Rebuilding the original 307

[oneowner88]

Hi guys,
I'm the noob who was at first planning a Ram Jet swap into my '88 CSC. Then I thought of doing a rocket 350 swap.
Well...due to recent dental surgery and a few other house repairs, I'm NOW financially unable to spend the money on a newer engine. My logical solution is just rebuilding the original 307 and putting a swap off for a few years,( 7 to be exact; it's when I retire and turn 60), and wanted to know if anyone here has kept theirs,and if so, any advice to share.
Unfortunately the 307 I have is the lower 145hp.,7A ports, from factory.
Thanks for any/all replies. 🙂

 

[lg1200]

find you some 5A heads and upgrade to an edelbrock intake and holley 600. this is probably the cheapest route..i'd just keep the eye out for a running olds 350 thats in good shape that you can just drop in your ride..maybe change all the gaskets and drop it in..it'd be cheaper than rebuilding the 307.

 

[papabearxl]

I haven't any advice on the 307, but I do have a 71 Olds 455 and turbo 400 I will sell. Condition of each is physically unknown, but I was told both were in good working order. 455 needs the accessories, brackets and distributor. I haven't had time to put it on a stand and open it up, as my 330 is on it now. Don't know where you are, but I can ship it, and will, just rather not. I am asking $350 for both. (plus shipping if required)

Not in a rush to sell, or need to sell, but wouldn't mind the extra cash. Extra intake and heads (both needing reworked) included, if wanted. I can help load, or trailer a small distance for a reasonable amount.

I am in east Tennessee, in Newport.

 

[oneowner88]

Thanks for the offer papa but we are 2200 miles apart,so shipping might be a tad expensive..lol.

 

[papabearxl]

Thanks for the offer papa but we are 2200 miles apart,so shipping might be a tad expensive..lol.

lol...yeah it would probably be .....sorry. Thought I would offer. Good luck on the 307.


I have shipped by freight though, and it wasn't as bad as you think ( I think I shipped a 302, yes a F*rd block and extras out to Nebraska ) by truck for around $150 IIRC.

Anyway. That was about 7 or 8 years ago...Good luck. I am sure someone on here can help ya.

 

[DRIVEN]

What's wrong with the 307 you're running? If it's just underpowered, you might just live with it until you can afford what you really want. If it's damaged or just too tired to be driven, you might just look for a used 330, 350 or 403. Should be able to find one for $300-500. All are basically a direct swap and well documented on this forum and others. If you have the money to rebuild the 307 -- you have the money to rebuild any of the others. A rebuildable core should run $100-300. Spending the same amount of money on a 350 as a 307 will easily make (at least) 100hp more. I wouldn't spend money rebuilding a 307 unless matching #s is your main priority. Guessing from your Ramjet statement I doubt that's the case.

 

[olds307 and 403]

Do a compression test and put an oil gauge on it. I had a 307 last over 400,000 km, stll ran decent. I had all bills from new, just needed the timing chain done. They are reliable engines, just under powered. I would add headers and dual exhaust, will fit on the larger SBO's, later on.

 

[Minion1186]

gears make all the difference in the world. Switching to 3.23-3.73 gears really wakes up the car. For the 307 though, If it was mine, i would have it thermal cleaned, .30 overbore (later 307's supposed had eggshaped cylinder bores and burnt off oil) stock bearing clearances, VIN 9 camshaft (special order them through napa from what i've read) or one that combatable with the computer if you're using the compuer and upgrade to 5A heads and an A4 intake if you're on strict budget. I think you would probably have to bush the lifter bores with bronze bushings to an .842 diameter in order to use a hydraulic flat tappet cam because late model 86-up had .921 diameter lifter bores and used roller lifter and cam and the shitty 7A heads. This is just what I would do to give you an idea.

My 86 cutlass salon had a rebuilt 307, .40 overbore, stock 7A port matched heads and even though it ran lean because of a carburetor issue, it was a reliable motor, no leaks and didnt burn oil.

 

[88ss408]

well you can't get nothing for free. but you should get a set of 80-85 heads .and have them worked a bit . good clean up gasket match the ports a good valve job. and mill them some.
your biggest expence will be the heads.
now get a set of headers and a dual exhaust system.(that can be used on a bigger motor down the road)
edelbrock intake and carb of your choice and a good HEI distributor (also can be used on the bigger motor )
and you have a roller block so it will be a bit more expencive cam swap.
so really there is only the cam and the heads that will be baught that will not be able to be used on another project.
and this is all if your motor is in good shape and just under powered .

 

[86-blk442]

If youre looking, I have a set of 5A heads that were on my 350 for about 1500 miles. They have been freshened up with some minor bowl work, comp cams springs, and studs. Only reason I took them off was because I had a set of #5's with W-31 parts built.