[Johnny406]

I'm doing a little research/information gathering for a company that may seriously consider bringing a new forged crankshaft to market as well as some hybird connecting rods that I believe our hobby can really use.

Crankshaft: Forged Steel 4" stroke, 3" Main, 2.20 BBC Rod journal

Connecting Rod: H-beam rod Pontiac length 6.625" .980 pin with a BBC 2.20 rod journal

This crankshaft would be more feasible to produce as it will fit both those who wish to use longer connecting rods and this hybird connecting rod would allow others to use off the shelf Pontiac pistons in our builds for both 4" stroke and 4.21" stroke combinations.

Whether you love or hate this idea or couldn't care less, please be professional and courteous. I'm conducting this poll here because I believe that we are the potential customers and and are far more dignified and sincere than a Facebook group.

[25stevem]

If this comes to fruition I hope that the cranks rod journals get made with the lesser width needed for the BBC Rods as opposed to Pontiac Rods so that the excessive side clearance can be brought into spec to stop excess oil that these conversion's always have kicking around.

[Scott65]

Ditto that ^ And yes I'd be interested.

['ol Pinion head]

Am very interested in a 3" main, 4.00 stroke forged crank.
a 2.25 rod journal would however allow to duplicate another offset ground 4.00 stroke build using same rods.

[Sirrotica]

I always liked the 4 inch stroke Stratostreak engines, more torque that the 3.75 engines, but not having the FPS piston speed of the longer stroke engines. That was the platform I used in my last oval track engines.

It seems when the 4 inch forged cranks become available, they sell out first, then you only have the 455 stock stroke, and longer available in forgings to choose from.

Not to mention the 421 and 428 engines only were made from late 1961 until 1969 so a much lower production window to pull used cast cranks from too, add to that it was an extra cost option over the 3.75 engines.

I have never built one, but always wanted to start with a .030 over 455 block (440), and use a 4 inch crank in it with round port heads, cast iron, or aluminum. Sure you'll have more torque with a 455 or longer stroke, but hooking one of the long stroke engines with street tires is not easy, they just incinerate the rear tires.

When I ran autocross, it was always a struggle to hook a 455 car, a 400 was much easier to transition out of turns into a straightaway with out lighting the tires up, and consequentially slowing your lap times. I never did run a 4 inch stroke engine in autocross, but would have liked to. 428s are much tougher to find than a 455 core is, and a 421 buildable core, is like looking for hens teeth. Having a BBC rod opens up a whole lot more rod bearing availability in standard size, and undersized bearings, and rod choices.

Definitely interested in a 4 inch crank with rods to compliment it. Be nice if the parts were made here, but that might be a big ask in todays economy. I believe that more 4 inch stroke Pontiac engines would be built if there were more 4 inch stroke cranks available, JMO.

[tooski]

I am considering (mostly dreaming) of doing a 4" stroke (433 ci) for a bit more torque for my heavier car. I would go with a forged crank. Off the shelf forged pistons instead of the costlier custom racing pistons would be a plus. Also same with the rods. The Pontiac H beams rods tend to be a bit more expensive than the BBC. Then again if the added cost of the forged crank can be handled, why worry about a few extra bucks for rods n pistons.

[jhein]

I would have probably gone with a 4" stroke forged crank for my build if it were available.

[Dragncar]

I hope you get it done.
I sold a Scat 4" stroke 2.20" journal crank for 600$ years ago. Kicking myself for it now.
If you could get it done with a fully counter weighted crank lots of people would buy those. In 4.25 and 4.5" too, they would sell IMO. Takes a billet to get that for Pontiacs . You can buy a fully counter weighted crank for a BBC for under 2K. People would pay that for a Pontiac version.

[adamo]

I have been looking for a 4” stroke crank with Pontiac rod journals for a long time. Even considering turning down the mains on a 428 crank .

[Formulajones]

https://butlerperformance.com/i-2445...tegory:1234870

I'd rather have the 6.7" rod.

[tom s]

I would want pontiac rod Js.Tom

[Half-Inch Stud]

I'm in for Crank and rods. We need affordable Forged slugs for this deal.

[PAUL K]

There are readily available 6.635 BBC dimension rods out there that can be used to connect a Pontiac style piston to a crankshaft using a Chevy rod journal. The Pontiac style piston has to be honed for a .990 pin and it opens up your choices for a specific wrist pin for the job at hand.

Years ago crank suppliers couldn't sell the 4" stroke cranks so a lot were discontinued. Nowadays the interest for the 4" crankshafts has seemed to increase.

[1_Wild_Cat]

There is a 4” stroke forged crank in my near future. I’ve noticed here and in the Pontiac community in general that 4” stroke engines get a lot of support - but often people seem to change their plans when the crank isn’t available.

[hgerhardt]

You might want to update the title of this thread:

"Research Poll on a new 3" stroke 4" main forged crank and hybird steel connecting rod"

And, yeah, good idea to get this crank made. It's still my favorite stroke. Not so much torque that you can't hook it up, and also likes to rev, which is where the HP comes from. My 434 sounds and runs awesome at 6500 rpm!

[Johnny406]

Originally Posted by hgerhardt

You might want to update the title of this thread:

"Research Poll on a new 3" stroke 4" main forged crank and hybird steel connecting rod"

And, yeah, good idea to get this crank made. It's still my favorite stroke. Not so much torque that you can't hook it up, and also likes to rev, which is where the HP comes from. My 434 sounds and runs awesome at 6500 rpm!

I ran out of room

Thank you for your input and for all of those who have chimed in. I think it would me for an ideal bracket motor and even a real good power adder combo.

[hgerhardt]

Originally Posted by Johnny406

I ran out of room

You didn't see it: your title says 4" main and 3" stroke.

[b-man]

Edited the title.

[Johnny406]

Originally Posted by hgerhardt

You didn't see it: your title says 4" main and 3" stroke.

I also typed 4.20 instead of 4.21 stroke (455 Pontiac) on the first post as well.

[Elarson]

The best market positioning would be to make enough meat on the forging that it could be machined to a range of strokes and rod journals.

FWIW,
Eric