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Thread: Push rods

  1. #1
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    Push rods

    What size push rods will I need with hemi head cut 80,ss valves,55#springs,307nr cam?

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    You should be fine with stock length...

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    Lil Long Son

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    Quote Originally Posted by astrowrench View Post
    Lil Long Son
    I would think so too....

    Who has cut to fit push rods for this application?
    Would it be advantageous to use a GX160 lifter and an even longer pushrod if required ( with a milder cam of course )
    Seems to me I recall a briggs lifter could also be used but it is longer than the 200 ( not sure who said it or how it worked ).

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    5.175 will do the trick and yes a 160 could be used too.Lot has to do with lift of cam and how much off the head was taken.
    if still running a stock lift cam you could take .080 off and still be fine with stock length push rods but would not be the case
    if now going with more lift.

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    Which is why he should check before he fires it up!
    Now a Mod2 cam with a 1.3 rocker on intake comes to a .294 lift, not too far off a 307...

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    You have the 55lb springs installed in the head??

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    JMO but a little to much spring should be in the 37 range
    I run 356 with 32 and I know guys who run 26 with a 308

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    Please post a pic of the 55lb springs installed bc I have yet to see any done a hemi.

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    The head is at kart shop right now getting this done, why will the 55s not work they are enlarging spring pocket to accomadate? I will post pic when I get it back might be awhile

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    Quote Originally Posted by WinstonSmith View Post
    I would think so too....

    Who has cut to fit push rods for this application?
    Would it be advantageous to use a GX160 lifter and an even longer pushrod if required ( with a milder cam of course )
    Seems to me I recall a briggs lifter could also be used but it is longer than the 200 ( not sure who said it or how it worked ).
    Many parts dealers have cut to fit pushrods for sale.
    I like the longer lifters, shorter pushrods. Less pushrod flex.

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    55 lb springs is just fine won't hurt anything. I've been running 55's in my motors with 308 and stamped 1.2 rockers for years now with absolutely no problems, I keep the springs fresh too change about every 6 races and turn it 8200-8400 rpms. I've never run single springs in any of my motors, I'm running 60lb springs in my motor now with a 315 with arc 1.2's.

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    I guess that I've been thinking about this all wrong, I've been running the GX160 shorter lifters and cut to fit moly push rods from NR Racing,... thinking I was running components with less weight. jmo
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    Quote Originally Posted by Flash06 View Post
    55 lb springs is just fine won't hurt anything. I've been running 55's in my motors with 308 and stamped 1.2 rockers for years now with absolutely no problems, I keep the springs fresh too change about every 6 races and turn it 8200-8400 rpms. I've never run single springs in any of my motors, I'm running 60lb springs in my motor now with a 315 with arc 1.2's.
    You have 55lb on a hemi head?

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    Quote Originally Posted by youngengines View Post
    You have 55lb on a hemi head?
    No haven't got into hemi yet, I didn't know you couldn't make them fit before I said that sorry, but if you could put them in there I cant see why it would hurt anything anymore than a 6.5. I know on a 6.5 I've never had any problems with them.

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    Quote Originally Posted by Flash06 View Post
    No haven't got into hemi yet, I didn't know you couldn't make them fit before I said that sorry, but if you could put them in there I cant see why it would hurt anything anymore than a 6.5. I know on a 6.5 I've never had any problems with them.
    I wasn't trying to be mean, I hope it didn't sound that way. The problem I see, is the way I port (raise the intake port), it get's real thin at the spring pocket (the angle of the valve makes it that way).

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    I wasn't taking it that way youngengines I was being sincere not upset at all, I really have not peeked into a hemi much still playing with the 6.5 and haven't had the need to get into the predators.

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    Quote Originally Posted by Flash06 View Post
    I wasn't taking it that way youngengines I was being sincere not upset at all, I really have not peeked into a hemi much still playing with the 6.5 and haven't had the need to get into the predators.
    Cool, just making sure. I like the Predators, as well as 196cc's too.

