Mix & match 170/200/250

[Henry66]

I want to rebuilt a six for my '66 Bronco. The 170 that was in it is a 1961 and shows it. I have a 1968 200 and a 1969 250. The question I have is what would be the best case scenario for mixing parts. The 200 block is preferred (the 250 is cracked between 3 & 4). The 250 was a fresh rebuild the blew a head gasket and cracked. I could use the fresh components from it (.20 over pistons, cam, rockers). I realize the crank and rods are not compatible but is the cam, gears and chain? Are the forged rods from the 170 better than the cast (I think) from the 200? The 250 head did not pass inspection. The other two have yet to be cleaned & fluxed. Is there an advantage between them if they both pass? (Yeah, right!). You can probably see what my situation is though my description is not he best. As for performance I want to be able to do some moderate off roading for a long, long time. Any suggestions would be appreciated on the mix and match. Thanks, Henry

 

[rbohm]

I want to rebuilt a six for my '66 Bronco. The 170 that was in it is a 1961 and shows it. I have a 1968 200 and a 1969 250. The question I have is what would be the best case scenario for mixing parts. The 200 block is preferred (the 250 is cracked between 3 & 4). The 250 was a fresh rebuild the blew a head gasket and cracked. I could use the fresh components from it (.20 over pistons, cam, rockers). I realize the crank and rods are not compatible but is the cam, gears and chain? Are the forged rods from the 170 better than the cast (I think) from the 200? The 250 head did not pass inspection. The other two have yet to be cleaned & fluxed. Is there an advantage between them if they both pass? (Yeah, right!). You can probably see what my situation is though my description is not he best. As for performance I want to be able to do some moderate off roading for a long, long time. Any suggestions would be appreciated on the mix and match. Thanks, Henry

8) yes you can use the 250 pistons in the 200 as long as the bores are the same size. in other words if the 200 is .030 but the 250 is .020, the you cannot use the pistons. if both are .020 then yes. as for the 170 rods you can use them in the 200. you can use any small six head, you may have to mill a head with larger chambers to bring the compression back up to where it belongs. you can use the cam, but not the timing chain and gears.

 

[Henry66]

Thank you, I intend to have the 200 block bored .20 over for the pistons, decked also. (The 250 motor was a fresh rebuild gone bad). Glad to know I can use the cam as it is nearly new. What about the rocker assy. off the 250? Will it fit on the 200? Henry66

 

[rbohm]

8) yes you can use the rocker assembly with no problem. one thing, when you pull the lifters, make sure you put them in the proper order so that when you install them in the new block, you dont have to break the cam in again and risk wiping a lobe.