[fiedlerh]

I believe Pontiac bore spacing is 4.620
Mfr Bore Spacing
Packard 5.000
Cadillac 5.000
CN Blocks 5.000
Ford 4.900
Chevrolet DRCE 4.900
Chevrolet 4.840
Oldsmobile DRCE 4.840
Mopar 4.800
AMC 4.750
Buick 4.750
Ford 4.630
Oldsmobile 4.625
Pontiac 4.620

[Craig Hendrickson]

Originally Posted by fiedlerh

I believe Pontiac bore spacing is 4.620
Mfr Bore Spacing
Packard 5.000
(snip)

You bring up a good point that I was talking to Tom Vaught about tonight.

The Packard V-8 was brought out the same year as the Pontiac and Chebbie, i.e., 1955. The Packard was a very physically large engine that was "designed" to eventually be bored/stroked out to 500CID. As it turned out, the largest production displacement was 374CID in 1956 and there was a 1957 prototype extant that was supposedly 440CID.

Another interesting point between Packard and Pontiac is that John Z Delorean worked for Packard from the late 1940s until sometime in the early to mid 1950s. He was primarily a transmission engineer, but he certainly would have seen Packard's plans for their V-8 while "hanging around" the engineering department.

There are other similarities between the Packard and Pontiac V-8s such as the center Siamesed exhaust ports, a separate valley pan, Delco electrics, etc. I once had a conversation with Pete McCarthy about these similarities, which Pete explored, and he came to the probably correct conclusion that there was no "cross intellect" going on between Packard and Pontiac during that era despite Delorean's mutual employment.

If Packard had continued beyond 1956 and "fixed" some of the design problems with their V-8 then no doubt it would have been one of the outstanding wedge valve V-8s of the early 1960s. It certainly had the ability for large displacement, but then again so did the Caddy 500CID.

It's all moot at this point, but thanks Tom for bringing this subject up.

[john marcella]

Tom,
You know as well as anyone that building race motors is about manipulating every part and component of the engine to just shy of its yield point. It will always be this way.
And those are the people that will be fast.
You go 4.800 BS and there will be a 4.600 bore in it.

If you want bigger bore spacing you can buy that, and it comes with way better parts for making power as a bonus. BUT IT WILL NEVER BE A PONTIAC. JMO

[PONTIAC DUDE]

Originally Posted by john marcella

Tom,
You know as well as anyone that building race motors is about manipulating every part and component of the engine to just shy of its yield point. It will always be this way.
And those are the people that will be fast.
You go 4.800 BS and there will be a 4.600 bore in it.

If you want bigger bore spacing you can buy that, and it comes with way better parts for making power as a bonus. BUT IT WILL NEVER BE A PONTIAC. JMO

X 2

If your gonna change the block and heads, intake, crank designs, you might as well just build as BBC, Ford or Mopar.

Makes no sense to start over with a lot higher cost to build an engine that no longer is a Pontiac motor division engine externally. Already did the BBC stuff for 18 years and have built a few 572 BBC's that fly, make more hp cheaper to do then an equivalent Pontiac cost wise.

Now playing with what is available and making cubes that live, make hp and torque. That's where the interest should lay.

So who has the info to stretch the existing bores with std inline heads. As to my question above.

[J.C.you]

Originally Posted by PONTIAC DUDE

X 2


So who has the info to stretch the existing bores with std inline heads.

With what is available a head porters version head would have to be used to move the stuff over, or cut the head and move the stuff over and reweld.

Or...... one could take a brand x head and make it work.

[BruceWilkie]

Originally Posted by john marcella

Tom,
You know as well as anyone that building race motors is about manipulating every part and component of the engine to just shy of its yield point. It will always be this way.
And those are the people that will be fast.
You go 4.800 BS and there will be a 4.600 bore in it.

If you want bigger bore spacing you can buy that, and it comes with way better parts for making power as a bonus. BUT IT WILL NEVER BE A PONTIAC. JMO

While I agree with Tom if you are going to go after the big ci motors we need more bore.

I tend to agree with you John it changes everything. IMO it would be better to make revisions to deck height(our 301 deck height and maybe a deck between standard and the 301) and maybe main/rod bearing size and concentrate our efforts on competing with the big inch LS motors.

Most of us I think, fit the "sportsman" category and when you really look at things the LS seems to be on top in that category. I think we would do well competing there with the right changes and could still retain our "Pontiac" heritage. Classic inline heads, RA5 configuration. Warp6 or the upcoming CV2 configuration(both of which really amount to revised RA5 heads) or a revisit/redisgn of the old M/T hemi heads for those that want to go a bit beyond the traditional head configuration would be ok to me.

