307 to 403 OLDS

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JAMCAR223

Royal Smart Person
Jun 6, 2014
1,853
5,507
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Houston, TX.
Do you have 93 available? You will need it will 9.5 to 1 and that cam. I ran 9.6 to 1 with that cam in my 350. It liked to ping even on 91. I retarded the part throttle timing around town and ran very cold NGK 5670-8 spark plugs, felt meh driving around town but ran equal to mid 14's in the 1/8, a 9.4 with more in it with a 2300 stall, 2004R, 3.42's in my 3750 pound 1988 Cutlass Supreme Classic. I would seriously aim for 9 to 1, the cam will act even smaller with 53 more ci. It will make driveability nicer as you can add much more part throttle timing, it makes an Olds V8 feel crisper.
93 octane is available on every corner in South Texas. 9.5 - 1 is a goal. A tenth or 2 either way I think would be acceptable. BTW, I like crispy! :giggle:
 
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rogue_ryder

Master Mechanic
Oct 27, 2017
267
549
93
Colorado
Here are some specs and pics of my 85 Salon with a built 403. Oh yea, it's for sale. This car ran mid 12's
The engine is an Olds 403 .040 over with:
Arias Pistons
330 Steel Crank
J&S 4 Main Girdle
Old Performance Products Oil Pump
Midon 7qt oil pan
Lunati VooDoo cam and lifters
Comp Cams roller tip rockers and rod guides
RPM Performer Intake
#8 Ported Olds heads
SMI Quadrajet
Hedman Elite Headers
Be Cool Radiator and Fans

200 4R Transmission:
CK Performance shift recalibration kit.
10 Vane Pump
Sonex Servo
GM 2004R 12" LOCK UP STREET STRIP CONVERTER HIGH STALL
Hardend sun shell and stator tube.
Eagle Steels and Clutches has 1 Extra clutch and steel

That sounds very similar to my 403 that I'm building! What was your Compression Ratio?

I started off wanting to do a "budget" build. now I'm in pretty deep. I'm running .030 over Autotec pistons from Mondello (yeah yeah) I also have the 330 crank, J&S 4 main girdle, lunati voodoo roller cam 272/280, hylift lifters, 7 qt pan (generic Moroso knock off), performer RPM, H-S rockers, and C heads from a 455 (scored them completely redone bowl clean up, valve job and blocked crossover and Comp Springs for $400!) I just finished putting together the bottom end and I ran the numbers http://www.diamondracing.net/tools/ and with a .040 Cometic head gasket (81cc head volume, pistons a -4cc and .019 "in the hole") I'll be coming in at 10:1 Compression Ratio per that calculator. I plan on running just 91 Octane (highest we get here) and hopefully that will be fine since most of my driving will be over 5,000' elevation and in the summer density altitude is even higher. My trans is a 2004r that is supposed to hold up to 500hp and 500 lb/ft according to Jegs (If it blows up I'll put the CK goodies into my old 2004r). I have like 0 time to get to the track so it'll mostly just be getting beat up and down the canyon roads around where I live. I have spent so much money now probably around $4K I'm guessing and If I had to redo the project I'd just get a Mabbco short block and find some remaned Iron heads off of a late 60s 350 and call it good.

The 307 even the VIN 9 version (better cam and intake) with a dual exhaust all tuned up (fresh carb, plugs, timed etc.) is still a DOG! I hate that my mustang buddies call these cars the Gutless but they truly are! I think it would've been ok back in the 1980s but today everything is faster. After 30 years and 100,000 miles I bet my 307 is down on power 20% then take another 20% off of that (power loss at altitude) and we're looking at a whopping 128hp at the crank in a 3400 car at best (factory specs) mine would make 160hp at the crank here in CO, I'm pretty sure that's less than what a modern Toyota Corolla is putting out.
 
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Oct 14, 2008
8,806
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Melville,Saskatchewan
Having 93 helps. I might push 9.5 to 1 with only 91 available here but it will be much larger than the 204/214 cam, probably low 220's roller cam, whatever Cutlassefi specs. I have similar parts, a 330 offset ground crank, custom Venolia 4.390" pistons on Scat rods for 424ci. Also ported 2/1.625" with crossover filled #6 heads and Scorpion 1.72 roller rockers. I also need a 5 main girdle. I need to work more this winter to afford the machine work for my 403.
 
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TURNA

Rocket Powered Basset Hound
Jul 24, 2009
10,941
19,990
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Socialist NY
Any machine need to be done to a 403 for a roller cam setup?
 

fleming442

Captain Tenneal
Dec 26, 2013
13,046
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Not necessarily, but Travato offers his grinds in Comp cams with a bronze thrust washer. Mark Remmel has the best price on lifters; Bill will try to juice you for Comps ($600).
 
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fleming442

Captain Tenneal
Dec 26, 2013
13,046
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Me no likey that answer
You'd have to talk to Bill. I don't think Trimble had to do anything to my block for it; I'm 95% sure Travato takes the thrust washer thickness out of the cam blank. Either way, get a roller thrust button, and make sure the end play is set correctly.
 
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