Thread: 307-hp?

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I had a 307 in a 69 nova years ago.I think it was a stock engine,it had a power gliude behind it,didnt run to bad.I just found me a 71 nova,307,th350,been in the same family sence new.71000 original miles,ac car,I really like that.Point is I dont want a drag car but would like a decent running street car.I've always built 327-350's,not to hard to get decent HP out of them.What can I do to this 307 fairly cheap to make it run and hold together?

I found out a long time ago that when your rebuilding your engine if you spend a lot of time in a machine shop (like balancing and blue printing ) you can release a whole lot of horse power plus the engine will last longer.

230hp at 5,000 rpm and 278 lb-ft torque at 4,000 rpm.stock.. Heres a very good article on that engine.

Read more: 307 Chevy Dyno Test - Super Chevy Magazine

The 307 has been kicked around as the “red-headed” stepchild for a long time. True – it’s not the one I’d build a full-tilt-boogie car around, but it can be a good, dependable daily driver and with a few bucks, can have some snap and good bark.

First thing I’d do is buy a couple cans of Gunk and spray the daylights out of the engine bay and the transmission. Of you have a pressure washer, you can do this at home – otherwise, go to the do-it-yourself place and bring a big handful of quarters. Remember to cover the distributor very well (plastic bag and a tight wrap of aluminum foil) or you’ll have fits getting it started again. Also remember to wear good goggles to protect your eyes as you will get wet!!

Next, run a compression test. If all eight cylinders are 150 +/- 20%, proceed with the following. If compression test is “no-so-good”, it’s time to price a 350 long block and then proceed with the list below.

All parts are from Summit Racing - you can shop around, but this is a good baseline to measure from:

Edelbrock 7104 – Performer RPM $185.95
Edelbrock 7201 - Edelbrock Intake Manifold Gaskets - $15.95
Edelbrock 8504 - Edelbrock Intake Manifold Bolt Kit - $14.95
Summit SUM-210216 - Remanufactured Quadrajet Carburetor - $299.95
Summit SUM-850030 - GM HEI Ignition Tune-Up Kit - $71.95
Summit SUM-868836 - Ignition Wires - $29.95
Autolite 25 - Copper Core Spark Plugs, #1.50 EACH - $12.00
Hooker 2451-1HKR - Hooker Competition Headers - $379.95
Hooker 10925HKR - Hooker Mounting Bracket for A/C - $31.95
Mr. Gasket 3409 - Header Bolts - $13.95

Performer RPM with Quadrajet is a bolt on – literally. You should be able to attach your stock linkage for both accelerator and transmission kick-down using the stock brackets. This is the best combination for drivability and gives a “kick-in-the-pants” when you punch the secondaries open – bear in mind such activity will quickly drain your gas tank! Buy all the gaskets and bolts listed and make sure you crank the engine to TDC before removing the distributor (makes it easier to re-install and time).

Get a new lease on the stock HEI with the tune-up kit. Cap, rotor, coil, etc.. Follow directions and make sure to get the button in the right place. Do the plug wires and plugs at this time as well.

Hooker Competition headers are, in my opinion, the best from an “ease of installation” standpoint. These are ceramic coated and yes, I know they’re expensive – but you’ll only do this once. Use the A/C bracket and by all means, the new bolts. Take the car to a muffler shop and get 2-1/2” pipe with a cross-over pipe after the collectors. Install 40 series Flowmasters (nice rumble) and have the exhaust taken all the way out to the rear bumper with a couple nice stainless tips. This should be +/- $600 depending on the shop.

So – for about $1700 you can add probably 50-75 horsepower and the car will feel good and sound very nice!

Good Luck!
Glenn

Glenn is right on the money. But I might add,it would probably be a good idea to change the cam and lifters out because if I remember correctly thats about the years that G.M. was having trouble with cams going flat. I would change it out with a roller set up because the oil we have today will not work with flat tappet cams. I don't have a cam recomendation, but I would not get very radical with it.

Cam and lifters would also be a good addition - I was trying to keep it "bolt on" but by all means, if you're comfortable with digging into the "bowels" of the engine, a cam kit would be good. Summit SUM-K1102 is a good bet - 262/272 with .420/.442 lift and it's a hundred bucks out the door. You'll probably want to stay with a hydraulic flat tappet cam as the conversion of a 307 to rollers would not be justified (IMO). Broken in correctly, a flat tappet will be fine.

Bear in mind, that changing out the cam is a lot of work - i.e., taking the entire front of the engine off as well as the intake manifold and rocker arms. If you've built a 327/350 you know what has to be done. I've changed a fair number in the car, but I prefer to do a cam if the motor's out of the car just because it's easiest.