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rube'68'03 10-30-2012 06:30 PM

Need some 307 advice
Hey everyone, first time poster. I just came back from my overseas tour and thought it would be nice to get a project truck. Picked up a '68 chevy C20, hoping it had the 327, i got stuck with the old 307. Im looking for suggestions to get some horsepower out of this thing. I read that a lot of people said to trash it, but i want to see what shes got.

69 widetrack 10-30-2012 06:39 PM

Welcome, how far did you want to go on the horsepower. The 307 was never a popular motor to build for performance. I don't believe they ever made a 307 with heads that didn't suffer from asthma. Again depending on what you want, a different set of heads would be a place to start...then there's the intake, if I'm right they where all 2 barrels. If you wanted to I'm sure you could make it go fast if you threw a bunch of parts and money at it.

rube'68'03 10-30-2012 06:44 PM

Well seeing as how the only way i could determine which i had between the 327, and 307 was to pull a head and measure a cylinder, i might as well get some new heads. I already picked up a edelbrock high rise intake and 600cfm carb. I have some headers for it and an msd streetfire distributer. I would like to know where to go as far as heads, should i upgrade my cam, lifters, rocker arms, things of that nature.

vinniekq2 10-30-2012 06:53 PM

think of your 307 as a stroker 283. 275 to 325 horse power would be as far as I would go. very simple build.Any decent small chamber heads, camel bump 194s or 202s, that 600 carb you bought,small dual plane z-28 clone manifold,9.5:1 CR , small solid flat tappet cam,(hydraulic if you must) small tube headers, good to go, balance the crank/rods/pistons. If you find other cheap heads,as long as they flow 200 cfm on the intake side and the exhaust side is cleaned up. Tune the engine for your cars application.

69 widetrack 10-30-2012 06:53 PM

Again, how fast do you want to go, or how much power do you want to make. If your going to a head that's going to increase compression and by how much, then will the bottom end hold up. If you are getting new heads a more aggressive cam would help it breathe.

Many aftermarket heads out there, or even factory 194 or 202 heads, but remember all your parts need to work in conjunction with each other. Just because somebody puts a cylinder head on their engine with big valves doesn't mean the engine will make a bunch more power.

If you where to lay out a budget of how much you want to spend and let the Guru's here know how much power you want to make I'm sure you will have an engine you are happy with...You need a budget and plan first.


rube'68'03 10-30-2012 06:59 PM

$1200 budget. I honestly dont know much about heads what what works better on which application. So, if you had the 1200 to put into this, what would y'all do? Guru away my friends...

ap72 10-30-2012 07:25 PM

$1200 budget? Swap in a $400 junkyard 350, spend a few hundred on a swap meet intake, headers, and a basic cam kit, and spend the rest on a mild torque converter.

The grin on your face will be twice as wide.

vinniekq2 10-30-2012 07:28 PM

you are going to have to get your hands dirty. look for some 194s and do a basic stock rebuild.mild cam,probably get stuck with a hydraulic flat tappet

rube'68'03 10-30-2012 07:39 PM

Im ready to get my hands dirty. I thought about getting a 350 but the truck itself is in amazing shape so i would like to keep the motor somewhatat original. Are the 194's hard to come by? Do you think its worth it to bore it out to a 327?

vinniekq2 10-30-2012 07:44 PM

not likely you can bore it to 327.first decide what you want. 307s mostly have cast cranks. keep power levels low. If you want power do what ap said,go 350. if you want a fun 307,build it mostly stock like what I first posted. camel bump heads are era correct but not 307 correct. they are cheap.

rube'68'03 10-30-2012 07:46 PM

Ok, sounds like a good start. Do you have a suggested seller for the heads?

American Muscle 10-30-2012 08:23 PM


Originally Posted by rube'68'03 (Post 1605290)
Ok, sounds like a good start. Do you have a suggested seller for the heads?

I would suggest rebuilding the engine with all orginal parts. Freshing up heads etc. Then bolt on all the things you mentioned you had( headers etc). Then id swap out rear gears. if its an automatic id opt for a 700r4 with 373 gears. If manual it should alreafy have steep gears. Point being, my first performance purchase would be a new set of gears. Just my two cent

rube'68'03 10-30-2012 08:50 PM

I need to first find out what gears it has. I was told it has an eaton rear end and i have no idea if thats stock, and either way im unaware of whats inside.

techinspector1 10-31-2012 12:40 AM


Originally Posted by ap72 (Post 1605281)
$1200 budget? Swap in a $400 junkyard 350, spend a few hundred on a swap meet intake, headers, and a basic cam kit, and spend the rest on a mild torque converter.
The grin on your face will be twice as wide.

Makes sense to me.

Valkyrie5.7 10-31-2012 01:23 AM

For a $1200 budget you can't go wrong with a junkyard 350.

If you plan on building up the 307, it's a lot like building up the 305 except it has a slightly better bore and a much worse reputation. As said before it shares it's bore with the 283 and it's stroke with the 327. Thanks to quality control issues these engines get avoided like the plague. There's a couple 3rd gen f-body guys on here that know the 305 well and have probably given great advice a million times on how to make power with them. Search the user "F-BIRD'88" on here and I'm sure you'll get a wealth of information on how to make great power with small cubes.

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