rage03usa wrote:
the 350 deal fell thru, but i managed to get a 81 - 85 olds 307, th350, and a 70's 350 intake for $150. What can i do to get some performance out of the 307? im looking for at least 250+ hp and 300+ ft/lbs, but prefere around the 350+ / 400+ range. Some parts of my 442 307 should still be usable, so should i grab them? would i see any benifit from using that 350 intake? or is it possible to have that 307 bored to 350? im looking to spend about 1500$ for the build up, so let me know what i should do... thx
Vince
I hate to break the news to you but there is no way your going to get a 307 in the 350+ HP range with just $1500 and have it stay together for any lenght of time.
The problem with the 307 is that the bore is really small which limits the size of valve in the head you can use which limits your horsepower potential.
All second generation small block Olds engines use a 3.385" stroke. This includes the 260-307-330-350-403 engines.
The way Olds increased the displacement was to increase the bores size of each engine.
Here are the bore and stroke for each:
260: 3.50 x 3.385
307: 3.80 x 3.385
330: 3.938 x 3.385
350: 4.057 x 3.385
403: 4.351 x 3.385
You'll notice that the 403 has a HUGE bore. A 455 big block Olds engine has a bore of 4.126 stock so the 403 is even larger.
Needless to say, there would not be enough material in the 307 cylinder walls to bore it out to a 350. And even if there was why would you want to? You would then have a MAXED out 307 that was only as big as a STOCK 350. You would just be better off and money ahead to buy a 350 in that situation.
As far as the intake goes, you can run it but I would personally go to the junkyard and grap an '81-'85 307 aluminum A4 intake. It flows just as well as the older intakes but as a weight savings to boot. And doesn't cost a lot of money. Did the 307 you buy come with an intake and you just want to swap it out for the 350 intake? If the 307 has an intake on it currently I would check to see if its an A4. If so, stick with it.
As for your 250HP goal, its possible but at the same time, you could build a 350 or 403 for the same money and have a lot more horsepower without reaching the absolute limits of the engine itself.
Both the 350 and 403 will bolt into place of the 307 and accept all of the original accessories.
Here's the buildup of my brother's 403 that we did for his '81 Cutlass:
'77 403 block, bored .030" over (408 cid roughly)
Stock crank with new ARP main bolts
Stock rods with new ARP rod bolts
Stock replacement CAST pistons .030" over
Moroso Deep sump oil pan
Melling High Volume oil pump and pickup
Rollmaster double roller timing chain
Ultradyne hydraulic camshaft: 221/230* duration @ .050, .485"/.485" lift, 112* LS installed on a 107* centerline
7
A heads (from a '72 350) with stock ports and valves. Bolt holes enlarged to fit 403 1/2" head bolts
Performer RPM intake, unmodified
750cfm Speed Demon vacuum secondary carb
Stock HEI distributor, recurved and fitted with Accel HI-Po module and High outpu coil
Dynomax Jet-hot coated headers. 1 3/4" primaries into 3" collectors
2.5" true dual exhaust with H-pipe and Dynomax Ultra-flo welded race mufflers
Th-2004R with 2200 stall 12" lockup converter
Rebuilt 7.5" rear end with Auburn 3.73 gears and limited slip
Earlier this summer the car ran a best of 13.4@101mph using just an Edlebrock Performer intake and shifting at 5300-5500rpm. That was also with a transmission that kept slipping and shifting whenever it felt like it. LOL
Since then we installed the Performer RPM intake and picked up a TON of top end power but the trans has finally been killed by the power unfortunately. And with the camshaft in the car now, it really needs a 2800-3000 stall converter to get back some of the low end torque. With a new converter, rebuilt trans, and drag radials, this engine would propel is '81 to a high 12 second low 13 second 1/4 time. And its not very radical at all. Idles smooth and gets around 11-14mpg combined city/highway/race.
The power output is roughly (basing this on trap speed and weight of the vehicle) is around 350hp-380hp at the crank and around 440ft/lbs at the crank.
Now that I'm done trying to pursuade you away from a 350 or 403, you might want to check out this site for some info:
http://tlentz.oldsgmail.com/more_power.html
I should also mention that the above 403 will cost more than $1500. For $1500 all your going to get is a stock rebuild. Machining assembly costs will be over $500 for the block, crank, rods, and heads alone. Then factor in the parts you'll need like new pistons, cam, carb rebuild (if you don't buy new), etc and it adds up quick.
For $1500 I would focus on building a strong bottom end that you can grow into later. Then down the road as money allows, add more high performance parts to make the car faster without worrying whether or not the bottom end of the engine will be able to handle it.
For an idea on parts:
750 Speed Demon carb $400
Cam and lifters $180
Headers $100-300
w/Jet-Hot coating $375-575
Torque Tech 2.5" exhaust $300
Moroso deep pan $200
Melling pump $40
Pick-up $30
A4 intake $20-50
ARP head bolts $80
ARP main bolts $40
ARP rod bolts $50
And so on. Not all of the above parts are needed. You may not need or want to go to a different carb and could have yours rebuilt. Cam and lifters can be found cheaper but Ultradyne cams are one of THE best cams for an Olds engine.
Just some thoughts. Of course you could always go with a 425 or 455 big block.
