I get a lot of people asking me for suggestions to spice up their little 307's, so I thought I'd write it down here. The 307 is a good engine--reliable, decent gas mileage, easy to find parts for, and it comes with a 4-bbl Quadrajet! Some of the recommendations are from personal experience, some have been recommended by others, all have been tested and proven. Your mileage may vary, perform any modifications at your own risk, wash dark colors separately, and all that other standard disclaimer type stuff. First off, it depends on what version of the 307 you have. It comes in several flavors. Now, to thoroughly confuse you, Olds made two different version of each of these engines. Up through Mid-85, 307's had normal 5A cylinder heads and normal hydraulic flat-tappet lifters. In Mid-85, GM changed over to a 307 with 7A cylinder heads and a hydraulic roller-lifter drivetrain. The 5A heads seemed to appear for a while after '85 in the VIN 9 engine, but there are 7A headded VIN 9 engines too.

To see which version you have, look for the number on the front of each cylinder head. Follow the negative battery cable to where it attaches to the head, right next to it you'll see the raised number and letter. The 5A head engine is preferred for performance use because it has "normal" sized ports in the intake and cylinder heads. 7A head engines have tiny ports in the intake and heads (and exhaust ports too, but the manifolds are the same) designed to work in conjunction with the roller lifters. This is why an Edelbrock performer intake will not fit 7A head engines. (Actually it will physically FIT, but there would be an awful port mismatch causing reversion and you would be very unhappy). Now, on to the modifications! First off, let me state the goal and make sure you don't have any unrealistic expectations. Unless you throw thousands and thousands of dollars at a 307, you will not be able to go out and eat Z-28 Camaros for breakfast and stock Big Blocks for lunch. If your goal is that kind of power level, your money is best spent on a larger engine.

Call it what you want, "Return on investment", "Bang for the buck", "HP per $$", etc. But swapping in an Olds 350, 403, 425 or 455 would get you where you want to go most efficiently. The 350 and 403 are the same block externally, so all accessories will bolt up, the computer will work (if you keep the cam mild), and nobody will be able to tell the difference unless they check the numbers. A 425 or 455 Big Block will fit right in, but is a bit more of a project and won't be covered here. The goal here is to have a reliable and streetable car, that's a pleasure to drive in traffic, meets emissions, and keeps the stock computer while delivering as much power as possible while keeping all the creature comforts (A/C, heater, cruise, etc) without crossing that dollar and effort line where you could have just as well put in the 350 or 403. Ride and handling will be addressed also, where obtainable on a budget. Before you start with any mods, you need a smooth running baseline engine to start from.

You may be able to do some of these at the same time as other modifications (such as putting in the new thermostat while you have the engine drained to flush it). Now you've got a smooth running 307 that you can feel confident in taking anywhere! I'd do this step sometime between stage I and II. ...see any of our advertisers displaying the MP logo.AR Engineering Ltd.mopar performance air cleaner lid Sold only thru dealers, see website for listWhere we got the stuff:harley billet air cleaner medallion kit A fast and quick Road Runner for the street, one that�s not afraid of twisty roads, too.air duct cleaning thornton Longtime M.A. readers know that we like fast Mopars. Hey, you probably do, too, or you wouldn�t be here.

Most of you also know that we�ve long touted the basic �goodness� of Mopar�s rigid and light unibody construction, indirect-spring (T-bar) front suspension, asymmetrical leafs in the rear, etc. We�ve surely validated our theories via running our Green Brick 1969 Valiant in the Car and Driver One Lap of America and kicking some serious butt - again and again. The Road Runner will kind of be a 12/10ths scale Valiant, although, while it will surely be a corner burner, the emphasis will be more on straight-line rice butt-kicking. As Dodge�s NASCAR driver, Jimmy Spencer said to the press recently: �Those sons of bitches bombed Pearl harbor, don�t forget. Dodge kick(s) their ass� Amen to that, Jimmy! OK, we digress (but it was fun!) We began with a well-used �69 Road Runner, with decent paint Click to Load Full Size and a tired 440 under the hood. The plan was - and still is - to build a 600+ HP big-block, 100% pump-91 streetable, using the cheapest pars that would still be stone-axe reliable.

We enlisted the services of well-known Mopar engine Builder Ray Barton to make the numbers for us. DECEMBER 2002 issue - Basic premise of project, parts selection - junkyard block, etc. FEBRUARY 2003 issue - Block prep, installing billet main caps, align honing, bore work APRIL 2003 issue - Partial shortblock buildup JUNE 2003 issue - Shortblock, continued, good rods, etc. AUGUST 2003 issue - Oiling system OCTOBER 2003 issue - Edelbrock heads DECEMBER 2003 issue - Valvetrain FEBRUARY 2004 issue - Chassis stiffening to handle the torque APRIL 2004 issue - Manifold dyno shootout - 593 HP JUNE 2004 issue - camshaft test, jetting, timing changes, 616 HP AUGUST 2004 issue - Dressing the engine - pulleys, mounts, water and PS pumps, etc. OCTOBER 2004 issue - engine installation secrets As we got the mill ready for installation, we also were prepping the rest of the car to not blow up under the gaff of Barton�s 600+ HP, and we got the �Beeper to the strip - and a chassis dyno!

