Will 496 heads and intake fit a 1992 OMC 454?

[miike]

Thanks,
Mike

[RedDog]

define "fit"?

[VetteLT193]

blocks are different and so are the heads. the bolt pattern is not the same

[Dr. David Fleming]

Some engines and their parts are developed from one generation to another. Small block Chevy has evolved but it is still the SBC - variety of heads. The Big Block Chevy has evolved from the 1964 creation to Mercruiser 502 - most heads and parts are similar if not interchangable - you have to know your years.

Occasionally they take out a blank sheet of paper and make an entirely new engine - this is the 496 - new modern and now that GM is downsizing - it is dead.

The cylinder heads you are talking about from the 496 have nothing to do with the 502 Big Block Chevy or the 350 Small Block Chevy engines.

General Motors in its infinite wisdom has created a number of V-8 engine families over the years with no parts interchangability. For example Pontiac made its own unique engine, so did Buick, and Oldsmobile. At any one time GM made 4 or 5 engine family lines with no regard to production cost, tooling, research and development or parts interchangability.

At one time they tried putting Chevy engines in Oldsmobiles and they got sued for using cheap chevy engine in the oldsmobiles - even though the chevy was a lot better engine folks thought they were getting cheated.

Finally after years of doing this they got on board with Chrysler and Ford who only had one or two basic generic engine designs - they made a Generic GM engine - the 496. But it was too late as the days were running out for big american V-8 motors.

The 496 is DOA - Long Live the BBC!

Your parts won't interchange, most people understand this and is the reason your question is drawing sarcastic responses.

[miike]

Yeah I figured 496s were a bit too different, but just to be sure, I'm going to take the heads into the OMC dealer and match up to the gaskets.

[VetteLT193]

if you are doing a rebuild check around for complete engines. you might be surprised to find something cheaper than you could build one for....

[Barry Eller]

Yeah I figured 496s were a bit too different, but just to be sure, I'm going to take the heads into the OMC dealer and match up to the gaskets.


There are 2 basic head designs if your engine is stock with original cast iron heads. A 1992 454 would be the GEN V version. Standard low HP version, such as 454/330 would have oval port heads. HO versions with more HP have the rectangular ports. That will be the only difference in head-gaskets matching. Of course be sure you get 'Marine' grade gaskets. Felpro makes good ones.

[Barry Eller]

The 496 is DOA - Long Live the BBC!

Your parts won't interchange, most people understand this and is the reason your question is drawing sarcastic responses.
And where is the sarcasm?

[Walt. H.]

The 496 is DOA - Long Live the BBC!
Your parts won't interchange, most people understand this and is the reason your question is drawing sarcastic responses.

And where is the sarcasm?
Yeah!
I was wondering the same thing myself, since we're all pro Chev power guys here.

Say Doc' help me out, when was the last time you read someone here suggesting a removal of a small or BigBlock Chev and replacing it with a small or B.B.Ford? :boggled:

[zelatore]

I thought the sarcasm was the 'define fit' comment?

Not insulting, but more of....well, sarcasm.

As for being a Chevy guy, I'll never consider myself a Chevy guy! Of course, in the boat I'll be sticking with chevy power just because it's easier and cheaper. So maybe, if push comes to shove, I'll admit to being a marine chevy guy. But only if you make me. :wink:

(from a guy who grew up racing Fords before switching to funny little furrin' cars)

[realbold]

As for being a Chevy guy, I'll never consider myself a Chevy guy! Of course, in the boat I'll be sticking with chevy power just because it's easier and cheaper. So maybe, if push comes to shove, I'll admit to being a marine chevy guy.
Dittos...if parts were as cheap and readily available I'd be runnin a Ford.

[Walt. H.]

Dittos...if parts were as cheap and readily available I'd be runnin a Ford.
But what about reliability?

Sorry not wanting to start a political engine manufactures debate but remember: HP to cubic inches and lasting reliability just because of better breathing heads and stronger blocks with four bolt mains and superior oil delivery, Big & SB Chev always had the Ford engine beat, especially going back to the late 60's & 70 drag race days.
Not to forget you could build two Chev's to run faster for what it would cost to build one good Ford, whether you compared a chev 283 to a Ford 289 or a 428 cobrajet or even a 460 to a 396/427 Chev came out on top without a sweat.
And hey now to confuse ya!
I even worked for a Ford dealer for almost 3 yr's back in the mid 70's and drove a Pontiac, of course I wouldn't own a new GM/Chev truck today anymore only a Ford or Dodge.
But getting back to boats, GM/Chev engines are the best all around bang for your buck, unless you're running outboard engines.

[Walt. H.]

