318 poly to 318 wedge conversion
#1
318 poly to 318 wedge conversion
I've got a '66 satellite with a 318 poly (wide block) that needs rebuilding. If I pull it apart and can't salvage much, i'd like to put a more modern 318 wedge in it. I'm restoring it to be a daily driver - '66 is the last year they made that polysphere engine and some parts are really hard to find - the headers/carb aren't original and pretty shot, I suspect the crank is spun too. From what I can tell it's a pretty simple swap to a post-'66 318, but one engine mount will have to be custom built. Has anyone done that?
#2
dang i thought it was just a drop in, ive done it before years ago i thought it used the same mounts, i think the wide block is a better engine as far as torque.
more and more parts are becoming available for the poly, check ebay?
more and more parts are becoming available for the poly, check ebay?
#3
I'd love to save and restore the poly, it's just a question of how much is salvageable. From what I understand, the poly peaks in it's torque curve sooner than any other comparable engine, more like a diesel. That means you can get a lot of power to the wheels without having to rev the engine or downshift.
I'm going to start to pull it apart next weekend if nothing else comes up. After I get it apart there is a local machine shop in Raleigh that has done the poly before. The valve grinding is the odd part, because the intake and exhaust valves are at different angles. I'll see what they have to say about the crank.
The problem with my car is in the lower block, when I bought the car it would loose oil pressure after running for 10 mins. No telling how torn up the lower block and crank are. The car shows 88K, I'm guessing from what I know about the car it probably has 188K on the factory engine, which has had a valve job once already.
I'm going to start to pull it apart next weekend if nothing else comes up. After I get it apart there is a local machine shop in Raleigh that has done the poly before. The valve grinding is the odd part, because the intake and exhaust valves are at different angles. I'll see what they have to say about the crank.
The problem with my car is in the lower block, when I bought the car it would loose oil pressure after running for 10 mins. No telling how torn up the lower block and crank are. The car shows 88K, I'm guessing from what I know about the car it probably has 188K on the factory engine, which has had a valve job once already.
#4
Looks like I'm going to save the poly and rebuild it. I found a great site for 318-poly specific, if you are interested in poly's, here it is:
http://autos.groups.yahoo.com/group/318poly/
http://autos.groups.yahoo.com/group/318poly/
#5
If you were still interested in swaping a new model small wedge in its place it is easy. First off the 273 v8 was available in that car in 1967 . Use the stock brackets and motormounts and it drops right in. You can use the same exhaust manifolds from that application as well or get headers. The trans should bold right up.
#6
the motor mounts are the same as any 318 til 72. your poly mounts will work on any 318. The poly had a steel crank. not as strong as the 340 steel crank but stronger than the cast 318. the cranks interchange too. tranny bellhousing is the same boltpattern. Hot set-up would be .090 over (sonic check but most are doable to this overbore) and a 4" stroke crank. would come out to 402. (using standard bore 360 pistons). torque-monster !!
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