72 engine rebuild
 

Hi all, my wife recently bought me a 72 chevelle to restore. It came with a 307 and I was hoping to keep that engine so it would keep the close tooriginal, I just want it to put out a decent amount of HP. I was hoping for 375hp or around there. I know that the 307 is a 298 block with the stroke of a 327. I'm guessing it would be able to get a decent amount of HP out of it with a little bit of money and time. I was hoping for some thoughts and advice if possible. Thanks

Hi and welcome. Congrats on the new Chevelle. Great wife you have.

While you can build the 307, your best bet would be to leave it alone and store it. It is much easier and cost efficient to get that level of HP from a 350 or a 383. Like they say "there is no replacement for displacement"

Good luck and post some pics of your 72.

Mike

I agree, 375HP from a 307 would be a tall order. You can get a streetable 400 HP from a 350 without even trying. It will look similar to the 307 as well. Just make sure you match all the parts - and don't neglect the transmission and rear differential. You can have a great engine, but it won't perform worth a crap if it has a stock transmission/converter and highway gears. Just my $0.10

Yea I figured it might be a tall order and expensive I was curious about thoughts. If I change to a different engine I wanna look for a 4 manual trans and maybe a 454 or 396.

A big block and four speed would be my first choice. But, I am biased.

Now to track down a 4 speed and big block.

Piece of cake. They are everywhere. Be patient, and you will find exactly what you want.

That's better. :cool:

Mike

Yup, know you're talking. Put that 307 in the corner somewhere and go for some real fun. A built 350-383 can produce some pretty impressive HP but a big block has massive torque right form idle. Be sure to put a little extra money aside for tires.

yea i was leaning towards a new engine but thought it would be nice to keep it close all original but i like the power from the 396 i drove before. My 72 came with a full exhaust, the mufflers are Sonic Turbos i believe but i havent heard of these before. Does anyone have a set of these or heard them before? i want a nice deep throaty sound from my chevelle so if these wont do the trick then i'll look for something different

Get a 454, don't look back. (same outward appearance as a 396) You'll engine the extra TQ it has. Never heard of those mufflers. Get everything swapped over and see how it sounds. If it doesn't fit the bill, try a set of Magnaflows.

where do you live i have a 454 with a big block you can buy off me :)

I live in Canada. What would you want for it? Is it just the block or is it complete?

that would be one hell of a shipping cost..lol it would be complete all you would need is to wire it up and go :)

Yea it would be. I got a guy I know in Albany though that might be able to get it for me if need be. Do you have a price so I can figure out if its in my budget for this year?

no clue any more on what to sell it for. i was thinking 2500 but no clue anymore what i want to sell it for

Well if you're not sure if you want to sell it for that no worries. If you want to talk more about it you can private message me. Thanks tor letting me know do quickly though.

I've got the same problem, but my 72 came with a 1984 305 from a truck, not sure what I'm gonna go with either, let me know what you decide.

I don't have any experience with the sonic turbo's but I can tell you that the old 400ci smallblock in my old black Malibu was a great little engine with plenty of power. You could swap in a healthy SBC chevy and keep all the accessories and mounts and not have to worry about modifying driveshafts or anything too. It is the cheapest way to go. An old performance rule was 1hp per cubic inch was a good baseline. I am a Big Block guy (hence the 454 in my current Chevelle and my Suburban I use for towing) but I wouldn't rule out a healthy streetable mouse motor. Doing a big block swap correctly costs a lot more than some people realize. For starters, you are going to want to upgrade your front springs and sway bar at the least, most likely add a rear sway bar and boxed control arms- and throw enough HP and torque at the 10 bolt rear and see what kind of carnage you get. IMO anything around 400hp and over and I'd be running a 12 bolt or a Dana 60 or 9" F**d rear. That alone is going to require fabrication to put a non GM axle in if you can't score a good deal on a 12B. Don't forget you'll need a new radiator and fan shroud and accessory brackets for your power steering and alternator. You now have my .02 :o)

Speaking of the rear end, i have a couple pictures of it and as far as i can tell it is a 12bolt and i do believe the control arms are boxed as well. Let me know if i am mistaken or not.
http://chevelleforum.org/picture.php...pictureid=2962
http://chevelleforum.org/picture.php...pictureid=2963

Yup, 12 bolt rear. Looks like aftermarket upper control arms.

thanks, i didnt think they were stock ones either. now i have to find out what gears the guy put in the rear end to see if they need to be swapped and figure out where he was heading with the resto

also, do you think that the control arms on there now would work if i put 400hp to the rear end or should i up grade them too?

Pop the cover and count the teeth on the ring gear and pinion gear. Plus you can check the wear pattern, etc. at the same time. Those uppers are geared towards racing, and will increase ride harshness and noise. The stock upper arms are plenty. They used the same stamped arms on LS6 Chevelles. Those cars were heavy and rated @ 450 HP/500 TQ. My father and his older brother bought & raced one in 1970-1972. It ran high 11's in stock class. (slicks, gear swap, open headers) There are a few stealth ways to reinforce them if you feel it is needed. (stock upper arms)Usually a good set of polyurethane bushings are all that is needed though.

Thank you for the info, i appreciate the help and advice

Happy to help. :D

Well after some more research and digging around i found out that the engine and tranny that i got with the car are not original, the engine is and tranny are out of a early 80's, the engine is a 307 and tranny is a 700r4 auto. I have now decided to build a 383 stroker for my car, i picked up a 350 block already. I now want to make my car a standard and am looking at a 5 speed. The stroker and 5speed should be a nice fun combo to drive.

I see burnouts in your future ,keep us posted .

Should be a fun ride when you get it done.