307 V-8


Asked by kamcityroller May 20, 2015 at 01:31 PM about the 1987 Oldsmobile Cutlass Supreme

Question type: Car Customization

Ive got an 87 Cutlass supreme with a 307 its a brand new re-build as well the tranny is brand new re-build.Its got nice mags and stinger tires. I am looking to get more B.H.P out of this engine i think stock its got around 180 b.h.p and i ould just like to get it up to 250-275 any thoughts on what i should start with in getting this done?

20 Answers

William Markussen

well it depend how much money your looking to spend. I mean easiest thing to do is swap for a 350 crate, would probably cost you just as much if not more money on upgrades for the 307 to get as much horse as the 350.

5 out of 5 people think this is helpful.
Michael Urbanski

I agree with Markussen. Plus there are many upgrades you can make with a 350 than with a 307. Also, the 307 only had 140hp, only the 442 with the "9" code 307 had 180.

3 out of 3 people think this is helpful.
Skyler Sorensen

Yeah a 350 would easily have more power, but this guy asked how to upgrade his 307, not what motor to swap. S.S.S.

5 out of 5 people think this is helpful.
James Cronin

unfortunatly those guys are right, the easiest and cheapest way to get those kinds of horsies are to upgrade an engine. The 307 was a terrible engine as small-blocks go. So here are some options: If you want to keep the 307: -have the heads planed to close up the combustion chamber, increasing compression and horsepower -High-rise aluminum intake with a nice big carb -different camshaft -upgrade ignition system -headers and big exhaust If you want to upgrade engines: -buy a 4-bolt main 350 and start swapping heads, and all of the above for a small block -buy a 455 cu in Rocket big-block V8 (which are hard to come by, BUT I have one for sale, with a stronger tranny a TH400) and go for the big horsepower

2 out of 2 people think this is helpful.
James Cronin

The engine I have is out of a 1973 Cutlass, so it is either 400 bhp MAX or as low as 250 bhp. no upgrades yet, but she ran awful nice and quiet.

1 out of 1 people think this is helpful.
James Cronin

Here a pic of the engine for sale

3 out of 3 people think this is helpful.
Aaron Schweigert

True being that a 350 swap is much more cost effective.. that being an olds 350.. don't let all these guys b.s. you about puting a chevy in there. that requires much more work than the "direct" bolt in of an olds 350. also the 307 wasn't meant for hp.. olds motor's are notorious for the torque they make. not the h.p. yeah 140ish hp but into the 200's torque. I say if you are looking for 275 torque, that is much easier to achieve with a 307. start yourself off with a mild cam 204-214ish lunati. get an intake, performer or performer rpm depending on how high you plan on revving the thing. re-curve your distributor to run a little more timing and you should be around there with a good tune. But also it depends if you are going to keep the car running on the computer. If the heads were milled, you are probably looking at a small compression boost which will also help you in the hp/tq department. I guess more info would be needed. also if you have the stock th200 trans you might kill it in stock form if you make much more power than a stock 307 would.

1 out of 1 people think this is helpful.
Bobby Key

To be perfectly honest its less time, labor, and money just to get a 305 and build it up and the old 307s. Or just go for a 350 or 327.


Greetings: If you take the quadrajet and overhaul it ,many were tuned for racing boats where the engine well tuned would out perform aftermarket carbs...Go to Cartech books to rebuild and correct its design faults,and... Now that you’ve learned how the Quadrajet works, how to correctly rebuild it, and what different models were available, it’s time to apply some high-performance modifications. With the correct modifications in the right places, the Quadrajet has no trouble being up to the task of powering your new engine combination. Even if you are still working with a basically “stock” engine, the modifications mentioned in this chapter help improve performance, driveability, and fuel economy. and this is from wikapedia : Main article: Oldsmobile Cutlass Supreme 1986 Oldsmobile 442 The 442 name was revived in 1985 on the rear-wheel drive G-body Oldsmobile Cutlass Supreme. The name was now defined as referring to the car's 4-speed 200r4 automatic transmission, 4-barrel carburetor, and 2 exhausts. This W42 model replaced the 1983 and 1984 Hurst/Olds model and used the same 5.0 L LG8 V8. The shifter was mounted on the floor in a console between the front seats, and the upgraded F41 suspension package was included. 3,000 were produced in the first year, and all were sold quickly. 4,273 were produced for 1986, and 4,208 were made in 1987. The 1984 Hurst/Olds and 1985-87 442 were equipped with an 8.5" GM corporate differential usually with a 3:73 ring and pinion gear. Rather than using the weaker 7.5" rear differential found in the Monte Carlo SS, these models used the same stout unit found in the Buick Grand National. The 1983-84 Hurst/Olds and 1985-87 442's are distinguishable by there being a "9" as the engine code found in the 8th character of their VIN's. These were the only models to get the hotter VIN 9 307 cubic inch engine, and it was the only engine available. From 1983-1985, this engine was flat-tappet valvetrain, and rated at 180 hp/240 ft·lbf torque. In 1986, the 307 engine received a roller-camshaft valvetrain and new swirl-port heads to improve economy and low-end torque. HP dropped to 170, with torque climbing to 250. The 1985 442 used an OZ code THM 200-4R transmission... (Same base trans as your Supreme and as well as mine,,,can be a great runner, Ernie)


I would just get a Garret turbo charger with 18 lbs of boost. That aughtta make that sumbitch scream like a whore on a Saturday night!

