For all the costs involved with rebuilding a bad 305, you will be disappointed with the results. The machine work alone will run you $500. Around where I live, I can get a junkyard 350 for about $125, less if I don't want the heads.
305 Swap
- Thread starter 1984Cutlass
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if i where you i would keep the 307 ! because if you go to the 305 or any sbc for that you are going to have to change the motor mounts too.
and if you dont want a rocket just a good driver you can make it out of the 307. alot of people dont like smaller displacement motor like the 305/307
but they are not all that bad .
you did not say what year of 307 you had if it's b4 85 you have a good start because you need the A5 heads if you have a 86-90 motor a set of older heads should not be hard to find
so if you motor is running good ,good oil pressure ,not leaking oil or anything go for a cam nothing to big because the olds motor dont rev.like a sbc does.
a 307 H.O cam is good to start or a little bit bigger if you want (i heard of a guy using a stock 455 cam )
get your heads ported and mill them a little for better compression get a edelbrock intake and carb headers if you like or the older exhauset manifold's along with a dual system and you should be good for 250 h.p. give or take
and if you dont want a rocket just a good driver you can make it out of the 307. alot of people dont like smaller displacement motor like the 305/307
but they are not all that bad .
you did not say what year of 307 you had if it's b4 85 you have a good start because you need the A5 heads if you have a 86-90 motor a set of older heads should not be hard to find
so if you motor is running good ,good oil pressure ,not leaking oil or anything go for a cam nothing to big because the olds motor dont rev.like a sbc does.
a 307 H.O cam is good to start or a little bit bigger if you want (i heard of a guy using a stock 455 cam )
get your heads ported and mill them a little for better compression get a edelbrock intake and carb headers if you like or the older exhauset manifold's along with a dual system and you should be good for 250 h.p. give or take
88ss408 said:
It's an '84 model it's the original motor in my 1984 Cutlass. The motor runs great! I pm'ed a guy on here about a set of 307 H.O. heads and an H.O. intake manifold i'm interested in buying but he hasn't replied back yet. I think thats a good start all i'll need is a cam, carb and a nice exhaust system and I should be set. Thanks for the input!
i am not a old's guy so i dont know everything about everything but i think that the olds 307 and 307h.o use's the same heads they are A5 heads but sombody that know here will tell ya for sure ! maybe the intake is better not sure you should try to look around for a edelbrock one
'84Cutlass,
If you have an 84 you should have a 5A head (not A5). The casting number should be 3317, and it has 67cc chambers in it. The H.O. motors have a different cam, regular flat-tappet / lifters whereas the later motors were roller and used peanut port 6A & 7A heads. Don't let this lead you to believe that the H.O. motor is monster - it's not, was never meant to be.
If you swap to earlier heads (not 100% sure they'd fit anyway) you'd want to try to get #5, 6, 7 or preferrably 7A heads (the "A" is capital but subscript, casting #409147). These heads ran from 1969 - 72, with the 7-subscript A heads having the hardened seats (this "A" meant the hardened seats, the earlier ones don't). Also note that these heads have 7/16 bolt holes, not the '77-later 1/2" holes. Also these later heads had huge BB-size chambers in them, except for the 260 heads, plus they were cast by PMD. Note that switching to an earlier set of stock heads, with the 64cc chambers would only gain you a few tenths of compression, unless you upgrade the pistons, deck the block and some other things. I don't think BB heads would fit. So you should just stick with the 5A heads you have on your motor.
Not 100% sure but your stock intake may be aluminum, but an Edelbrock intake may give you a little more power. Maybe some headers, hi-flow cat and/or cat-back exhaust to wake her up a bit.
The 305 might have been an option if it was fully assembled, with the accessory brackets and such. Since it's a long block I'm guessing you still would need the intake, carb, dist (can't use the one from the 307), water pump, brackets and the other accessories. As others on here stated, if you're going to go through all that, plus the cost of the rebuild, go Chev 350. I would suggest you run the 307 for now, save up your money to do a proper 350 swap (Olds I hope). If you're going to Chevy route, check the board here; a few guys posted their swap, with details and parts lists.
Hope this helps.
If you have an 84 you should have a 5A head (not A5). The casting number should be 3317, and it has 67cc chambers in it. The H.O. motors have a different cam, regular flat-tappet / lifters whereas the later motors were roller and used peanut port 6A & 7A heads. Don't let this lead you to believe that the H.O. motor is monster - it's not, was never meant to be.
If you swap to earlier heads (not 100% sure they'd fit anyway) you'd want to try to get #5, 6, 7 or preferrably 7A heads (the "A" is capital but subscript, casting #409147). These heads ran from 1969 - 72, with the 7-subscript A heads having the hardened seats (this "A" meant the hardened seats, the earlier ones don't). Also note that these heads have 7/16 bolt holes, not the '77-later 1/2" holes. Also these later heads had huge BB-size chambers in them, except for the 260 heads, plus they were cast by PMD. Note that switching to an earlier set of stock heads, with the 64cc chambers would only gain you a few tenths of compression, unless you upgrade the pistons, deck the block and some other things. I don't think BB heads would fit. So you should just stick with the 5A heads you have on your motor.
Not 100% sure but your stock intake may be aluminum, but an Edelbrock intake may give you a little more power. Maybe some headers, hi-flow cat and/or cat-back exhaust to wake her up a bit.
The 305 might have been an option if it was fully assembled, with the accessory brackets and such. Since it's a long block I'm guessing you still would need the intake, carb, dist (can't use the one from the 307), water pump, brackets and the other accessories. As others on here stated, if you're going to go through all that, plus the cost of the rebuild, go Chev 350. I would suggest you run the 307 for now, save up your money to do a proper 350 swap (Olds I hope). If you're going to Chevy route, check the board here; a few guys posted their swap, with details and parts lists.
Hope this helps.
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