Alright, I have decided to rebuild the six instead of going with a 302. I have an 81 F150 that is need of a rebuild, but I wanted to have more power. Could I bore out the pistons and add a cam to get more HP? I wanted to hear from those that have already done this. Does it make a difference? I am going to the 4bbl intake and 4bbl carb later. How much can I bore out and what kind of cam should I buy? I'm looking for an overall performance (HP and Torque).

 

well first off this is a good idea but boring is not meant to give HP. it is to clean up the bores of they are badly out of round or scared. when you take the pistons out look to see if you can see the crosshatches in the cylinder walls. if you can see them all the way through each cylinder then you should't have to rebore. just rering it and put all new bearings in it, even cam bearings but the machinist will do the cam bearings. but if you do rebore, bore it to the next biggest size that you can. you won't feel the difference. you will feel the motor have it's life back but only because it is like haveing a new engine dropped in an old truck. you will need to get the right size piston and rings if you overbore. get the head rebuilt and have a 3 angle valve job done. you may need to have your crank turned to take away any deep scars and chips. when you do this you need to get the right size bearings. the cam is sold in jegs.com also is the offenhouser intake and holley 390 cfm carb. headers are also available and as always get a new timing set. if you port and polish the heads you will really open up the flow and you will feel the difference. if you get the block 0 decked where the pistons come even with the top of the block you will feel a good deal of power as this ups the compression.

 

Yep, thanks for the info. I bet the pistons will fall right out of the block. There's a pretty bad problem with a blow-back from the heads. It needs a rebuild bad. I think that I might take it in to get a rebuild, but I'll make sure that it will get a new cam.

 

the blowby may just be the valve guides or something in the valves. that is when you crank it and smoke puffs out the pipes then stop, that is the heads needing a rebuild. but your piston rings may just be worn and you may not have to bore still. if it smokes all the time then chances are your rings are bad

 

It doesn't smoke. But, there is a problem with excessive oil that comes from the oil filler cap to the air cleaner....lots of oil. The PVC valve also has oil coming out. That's a lot of pressure, I figured that it must be the rings.

 

change the pvc valve and see what happens

 

I've done that, and I also tried to put a breather/oil filler cap on the cover, and it bleeds oil. Rings right?

 

well then i guess so i bet the bores are still in good shape
how many miles are on it

 

Offically, 205671 miles..... Unoffically, it's closer to 300000. There was a time that I ran w/o replacing my inner speedo gear. It's an 81 F150 pickup.

 

is it still in the truck when are you going to take i apart when you do i want you to tell me what the cylinders look like.are you going to build it yourself. i would recomend that you do, it isn't hard and you only need regular tools plus a ring compressor to put the piston and rings back in. i would highly recomend that you take the block to the machinist and have it 0 decked and have them put new cam bearings in. don't bore unless you have to as this will be more expensive. also take your crank to them and have them check it out to see if it need to be turned. your head also needs to be rebuilt and if you have extra money, get it ported and polished. bring them the intake to get it matched with the intake ports on the head if you get the head ported. along with the cam headers carb new intake and the block 0 decked you will be making a great deal more HP and TQ out of you 300.

 

Yep, it's still in the truck. I need to do some research about the machine shops around here, make sure that I don't get a retard to work on the block. I'll probably do most of the work myself, this summer. It's a bit cold and the weather isn't that predictable. I'll post when I begin. Thanks for all the input.