Bluedane

Have a blown 350 rocket in my 72 cutlass, found a nice 403 below. Will this bolt up and/or will I have to make any other mods? I read conflicting accounts. I also have headers and read they will match up as well? Any help is appreciated!

Feedback on the engine is also appreciated:

77 Olds 403 from a trans , completely rebuilt, new internals, punched out w custom forged flat top pistons, performer rpm camshaft. adjustable roller rockers.1972 350 heads, with all new oversized valves. old school Offenhouser dual carb intake. twin edelbrock carbs. progressive linkage, flame thrower ignition. all arp bolts. over 3 grand into build. has about 200 miles on it. runs good, with pistons and heads it's about 11-1 comp. runs on a higher octain fuel, great street rod engine.http://postimg.org/image/sf2off9xz/

joe_padavano

The 403 is externally identical to the 350 (and every other small block Olds), so this is a completely bolt-in swap. All 350 manifolds, headers, accessory brackets, mounts, starter, etc. bolt right up to the 403. The only difference is that the original 403 heads would only have five of the ten valve cover bolts drilled and tapped (it was a cost-savings measure). You can still install early ten-bolt covers using only five of the bolt holes.

As for the particular engine in the ad, is that what you really want? The flattop pistons and early small-chamber heads definitely push the compression ratio into the high 10s or 11:1, as noted. You won't be able to run this on readily available pump gas. The only dual-quad intake available for the SBO is the single-plane Offy, which is not my first choice for a street engine. This likely will not be an easy motor to run on the street. Your call if you want that or not.



Personally, I'd replace the 1972 heads on that motor with some BBO C-heads, yielding big valves, better flowing ports, and a street-friendly 9-ish:1 CR. Mill the heads a little for mid-9s. Use an E-brock Performer RPM (ported to match the BBO heads) and that will be a very nice motor for a Cutlass. I'm guessing that the asking price on this 403 probably precludes spending additional money on it, however.

Bluedane

Good to know it will bolt up. I am looking for something to just cruise around town so I think its what I want. Hes asking 2500 for it which is the best deal I have found so far for a complete drop in engine, professionally rebuilt. For gas, we have 93 on every corner so I think I will be ok with that unless there's something higher that I havent seen?

RetroRanger

I think what Joe means when he says "You won't be able to run this on readily available pump gas." is ....You won't be able to run this on readily available pump gas, that means 93 as well. you would likely need race gas or av gas to run this engine without pinging. The BBO heads are easily obtainable and would tame this motor down to run on 93 or less , but the single plane dual carb setup can be finicky and likes to run at high rpms not the typical cruising on the street set -up.

these guys are right in TX

http://www.ebay.com/itm/GM-Oldsmobil...item3a8606d8d0

I know nothing about them but they appear to offer what you need and are close( enough) by you, all you would have to do is swap your already known good working components on this long blck and install

Bluedane

Thanks for the link, I have been looking for a local builder. Like the warranty too.

I'm obviously out of my league with this stuff. I'm trying to get the best thing I can for $2,500 since the shop is going to charge me $800 to install it. I have teetered between buying the block and transferring some of the stuff from my 350 (heads, cam, crank, etc?) but the shop told me without taking the block apart they dont know whats in it and/or what the damage is. $100 here, $800 there -- for sanity purposes I want to just lower something into the damn car and bolt it in!

I do have some heads on my 350 that may work with this 403 so that may be a way to save some $ to make it feasible to drive around town without having to fill up at the airport. I have a Demon 750 but its been hard for people to adjust so I dont know. ***** this is all a pain in the ***.

Bluedane

Another option $1500 and I can donate the leftovers. But does it blow up before I get home like the last one... http://atlanta.craigslist.org/atl/cto/5138627374.html

smash72

Why not look for another 350 ? There pretty available I wouldn't mess with that particular 403 for a cruiser. The guys probably selling it cheap for the same reason.

Cman7713

So just curious where that pic came from of the 403, there is a guy selling a 69 Cutlass in Illinois with the exact same picture for his sale ad.

http://chicago.craigslist.org/wcl/cto/5132362228.html

1969 Oldsmobile Cutlass S, Built olds 403 offy intake, dual edelbrock carbs. auto trans, factory 12 bolt posi, Black bucket seat interior with console, tilt, Cragars with Mickey Thompson tires, Wilwood brakes, ladder bars. Flowmaster exhaust with electric cutouts.both bumpers are new. grills new. asking price is a lot less than what has been invested so far. $12,000.00. Pos trade on a 1967-68 Camaro.1966 1967 1968 1969 1970 Nova, Please leave a message, Thank you. 815-
do NOT contact me with unsolicited services or offers

joe_padavano

It's from the link the OP put in the very first post.

bccan

That 403 seems like a good bargain IF it doesn't have issues.

Does it run on 93?
Does it have any cooling issues?
Why does it have 200 miles on it & up for sale?
Is it near enough to you to check out in person?

As long as the short block is built soundly you can swap the intake if there are any issues w/ the dual quad and if you have to tame the CR it could be done @ a later time by whatever means necessary.

Any details you can add might help people here give you opinions.

1BOSS83

FWIW- I can empathize as my $3,500 build is well over 5k at this point with "drop in " radiators that didn't fit, surprise leak in the intake manifold, 3 different starter combinations etc. etc. I've resigned myself to the attitude that unless you have Bill trovato on speed dial nothing is going to bolt right in. I scored a nice running 350 for 500 bucks and still tore it all the way down because the fact is you don't know what you have in that 403. It's my understanding the the mains and cylinder design of 403's can create overheating issues, I'd imagine a 11:1 403 puts off some serious heat. Also, $800.00 to put in a new motor sounds very cheap, I paid 1,000 in labor at the local speed shop and I'm still pissed at the job they did.

Octania

That is a lot of compression, as others have said.

Have you priced 100+ octane fuel lately? Around $6 a gallon last time I ck'd, which was a while ago.

You may be able to run that motor on PUMP gas aka 93 octane or lower with #8 large chamber heads and another intake.

What's wrong with fixing what you have again?

I have a drop in [ish] 403 with much tamer compression but it's a bit of a drive from you in central MI

Bluedane

I got a 455 see thread in engines section
QUOTE=Octania;849324]That is a lot of compression, as others have said.

Have you priced 100+ octane fuel lately? Around $6 a gallon last time I ck'd, which was a while ago.

You may be able to run that motor on PUMP gas aka 93 octane or lower with #8 large chamber heads and another intake.

What's wrong with fixing what you have again?

I have a drop in [ish] 403 with much tamer compression but it's a bit of a drive from you in central MI[/QUOTE]