I am running a 'Smokey and the Bandit' 403 in my 68 Malibu. the engine has less than 30,000 miles and runs great. It pushes a bone stock TH400 coupled to a 308 single traction rear end. This combnation won't burn out tires on launch but it digs in real nice and for a street car, it feels great around town. These old 403's crank out only about 230 ponies and 340 foot pounds of torque. I wonder if I can get the same or better out of a crate small block??

A "Targetmaster 350" can make 275HP pretty easily with a Qjet, dual plane intake, long tube headers, etc, even more if you swap out the came for a modern one with the same lift figures. Targetmasters are cheap too. I'm not sure how the torque compares to your 403 though.

But if I were buying a GM crate, it'd be one of the 300+ HP versions. Small Block crates can easily do the same or better than that stock 403.

That said, if you're going to have to buy headers, brackets, pulleys, water pump, intake, distributor, etc, since you're swapping for an Olds(?) engine to a Chevy, you might as well get an affordable BBC and blow both the crate SBC and the 403 clear out of the picture in both HP and TQ.

I hope I don't offend any Chevy guys here by tallking about an Olds motor. I do currently own a '66 Chevelle, but I was a Pontiac guy before and have owned several Firebirds and T/A's. I remember reading an article either on the First Generation Firebird or the National Firebird & T/A web site about the Olds 403. For not too much money (less than $1000) they had a formerly stock 403 putting out over 400 horses on pump gas (no blowers or turbos). Since it is not a big block it can rev up pretty high and be an impressive performer. The Olds 403 is a nice strong motor and may be worth holding on to. Check those sites out. It may help.

Vince
'66 SS

The main problem with the Olds 403 is that to save money on metal, GM windowed the crank main bulkheads so that part of the block is relatively weak when compared to all the other 400 up to 454/455/472/500 GM big V-8's!

Great B/S ratio and it should wind very well IF the crank, rods and main bulkheads can take the extra rr's which I don't think they can..

Sorry, but in it's stock application, it is a great motor, imho..

I figure GM did this knowing full well it was not going to be around very much longer!! Kinda like the 7.6 to 1 CR, 455 Pontiac V-8!!

Shame, shame, shame on GM..

pdq67

Thanks for the info, especially Vince and pdq67. I think I will try to get a set of headers that will fit and keep the 403 for now and up my exhaust from 2" to 2 1/2". I get way more attention car night at at A & W than the small block Chevelles, because the 403 is so rare.

403's are rare? How much do they go for? If they're rare, my local junkyards are probably goldmines, and nobody even pulls those engines!

I think what he meant is that right at the end, there weren't many big V-8 motors installed in cars so you don't see many of them..

Rare motor, no, not really.........

pdq67

Rare in a 68 Malibu though... :)

David

i once saw a '68 chevelle someone had put an old 60's 390 caddy engine in. to get it to work, they had to cut out the firewall. it was just shameful. i'd say a '68 with a 403 olds might just be one of a kind. incidentally, my transmission guy has a pretty well built 403 in a '77 cutlass dyno'd at 440 horsepower without really trying that hard.

If you want to build a nice strong 403 Olds and are concerned about the lightened block strength, start with one of those giveaway 350 Olds Diesel blocks. The Olds 403 has a 4.35" bore whereas the 350 has a 4.06" bore. Stroke is the same at 3.39". My ’77 Olds 98 was powered by a 403. 185 net h.p. @ 3600 rpm; 320 lbs/ft. net torque @ 2000 rpm. Building a 403 inch version of a W-31 could be a lot more interesting.

Now that you mentioned the 350" Diesel block!!

Yes, it can be bored like a 1/4" over and then by adding a reworked 425" motor's crank, you can come out with something like a 440" or 450" motor!

Very good combination for an Olds, but pricey vs our motors..

pdq67

Don't overlook the heads on the 403 either. Olds dropped compression by using heads with bigger chambers instead of dished pistons on the 403. If you can scrounge up a pair of 70-72 heads from an Olds 350, they'll do wonders for your 403 the way it is. You'll just need to open up the head bolt holes a bit though, the 403 uses larger diameter bolts.

FYI, the olds 403 IS a smallblock. To really wake it up you need aftermarket heads.

Semantic's here is all b/c a 403 is REALLY a "low-deck" standard Olds big-block, imho...

And right, even Olds calls it a SB motor...

pdq67