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307 Chevy build-up

47K views 18 replies 14 participants last post by  lojack 
#1 ·
I'm getting a 70 Chevy 3/4t 4x4 parts truck soon with a possibly running 307 in it, and I was wondering whether they were worth hopping up or not. I'm thinking about putting a SBC in my truck, but wasn't sure whether to soup a 307 or just throw a souped 350 in.
I've read some pretty fascinating stories about the 307's, but also some stories that they are just plain dogs not matter what you do. I know everyone except 1 or 2 guys will say put in a 350, but I like to be different. Any input you have about building a 307 Chevy would be appreciated.
Jake
 
#3 ·
If the 307 is in good shape (not in need of an overhaul) it can produce some respectable HP. However if the engine is tired and in need of an overhaul you would be better off finding a 350 to rebuild and hop up.

Contrary to popular opinion the 307 is not quite the dog people though it was. I had one in a 70 Nova that would run very solid mid 13 second quarter mile times.

Viince
 
#5 ·
I know what you mean about building something different, and I'm guessing you don't have a 502 caddy just lying around. 307s are fun to play with, but if I was hauling a load or pulling a trailor I would want at least 350 cubes under the hood. That said, 307s are cheap and fun to build because they respond well to smaller parts that most people don't want. 305 1.84 valve heads work well with their small chambers and larger ports, and are very cheap on ebay. Same for 283 powerpack heads. These heads will choke a 350 but are just right for a 307. The best setup I've had on mine so far is 461 camel humps w/1.94s and .030" milled off, edelbrock c3bx intake that was virtually left for dead in my garage, duntov 30/30 solid cam, and 600cfm carb. I've rebuilt this motor several times, and I'm finding out the smaller I go the better it seems to run. No single plane intakes, 2" spacers or 750 carbs. Also, you'll either want to get an msd blaster2 coil or replace points dist with an HEI.
Friend of mine had one in an 80s camaro with a saginaw 4spd behind it. When he got it revvin it would plant you in the seat. Definitly liked the 4spd. We seen the car at the track a few years after he sold it, and found out people had been passing it off as a 327. :D
 
#14 ·
307

i had a 307 in my 70 nova also. what i did was i got a set of vortec heads. mine came off of a 97 tahoe. i used a compcams 270h hyd. flat tappet cam. it gives it a nice little rumble. for my intake i got a summit stage one duel plane intake. and a edelbrock 650 carb. hei ignition. i was surprised how much that thing pulled. i did that because the bottom end was still good. but if you have to rebuild it put the money in a 350.
 
#16 · (Edited)
venolia made custom pistons

machine shop tom said:
Even 2 years ago to now, nobody makes a piston to work with a 3.75" stroke crank and a 3.875" nominal bore. If they did, it would be a 359 at .030" over.

tom
yes, its does make a 359.47 cid engine, the pistons i have are from venolia
they are for a 3.905 bore, 6" H beam rod and a 3.75 crank ground to 350
specs AKA a 383 stroker crank, the engine combination was built
by a engine builder for a guy running a dragster who tried to
set a class record as the block casting denoted that it was a 307
engine but was busted during a tear down. i purchased the rotating
assembly from a guy who was running it in a dirt limited late model
but went to a 434 cid engine
 

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#17 ·
307 engine.

A friend of mine had a 307 in his 55 chevy back in the 70's with a two barrel that thing would get after it after he replaced the clutch I ran him in my 70 GTO from the start he would hang with me but after a little bit I was gone I really liked that engine it took a beating he ran it with out a air filter and towards the end of when he had it the car would use 15 quarts of oil on a 350 mile trip it was funny because once he would hear the engine make a certain sound he would pull over and add 5 quarts of oil but she held up.
 
#19 ·
I am in the midst of redoing a 307, its out of a 68 gmc half ton, and its possibly for my 17 year old neice, so jam isnt an issue. Also its the original motor and theres somthing to be said for keeping things original if hp isnt what your looking for. That being said, when I dropped the block off to get hot tanked, the guy that I was nuts! He said this is either a 283 or 307, I said 307 he said they were smoggers lol. and I should just do a 350, but I kinda expained the situation and he said oh ok. I dunno if he agreed with my reasoning though, but hey whatever,
 
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