[Half-Inch Stud]

4.84" BS is all about fitting a larger slug. So, I propose going for LARGE slugs in the order of 5" to 6"' and geez, make a PMD 6CYL GM V6 style. Large intake valve and 1000HP NA will be typical.

[J.C.you]

LSM will whittle out any bore spacing you want, with any engine (ala pontiac, chebby, mopar, etc.) design features intergated together. Wet or dry.

[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

[Tom Vaught]

First, All of the point made by the members are good ones.

Second, Pontiac Motor Division is Dead and the Traditional Pontiac Engine has been dead since 1979.

Third, no one will spend any new money on Pontiac Engine Research. I read the common remark often: "If your gonna change the block and heads, intake, crank designs, you might as well just build as BBC, Ford or Mopar."

Fourth, Pontiac designed a GOOD Engine. As Engineers and Racers kept pushing the limits of the design there were more failures. Ken Crocie made a good point that in some cases, a normal Pontiac Engine would have a gasket failure in the field. I believe that. Most sharp Mechanics and Engine Builders came up with fixes to get around the issues. As we move into the Boost world more and more we will have to understand the current design limits of the Boosted Engine. I think that Travis and Rodney have a good start in this area.

Just pointing out in this post that you can't really blame Pontiac for having a inferior design when the design dates back to 1955 and the changes have been really minimal over the years vs the other guys making many updates over the years. The LS-X being a good example vs the SB Chebby.

Tom Vaught

Agree completely Eric, as I was typing my reply I see you posted.

[Elarson]

My previous post wasn't meant to disparage anyone's projects, although in looking back, I think my "Nuts" category reads that way. I'm all in favor of anyone doing anything that makes them happy. Apologies.

Eric

[Dragncar]

"Nuts" is OK.
We all have to be kind of nuts to try and race a obsolete engine that has been out of production for 30+ years.
Hey if I would have won the Megga I would have built that 1970 427 SOHC Hemi( and a lot of other things too). Plenty would have called me nuts. But I would have had the money to be crazy as as goose and sleep well at night.

[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

[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!!

[cfmcnc]

We have an IA2 block with 4.660 bore spacing,it will be 4.435-4.444 bore and will work with a standard crank,any more spread and the crankpins will have to be moved.Heads will be welded and relocated Tigers.Bill C.

[455Grandville]

I've seen SBC 400s run in circle tracks with as little as .215 thou (.060" overbore) between cylinders hold up well and those were siamesed cylinders.

Ideally IMO you do want space inbetween cylinders but I've seen them run well damn near kissing each other ?

[cfmcnc]

.170 between cylinders on NHRA Prostocks.Bill C.

[PONTIAC DUDE]

Originally Posted by Dragncar

"Nuts" is OK.
We all have to be kind of nuts to try and race a obsolete engine that has been out of production for 30+ years.
Hey if I would have won the Megga I would have built that 1970 427 SOHC Hemi( and a lot of other things too). Plenty would have called me nuts. But I would have had the money to be crazy as as goose and sleep well at night.

Nope. Just buy that Sonny's 1000 cu.in. B.B. that's out there in development & production.

[242177P]

Originally Posted by Tom Vaught

... and now the Racers have reduced that dimension over the years to .270"!!!!!!!!!!!

PMD was in that territory in 1968, when they moved the "big valve" chamfer in the bore. The bore might have yielded .410, but the deck surface...
Trying to measure off of two angled surfaces with a dial caliper is like herding cats, but ~.260 for what it's worth.

[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.

[BruceWilkie]

BTW

IMO going to a 301 deck height block you really dont need to raise the cam tunnel. Its already same place as our standard deck and I dont think you could run a stroke long enough to require it with the short deck height. More material for roller cam bearings would be a plus though. Big advantage to shorter deck is shorter lighter rod and good compression height on the pistons to cut recip weight. Cast in bosses to accomodate 6 head bolts would be nice as well. Shorter deck allows intake design that has shorter runners which favor higher rpm. A smaller main journal would be a plus but I think with oil path improvements we could get by with a 3" main.

I think its time we went LS huntin'!

[Milepost]

Originally Posted by BruceWilkie

BTW

IMO going to a 301 deck height block you really dont need to raise the cam tunnel. Its already same place as our standard deck and I dont think you could run a stroke long enough to require it with the short deck height. More material for roller cam bearings would be a plus though. Big advantage to shorter deck is shorter lighter rod and good compression height on the pistons to cut recip weight. Cast in bosses to accomodate 6 head bolts would be nice as well. Shorter deck allows intake design that has shorter runners which favor higher rpm. A smaller main journal would be a plus but I think with oil path improvements we could get by with a 3" main.

I think its time we went LS huntin'!

I agree Bruce. Main reason for raising the cam tunnel is to allow a 60 MM roller cam core. Extra head bolts should be pretty easy to add (like the Mopar R3 blocks). 3" mains are probably okay up to 8500-8800 RPM but 2.5" mains and priority main oiling would allow us to hit 10,000+rpm without major oiling problems. BTW a 3.75" stroke / 4.350" bore = 446". Add some 510-520 cfm "pro stock" style heads and watch the BBC crowd cry foul!!