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Rod question
Looking to purchase a stroker crank for a 400 block what rod journal pontiac or bbc
Looking for 550 hp natural w/ a small hit of nitrous 150 or so Thanks |
The smaller then stock diameter of the rod journal that you get with a aftermarket crank really only helps out if your planing on spinning the motor up over 7200 or so.
What matters more is the how you can change the center to center spec of the rod itself. Stock is 6.625” A longer C to C such as 6.800” will ease the loading of the lower part of the cylinder bore and help to reduce piston skirt scuffing . This helps to lessen friction and the rocking of the piston around BDC which can cause poor ring seal. |
How much of a stroker will drive rod length much of any stroke longer than stock BBC rods are the way to go just by shear fitment off the shelf options and quality rod availability
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4" stroke
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There are no 2.25” pin diameter aftermarket 4” cranks available anywhere. If you don’t have a factory 4” crank your stuck with the 4” crank with 2.20” BBC pins. Molnar made some 6.635”BBC H beam 2.2” rods with Pontiac .98” wrist pins for standard 428 Pistons. You would have to check with them or a supplier for availability. Otherwise you will have to use a 6.8” rod and a .990 pin piston with an 4” aftermarket crank.
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Molnar is who I would like to buy from.
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I have no problem using the bbc rods but would that setup require custom pistons?
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Will do thanks
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If Molnar is on your short list, I don't think you will get any push back from anyone. IMO, Tom Molnar's parts are a large step up from the typical Chinese stuff out there. They are spot on dimensionaly, only requiring checking before installation.
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I still have a 4" built with 3" mains and 2.25 rods "P Dude" got made before all the forged cranks came out.And some 6.8 Crower Sportsmans with a Pontiac journal I got from Paul Spotts years ago.
I bet any difference in a 6.625 rod vs 6.8 is going to be theoretical. It was used to have an available rod before we had Pontiac forged rods out there other than Carillo and Crower billets. |
Did my homework and they came out on top
I am now looking for a Pontiac savvy machine shop Len Williams or maybe Westside in Houston I am in no rush the motor in the car now has less than 1k miles I live in Houston but don't mind a road trip |
I've used Westside before for a couple of motors, taking a block and some heads there in a week or so. They have a dyno there also.
Kleat there has a guy selling a 880+ HP Pontiac motor fully built |
the 4" stroke, 3" main crank i got on the shelf is pontiac rod.
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Molnar has had both Pontiac 2.25 RJ and 2.2 BBC RJ available for 4” cranks.
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Yes I saw that
I was just wondering at the level of build was there any advantage or disadvantage to using pont or bbc rods Thanks for the info |
There are more bearing options for BBC RJ’s, more length options, and available styles.
Overall though, A .175” longer BBC rod and a .050” smaller RJ will not have any effect for what you want to do in terms performance or dependability. |
I do like options
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I figured at the hp I am shooting for it would be to close to really call
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