[ho428]

Originally Posted by Transporter

ho428, let me ask you this, just throwing it out there, I DO understand you wanting to run in that class if possible, but in all honesty in that type of racing I would think running the Pontiac which is probably the heaviest motor in that class at that small of a cubic inch, aren't you giving up quite a bit just on front end weight alone?

Would you not be better off moving UP to the largest CI combo (as Roger does) and run against the BB Vettes and Fords and Mopars?

I'm not looking at it from a power output equation, as much as I am a total power weight equation, I just think that you would be lucky to match what those small block 300 cube motors will put out, and then to add the extra front end weight, it just seems like a real uphill battle?

Not telling you what to do, or arguing, just asking about the big picture.

Back story is my old group that I've been with since 2010 had a pwr-wt ratio of 6.5:1, at my cars weight I could run right at 575 fwhp, ratios are rwhp dyno pulls. I'd been running a 407 that was way underpowered, (~8:1 pwr-wt) but did ok until some new guys came in with more power and lighter cars, so I started building a 433 to try and hit 6.5 and I've been taking weight out of the car.

That series hasn't been doing well lately and we're still trying to recruit more cars to keep it going, but to keep my options open I started running limited races with other Vintage Sanctions to test the waters, the only class my car fits into though is M/P-1, but those guys run 500+ cu in aluminum BBC pushing 850 hp, dry sump systems, in 200-300 lb lighter cars, mainly 69-70 Corvettes.
Rogers car could not even run in that class as they still must run period suspensions, engines are unlimited though.
In the M/P-2 class the cars are very similar to mine, a lot of mid 60's Mustangs and 67-69 Camaro's, but it has the 355 cu in limit and requires 15" wheels and bias tires. I run 17's with 13" Baer brakes and Hoosier R6's now, so I'll have to change wheels tires and brakes as well.
The T/A and A/S classes are the same period requirements but also require a 303 cu in engine.

So, I basically have this season to figure it out, if our OVR series can't get an influx of cars I'll be forced to change in 2017. This season I'll run with two different Vintage sanctions in two different classes through September gauging everything, after that if I have something figured out I'll pull the car down for a 6 month rebuild for hopefully one class in 2017 that crosses sanctions.

The M/P-1 class would be very difficult for me to build for and be competitive in, my pockets aren't that deep but it's not unthinkable.
M/P-2 I'd probably be mid pack with a Pontiac engine, might get lucky at a few events and run up front though. The regulars in that group have deep pockets as well, but that class is the easiest to build for.
In the T/A class I'm pretty sure it'd take years to progress my car up the ranks, but the class of cars is awesome and the pedigree it gives your car only enhances it's future value, and no one as far as I know is running a 303 Pontiac, what Pontiac's that do run I believe all run SBC's.

So far the options I like the best are:
1-Destroked 366 crank and aftermarket short deck block for a 355 for M/P-2
2-All aluminum std deck 4.35 x 4.0 475 cu in for M/P-1

Building the 303 looks like it'd be a royal PITA and still be at a disadvantage weight wise, especially if I ran the Iron heads.
Basically it'd be a full custom one off build.

[Rocky Rotella]

Thanks for the detail, Tom!

And by the way, that "no one" wasn't directed toward you. I meant when I called the crank companies no one could remember what owners/employees contributed what concerning the Pontiac forgings. As you noted, many are not even around any longer. Your explanation pretty much sums it up!

[Tom Vaught]

Originally Posted by ho428

So far the options I like the best are:
1-Destroked 366 crank and aftermarket short deck block for a 355 for M/P-2
2-All aluminum std deck 4.35 x 4.0 475 cu in for M/P-1

Building the 303 looks like it'd be a royal PITA and still be at a disadvantage weight wise, especially if I ran the Iron heads.
Basically it'd be a full custom one off build.

The 303 would be a PIA in my opinion and not that competitive.

Your options 1 and 2 both look like you have some opportunities.

Frank said that he only had one or two short deck cast iron blocks left and was not making more so #2 may be your only aftermarket block option after talking to him.

Tom V.

[tom s]

As long as we are off topic a little.Not all 366 blocks were the same even though they had the same casting number.Mine is missing the dry sump provision.I know of one right now that has it but does not have the joined lifter bores.I think there might have been less 366 blocks made than short deck 303 blocks.Tom

[Jack Gifford]

Originally Posted by Craig Hendrickson

... Gee that sounds familiar...

