dumb displacement question

[Guest Anonymous]

what is the largest cubic inch displacement engine that will fit in a 71 240z, i have a variation of engines that i found for cheap a 73-76 pontiac 400ci engine or a 73-76 pontiac 455ci, or im also considering a Big block olds engine. does anyone know if pontiac or olds are more reliable. oh yeah and have there been any big block 240;s before, thanks for the input

[grumpyvette]

the PONTIAC 455 is a FAR BETTER,STRONGER,AND CHEAPER ENGINE to build not even mentioning LIGHTER and smaller than that oldsmobile boat anchor (in case you have not got the answer yet) olds engines are weak,onless the bottom end is modified,(expensive to do) heavy,wide,expensive, and harder to get parts for

 

Olds V-8s weigh 620lbs- 760lbs

 

pontiac 428,455 640lbs

[Kevin Shasteen]

FWIW,

 

Olds engines are not weak-they are the beefiest blocks ever made by GM. In case anyone has forgotten-GM chose the 455 Big Block to build their first diesel. The gas converted big blocks were tooled to the small block internal spec's-yet it was actually the 455 block's outer dimensions. GM didnt use the Pontiac Engine, nor did they use the Buick Engine, nor the Chevy Engine for that diesel-they used the Olds engine; why, because it was the strongest block they had. Even tho it was a silly idea to attempt a Diesel from a gas engine-marketing isnt always an mfg's best friend; the Olds engine was chosen because it was the strongest block GM had at the time.

 

If you are referring to the Olds Oiling inadequacies at higher rpm's-then I agree; the Olds is weak in that area but not because it is weak. The oiling at higher rpm's is inadequate because of the block's 3" mains yea that's correct "THREE INCH MAINS", and must be modified to handle constant high rpm's above 5000rpms..as are most engines.

 

Also, the Olds cyl.heads dont flow as well: it doesnt mean they cant-it just means you'ld spend a lot less money if you went with what was already out there...such as the Chevy, Pontiac or Buicks-that tend to breath better: they have larger intake ports.

 

During the 80's GM chose the Pontiac blocks for their "Lightness" (weight saving) and good performance-their engines do breath well-and put them in their F bodies and just about everything else. The Pontiac engines also have "LONGER CON.RODS"...a definate plus. In an attemp to lighten the Olds engine-GM made the 403; it was a good engine-but had windowed main supports which is good for lightening the block but not so good for structural integrity when all out performance is an issue...if this is what is meant by "weak", then I agree: windowed main supports are stupid-yet the 403 was the only engine within the Olds line to get the windowed main supports.

 

Also as a reminder-it was Olds that GM tested for their Hemi heads-back in the late 60's/early 70's just prior to the Insurance Premiums Sky Rocketing & Unleaded Gas coming onto the scene-while Leaded Gas was history. As a result, the Olds Hemi's Heads were scrapped, yet Olds-still has a few of them in crates as memorabilia: some high perf.magazine will do a write up on them every few years.

 

The Olds cranks utilize 3" mains; both the Small Blocks and the Big Blocks-after their redesign from the late 60's; the only engine in the GM family to use the 3" mains-this is why their bottom end is brutally strong. The Olds engines are not weak-just ask Joe Mondello who has made a lifetime of proving his case.

 

As with any engine you wish to tweak-you have to know what the factory has available -vs- what will have to be custom made....for unknown reasons-GM has chosen the lighter blocks for their performance trends.

 

Timing is everthing-Pontiac/Chevy enjoyed the 50/60's muscle car days-so too did Olds/Buick-but not as much as the other two. GM concentrated more on Pontiac/Chevy more so for the late 70/80's: due to the popularity of racing and for Pontiac-you can thank the inspiration behind the GTO..."Jim Wangers". As for Chevy-they have always been GM's go to line: so, basically all Chevy from the late 80's up to now.

 

Olds has always been the car line that GM "experiments" with, then if that experiment has good results-then Cadillac or one of the other lines gets the face lift also.

 

If you wish to beef up an Olds (you will spend twice as much compared to other lines), but if that is your wish I'ld advice you to contact Joe Mondello-he not only sells his performance catalogue but also sells a "How To Modify" the olds blocks for maximum performance: he also sells a pair of Alluminum Cyl.Heads for the Big Block.

 

Yea, I like Olds-I've juse come to the conclusion that Chevy has more to offer the perf.oriented...and Pontiac is the next in line as far as the GM mfg's are concerned.

 

Anyway, just my .02's worth (Speaking as an ex-Olds fan that is).

 

Kevin,

(Yea,Still an Inliner)

[grumpyvette]

Kevin Shasteen

heres web sites that gives lots of olds info

 

http://my.en.com/~thall/olds/ofind.htm

 

http://www.mondellotwister.com/engine_blueprint.html

 

 

look closely at the main caps

olds engines have two bolt main caps, on this picture notice that the caps are milled and strengthening straps are used, this is common on olds engine builds when the engine is expected to build good power as the stock maincaps tend to be weaker than the chevy 4 bolt mains and most olds blocks don,t have 4 bolt maincaps,in fact a cap support system (like this)

 

is used if over 600hp is planned . now to be fair both the pontiac and olds engines can be modded to produce over 600hp but the pontiac will weigh less, cost less to build and has far more parts available for it.pick up any performance catalog and the first thing youll notice is that the parts for olds engines are rare, and expensive, in fact if your not building a chevy, ford or mopar that lack of parts and higher cost is to some extent true of most other V-8 engines. now Ive built several 442 (455 engines)over the years and they have massive mid range torque, but in each case the rod bearings gave problems when a good shot (250hp) of nitrous was used,the same EXACT system was swapped onto and used on a 455 and 467 pontiac engine with no problems

[Mike C]

Kind of a strange question since engine displacement has only a little to do with overall dimensions. ie a 426 Hemi is way too wide, but a 434 SBC fits easy...and both are $. I assume you mean just readily available OEM displacements? A stock Vortec 350 will run circles around a stock low compression Pontiac or Oldsmobile regardless of their displacement,(STOCK to STOCK)and this swap is well documented... Big block chevys can be had in displacements to 600ci with stock deck height, more with tall deck, but makes the install in a narrow car more difficult.