In fact, on Feb. 14th, 2004, we baselined the car with the high-mileage, near-stock 440-6. We did this with the help of the cool folks at Bristol Dyno Service in Bristol, CT. It was a fun mid-winter break, here�s the Videos: Hey, what were you expecting? It was rated 390 HP, SAE gross. That�s maybe 330 or so, SAE net. Then the drivetrain loss.. note that the first 2 runs were in second gear, the last - and best - was in third. We couldn�t pull it down low - the TorqueFlite would downshift! Then we installed the new Barton engine DECEMBER 2004 issue - tuning for street driveability Before attacking the track, we concentrated on prepping the �Beeper for immaculate road manners - �driveability� in Detroit-ese. We also took pains to prevent trouble before it showed up! We installed a full-length TTI exhaust system (awesome 3" mandrel-bent stuff), 3/8" fuel pickup from Year One, full-length 3/8" lines from Inline Tube, a superstrong Denny�s aluminum driveshaft, a really, really slick kickdown cable setup from Bouchillon Performance - paired with AR Engineering�s tall throttle bracket kit, swapped to the latest Holley high-tech 870-CFM vacuum-secondary Street Avenger carburetor.

We also spent quite a bit of time dialing in the advance curve in out MP vacuum-advance distributor � this proved to be a key item. Without reworking this distributor, your chances at streeability are near zero! We also turned the underhood area into a plumber�s nightmare, by adding a super-trick fuel vapor return setup that imparted EFI-like starting, idling, etc., and a PCV collection system that guaranteed an oil-free intake charge. All this on pocket change!� we ran the now slightly detuned 496 on a Dynojet chassis dyno. Where, on 91 octane pump unleaded, we made � get this � 60% more power than our old 440 6-Pack engine! FEBRUARY 2005 issue - at the drags Before heading out to the drag strip, we had a few more minor chores to attend to. We knew, from our original dyno testing at Barton�s, that the original �68-69 round air cleaner setup was restrictive, so we ordered up one of Comp Cam�s lightweight, free-flowing 14" units - a 30-second installation.

We did a bit of �by ear� and �seat of pants� carburetor tuning on our new Holley. Wanting to keep out lower extremities intact, we slipped in one of those way-cool composite tranny shields from CSR. From experience, we knew that one of the first failures was likely to be the left engine mount insulator, so Schumacher�s hooked us up with his way-cool bolt-in adjustable, urethane-insulated torque strut kits. Since it bolts in to the K-member at the swaybar points, we took the opportunity to upgrade to a fat-boy front bar from Firm Feel, Inc. And, although it nearly gave us a coronary to send any money to the French, we had little choice if we were gonna hook up at all � we needed a pair of BFG Drag Radials. Result: our street tuning was way off for drag strip / drag tire launch, especially with the huge-diameter tires coupled to 3.23:1 cogs. First gear was nearly all bog. Still, 12.5 @ 115 was respectable, considering that we drove from the interstate at 65 plus - plus right to the starting line.

But we know there�s lots more to come � after all, our second name�s not Action for nothing! APRIL 2005 issue - At the Auto-X! For this installment, we decided to attack -- literally -- a sports-car autocross held at a local airport. Before heading out, we headed off disaster by plumbing in Moroso's 3-quart oil accumulator, keeping the Barton 496's bottom end supplied with solid oil even if the pickup tube became uncovered. We also cut way, way down on understeer by installing one of Firm Feel, Inc.'s new over-the-axle rear sway bars -- basically, one of the 'good' (no unsprung weight increase) E-body designs, re-engineered for B-body use. While we didn't win the 'cross, we were also one of the minority of entrants that took down no cones all day. Our decades-old rock-hard tires hurt us, but the chassis response was truly excellent. Read all about it in the April issue. Or, just go slow around corners. JUNE 2005 issue - Brake upgrades /Tech/archive/disc-main.html), with our newfound velocity, thanks to 500 cubes of Barton-Edelbrock HP, we soon learned that we needed even better brakes.

With a cool set of CNC billet adapters from AR Engineering, we retrofitted Viper / Brembo 4-piston aluminum calipers onto our stock Mopar 12" cop-car rotors. Amazingly, it this setup even cleared out 15" OEM Mopar wheels! As icing on the cake, we added a pair of stiff �n� light tubular upper control ams. While we were looking at (and wrenching on!) brakes, we decided to see what else was out there. We uncovered several cool gems, including a low-cost solution for pre�73 A-body owners desirous of keeping their 4-inch bolt circle, and some solutions for - get this! This is one issue you don�t wanna miss. AUGUST 2005 issue - Brake proportioning, steering upgrades With our new Viper calipers, we needed a way to get the front/rear brake proportioning dialed in. We used the typical adjustable valve, and we show you all the secrets to getting the proportioning dialed in correctly, which can make a huge difference in stopping distances We also have some cool steering upgrades, via Firm Feel Inc., up our (tie-rod) sleeves!