Tweaking an 87 Olds 307 - opinions?

[DoubleV]

Horsepower numbers can be a bit vague especially when one person's talking gross HP, the other's talking net HP, and the other guy's thinking RWHP. What do you want this to run at the track ( ET and MPH )?

Also, how far away from stock appearance are you willing to go? You wanna run headers or the stock manifolds? Either way it sounds like you're looking for more than just some 'bolt-ons' to reach your goal. You're going to have to tear into this engine and do some upgrading. This is right around the level where people will start to try and convince you a 350 would be the better choice. Sounds like you should just buy my 350 which will be out of my car this weekend....

 

[King_V]

Just as an example of the difference between gross and net...

Dodge 318 2-bbl. In 1971 was 230hp, in 1972 was 150hp. It's the same, just one is gross, and one is net with single exhaust.

Buick 350 2bbl. In 1971 was 250hp, in 1972 was 155hp. Again, same thing, gross vs net, and it's a single exhaust car.

Both would gain about 15-25 net hp with dual exhaust off factory manifolds.


The 1987 307HO is 180hp net. Probably the equivalent of 240-270 hp or so as measured by pre-1972 numbers.

 

[83hurstguy]

With your goals of 250-300 hp, and 300-350 lb-ft, go with a 350. How much cam and compression is in your shed engine? That will depend if you can use the computer or not. If you ditch the computer, you'll need to work up some A/C and torque converter lockup controls, not too hard.

However, if the cam and compression are mild, you could keep it with manifolds, put on true duals, paint it black so it looks stock, go have fun. You will want to know how the CCC system works through (make sure you have factory CSM). Can always upgrade to American Racing Headers in the future for more power. Given your $3k budget, you probably don't want to blow $1k out of the gate on headers. :lol:

 

[skryla]

With your goals of 250-300 hp, and 300-350 lb-ft, go with a 350. How much cam and compression is in your shed engine? That will depend if you can use the computer or not. If you ditch the computer, you'll need to work up some A/C and torque converter lockup controls, not too hard.

However, if the cam and compression are mild, you could keep it with manifolds, put on true duals, paint it black so it looks stock, go have fun. You will want to know how the CCC system works through (make sure you have factory CSM). Can always upgrade to American Racing Headers in the future for more power. Given your $3k budget, you probably don't want to blow $1k out of the gate on headers. :lol:

I'm guessing the "shed" engine is stock at 8.0 compression. Will I pick up any compression with the #5 heads. Then I guess I need to decide on a valvetrain and cam.

I am not building for the track. Just for driving fun. I have the BTR Built 500hp/600tq 496 in my 72 442 Vert if I want to go to the track. I'd like it to look stock under the hood but will go to headers and true duals.

At what point do I need to loose the computer? What does the computer control and using what input?

 

[83hurstguy]

I'd keep it below 9:1. Cam probably shouldn't be more than 210/216ish.

Computer controls the timing and also the primary side of the carb. The downside is it will tend to run lean under cruise, especially with the roller cam calibration. The secondary side is easily adjustable. I've never checked availability of aftermarket primary rods/jets.

 

[olds307 and 403]

You will not gain anything with #5 heads, you already have small chamber heads. Your motor has big dish pistons. Small cam, headers and duals would wake up that 350, again if in good shape.

 

[skryla]

You will not gain anything with #5 heads, you already have small chamber heads. Your motor has big dish pistons. Small cam, headers and duals would wake up that 350, again if in good shape.

The #5 heads are from a W31 and have 2" intake. What compression ratio could I expect with the big dish / #5 combo? Still 8-1? How about if I mill them a bit?

 

[olds307 and 403]

You need to mill the heads to 60cc and pick up a set of custom shim head gaskets from M+J Proformance. The shims measure .011" thick, slightly thinner than the factory gaskets. That would put your compression around 8.75 to 1, perfect for the computer. A good cam would be the Lunatic High efficiency series 207/207 .461/.461 ground on a 112 LSA. That is important on the computer along with the low duration. Get the matching springs from Lunati and it should easily meet your goals. Add a set of Sanderson shorties or Hedman headers or ARH if you feel rich, a good 2.25 or 2.5"dual exhaust and have fun.

 

[lg1200]

i asked these same questions when i inherited my Regal. If you're looking for horsepower then the 307 is not it. For the money you'll throw at it, in the end you'll still be looking for more HP. With that same money you can definitely stick with Olds or Buick and FIND a 350 thats not an eyesore when you see it. Or if you put a chevy 350 wouldn't be a bad option. You can always find a 350 on Craigslist in good running shape for the low..lots of options here all within budget of using that same money you were putting in the 307. I built a 355 from the bottom up with all new everything and spent over $3000 doing it. It's dyno'd 402 HP. But knowing what i know now I was stupid for putting that much into it, but I learned alot in that process. Put money into what you'll get your best return.

 

[skryla]

As always, thanks for the info guys!

For my own knowledge:
does anyone know what a stock 87 307 dynoes at compared to a 72 350? Crankshaft HP.