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tomnoller
07-26-2012, 05:07 PM
I installed a new oil sender for the SW gauge in the 63 Avanti I've been working on.
This car has a chev 305 with a TH350 and took a test drive today that was an eye-opener.
25 lbs pressure on start up and showing zero at idle once warmed up! I have no idea how many miles this engine has gone or how it was treated with previous owners, but I don't want to go anywhere with it before I address this.

Am thinking I could take the freshly rebuilt 289 out of my 63 Lark sedan (3 speed OD) and drop it in the Avanti, rather than rebuild the 305.

The Stude six I pulled out of the Lark, which I rebuilt over the past winter and is just sitting in my garage, could go back in the sedan. Only hitch is, I gave away the T96-OD tranny that came with the car. :-(

Maybe next winter I could tear down the chev for something to do. Anyway, does this idea seem logical? Brutal honesty, please!

tomnoller
07-26-2012, 05:08 PM
BTW, the sender is also a Stewart Warner from Summit, so I know they're 'talking to each other'.

tomnoller
07-26-2012, 05:14 PM
To avoid a clutch pedal & hardware, should I consider an adapter on the 289 for a GM auto tranny - maybe something later with 4 speeds?
(sorry to keep blathering on here)

gordr
07-26-2012, 06:28 PM
Step one: get a mechanical oil pressure gauge, and hook it up right on the engine, if you can. Just to be certain that your low oil pressure isn't just a bad ground!

If the engine is indeed worn out, I honestly think it would be less trouble to replace it with another SBC. So many things were changed on the car to make the Chevy fit, the going "back" to a 289 would be a huge job.

Presumably the swap entailed the use of a GM transmission, so you'd have to change the transmission, too, or use an adapter plate.

To do the swap "right", you would need at least an R1 engine and Powershift transmission. A plain 289 and a Flightomatic might work, but it would no more be an "Avanti" power train than what is in there.

What shifter quadrant is in it?

tomnoller
07-26-2012, 08:10 PM
Thanks Gord! After lots of looking and head-scratching the same thought came to me. It's been re-set for the SBC and just easier to rebuild this 305.
By shifter quadrant do you mean: PRND? That's the order from front to back on the console.

gordr
07-27-2012, 09:27 AM
Yeah, the sequence on the console. Sounds like maybe it is a TH350 transmission. I doubt a 305 and Powerglide would have come come together from a donor car.

Check out the prices of crate engines from Jegs or Summit, or even your local speed shop. You know I'm not a crate engine kind of guy, but when replacing one SBC with another, often it's the way to go. Gets you on the road a lot faster than rebuilding what you have, and a 350 has more zoom-zoom than a 305 for sure. Might even cost less going that route.

The CASO way to do it would be to buy another donor car with a sound SBC in it, and do the swap.