Will 496 heads and intake fit a 1992 OMC 454?
Thanks,
Mike
Back to the original question asked:

You can put gen-IV & V heads on a Gen-V & Gen-VI block but not the other way around except for Gen-V (can not put Gen-VI 496 heads on a Gen-IV or V 454) even though they will bolt up aka fit, because you risk water getting into the block via valve gallery side of the head due to the larger water passage hole size difference in the Gen-VI heads leaking coolant directly into the vave gallery of the block.

[thehow33]

Since Walt H. answered the original question we can go back to the non-question post :wink:
On the marine side of engines I will go with a chevy every time. On the car side I'll take a 302 block any day, stroke it out to a 331, fuel inject it, and drop it in a mustang. (drag or open road). Not to mention 302's have a greater resource of aftermarket parts, which makes them cheaper so that also helps.

[Walt. H.]

I remember when a 331 was the ideal combo back in 1970 thru almost 74' by taking a 350 Chev block and destroking it with a 327 crank, Bill Jenkins aka Bill Grumpy Jenkins ran that combo in his pro-stock Vaga with 6-lbs per c.i and held that title against Soxs & Martin and Butch Leal's Prostock 426 Hemi Cuda's with a 7-lbs per c.i. weight bracket.

And for factory production built hi-perf cars the 1969 Z-28 Camaro with the 302 hi winding small block H/P monster, was accomplished by taking a 327 block and running a 283 crankshaft.
With 4:56 or 4:88 gears you could pull the front wheels off the ground right out of the showroom. WooHoo!

[BUIZILLA]

327 +.030 is a 331....

that's what they ran, since the 350 had the large journal crank, and the 327 was small journal, and the 331 revved to the moon..

[VetteLT193]

I thought everything was large journal starting '68. Super rare small journal 350's were made in 1967. so you could have a large journal 327 from say, 1969, or a large journal 350 from 1969 and make a 331 out of either of them and have the same engine in the end.

What's the difference in using small journal Vs. large journal to make a 327 or 331 in power? I wouldn't think it would be that much different.

[BUIZILLA]

What's the difference in using small journal Vs. large journal to make a 327 or 331 in power? I wouldn't think it would be that much different. I've never seen a small journal 350, at least that I can remember..

less bearing *surface area* on the small journal allows the engine to rev faster... and rev it did.... I had a couple 327-365 engines that would rev to the moon faster than you could push the peddle down..

[VetteLT193]

I've never seen a small journal 350, at least that that I can remember..

less bearing *surface area* on the small journal allows the engine to rev faster... and rev it did.... I had a couple 327-365 engines that would rev to the moon faster than you could push the peddle down..

gotcha, surface area makes sense.

350 small journal... look at 1967 Camaro SS with the 350... super rare.

[Walt. H.]

I've never seen a small journal 350, at least that that I can remember..

less bearing *surface area* on the small journal allows the engine to rev faster... and rev it did.... I had a couple 327-365 engines that would rev to the moon faster than you could push the peddle down..
If I remember correctly?
350 with a narrow 6" harmonic balancer had a two bolt main and small journals crank, where as the 8" fat balancer version had 4-bolt mains and large journals. But you know the ProStock guys and anyone else that took their engine work seriously used the 4-bolt main block of course and after market forged steel cranks, but after 35 yr's i'm forgetting the outfits that made those stroker & de-stroked cranks.
One company I think was Jewel crankshafts?

[BUIZILLA]

I think the older balancer was a thin 7".. i've got one here somewhere..

i've also got a FACTORY 283-283 dual quad intake..

and a set of 348-409 heads, w/ complete tri-power intake and carb setup..

[Walt. H.]

Hah ha !!
would you believe I too have a 67/68 427 tri power alum manifold complete with a triangle air cleaner less fuel line hardware and a dual quad pontiac offy alum manifold for a 65' and newer 326/389/421 pont eng and some othe misc parts.

[mrfixxall]

67 and down had the small journal rods,and remember they also had pressed on balancers with no bolt to keep them from flying off,remember the old trick to drill and tap the crank for the harmonic balancer bolt :)

Walt, if my memory is correct the 67 tripower 427 intake were different then the 68,425 hp vs 435 hp due to hood clearance in the corvette's

[Walt. H.]

You're correct' 67' 427/435 tri-power was hi-rise while the 68' 435 tri/p was flat-rise alum including the low perf hyd round port 427/400hp.
While the same lo/perf motor with a Rochester quadrajet was rated @ 390 hp.
===================================
My bad I don't recall any SBC balancers being held only by a press fit w/o a crank bolt, but I do recall having most comp machineshops honing the balancer so that you could pull it off almost by hand for easier quick access on and off especially to change cam timing via excentric deg cam bushing until you were content with tuning.