W403

Any info on using BB Olds heads on 403? I've only read and it seems to go both ways?!? I have access to a 403 and a set of refurbished BB Olds heads, 2.07's and 1.68's, hardened exhaust seats, bronze liners, I believe they are G heads. Seems like a simpler way than going through and porting my 350 heads, installing new guides, larger valves, hardened seats etc. The bore shows no signs of wear, no cracks, decks strait, etc. and will use std size pistons instead of boring it unnecessarily (checked with a dial bore gauge, I didn't believe it either). Any advise on using KB flat top Hypereutectics in Std. size to get the compression up? Plan on a strong street engine, yet 5000 -5500 RPMs tops. It'll be going in a 70 cutlass, 350 auto, still has a 3.08 rear which I'd like to keep but could change out. Understand I'd need a 7111 intake, what gaskets would be best to use for that. Also besides reaming the head bolt holes o/s what's with the different size dowels? What about going with chebby sir rods, bushing them for free floating pins? Would appreciate advise on this, thanks.

85cutlass6.6

http://www.442.com/oldsfaq/ofe403.htm
Ive read through this a bunch of times, theres some good info, im also building a 403 but prob putting 350 heads

captjim

IMO, at that power level and RPM, stock rods should be fine. Build it for torque and keep the 3.08s. Cylinder walls are thin, nice that the bores are round. KBs would be nice, bump Cr up into the high 9.xx to 1, get a cam in the 215 @ .050 on the intake, should be all you need.

cutlassefi

If you're keeping the 3.08 gear then use 5, 6, or 7 heads. The smaller ports will give you better low end torque, just what you need with a tall gear. Plus you'll have the right compression with the stock pistons.

Put in an Erson High Flow AH (220/220 on a 110, .504 lift) or one of my custom grinds and you'll be good to go.

Jmo.

W403

Valuable advice and appreciated. I do have the set of heads that reside on top of the stock 350 (#6's), yet was hesitant to prep them for the 403 just in case I ever want to put it back in?! I have access to a machine shop, yet would have to buy the parts to do the 350 heads, BBO's heads are mine from a work trade and would save any ca$h outta pocket. Otherwise, I could only believe the 403 would hold up fine as everything seems to measure out as I'm not looking to buzz the wee outta it. Stock pistons/350 heads would solve that compression issue, as long as I work out the deck height for quench. How are those Cortico .028 gaskets at holding up on the 403's? Fel pro's .043's offer any advantage? Yeah, I know...more questions. Thanks for your responses though. Want to keep it all Olds. Now, what to do with those BBO's heads? Guess they could fund the 350 head work ...for sale sign?! huh? Any offers?

joe_padavano

I've said this before, but if BBO heads worked on a 400 BBO, why would they not also be good for a 403 SBO? Yes, you need the correct pistons to get the CR where you want it, but the larger ports and valves are better for performance.

Redog

I have to agree with Joe.

Wasn't the cc on 403 heads 80 or 83? I know that the "C" heads are in the 79 to 80cc area, so why wouldn't it work?

I can see swapping out 5 heads with a 68cc and going to C heads with the 80cc and losing a lot of CR

W403

Good to hear both views on this build. I'm up for more suggestions, especially since I already have the BBO's heads.

Heck, I've had this car for almost 30 years and my poor backside has a chance to do more of a performance build this time around. I do want to keep it street-able, figure the Olds torque motor is best suited for that. When it's opened up though, I want to hear it growl and feel it pull I don't want it to be a dog 'downstairs'.

It's always been 'someone else's ride' I've spoken about, Ram Air's, 442's, W-30 &31's SS's, GS's, GTO's Super Cobra Jet's,etc. and a painfully sweet ride in a 10.0 car... that was unreal! I now understand the '$100.00 bill taped to the dash' story. Wasn't much in the way of being able to grab it with the car trying to slam through the backside of your body in every gear...heheh

Once again, I appreciate the valued input as this will help solidify the build plans. As far as cam goes, there are a LOT of grinds in the RPM range I'm looking to build power in!?!?! Seems to be a few of them that are the most popular. (.448/.472. 204/214), Ultradyne, Lunati and the recommendation from above. Sound is important too, yet it needs to perform. Choices I gotta make. Keep 'em coming, thanks!

cutlassefi

True, but remember that the bb 400 has a much longer stroke, offering more low end torque right off the bat. He has a tall gear and no stall. I still believe the port velocity of the small block heads would be better served here.

Jmo.

Run to Rund

I'd talk to Jim Lapikas at J&S Machine. He has a 403 in the 11s at 114 mph and makes girdles, etc. for them.
http://www.jsmachineoldsmobile.com/PRODUCTS.html