Agreed... for Pete's sake... he asked for 307 upgrade advice and nothing more... I'll repost what I originally posted on page 1 to help get this back on topic:
No real love for the 307 here?!, its a good motor for what it is, but its not a really "hot" engine... but if you trim weight out of your Olds, Buick, or X- Wagon, it'll put you down the quarter mile well into the 15's pretty easily without any serious mods... I have seen an Olds 307 Cutlass run into the low 14s...almost broke into the 13's... that said, any engine can go fast if you throw enough money at it. (SORRY FOR THE "CULTASS" TYPO, NOT INTENTIONAL.. EDITED)
SO, How many miles does you 307 have?
The REAL source for noticable power gains for any engine is in the heads and camshaft.
There are trade-offs, but if you just want to get more pep outta that 307 and still knock out decent mileage, pulling that engine and heaving it isn't exactly the best option... especially if you're in school and not independantly wealthy.
Going backwards a little... always think about an engine like this: its just a big air pump... it sucks in air, injects gasoline, burns it, then expels the results out the exhaust. The easier and more volume you can flow through it, the more power it will produce.
As said above, you likely have either 6A or 7A "fast-burn" high velocity swirl port heads (casting 0142). Not exactly good for drag racing, but they are very adequate for mild street performance and have good velocity... the "Swirl Ports" were designed to bump up low end torque and improve the engine's ability to utilize low octane gas without pinging to death. You can clean out the casting flash and port match them. You can also clean up the runners a little, without removing the cast-in ramps (bumps) that cause the "swirl", although a slight rounding of the top of it may improve flow. Having the heads rebuilt, ports cleaned up, and valves recut will improve things...
If anyone really wants to know some serious info on swirl port heads, this link is great information:
http://www.thirdgen.org/techboard/tbi/3 ... dflow.html
The factory "Roller engines" are "better" because they cause less friction in the valvetrain and in theory, it frees up horsepower... the flip is that the roller valvetrain components Olds used were heavy and not designed for higher RPMs, but they do their job well.
The Camshaft... this is the heart of every engine and gives it its beat. Most factory camshaft profiles are pathetic. The '85-up Olds 307 roller cam is no exception. The VIN 9 "HO" roller cam will give your engine a good shot in the arm. Swapping to a '85-88 VIN 9 HO ECM/PROM or a Hypertech VIN Y upgrade PROM chip is recommended... the VIN 9 ECM/PROM is the better route IMHO.
QJet Carburetor... lets put the myths down now... The Quadrajet carb is THE Best carburetor ever designed and the "Electronic" QJet is at the top of the evolution. GM's Rochester Fuel Systems Division designed this carb to work on any gasoline engine GM made, while providing excellent fuel metering/good mpg capability in the primary circuit, good metering throughout the RPM band, and a healthy fuel dump at Wide Open Throttle (WOT). Most Q-Jets are capable of flowing 750 cfm, some special variants could flow 800cfm... this is well beyond what street engines can use and more than what aftermarket carbs can flow.
The "Electronic Quadrajet" series is the most advanced carb ever designed and can out perform most TBIs of the same era, if tuned properly...both in either mpg or performance capability, depending on which way you want to go. The "CCC" engine management system controls the idle circuit, maintaining the magic 14.7:1 Air to Fuel Ratio (AFR)... it doesn't control the carb otherwise... it worked so well that AMC, Ford, & Chrysler all bought them from GM in the 80's and used them on their V8's as stop gaps while they developed their own fuel injection systems...
Oldsmobiles use the E4MC, "C" being hot air choke... Chevy used the E4ME...2nd "E" being electric choke. The obvious difference is the fuel inlet sticks out straight from the carb. The VIN 9 HO QJet has a richer hanger and metering rod combo... this carb is worth finding if you can... I don't have the PNs handy for the HO carbs, or the specs on the rods and hanger offhand. (Chevy did the same for the L69 305 HO Qjet). I should also mention that these carbs use a different style of meetering rods and hanger than the older 4M series carbs and they don't interchange... sourcing replacements is very difficult now.
Now, if yours isnt working right, it probably needs a rebuild. There are a number of shops out there... like Sean Murphy Induction that can fully rebuild your carb and upgrade it to perform to HO specs or better if desired. The biggest problems for these carbs is poor maintenance, shade tree mechanics, and wear. The 1st two are simple to solve, have a person who actually knows what they are doing work on it.. not the guy that used to long ago... load of crap that'll lead to a messed up carb that'll never run right. The main problem outside of those is wear... with age comes problems. A common issue is for the throttle blade pin bores to wear out and cause vacuum leaks & deteriorated vacuum lines that are cracked and bleeding vacuum. Another is gasket deterioration and clogs in the vacuum passageways caused by oil residue and carbon being sucked into the vacuum lines. I've seen guys with fuel issues caused by a dirty fuel inlet filter even. If all of the engine sensors are old and original, replace them, especially the O2 sensor (only buy an AC Delco O2 sensor, trust me).
If you think ripping off the carb and putting a Holley or Edelbrock will solve your problems, you are totally mistaken... you might come to regret it. First, the 200R4 lockup is controlled by the "CCC" Computer Command Control System (ECM/PROM) so you'll either need a retrofit kit or consider something else to prevent burning up the Transmission. Second, the CCC controls the timing of the distributor... if the CCC senses a serious problem, like no engine sensor readings, it'll go into "Limp Home Mode", pull out timing, and run like a lame dog.... so you'd also need to replace the distributor with a vacuum advance HEI unit from an older, non computer Olds or buy a new aftermarket one.... $$$ Third, you'll have terrible gas mileage vs running the CCC system and E4MC QJet... I managed to get just shy of 27 MPG out of my old '86 Firebird, LG4 305/700R4/2:73 gears.. no barn burner, but she was well-tuned and had no trouble breaking the tires loose... it was Late Fall each time as well... I averaged about 20-24mpg when I stayed out of the secondaries on the highway with 70k+ miles. My '83 Monte was a little bit less, but she had a TH350 and 250K miles on the clock... The '84 Grand Prix was a bit of a pig when I got it but I tuned her up and rebuilt the Qjet... she got about 19-22 on a good day, but she was finicky.
The stock A5 intake leaves a lot to be desired, BUT its not a piece of scrap aluminum either. It can be ported and polished at home and the plenum can be opened up, you just need to be careful not to over do it and take out too much material... best part is that they are a GM Part that fits 100% and as a bonus, theyre dirt cheap usually. Just like the variants of the Chevy LG4/L69 aluminum intakes... there's definately room to improve them and the techniques are the same... port match, clean up the passages, and open up the plenum similar to the way the Edelbrock 2101 looks.... fair bit of work, but its a better option than nothing.
The exhaust is another area worth looking at. I dont believe Oldsmobile used larger dia. exhaust manifolds on the HO engines vs the regular 307's. On the '83-'86 F-Body L69 305, Chevy used larger diameter manifolds, (resused them on TPI 305 & 350). If they did, they'd be worth looking into. That said, headers do have benefits, but also have a bunch of negatives... IIRC there's only 2 companies making Olds 307 headers. The downsides of headers are poor fitment/poor sealing to exhaust ports/gasket failure, rust, unwanted extra heat in the engine bay (get ceramic coating), problems with them touching/hitting other parts of the car, & making spark plug changes a ****. Personally, I avoid them... just not worth the effort on a street car vs the problems that come with them.
Upgrading to a high flowing catalytic convertor and High Output style 442/Hurst-Olds exhaust will also help out a lot