I knew it would- thanks for chiming in. Help me remember- were there some '56 forged cranks?

[ho428]

Originally Posted by Tom Vaught

The 303 would be a PIA in my opinion and not that competitive.

Your options 1 and 2 both look like you have some opportunities.

Frank said that he only had one or two short deck cast iron blocks left and was not making more so #2 may be your only aftermarket block option after talking to him.

Tom V.

I checked with the rules guy on M/P-2, it's actually 5.8L (max) which is 353.9 cu in, so technically even a stock bore Pontiac 350 is too big.
Once again they've stacked the rules in favor of Chevy and Ford, couldn't go to 6 liter and get Pontiac and Mopar 360's in...
Granted they probably wouldn't pump my engine unless I was outrunning the "in the clique" guys, but I'd feel better running legal.

I've talked to Frank, and Jeff, about their Aluminum blocks a month or so ago, but I needed to explore all the classes, rules and build options first.
I still like the idea of a short deck 350-ish engine. That could actually be a good performing combo and put me in a class with similar cars, just not easy to build.

[johnta1]

Even for that combo, I'd use the bigger bore like 4.12 (400) and a stroke like 3.25 for around 346 CID.

You need around a 4.x something bore so you can use a big valve head.

The RPM's shouldn't be a problem especially if you use the HP.

[tom s]

I think MR-1 has done a 9in deck.Tom

[Transporter]

If your limit is 353, then yes, the easy way out is the 400 with a real short stroke crank like Johnta1 said, I guess my question would be since you already have the 350 block, and I am pretty sure there is a lightweight 3.50 stroke crank available off the shelf, has anyone ever sonic tested a 350 block? Are they fairly thick cores?

Because a 1.25 over 350 block and a 3.5 stroke put you at 352 CI, with a 4.0 bore, I just have no idea on how far you could take a 350 out, I do know of 1.20 over 400's, so I guess it's not "out of the question" and would be a cheap build.

[ho428]

First pics are M/P-1
4th is M/P-2
Huge difference in speed and handling.

[ho428]

A/S and T/A cars

[ho428]

And my car.
I was allowed to run in T/A part of last year, but I can't stay there with my engine, wheels, tires and brakes.

[Craig Hendrickson]

Originally Posted by Jack Gifford

(snip) were there some '56 forged cranks?

The only two I personally saw were out of wrecked 1956 GMC armored trucks and they were forged. One was in the H-O Racing 326. The other was a never used spare because the first one never failed and we never had a bearing problem in that engine.

[ho428]

What is the minimum pin height that can be run?
Ok using a ring support but what's the minimum based on the CH and the ring stack?

[Tom Vaught]

The Mahle Piston guy told me that they have pistons for a NA GASOLINE application in the 1.150" range using the modern Millimeter dimensioned ring packages and a .927" chebby style pin.

Malhe or Diamond Racing in the Mt Clemens Michigan area both do a very short pin, (thick wall) X-Type racing style piston. CP Pistons are used by many NASCAR TEAMS and are a very good source for custom Pontiac Pistons. Several Pontiac Guys are running their stuff.

https://www.cp-carrillo.com/pt-3507-pistons.html

Pictures of CP Piston "X Pistons" attached"

Tom V.

[ho428]

While I'm waiting on getting information back on certain parts I did a little more net research on the 350 block 303 concept.
"If" we can grind that raw 366 crank down to 3.2 we can use a BBC 7.10 rod and a 1.5 CH piston with a 3.915 bore for 308 cu in.
Using my 65 cc KRE heads that flow 290 and have 2.07 and 1.66 valves we'd need a 10cc dome to hit 11.5:1, I could always send the heads back for a 310 port job. Need a good, innovative? solid roller cam profile.
But, other than the rod length this is pretty similar to the 4.8L and 5.3 LS.

I think we could hit over 500 hp using a carb and single plane intake, I'd feel better if we could get to around 575 though to compete against the sbf's though.
We'd need to spin this thing upwards of 7000+ rpms and while the 7.10 rod is a concern for rpm I don't think the 1.5 CH is too bad. Eagle list that rod at over 1000 hp so it should be plenty stout. Piston weight might could be worked on.