[oldman]

Yep one of the biggest bore shortest stroke engines made. so revs are up. It is strange to me (I know the block is shorter) maybe the 350 head has different exhaust port shapes or locations, why did Olds NOT put the 455 semi branced, port separated exhaust manifolds on the Ram Rod? I guess they figure that almost everybody would be adding headers anyway so why bother. Was the last version of the engine with the same size but aluminum intake. I remember watching Nick's garage and from memory Nick could not find an aftermarket aluminum intake that put out as much HP as the cast iron one, even though it had larger ports and smooth and newer design... Have to go back and look at that one.

One thing I will say about the 340, Mopar has a really big cam bore so for any given lift a much smaller 340 cam in duration, has more effective lift and duration because the larger lobe / lifter size combo gives it a distinct advantage and still OEM wear life. So the 340 can produce decent HP from a cam that is just a tad bigger than most OEM's regular gas, everyday 4 bbl engine. That means a 340 and actually the 440 can support an A/C. Important if you live n Texas.

[rocket403]

I tried out both a 69 cast iron non EGR intake and the Edelbrock Performer RPM intake on my 403 and with 11:1 compression the RPM intake made the engine more responsive.

Friend on mine is running a 425 Olds with 454 chevy pistons 440 mopar con rods and a custom forged crank with Edelbrock Heads and air gap intake over 700hp and torque

[rocket403]

With the overbore the engine is 519ci and 1100hp with 400 shot of NOS

[oldman]

This is a mild 350 310 HP build it has a little more cam and a little more compression basically making it a Ram Rod 325 HP engine.
384 stp bhp with stock intake (miss match to a square bore Holley)
391 with performer RPM, much nicer and flatter dyno.
Too bad a stock Qjet could not be found, the stock intake may have pulled 400 BHP!!! from a "small block"

[rocket403]

I'm running Forged TRW pistons Crane Cam with 510 lift 1.80 Roller Rockers 2.07/1.625 valves 69 heads 64cc chambers 2004r Trans 2800 stall. It is built way past what any W31 engine would be at.

I never had it on a dyno but plan to pull it apart to rebuild it. I have picked up a forged 330 crank and plan to beef it up again but pull some compression out of the build to run just 94 fuel

[oldman]

I would hate to lose the cubs, the engine is way oversquare already. The stock cast crank is probably stronger than you think, esspecially with the stock stroke. While in general I would agree that a smaller engine with the same breathing will make similar HP numbers, a 455 is a whole lot bigger and large stroke engines have a fast piston speed which does a lot for feeding an engine. So yes the smaller engine can spin higher but can it spin 30% higher to make up for the piston speed, and even then it is injesting a lot less air. Nutshell keep the 350 crank, run ligheter rods and maybe even a cast piston hyperuthetic. The car itself is beautiful, I like Olds from 1968 to the 90s actually... That is far longer than I liked most cars. But who knows I had a Gremlin in HS with a 304 V8, then got a 390 out of my sister's Scrambler, put the 1970 heads and fancy exhaust manifolds on it from an AMX, the only car I know that could take N50 outback with minimal mods... It was green and air burshed "road toad"... was petty fast, not as fast as my 440 Dart that I got in college. Never could afford an aluminum manifold for it so it was all cast iron: intake and exhaust... oh and it had side pipes...

[rocket403]

I went with the biggest SBO that way all the brackets for the air conditioning were not an issue, also with the BBO in an 80 Cutlass you have to modify the air conditioning housing to clear the rocker cover. I will stay with my 403 in that car but when I finally find the 70 Cutlass I'm looking for I will Go with a 455 or 425.

With the Heads I have had a lot of work done they were flowing 245 or 255 on the bench if I remember correctly I had a lot of material taken out.
I was thinking that the Forged crank from the 330 would be much better than the Nodular 350 crank that I have in the 403.

