Olds 403 Build

[QS442]

Cool car to restore with an OLDS 403! Good luck

 

[88hurstolds]

Heads are heads
gasket matching is fine
those valve guides should be almost non existent
not to mention all the ridges left inside the ports
See the difference in the walls
See the difference in the guides

Not sure what you're trying to say...
Flow, dyno and quarter mile numbers don't lie, you're comparing a Chevy to an Olds, heads are NOT heads... valve placement is much different with an Olds as well.
Lowering the floor on an intake port is bad, all the port work on these were done raising the ports and opening up the exhaust and Rallye Bob was putting a very heavy stock 1970 Rallye 350 on two wheels and consistently doing 10.3's with an Olds 350 with these heads not to mention the heads have seen over 10 race seasons... ports aren't going to be shinny.
I had them tanked, valves done and the gasket surface milled .006 to clean it up and then used them as is.

 

[88hurstolds]

Stock #6 heads would be more like 190/160 for flow and around 210/165 with 2"/1.625" with a bowl hog under the valves, my other #6 heads have 2.05"/1.56" valves with the bowl hog opened up the bowls. Stock big valve BBO heads flow around 215/170, not impressive but better than the 1 through 5's 190/160 along with 8, J and 4A's 190/120 stock numbers. My #6's should be in the 220 range, ports are bigger than stock and guides hogged down. Filling the huge crossover's is supposed to help a lot as well,mine are filled. It does make cool weather running shitty from running them on my 350. My divider's aren't welded but the gap is very small compared to the awful later "#A" heads. I would believe the flow numbers from Rocket Racing especially considering Ralleye Bob's car really hauls *ss and those heads pushed it into the 10's.

Head flow numbers:
http://users.erols.com/srweiss/tablehdc.htm

 

[88hurstolds]

Dyno sheet

 

[olds307 and 403]

Head flow numbers:
http://users.erols.com/srweiss/tablehdc.htm

Don't believe all those numbers. Any of the Mid Am numbers are ported and very questionable. The iron 350 7A numbers are accurate, SBO heads with 1.875/1.56 valves don't even break 200 cfm. Cutlassefi flowed a set of #7 heads with 2"/1.625" with just the bowls opened, I think around 210/170. It shows how good your #6 heads are over stock. He uses Champion Race heads in Florida.

 

[88hurstolds]

One of the initial dyno runs to 5000rpm:

 

[Pronto-]

Good street build. I had a similar build for a 403 in a 79 TA. With 3.42 gears it ran 13.5s and was fun on the street. I friend of mine has a Can Am but with a Pontiac 400. I am surprised it's a 403. Thought they all were Pontiac 400s. Either way the 403 will be a fun street engine.

 

[Texas82GP]

Some were curious on the 403 dyno results from Friday:
430hp @5500rpm and 471ft-lbs at 4100rpm, my guess was 430/475, not a bad guess

Specs: 410.6 ci, 9.789:1 final CR, includes top ring piston to cylinder wall gap otherwise it was 10.2:1 prior to final assembly
.030 cometic gaskets
#6 heads shaved to 57cc, .080 cut from Performer RPM intake to compensate...
fully ported, large valves flow 262/186 @.600, ported by Dick Stolpa of Rocket Racing, flow better than C heads
HS rockers, Smiths Bros push rods, modified Comp Cams guide plates for 7/16 studs
330 forged steel crank
Lunati Voodoo cam 219/227 .499/.510
Quick fuel 650
7 quart pan and HV Oil Pump

Unfortunately its not going into a G-body, I built this engine for a '77 Pontiac Can Am, 1 of 42 high altitude cars that was originally equipped with an Olds 403
I did build the driveline to with a G-body in mind: 3.73 posi, TH2004R, CK Performance billet HS converter
and cant forget the Lightning Rods...
One of the dyno runs to 5k rpm:

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What a cool car!

 

[L92 OLDS]

One of the initial dyno runs to 5000rpm:

I’m glad you’re having fun with it. Thanks for sharing the video