I would save the original motor to sell with the car or swap it back into place if you decided to sell it. No one is looking for an original 307 car, they want the original high performance engines. Its cool to have a low mileage car and motor like you have though, I just doubt it would fetch a higher price than one with a big block and a cowl hood. Thats just my opinion though, I could be way off base.

 

Sounds like a good plan! I really don't have room in the garage for store a full motor and transmission though. Since the 307 is not that sought after I may lean towards the 396.

 

X2 on doing the swap but keeping the original parts. Win/win situation. I would be leery of putting a TH350 behind a big block though but that's just me.
Good luck.

 

Agreed the car would be more desireable with a big block. A TH400 would be an improvement over the 350 and one of the overdrive automatics would be even better.
If a big block is swapped in I cant imagine anyone going back to the 307 but hang on to it anyway as it wouldnt be worth it to sell.

 

If you want to help the value ditch both of those trans and get an overdrive

 

I'd forget about the 396 and put in a nice 350 with a TH350 or OD trans. With a 396 you'll likely need a bigger radiator, different bracketry for accessories, etc. Then there's exhaust system headers or manifolds specific to big block Chevelles. The list grows.

 

I would definitely do the big block swap. The TH350 can be reworked to support the 396 if not already. New aluminum radiator and fan set up. If you can’t store the 307 get rid of it. The car is much more desirable with the 396 for resale. Nice car and would make a beautiful sleeper. Love the Moon Eyes.

 

I would definitely do the big block swap. The TH350 can be reworked to support the 396 if not already. New aluminum radiator and fan set up. If you can’t store the 307 get rid of it. The car is much more desirable with the 396 for resale. Nice car and would make a beautiful sleeper. Love the Moon Eyes. View attachment 832590

Yessir, mooneyes for the win!

 

More desirable yes, but from a value standpoint only realistically how much value would a non matching big block be over the 307?

 

I'm a numbers guy, but I have to agree with the others that a 307 isn't that desirable. I'd keep the original engine/transmission and make the necessary changes to put the 396 in. it wouldn't bother me to run the TH350 behind it, either. Looks like your car (beautiful BTW) is a street cruiser, so a TH350 would hold hup just fine.

 

Very, very few would pay any sort of premium for a numbers matching 307/PG over .. anything more performance oriented. Numbers matching only matters for factory-desirable cars.

 

A 307 while a nice running engine is the bottom of the barrel. The only lower performing engine found in a chevelle would be a 283 or a six cylinder and the six cylinder has a certain cool factor about it.

Personally i probably wouldnt even hang on to it unless storage room wasnt a factor.

 

Ha, and i would. Forget about the BBC, invest in a 200R4/ 700r4 and AC for resale value. EFI for the over the top resale. Methinks those components increase resale value more than a BBC. Engine swaps are childs play in these cars. and stock 396s do not impress me a single bit.

You do know an LS swap would WAY EXCEED the resale of a measly 396. Not child's play however.

200R4. Sell the PG to a racer; thats all they;re good for these days. They take heavy horsepower. Your stock 307 will LOVE the new 1st and 2nd gear ratios. whether it can adequately power the car @ 70mph in OD would be my only concern.

 

 

1966 Full Size Cars had only two automatic transmissions, a Power glide and a Turbo 400 Trans. There was no 350 Trans for the 1966 Full Size Cars. If the motor and trans are original to the 1966 it would have to be a Turbo 400 as info

 

Numbers matching only really matters to a select few cars and people. It would need to be something special. Go for the big block if you want it. Heck go for a bigger big block.

 

So look at it this way. If there are two nearly identical Chevelles sitting there and the difference is one has a 307 with a Powerglide and the other has a 396 with an overdrive transmission. I'm betting the vast majority would pick the one with the 396.

 

I would change the transmission and call it a day

 

I don't think there is much of a market for a 307 with a PG even if it is numbers matching. Go for the 396.

 

you can take a 350 based engine and make it look like a 307 engine and most car show goers would never know.
but I think most buyer looking for cars to make engine swaps are looking for 307 cars

 

Put the TH350 behind your existing 307 and keep on rolling.

 

To be honest what I would do is definately acquire the 396 and before I installed it I might do a few upgrades if they are needed. Not all 396 engines were created equal. As long as I would be swapping I'd swap in a TKX manual transmission.

The 307 is a good running engine but it is a no frills engine to get one from point A to point B. Same with a powerglide or auto transmissions in general. A big block and a manual transmission transforms that car from a classic cruiser to a muscle car.

So it's all up to Middair as to what is important to him. Also it's not an afternoon project. So if this Chevelle is something that he sees as a long term keeper then may be worth the investment. If not 5hen leave it as is and it's original nature will appeal to the next buyer just as it appealed to Middair.

 

If you're on a budget, put a 4 bbl carb and intake on it with a good tune on the carb and dist. plus (easiest) a TH350 or for more money a built 200 4R or 700 R4. That will really wake it up. If that's not enough a mild cam and headers will do even better.

 

Thank you all for your input, it is greatly appreciated. You gotta love the Chevelle community! A lot to think about! I will keep you posted in the direction I go!

 

How about another opinion. I am a Big Block guy all the way . But that is such a sweet car I would put a modern drive train in it with A/C and the other amenities. Love the 68&69 SS hoods but just couldnt do it to this car. Love it.

 

Buy the TH350 from your friend and install it. You may have to locate the appropriate gear indicator for the 3 speed th350 trans.


FYI, with the right mods a 307 can be a very fun car. Couple that 307 with smaller chambered TrickFlow 175 heads with 1.94/1.60 valves to bump the compression a bit. your current heads are either 72cc or 75cc

56cc chambered heads should bump compression to 9.5:1 to 10:1 compression. Just need to check deck clearance to top of the piston, get the part number off the piston to find out + CC Value on the 4 valve relief piston in order to select a compressed head gasket thickness

 

Oh and check this article out for informational purposes

Long Rod Chevy 307 = Big Power

Here's a performance build-up of the often-overlooked 307 small block Chevy V8. Follow along and see how much horsepower it made.

www.onallcylinders.com

 

My 71 Nova was a 307/TH350 from the factory. I added 4bbl intake & carb, plus headers. It ran 15.70 @ 90mph in the 1/4 mile with the stock 2.56 rear gears. Your Powerglide car probably has a shorter gear, so would probably run even better. I've swapped a SBC car to a BBC in the past. Fun, but a lot of work and $$$. You can put that TH350 in your car in a weekend, for minimal $$$.

 

Not bad for a 307!