap headers($115.00).

You will need a v8 flywheel if your truck is a manual. If you get a v8 from a car, 99% of the time it will be an automatic(flexplate). Don't use the six flywheel. It's the wrong balance. Make sure the flywheel you get matches the year of the motor if it's a 302(pre 82 or post 82 balance). The spline count and bellhousing will match.

You will have to rig the throttle cable.

The thermostat housing for a truck has the outlet that points straight up. The cars usually point at a 45 degree angle. So if you go the parts store for a v8 truck radiator hose, it won't fit. But I kept the 45 degree outlet and used the car upper radiator hose(had the car there and it fit).