What would you guys think a running 403 might be worth on the open market? It is listed for $300 and comes with everything. It is up for sale on craigslist and I'm thinking of making the drive to pick it up.

It would end up replacing my 350 in my Cutlass. (Which I haven't even fired up yet! But 53 cubes is 53 cubes.) It is out of a '79 T/A if that makes any difference.

sb

 

If you can hear it run, then go for it. The motor purches and accys bring some good coin. You may be able to recoupe some of your investment.

 

Yes 300 for a complete is a fair price. Now a 350 or 403 can be built to have plenty of power. What you want to check when looking at this engine is the casting numbers. The number should be one of the these.
557265
553990
554990
Next the heads will be 4a on the engine.
If non of these match up with what engine has on it. I would hold up on buying it. The best thing you can do is look on the Tech page and print out casting numbers so have them with you when look at the engine. It might not be a 403 might be something better. So I would have all the info that you can to know what your buying.

 

Need some help with head ID. Example: the heads on my 350 say 716. What heads are those? In regard to 4a 5a etc...I don't know what those are..

sb

 

The number/letter is on the front of the head, behind the alt. right by the spark plug hole. A 350 came with 5,6,7,7a,8,3A.

 

If you already have a SBO 350 then why do you want a SBO 403? I don't think the displacement will make that much difference if you are going to rebuild the engine anyways. $300 does seem like a decent price though.

 

I guess its like this:

I dig slant six mopars....so I have a pile of those in storage. I build those, and collect them as people pull them out and throw in V8s. Granted I wouldn't pay $300 for one, but people give them away.

I have a 350 and a Cutlass. I'd like to build one from scratch...the 350 I already built, but its essentially stock. I got it off Craigslist as well, but it was mis-assembled. I fixed that, and will hopefully fire it off soon. So not really built, rescued from stupidity.

Now, for $300 comes a complete running engine, that I could build to my specifications that happens to be 53 cubes larger than the current one.

For now, it would be the beginning of my SBO pile.

Or I could wait it out and start a BBO pile......those just don't seem to pop up as often. And I am not the only one out there looking.

sb

 

Hey 80, where abouts do you live? (state) Sounds like we've got something in common... I'm building a 403, and my dad is the president of the /6 club...

 

Personally I'd stick to the 350

 

I had a 1975 350 in an 80 with a TH350 and 2.29 gears. I raced a 78 T/A with a 403 and I'm guessing 2.56 gears. I beat him and he was just a tad pissed.
Just because there are 57 more cubes it doesn't exactly equate to a more powerful engine.

 

Granted. However, equally built the 403 SHOULD be more powerful than a 350. Or am I missing something here?

Hey 80, where abouts do you live? (state) Sounds like we've got something in common... I'm building a 403, and my dad is the president of the /6 club

I am located in So. Texas, just a bit south of San Antonio.

The same stubborn outsider mentality that led me to /6s is probably what caused me to want to stick a SBO into my 84 cutlass instead of SBC like my old man tried to get me to do. Well, that and I couldn't find a 455!

So why, in particular, do some of you prefer the 350 over the 403? Windowed mains? Other factors?

sb

 

People like the 350 because there easier to find. The heads on the 403 are not the best. Most people use 350 heads on 403 some even use bbo heads on them. Yes the 403 has the biggest piston of all Olds engine, but use a crank with same stroke as a 350.

 

All things being equal that would make sense. But I believe he may be looking into just dropping in a running 403 (but I could be wrong), and if so might be disappointed with the end result.

Now if he's looking into a mild build with some early 350 heads on the 403 then yes, I'd agree with you for sure.

 

I agree with Randy. If you are going to do some work on the 403 then you can really "wake it up." If you just want to drop in a running engine then stick with the 350.

 

The #'s "403" are casted on the sides of the block. I would buy it. I had heard all the bad stories about the 403 when I got one in a deal. It was a ready to assemble .030 over. Because of all the "Olds folklore" about thier "fraglie-ee" windowed mains I did put a J&S Machine (309 361 0907)"halo" gridle in it. I used all odd-ball parts I had laying around, stock #5 small valved heads, used .496/.512 cam, stuffed in a $200 Regal with a $400 posi 3:73. Long-story short, I beat it for 3 years, the heads were the limiting factor. 12:96 @ 104.85, wrong intake, wrong cam, wrong converter but one of the most fun and "cheapest" engine/car I ever had. Because of the limited flow of the heads, I had to shift it early, 5300 and it came through the traps at 5150. It went over 6000 because of a shifter problem with-out hurting it. I still have it, I'll have to dig it out one of these days. So, to wrap this post up, I would buy it. Every engine has it's limitations, keep them under 6000. I had it up the Miller meet one year and 3 or 4 Olds oiled down the track but none were 403's. I think the Halo girdle is a good investment also. Now I have stirred up another hornets nest. Some people don't like 403's or Halo girdles but it worked for me. Plus it's a bolt-in for a 307/350. Just My Opinion, nobody has to agree me. Ken

 

Are the 716 heads worth messing with? That is what I have on my 350 right now.

Hope the 403 is still there. I'll call him this weekend.

sb

 

You need to look by the #1 spark plug for a large cast number. We do not know the heads by the 6 numbers cast into the head near the center exhaust ports.

 

They are 3a heads.

sb

 

77-80 350. I have those heads on my 78 350 in my Delta.