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Rocker geometry

Started by _threeblindmice_ , Jan 19 2016 12:36 PM

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#1 _threeblindmice_

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Posted 19 January 2016 - 12:36 PM

I have just started a 186 with a Crow 35647 cam , built by an engine builder , in which he fitted longer pushrods , but I have found the push rods are binding on the valve side of the guide slots in the head , is there a thread on valve geometry someone can direct me to ?

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#2 S pack

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Posted 19 January 2016 - 12:46 PM

1.5:1 or 1.6:1 ratio rockers?

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#3 _threeblindmice_

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Posted 19 January 2016 - 03:37 PM

Stock rockers , ground for extra lift .

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#4 I'm a Red Motor fiend

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Posted 19 January 2016 - 04:48 PM

Put a standard 186 pushrod in it, wind it over by hand and see what it does. Why are you using stock rockers on a fresh engine with such a big stick in it?

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#5 _threeblindmice_

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Posted 19 January 2016 - 05:07 PM

I have always run them with no real dramas , and it's an XU1 used only for the street .

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#6 I'm a Red Motor fiend

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Posted 19 January 2016 - 05:16 PM

Fair enough. Were the head and block decked much? I run a 202, 186 head. 30 thou of the block, 100 thou off the head and standard length 186 pushrods still give me reasonable geometry, a good contact patch and full lift. I can't work out why he put longer than standard in yours?

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#7 _threeblindmice_

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Posted 19 January 2016 - 05:27 PM

I put a stock set in and it and it runs without noise now , just want to make sure what to check , to avoid future damage .

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#8 I'm a Red Motor fiend

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Posted 19 January 2016 - 06:00 PM

Google " yella terra rocker geometry" some basic info there that will help you.

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#9 S pack

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Posted 19 January 2016 - 06:18 PM

That Crowe cam is a solid lifter grind isn't it?

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#10 TerrA LX

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Posted 19 January 2016 - 06:22 PM

I have just started a 186 with a Crow 35647 cam , built by an engine builder , in which he fitted longer pushrods , but I have found the push rods are binding on the valve side of the guide slots in the head , is there a thread on valve geometry someone can direct me to ?

How far off the centre of the valve tip is the rocker when this happens?

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#11 Ice

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Posted 19 January 2016 - 06:28 PM

That Crowe cam is a solid lifter grind isn't it?

Sure is with a massive 517 lift
mmm with stock rockers i dunno

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#12 _Bomber Watson_

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Posted 19 January 2016 - 06:35 PM

Thats the biggest solid crow makes, I think your going to have issues.

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#13 _threeblindmice_

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Posted 19 January 2016 - 06:37 PM

Neither do I Gene , a long running machine shop taken over , the motor sat for a while as I did the rest of the car , and now looks like it they are gone out of business .

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#14 _Bomber Watson_

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Posted 19 January 2016 - 06:46 PM

Personally I would be pulling it out and down asap to find everything else they #@$^%& up.

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#15 _threeblindmice_

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Posted 19 January 2016 - 06:59 PM

This is with the longer push rods

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xu1ra.jpg 82.71K 3 downloads

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#16 _threeblindmice_

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Posted 19 January 2016 - 08:29 PM

Could anyone tell me did the 73 Bathurst , 150 motors run roller rockers ?

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#17 EunUCh

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Posted 19 January 2016 - 08:48 PM

Could be wrong but it looks like that if that is at full lift that the rocker is on the outer edge of the tip where as it should be more towards the pivot (stud side)

from where it started out at zero lift,bit hard to tell from pic but it looks like more where it should be be at mid lift in the pic ?

The YT pictures are very basic

http://static.shop03...metry-guide.pdf

tits on a bull more or less...although they make some good products.

Like said...could be wrong..the frokin stupid settings on this pc wont let me upload a pic of the geometry that is "supposed" to be correct for travel of the rocker tip through the arc of travel.

Also looks like some plus 10's or 20's collets have been fitted ?

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#18 S pack

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Posted 19 January 2016 - 09:05 PM

Could anyone tell me did the 73 Bathurst , 150 motors run roller rockers ?

No, same rockers as all XU1's before them.

Also, whats with the shiny new looking rockers and the one discoloured one?

Are those new rockers the ones being flogged on ebay as original Holden 6 rockers but are in fact chev rockers that do not correctly fit the holden 6?

Edited by S pack, 19 January 2016 - 09:11 PM.

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#19 _Bomber Watson_

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Posted 19 January 2016 - 09:13 PM

Could anyone tell me did the 73 Bathurst , 150 motors run roller rockers ?

No, they also ran a LOT less lift and duration than your current cam.

Only benefit you have is, like most crow grinds, its a very, very lazy profile, so stock rockers might live, but I would never run pressed steel rockers with a solid cam, to much jarring on them during the lash phase.

Cheers.

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#20 ant285

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Posted 19 January 2016 - 09:30 PM

http://www.kustombit...r-geometry.html
This might help with geometry

Edited by ant285, 19 January 2016 - 09:30 PM.

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#21 _threeblindmice_

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Posted 19 January 2016 - 09:53 PM

I have been checking and the push rods the builder installed were 9.450 instead of the recommended PR726 which is 9.i3 in length , ( which would be closer to the standard ones I test fitted after the problem ) thanks Adam I found the article and will check them out when I get back to the car . DJ the car is all done now , rego in a couple of weeks , the first thousand miles will be easy , I'll see how it all feels before I decide to dismantle and check everything . Thanks for all the feedback guys .

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#22 _threeblindmice_

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Posted 19 January 2016 - 10:11 PM

No Dave he bought the dear stuff , the discoloured one was when I started checking and swapping things to see what gave me clearance in the guide on the head .