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    Quote Originally Posted by older n dirt View Post
    I guess that I've been thinking about this all wrong, I've been running the GX160 shorter lifters and cut to fit moly push rods from NR Racing,... thinking I was running components with less weight. jmo
    If it works for you do it. I won't say you are wrong. I'm just saying what I have found out through many years of testing by the major cam companys. Lighter weight makes a big difference on the valve side of the rocker but very little on the pushrod side. Also larger pounds of spring and rates make the longer pushrods flex more.

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    So will 55s not work&why

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    Quote Originally Posted by Lowbudgetkarter View Post
    So will 55s not work&why
    Good question, I'de like to know too.
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    Quote Originally Posted by youngengines View Post
    I wasn't trying to be mean, I hope it didn't sound that way. The problem I see, is the way I port (raise the intake port), it get's real thin at the spring pocket (the angle of the valve makes it that way).
    I agree . I was worried about the thin base after cutting spring pockets for duels so I used longer valve stems and cut my own keeper groove. This eliminated the need to go deep, Just a bit wider..
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    Quote Originally Posted by LOUMAR View Post
    If it works for you do it. I won't say you are wrong. I'm just saying what I have found out through many years of testing by the major cam companys. Lighter weight makes a big difference on the valve side of the rocker but very little on the pushrod side. Also larger pounds of spring and rates make the longer pushrods flex more.
    I guess that goes to show, you're never to old to learn !
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    Quote Originally Posted by Lowbudgetkarter View Post
    What size push rods will I need with hemi head cut 80,ss valves,55#springs,307nr cam?
    on one of my hemi motors, with an NR Racing race head (milled .080), i used Raceseng Adj Push rods. i did not want to use the cut to fits and have to "creep" up on the measurement). I determined the length but marking the top of the lash cap with a dry erase marker... setting it close, using a length given to me by two trusted builders, rolling the motor over, with oil in it) and adj as needed.. geometry is good... (the length may be between 5.35 and 5.45, depending on how much has been cut)

    however if you choose to use the racesengs, make sure the area in the head, where the push rods go through is smooth. hard to describe so will post a pic... i broke the intake push rod, during a test and tune... just clearanced this and putting the head back on, right now...


    initially the rod kept adjusting itself... then i used blue loctite as was recommended.. this stop the rod from being able to turn and unscrew itself... however this also allowed me to see the issue (because the rod broke)...

    here you can see where the rod was rubbing on the factory casting, the right hole is the intake side, the exhaust side rubbed very little, I clearanced both to make sure


    and after i massaged it a little

  25. #25
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    Quote Originally Posted by LSCustoms View Post
    on one of my hemi motors, with an NR Racing race head (milled .080)
    the motor has the following (main mods):
    ARC Billet Flywheel
    ARC 6236 Billet Rod (3.595" X .490")
    11132P94 Wiseco Piston (2.756" X .640")
    Isky Black Mamba cam (275" LIFT 246 DURATION @ .050" 108 L.S.A.)
    26 lb springs
    NR Racing Hemi Head (milled .080, 28mm/25mm, retainers, etc)
    honda (silver) .010 gasket
    GX390 Carb, adj jet
    Raceseng Billet Lifters
    Raceseng Adj push rods
    and misc
    it likes 100 octane VP, but havent tried any other fuel... trying to get it to someone to dyno tune

    for pushrod geometry, tip
    http://www.youtube.com/watch?v=Cqx8Cs6O6Vo

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    I built a similar engine lil bigger carb & int.vlv and it runs Very Well.........

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    One of the first steps to a quality build is to remove casting flash and deburr.

  28. #28
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    Quote Originally Posted by Kart43 View Post
    One of the first steps to a quality build is to remove casting flash and deburr.
    this motor is as quality as i could build, sir. and quality parts as well... i am learning a ton as i go and doing my own building (so far). i purchased the head, new and done, from a reputable builder... sold the stock... just bolted it on and set the geometry... i did not want to mill, nor port the head myself and i would not have known to do anything further to the head, without the problem occuring... if i would have used cut to fits, im quite sure it would nt have been a problem, as far as the thickness... also the standard head wouldnt have presented a problem... there wasnt much info on the hemi stuff out and about... i did a complete write up on it, including prices paid etc and remain humble in any constructive criticism on anything done.

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