My 305 TBI threw a rod and is ready for the trash.
I've been givin a rebuilt 1968 chevy 307 engine block with valve covers. I was wondering what I can take off my 305 and toss on the 307. Can I swap over the valve covers? What all am I going to need to make this work?

 

What year is your 305, and what transmission do you have?

 

The 305 is stock from a 1989 firebird. all I know about the trans, is it's an automatic with a shift kit. Vin decoder says Trans- M5,A4 if that helps.

 

You'll need a new flexplate for the 2 piece rear main crankshaft. Your TBI intake has a slightly different intake bolt pattern that won't match the 307's heads, and the 307 heads might not have holes to mount your accessories. You can put your 305 heads on the 307 block, though.

 

what can I do about the intake problem? Would i be able to take my TBI off my current intake and put it on the 307?

 

All you'd really want from the 307 is the short block. The heads and everything above that would come from the 305. Stock 307s came with pretty miserable cams as well, so you'd probably want to replace that while you had the chance.

 

So if i swap the heads and everything above I could do the swap with my TBI? I'm not against changing this car to a carbed car If I can get it done without too much of a headache. (and for under $500)

I don't think my mechanic realy wants to take the heads off, so If i have to carb it, whats the best route to take?

 

It would be less of a headache to do as Apeiron suggested and use the top end of your 305 on the 307.By using the 305's heads you can in turn use the intake/TBI setup.The 700R4 should bolt up to the 307.
If you switch to a carb - you'll need an intake,a computor controlled car(quadrjet)and a harness from a LG4 car.You can swap to a non CC carb but you'll also need a new distributor with vacuum and mechanical advance.Either of these will be over your budget.

The 307 was the 305 of it's day.It was meant as a low performance V8 alternative to the 250 I6.

 

I think the 307 is a better 305...

It has a slightly larger bore and shorter stroke but will work well with your 305 stuff. Everything from the 305 should be used EXCEPT...

Flexplate: the 305 and 307 use a different balancing so you need an old style (1985 or older) small block chevy flexplate to bolt up for your automatic transmission.

Camshaft: your 305 is a factory roller cam and your 307 is not. You can run very well with a stock 1986 non roller TPI camshaft (Z28 or Trans Am) or a factory 4 barrell 350 camshaft from 1977 to 1985. These profiles are not too out of line with factory specs to upset your computer

With your 305 heads you should be running between 9 and 9.5 to 1 compression.

 

So i'll also have to swap out the cam too?

So far i've got swap everything from the 305 from the heads up. Get a flexplate to bolt up the trans.

 

My engine is ready to come out. My mechanic doesn't want to swap the heads off the 305 (has over 170k miles on it) What would be best for me? Should i buy new heads or just say the heck with this 307 and buy me a 305 crate? I'm almost ready to say the heck with the 307 as my mechanic doesn't know a lot about it other then it's an older chevy smallblock. He can drop a 305 in it without any problems he's telling me.

 

dont get in over your head. If you are paying someone i would but a crate engine. 350ci

 

Those 305 heads should be checked before your mechanic writes them off like that. 170k is nothing for SBC parts... likely all it will need is new valve seals, and maybe some fresh valve springs. Then they would be just fine for your 307.

If the engine really did throw a rod though - meaning it parted ways with the crankshaft - I doubt the 305 heads are saveable, as the piston/rod would have slammed into the head when it decided to go on vacation.

If you do decide to ditch the 307, don't bother with another little motor. Just get a 350 and call it a day. 350 parts are much easier to find, and they are generally cheaper, because the 350 is probably the most mass-produced engine in history. Its well known to be the cheapest engine in the world to build. The 305, 307 and other less desireable variations of SBC are still cheap to build, but not at cheap as the 350, and the displacement-specific parts (ie. pistons, rings, etc) are more expensive for those motors.