[Kevin Shasteen]

I'm familiar w/the components to strengthen the two bolt design. You said the rod bearings failed under a 250 shot of NOS "ROD BEARINGS" are we not talking about "lubrication" as in the oiling system?

 

I still dont think that implies anything as to weakness-it is a reference to the oil system that must be given special attention. Are we not talking about oil starvation...as in bearing failure-not component failure? Yes, the oil starvation will lead to component failure-but the cause of the failure is oil starvation; yes/no-tell me what you think. Are we not talking about "Sheer Induced Viscosity"? Lack of oil-not a weak engine component.

 

The Olds Con.Rod Journals are the size of Chevy's Main Bearings-there is a 1/2" more diameter to oil on an Olds Main and its Rod Journal than any other engine. If you plan on spinning the Olds higher than 5000rpms you have to give special attention to the oiling system....the girdle you mentioned is a requirement, blueprinting the oil pump, using oil restrictors in the mains and cross drilling the crankshaft: among a few other things.

 

Joe Mondello has proven over and over (If you want to spend the bucks) that Olds Big Blocks can be made to run at higher rpms w/dependability & durability-you just have to be willing to spend the bucks. He is much better at it than I-he has been building performance Olds blocks for dragsters...for decades.

 

I agree you that a four bolt block will have more support to the lower end than a two bolt block-but we arent talking about the structural support of the bottem end; we are talking about the "Oiling System"...so those bearings dont starve of oil during that 250 shot of NOS.

 

Just my opinion based on Joe Mondelo's research and proven track record; let us not forget the Speed Boat Big Blocks....Hemi's, BBC's & Big Block Olds...I have not heard of Big Block Pontiacs or Buicks in the Speed Boats(?). Doesnt mean there are not any-just means that Mopar, Chevy & Olds are the leaders in N/A speed boats: why is that?

 

I still agree with Mike C-why not go w/a SBC or SBF-it is a proven system w/very well documented steps along the way; if you want a higher displacement-then build a stroker.

 

Kevin,

(Yea,Still an Inliner)

[Guest Tht1KSguy]

Don't forget the Caddy 472/500's GM never made an engine in stock form that produced more torque and power. Change to an aluminum intake, add headers and you're within about 40lbs of a small block chevy. Being top of the line GM they went with a high nickle content block for low wear. With valvespring change they will happily live up to 5200rpm. Pocket port the heads and just general cleanup. I don't think i'd pick this combination for a Zcar mainly because there are already enough traction problems, not to mention room for headers. I'll be putting a 472 (because it revs faster w/ its shorter stroke) into a '59 Chevy wagon or 2dr whichever i can find first

[grumpyvette]

Kevin Shasteen

you could be correct about the lube system on the olds engines being the weak point, after building several (yes I talked to mr mondelo (or at least the guy that said he was mr mondelo), a few times when ordering parts in the early 80s)I gave up on olds engines. now I build 500 caddys,and 400-455 pontiacs regularly and 455 buicks occasionally so Im not against NON-CHEVYS in any way, and those buicks also have the 3" mains but Ive yet to have problems with them. Ive often seriously though about swapping a 500 caddy into my 1985 vette btw

[Kevin Shasteen]

Grumpy,

 

You got more experience than I do at building any engine & will trust your judgement. I also know Mondello is to Olds what Smokey was to Chevy.

 

I have wondered about the Buick Big Blocks myself-they arent that wide of an engine nor or they that long of an engine for a big block; and talk about torque down low!

 

All I am saying, about the Olds, is that they have not been given the "Performance Push" by GM that Chevy & Pontiac have enjoyed in the last couple decades; with the exception of Joe Mondello.

 

Just like you have developed many little trade secrets along the way for the engines you build-I bet you a $100 if I bet you $1 that Mondello has developed a few of his trade secrets he doesnt share w/anyone. The only way to get at those trade secrets would be to buy an engine constructed by him...can someone say $$$!

 

But like you-I gave up on olds due to the oiling system & cyl.head airflow inefficiencies....only wish I had given up on them in the 80's like you; instead I was just get'n going on Olds in the 80's.

 

Would a Caddy even fit in your Vette?

 

Kevin,

(Yea,Still an Inliner)

[grumpyvette]

will a 500 caddy fit in the vette? HELL YES, I dropped a big block chevy into my vette to test fit it last time I had the 383 out doing a rebuild, the big block chevy is a bolt in deal, the accessories and exhaust would be very tight but the engine drops in and bolts up just fine, the 500 caddy is slightly smaller and quite a bit lighter than a bbc engine so with custom motor mounts and a B.O.P trans it too would bolt in with slightly more room (about 3/4") the only real reason I don,t drop in the caddy is the resale value of the car would drop about 70% but the bbc is slowly getting built to drop in when and if the sbc ever blows