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Pushrod Length with Hotcam and 1.6 RR's

This is a discussion on Pushrod Length with Hotcam and 1.6 RR's within the Performance forums, part of the General Discussion category; Alright,I know some of you guys are running the LT4 hotcam with the 1.6 rockers.What length pushrods did you end ...

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    Pushrod Length with Hotcam and 1.6 RR's


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    Alright,I know some of you guys are running the LT4 hotcam with the 1.6 rockers.What length pushrods did you end up using?
    DD: 1989 Taurus SHO
    Project:1995 ECSB,Auto-5 speed manual conversion,Vortec 357,LT4 Hotcam

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    Re: Pushrod Length with Hotcam and 1.6 RR's

    Going by your sig I think you have a vortec engine.If thats the case then the Hot Cam should not be different then your current cam as far as push rod lenght.If your heads haven t been milled then the stock 7.2 lenght is fine.
    Last edited by 383TBI; 09-19-2010 at 06:08 PM.
    87 Chevy Shortbed -383 ,serpentine belt set up,vortec heads,Lt4 HotCam,Edel 2912 inatake,Holley TB,Gm 80lbs Injectors,
    stock ignition with MSD coil,700r4 Probuilt Autos shift kit,still tuning with EBL

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    Re: Pushrod Length with Hotcam and 1.6 RR's

    Quote Originally Posted by 383TBI View Post
    Going by your sig I think you have a vortec engine.If thats the case then the Hot Cam should not be different then your current cam as far as push rod lenght.If your heads haven t been milled then the stock 7.2 lenght is fine.
    Thanks for the reply.Yeah I forgot to mention the motor is a 355 vortec and is going to replace the 350 TBI in my 95.
    Hopefully the short block will be completed tomorrow,I'm shooting for 10.5:1 CR so I may have to take some material off the heads depending how far down the hole the piston is...
    DD: 1989 Taurus SHO
    Project:1995 ECSB,Auto-5 speed manual conversion,Vortec 357,LT4 Hotcam

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    Re: Pushrod Length with Hotcam and 1.6 RR's

    there- a--re entirely too many variables to make any kind of guess on that. deck height, the position that the cam bearing bores were machined at, variations in the base circle of the cam, head gasket thickness, thickness of the deck of the heads, position at which the rocker arm studs were installed, valve stem length, the amount of material taken off of the valve face during valve grinding, the amount of material ground from the seat in seat grinding, the depth of the valve seats (as in the case of the 906s with hardened seats)...

    if you really want to know pushrod length, assemble your longblock, color the tips of all 16 valves with a marker, install and properly adjust all 16 rockers, and rotate the engine. if the areas of the colored seats is not centered on the valve tips, then you need to worry about adjusting pushrod length. what will work on one engine, may blow the valve guides out of the next.
    77 Chevy K20 - 80 GMC K2500 (in pieces)
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    Re: Pushrod Length with Hotcam and 1.6 RR's

    I understand the variables involved in valvetrain geometry,but I was trying to find a shortcut around doing it the correct way lol.

    Screw it,I'm ordering a length checker...
    DD: 1989 Taurus SHO
    Project:1995 ECSB,Auto-5 speed manual conversion,Vortec 357,LT4 Hotcam

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    Re: Pushrod Length with Hotcam and 1.6 RR's

    Any machine shop in your area will have a push rod tool. When building an engine, one of the last things you order is the push rods since the engine must be put together in long block form in order to get the correct length push rods. Whatever you do, dont guess or use some internet math equation to get the length. Do it right or you will be doing it twice

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    Re: Pushrod Length with Hotcam and 1.6 RR's

    Update...

    Pushrod length for my setup came out to 7.25".

    I just ordered some trick flow hardened chromemoly pushrods and some other odds and ends to finish this motor off.
    Next weekend I'm installing an EP381 fuel pump to feed the new engine and I'm looking about three weeks out for the engine install.
    DD: 1989 Taurus SHO
    Project:1995 ECSB,Auto-5 speed manual conversion,Vortec 357,LT4 Hotcam

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    Re: Pushrod Length with Hotcam and 1.6 RR's

    Also,I'm using tall cast aluminum valve covers for centerbolt heads.With standard body summit roller rockers there is only slight interference between the rockers and bolt guides,0.010 inch shaved off the valve cover guides would probably work.

    If any of you guys have tall aftermarket valve covers and are using guideplates,you don't need to spend the extra coin on narrow body roller rockers.
    DD: 1989 Taurus SHO
    Project:1995 ECSB,Auto-5 speed manual conversion,Vortec 357,LT4 Hotcam

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    Re: Pushrod Length with Hotcam and 1.6 RR's

    Another update...finally got the engine installed after many delays and hiccups along the way.
    First off some specs on said engine...357 cid with vortec heads 10.44:1 scr with an lt4 hotcam and square bore single plane intake being fed by 80 lb/hr injectors @ 27 psi.initial timing is at 4* Btdc.
    I'm surprised;not only at the night and day difference,but at how well this engine runs with no tuning except for changes in fuel flow rate,base timing,and cid constants.
    Steady cruise is effortless and rolling into the gas from a stop makes you feel what the engine is really capable of and how quickly this engine gets the truck up and moving.
    A couple issues I've noticed with this setup is the engines refusal to idle without a huge lope and a slight bog under tip-in...both of which should be easily rectified by upping the idle speed and adjusting AE/PE after I get the fueling in line.spark advance will be dialed in on a chassis dyno.
    DD: 1989 Taurus SHO
    Project:1995 ECSB,Auto-5 speed manual conversion,Vortec 357,LT4 Hotcam

 

 

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