I have a 351w that has been bored .080 and is practcally new in the bottom and a set of reworked high output heads.I would like to put this engine together to put in my 86 stepside,but I'm afraid it might run hot.It won't be driven a lot but I don't want to not be able to drive it to town or wherever if i wanted to.I know i'll need a bigger radiator but is it even sensible to try to build this, and has anybody ever run one of these bored that much?I got this engine from a guy that said it was .040 but when we miked it it was .080 it is also stamped in the top of the pistons .080

 

Which means he was confused, .040 on one side and .040 on the other side = .080 total.
If this guy is the one who built that engine (and who made that mistake) I'd run from it as
far and as fast as possible as there's no telling what other amateurish mistakes he made.

Ask in the small-block forum:
Small Block V8 (221, 260, 289, 5.0/302, 5.8/351W) - Ford Truck Enthusiasts Forums

 

That's pretty big, I heard 60 is a max safe limit with theses thin wall casting blocks. Sounds like you have the engine apart now, see if you can get hold of a sonic tester to see how thick the walls are. There is a safe limit to the wall thickness but I don't know what it is. Core shift during casting can also be a problem, making one side of the bore much thinner than the other.

Sleeving is another option if you want to come back to a standard size bore.

 

I second what ozstang65 posted. I wouldn't trust it otherwise.

 

most machine shops won't bore that much on newer blocks because they are thinner than the old ones, It was more common place back in the day. The only way to know if it will be alright is if its sonic tested. The symptom of thin cylinder walls is cylinder wall distortion at high rpm that will cause loss of ring seal and blown head gaskets. It might be fine.

 

I looked up the numbers on the block today in a cylinder head and block book and it says the block I've got was from 69-78

 

By having an older block do you think I may be all right?The engine is in nice shape.

 

My understanding is that everything from the 289 in the mid sixties onwards used the thin wall casting method. Sonic testing shouldn't cost much, I'd imagine most good engine builders would do this as a matter of course when boring an engine. I got a report like this when rebuilding a 302 for my mustang, ended up putting 3 sleeves in it.

 

Well, if your not racing it, i think it will be alright. What is your intended use? The racers I know use 302's. I if you ask most machine shops they will tell you they will "not" bore a 302 past .040 because they are to thin, but the guys I know bore them out to .060 and race them. As guys get faster the economical way to upgrade your block is to use a 351 because they won't split in half like a 302, but I have no practical experience with 351's. Some blocks have more material than others and the only way to know if yours has enough is to have it sonic tested.

 

This truck is just a toy.Occasional driver.I currently have a good running 351w in it but i would like to leave it stockish like it is to put in a 4wd I have,since I've got this clean nice .080 over engine here.I'm not planning to race it or anything like that,but i want to be able to play with it a little if I wanted to.Sure I ould take the engine currently in the truck and build it maybe but I don't really want to because the other one would basically be wasted.I would like to put a decent cam like a 280 competition h series for a nice little lope,but first I just want to make sure it will be ok to use this motor first.