I kind of like the potential of a 301 deck height in a 400 to 450 ci configuration.

[gene simmons]

So what happened with Lynn's wider BS block?

[Elarson]

Tom: all of your dimensional discussion is spot-on. Bore spacing is the single most important basic parameter for engine potential. But in my humble opinion, I see (3) distinct engine building philosophies:

Passionate Poncho - this camp likes the idea of using the 4.62 stock bore spacing because it is unique and takes greater creativity to make power. Prime example....Rodney & Travis run a 6.27 "with one hand tied behind their back" and it's way cooler than using a more generic race motor. Based on what's in my garage, I fit this category.

Serious ET - this group wants to make big power any way possible; to the limit of their checkbook. There's already tons of purpose-built race engines parts for 4.900. 5.000, 5.300, etc. bore spacing that will make big power with already-proven parts......with the development costs already absorbed by somebody else. In my mind, these purpose-built race motors aren't BBC's.

Nuts - spending 6-figure development money to make another wide bore spaced engine (in the same range as what's already available) just to be able to pretend it's a Pontiac. If I had lottery money and was going to develop a wide bore space motor, I'd do something that hasn't been done before...like 5.500".

JMHO,
Eric

[Milepost]

[QUOTE=Elarson;

This group wants to make big power any way possible; to the limit of their checkbook. There's already tons of purpose-built race engines parts for 4.900. 5.000, 5.300, etc. bore spacing that will make big power with already-proven parts......with the development costs already absorbed by somebody else. In my mind, these purpose-built race motors aren't BBC's.


Yep. I'd call Sonny's, write a check for $80K and have him build me one of these 1600HP - 727 cu in 5.3" B.S. SUPER WEDGIES. Bet he'd throw in a set of engraved "Pontiac" valve covers for free! LOL... Then I'd go home, crack open a cold one and call it a really GOOD day!!

[Milepost]

Originally Posted by BruceWilkie

IMO it would be better to make revisions to deck height(our 301 deck height and maybe a deck between standard and the 301) and maybe main/rod bearing size and concentrate our efforts on competing with the big inch LS motors.

Most of us I think, fit the "sportsman" category and when you really look at things the LS seems to be on top in that category. I think we would do well competing there with the right changes and could still retain our "Pontiac" heritage. Classic inline heads, RA5 configuration. Warp6 or the upcoming CV2 configuration(both of which really amount to revised RA5 heads) or a revisit/redisgn of the old M/T hemi heads for those that want to go a bit beyond the traditional head configuration would be ok to me.

I kind of like the potential of a 301 deck height in a 400 to 450 ci configuration.

X2!
IMO I like our "tweener" Bore Spacing. We still have a long way to go with our present configuration. Before we look at the expense of going to a bigger bore we need to "fix" what we have first. Things like shorter deck blocks, priority main oiling, smaller main size, raised cam tunnel, etc... Look guys, the Aussie Pro Stocks are running 400 cu inch NA small blocks with a 4.4" bore space and are making 1100+HP using SB2.2 and SC1 canted valve heads on the improved versions of the old school blocks! I am not aware of anyone running competitively with the NEW SCHOOL LS stuff down under as of yet. An improved 440-450 cu inch Pontiac should be capable of making 1300-1400Hp NA with good "PRO" heads. There is absolutely no good reason that reasonably priced"sportsman" bracket stuff can't make a 1000Hp NA and 1300-1500Hp with NOS. The added bonus is it fits between our fender and frame rails!! IMO... The very first priority is the Pontiac race community needs to stop all that "endless cylinder head wars" bickering and work together to keep Pontiacs competitive against the Chevy and Ford camps. The next priority is to get the sanctioning bodies to change class rules and recognize that our "tweener" engines are not BIG BLOCKS and give us realistic weight breaks..... Outlaw 275 & Milan would be a good start. Just my

[slowbird]

Originally Posted by Milepost

An improved 440-450 cu inch Pontiac should be capable of making 1300-1400Hp NA with good "PRO" heads. :

Now that would be really impressive, 3.1hp/cid is getting it done NA.

[john marcella]

Originally Posted by slowbird

Now that would be really impressive, 3.1hp/cid is getting it done NA.

Im pretty dam sure 3.1 has never been done N/A with a 2 valve head. With anything at any CID.
With a Pont-good luck with that