Can I use slightly longer push rods than stock on 454 Gen V?

[CLi87]

So I had several bent push rods due to seized valves so I bought a full set on ebay that supposedly came from an 89 454, which should be the exact same push rod as the part #'s are the same for the push rods between the 89 454 and my 93 454 Gen V, but upon examination both the intake and exhaust push rods are just a tiny bit longer than what I have, my intake push rod is 8 3/16" and the one I got is 8 4/16", same with the exhaust, mine is 9 3/16" and the ones I got were 9 4/16". Do you guys think it would still be ok to use these or will I have running problems?

 

[Scott06]

@Scott Danforth or @alldodge will likely know what fits /doesn't and what big block have adjustable valve train

 

[alldodge]

Wait scratch that, you are changing gens?

 

[alldodge]

Under normal conditions, of a hydraulic lifter, a 1/6 variation is not an issue. The lifter them selves have more lee way then a 1/16

 

[Scott Danforth]

So I had several bent push rods due to seized valves so I bought a full set on ebay that supposedly came from an 89 454, which should be the exact same push rod as the part #'s are the same for the push rods between the 89 454 and my 93 454 Gen V, but upon examination both the intake and exhaust push rods are just a tiny bit longer than what I have, my intake push rod is 8 3/16" and the one I got is 8 4/16", same with the exhaust, mine is 9 3/16" and the ones I got were 9 4/16". Do you guys think it would still be ok to use these or will I have running problems?

GM part numbers are not the same for the Mark IV motor and the Gen V motor

go to NAPA, get the right push rods

 

[jimmbo]

One of the risks of buying on fleaBay

 

[CLi87]

Wait scratch that, you are changing gens?

No, I'm rebuilding the top end of my Gen V

 

[CLi87]

GM part numbers are not the same for the Mark IV motor and the Gen V motor

go to NAPA, get the right push rods

Are they not the same part #?

MERCRUISER - 7.4L BRAVO (GEN. V) GM 454 V-8 1992-1996 - CYLINDER HEAD AND ROCKER COVER(7.4L BRAVO) | PerfProTech.com

Find your CYLINDER HEAD AND ROCKER COVER(7.4L BRAVO) diagrams at PPT using our MERCRUISER parts catalog.

www.perfprotech.com

That's the parts diagram for my Gen V by serial # and it shows part #75589 and #75590

MERCRUISER - 7.4L BRAVO GM 454 V-8 1988-1991 - CYLINDER HEAD AND ROCKER COVER | PerfProTech.com

Find your CYLINDER HEAD AND ROCKER COVER diagrams at PPT using our MERCRUISER parts catalog.

www.perfprotech.com

Parts diagram for an 89 Gen IV also shows the same part #'s for the push rods. However when I lookup the specs on the push rods it shows that the measurements on mine were correct and the ones I got were wrong by 1/16".

 

[alldodge]

ok, should be good

 

[Scott Danforth]

Are they not the same part #?

MERCRUISER - 7.4L BRAVO (GEN. V) GM 454 V-8 1992-1996 - CYLINDER HEAD AND ROCKER COVER(7.4L BRAVO) | PerfProTech.com

Find your CYLINDER HEAD AND ROCKER COVER(7.4L BRAVO) diagrams at PPT using our MERCRUISER parts catalog.

www.perfprotech.com

That's the parts diagram for my Gen V by serial # and it shows part #75589 and #75590

MERCRUISER - 7.4L BRAVO GM 454 V-8 1988-1991 - CYLINDER HEAD AND ROCKER COVER | PerfProTech.com

Find your CYLINDER HEAD AND ROCKER COVER diagrams at PPT using our MERCRUISER parts catalog.

www.perfprotech.com

Parts diagram for an 89 Gen IV also shows the same part #'s for the push rods. However when I lookup the specs on the push rods it shows that the measurements on mine were correct and the ones I got were wrong by 1/16".

No, they are not the same part number

your motor is a GM 454 Mark IV. push rod diameter is 3/8" length is 9.252 and 8.280"

the Gen V uses 5/16" diameter and 7.850 and 8.873

the Gen VI uses different length. 8.569 and 7.592 " https://www.chevrolet.com/performance-parts/components/engine/big-block/pushrods

 

[CLi87]

No, they are not the same part number

your motor is a GM 454 Mark IV. push rod diameter is 3/8" length is 9.252 and 8.280"

the Gen V uses 5/16" diameter and 7.850 and 8.873

the Gen VI uses different length. 8.569 and 7.592 " https://www.chevrolet.com/performance-parts/components/engine/big-block/pushrods

Wait my motor is a Gen IV? I thought 93's were Gen V? and I have the flat torque rockers, no adjustment nut, I thought that was a Gen V feature?

 

[Scott Danforth]

1965-1990 is Mark IV
1991-1995 is Gen V
1996-2000 is Gen VI
2001-2008+ is Gen VII

Crate motor 454's 502's are Gen VI

 

[Scott06]

Wait my motor is a Gen IV? I thought 93's were Gen V? and I have the flat torque rockers, no adjustment nut, I thought that was a Gen V feature?

Motor year and boat year are two different things

 

[snowbrd84]

No, they are not the same part number

your motor is a GM 454 Mark IV. push rod diameter is 3/8" length is 9.252 and 8.280"

the Gen V uses 5/16" diameter and 7.850 and 8.873

the Gen VI uses different length. 8.569 and 7.592 " https://www.chevrolet.com/performance-parts/components/engine/big-block/pushrods

Could you possibly point me to where you pulled that Gen V length info?