1 out of 1 people think this is helpful.

where can I find a 307 cutless supreme Brougham motor around 800.00 dollars


If anyone know where I can get a 1987 307 cutlass supreme Brougham. I live in the Raleigh Durham area please contact me at 984-244-4419 BRYANT Taborn

Kelly Mayo

HERES YOUR QUESTION OR THE IMPORTANT PART--- I am looking to get more B.H.P out of THIS engine ....OK,. 307s got a real bad rap early on as poor peformers, and it stuck with them. The primary reason for this awfull reputation, however, comes from one single mistake on General Motors' part...they equipped the 307 with a wimpy, unhardened hydraulic camshaft. These cams wore out very quickly, leaving the engines way down on power and way up on fuel consumption. Many owners failed to diagnose this condition, and just sold their cars in disgust, or swapped in 327 or 350 replacement engines. The fact is, a simple cam swap would have put their wheezing 307 right back in the fight, had they taken the time to check it out! So, obviously the first thing you should know about building a 307 is that you're GONNA have to buy a cam. Luckily, there are litterally THOUSANDS of factory and aftermarket grinds to choose from, so fear not, brave warrior! The small valve heads, along with the bore/stroke relationship will play a critical role in camsfaht selection. It is easy to "over cam" a 307 and make it perform WORSE if you ignore these factors, so avoid the temptation to use the same lumpity cam your buddy is running in his built-to-the-gills 350! You want a hydraulic cam with sensible duration and relatively small valve lift. This leaves plenty of options open, and it should be said right now that building a 307 for anything other than mild street/strip duty with limited RPM (under 6200) expectations is a foolish affair given it's specific shortcomings. For this reason, we will be looking at cams in this relatively mild range.A NEW CAM WHAT IT WANTS NEXT ADD A INTAKE AND CARB AND EXHAUST SYSTEM TO FEED AND ADD EXHAUST THEN ADD SOME GEAR.

1 out of 1 people think this is helpful.
James Kitlas

A 307" is low performance because of the low compression. I got max hp out of one just by adding a Crane RV duel profile hydraulic cam & kit for more torque, & tube headers too. It's possible to boost these engines up to 200-250 hp. Any higher would require new higher compression pistons, aluminum intake & 4-bbl carb or TBI. Hi-perf cylindar heads would then make it like a 302" sort of.

1 out of 1 people think this is helpful.

Good evening gentlemen I've recently acquired an 87 olds cutlass supreme with 55,000 original miles and looking to get some hp out of my 307. Can anyone suggest an intake, cam and carb. Corey

James Kitlas

Not much to do because it's a low compression low hp 307. But you can install a duel profile RV torque hyd cam, & add tube headers, & upgrad to a cat back Flow Master exhaust. Your 175-200 hp 307 can be made to produce 250-300 hp depending on the aftermarket add-on's. Cold air intake with K & N air filter, MSD ignition Box, solid center braided Noligy spark plug wires, E3 spark plugs. Upgrade the carb, like to a larger CFM Holley 2 bbl & carb spacer. Or small AFB 4 bbl & aluminum intake manifold $$$. Note: you can't go too wild on the & use a high RPM cam because you don't have high compression notched pistons. Check your stock cam duration spec's (research) & increase the new hyd cam only by 10+ degrees duration. The Crane RV hyd cam will make more torque. High lift cams will cause the valves to hit your flat top pistons.

James Kitlas

* have the heads redone also. Use valve springs from the new cam & (kit). Install hyd roller lifters $$$. Have a few thousands shaved off the heads too. Because new high perf cylinder heads are maybe UN-availible & expensive.

Ismael Iniguez

Thanks james i just got a 86 cutlass supreme with the 307.. And by reading all the mods i need to do. I just rather do the Ls2 6.0 Conversion. Thanks again you saved me tons of headeachs.


I bought a 1981 cutlass with a 307 ..so from whats being read here they are not such a good motor ?

Chris French

i have a 1983 cutlass 307 bourham supreme motor im tryn to build it has 55,635 on the dash and its all factory

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