[oldman]

Yes, that is what I'm saying the 350 already gives up a lot of stroke and needs to make it up with rpm, I would not give up 20 more cid for a crank. Cast is plenty strong check for cracks and make sure the fillets are good and your golden. Must Ford 351 were cast crank despite what the factory claimed. The 4v Cleveland is like the Ram Rod 350 with big flow for a small block. Even the Mopar 360 was cast so were most AMC 360s. Yes it is a 350 but your stroke is heck of small more like a Chevy 327, lots of guys reving cast cranks. I'd just keep the reciprocating weight down, H beam rods and maybe a cast hypereutectic piston. I realise you maybe using the 403 block, but we are talking cranks. So no 350 or 403 outside of the diesel came with a forged crank? Anyway I would be comfortable with the small stroke cast crank (350 / 403).

From memory most of the following engines have a cast crank: Ford 429 / 460, Pontiac upto 455, Buick upto 455, AMC upto 360, Olds upto 455, all inclusive were all cast cranks. I believe on the 429 SCJ had a steel crank, same for Pontica the Ram Air had steel, just about everything else had a cast crank. Heck AFAI the Buick 455 had a cast crank.

Here I found this, even the 455 Super Duty is cast:
https://www.pontiacdiy.com/pontiac-v...ormance-guide/

My bad, I just noticed the 330 has the same stroke... sorry for the confusion (my bad). I is interesting to note that outside of Chevy, most OEM don't use forged cranks.

[rocket403]

Great thing about SBO is that they all have the same stroke so my 403 with a .30 over is a 409 I think so there is no penalty for using the 350 or 330 cranks. The only issue that I will have going to the 66 330 is that they have a different bolt pattern for the flex plate so need to find a pre 68 unit and balancer.

[oldman]

looks like the 403 has very weak mains, can the 350 be punched say to 375? I've headed the block is super thick.
did you find the 70 1/2 supercar article with the w31 road test?

[rocket403]

In the Supercar article they stated their test car didn't have the ram air hood so it could not have been a W31
But it did have 4sp 433 gears with W27 rear. It would be a 310hp engine unless it was a mule or a special order car that had the 325hp engine

[rocket403]

Here is the article

[rocket403]

All Olds Engines after 76 were window mains, the 403 had some other issues that the other Olds engines didn't have, the bore of the cylinders was so big that they were Siamese cylinders and could only take a .40 overbore. With all these issues unless you plan on over 600hp and a rev limit into the 7000rpm range the 403 will stand up to the abuse, I had my engine built in 99 and have had many years of abuse with this setup.

I know on some Olds engines that they can have a huge overbore my friends engine was built from a 66 425 block I had it took a 145 thou overbore to take the 454 Chevy piston. I had 2 425 blocks and we had to check both blocks to see if they could take the bore. The 67 425 would not take the bore.

The Olds 350 will not take a huge bore but if you start with a 350 diesel block you can have it take a 455 crank and take it out to 400 plus CI.

[oldman]

Thanks for the article. I have most of the hi-performace car magazines. I also have the book Day One by Schorr, and Muscle Car Confidential by Oldham. The basically wrote about and tested these cars. Anyway the company had on had a stock W31 engine and put it in a 350 310 HP olds, in fact it maybe the same Olds which yep was a 310 version that they added headers and dyno tuned, then shoved a 325 HP ram rod engine in with headers, maybe for this year the added in a W37 and fiberglass hood? and tested it again. From memory their olds had 3.9 gears and they were talking about 4.3s. I would agree that functionally it would perform like a 1970 w31 (assuming 4.3 were an option with the W27). The article is by its very nature short. So they did not go into all the details, safe to say it was a "shop built" close. Probably with headers as I highly doubt they took them off between articles.

Looking at the pictures, I'm 98% convinced this is thier long running test car and the picture of under the car shows a standard 12 bolt. So they must have (just like they did with the RamRod 325 HP) order a dealer installed W37 rear with 4.3 gears into their test car. Their long running test car also had the same shifter and it had a scatter shield and schiefer clutch / aluminum flywheel and lack wood scatter shield.