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#1
07-04-2025, 09:26 AM
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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 |
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#2
07-04-2025, 10:56 AM
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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.
__________________
Wernher Von Braun warned before his retirement from NASA back in 1972, that the next world war would be against the ETs! And he was not talking about 1/8 or 1/4 mile ETs! 1) 1940s 100% silver 4 cup tea server set. Two dry rotted 14 x 10 Micky Thompson slicks. 1) un-mailed in gift coupon from a 1972 box of corn flakes. Two pairs of brown leather flip flops, never seen more then 2 mph. Education is what your left with once you forget things! |
| The Following User Says Thank You to steve25 For This Useful Post: | ||
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#3
07-04-2025, 01:56 PM
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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
__________________
........... The More You Follow The Herd The Less You Can Be In The Lead .......... |
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#4
07-04-2025, 04:18 PM
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4" stroke
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#5
07-04-2025, 07:45 PM
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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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#6
07-04-2025, 07:51 PM
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Molnar is who I would like to buy from.
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#7
07-04-2025, 08:02 PM
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I have no problem using the bbc rods but would that setup require custom pistons?
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#8
07-04-2025, 08:06 PM
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Quote:
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| The Following User Says Thank You to Jay S For This Useful Post: | ||
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#9
07-04-2025, 08:15 PM
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Will do thanks
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#10
07-05-2025, 07:57 AM
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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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#11
07-05-2025, 09:59 AM
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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.
__________________
Skip Fix 1978 Trans Am original owner 10.99 @ 124 pump gas 455 E heads, NO Bird ever! 1981 Black SE Trans Am stockish 6X 400ci, turbo 301 on a stand 1965 GTO 4 barrel 3 speed project 2004 GTO Pulse Red stock motor computer tune [email protected] 1964 Impala SS 409/470ci 600 HP stroker project 1979 Camaro IAII Edelbrock head 500" 695 HP 10.33@132 3595lbs 1964 Corvette Coupe 327 4 speed |
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#12
07-05-2025, 10:13 AM
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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 |
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#13
07-05-2025, 12:30 PM
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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
__________________
Skip Fix 1978 Trans Am original owner 10.99 @ 124 pump gas 455 E heads, NO Bird ever! 1981 Black SE Trans Am stockish 6X 400ci, turbo 301 on a stand 1965 GTO 4 barrel 3 speed project 2004 GTO Pulse Red stock motor computer tune [email protected] 1964 Impala SS 409/470ci 600 HP stroker project 1979 Camaro IAII Edelbrock head 500" 695 HP 10.33@132 3595lbs 1964 Corvette Coupe 327 4 speed |
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#14
07-05-2025, 02:00 PM
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the 4" stroke, 3" main crank i got on the shelf is pontiac rod.
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#15
07-05-2025, 03:40 PM
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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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#16
07-05-2025, 05:13 PM
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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 |
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#17
07-05-2025, 06:29 PM
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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. Last edited by Jay S; 07-05-2025 at 06:34 PM. |
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#18
07-05-2025, 06:35 PM
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I do like options
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#19
07-05-2025, 06:37 PM
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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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#20
07-05-2025, 08:19 PM
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Quote:
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