Bought some rocker posts to mount my yella terras on...tops are fine..7/16" anyone know the size of the std post thread that screws into the head? 5/16" maybe?
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Rocker Posts..304/308
Started by
_rorym_
, Mar 13 2007 10:21 PM
19 replies to this topic
#2
rodomo
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Posted 13 March 2007 - 10:24 PM
At a guess I would say 3/8 UNC as the nut where you adjust the rocker is 9/16 A/F and 3/8 UNF thread.
#3
_rorym_
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Posted 13 March 2007 - 10:26 PM
Thanks Rodo but I dont need a guess..The ones I have look 5/16" screw in head with 7/16" posts..I will check if they are 5/16" tomorrow.
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Edited by rorym, 13 March 2007 - 10:27 PM.
#5
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Posted 13 March 2007 - 11:40 PM
Still tipping 3/8 UNC 
#6
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Posted 14 March 2007 - 12:35 AM
#/* is standard, i think he is asking what size to take the head out to to accomodate the stud pictured above.
5/16 sounds right.
be carefull tightening them as takingg the posts out that far leaves them prone to cracking thru over tightening.
5/16 sounds right.
be carefull tightening them as takingg the posts out that far leaves them prone to cracking thru over tightening.
#7
_rorym_
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Posted 14 March 2007 - 07:24 AM
Nope..I want to know what std is..I think these ones are 5/16 base with 7/16 posts. Do they fit a std VN head is what I want to know. If they dont..what would they be for ?..5/16 is smaller than 3/8 by the way.
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#8
_82911_
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Posted 14 March 2007 - 08:50 AM
Rory. seriously.. have the heads drilled and tapped to take 7/16 screw in studs, it's not a big job and any head shop can do it for you.
WTF are those studs?????
The stress riser that the step in the stud would cause would be unbelievable!!!
I wouldn't put them in my mower let alone an engine that you are going to put a big set of valve springs on and then use in an endurance application.
7/16 studs and guides.. It is 1 less thing to worry about.
My personal favorite is the Yella Terra Platinum series of shaft mounts. rigid as all get out, and heaps quicker to adjust than post style rockers.
The downside.. they are not cheap.
The standard thread in the heads for standard rocker posts are 3/8" UNC 24TPI if that is what you were asking?
Cheers Greg..
WTF are those studs?????
The stress riser that the step in the stud would cause would be unbelievable!!!
I wouldn't put them in my mower let alone an engine that you are going to put a big set of valve springs on and then use in an endurance application.
7/16 studs and guides.. It is 1 less thing to worry about.
My personal favorite is the Yella Terra Platinum series of shaft mounts. rigid as all get out, and heaps quicker to adjust than post style rockers.
The downside.. they are not cheap.
The standard thread in the heads for standard rocker posts are 3/8" UNC 24TPI if that is what you were asking?
Cheers Greg..
Edited by 82911, 14 March 2007 - 08:53 AM.
#9
_rorym_
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Posted 14 March 2007 - 08:53 AM
Thanks Greg...still trying to ID these things though..
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#10
_82911_
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Posted 14 March 2007 - 08:56 AM
They look like some sort of a conversion stud to me.. Not the best idea really!
Where did you get them from?
Cheers Greg..
Where did you get them from?
Cheers Greg..
#11
_rorym_
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Posted 14 March 2007 - 09:07 AM
I bought some rocker guide plates I needed and they were in the pack.
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#12
_82911_
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Posted 14 March 2007 - 09:11 AM
Sydney Speed Suplies or AT Racing perhaps?
It looks like their engineering standards.
Put them in the bottom of the toolbox, you'l use them one day.
Cheers Greg..
It looks like their engineering standards.
Put them in the bottom of the toolbox, you'l use them one day.
Cheers Greg..
#13
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Posted 14 March 2007 - 01:52 PM
My error, I was thinking 6
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#14
_bones_
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Posted 16 March 2007 - 06:59 AM
Standard Holden V8 Rocker bolt thread is 5/16 UNC.
I wouldn't use those studs you have unless you are the type of guy that would be happy securing a HQ onto a car trailer with a few small plastic zip ties.
Bones
I wouldn't use those studs you have unless you are the type of guy that would be happy securing a HQ onto a car trailer with a few small plastic zip ties.
Bones
#15
_rorym_
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Posted 16 March 2007 - 07:31 AM
Thats pretty funny Bones..I am not using them.
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#16
_brett_32i_
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Posted 17 March 2007 - 10:14 PM
this is possibly on topic so i think i can get away with posting it here....
a mate has an old carby fed red 308 which had l34?? heads on it with roller rockers.
he has now dropped in an injected 304 and went to put the roller rockers on. they were totally wrong. pushing the valve way open.
question is... is it as easy as pushrods, or are the pedestals at different heights?
a mate has an old carby fed red 308 which had l34?? heads on it with roller rockers.
he has now dropped in an injected 304 and went to put the roller rockers on. they were totally wrong. pushing the valve way open.
question is... is it as easy as pushrods, or are the pedestals at different heights?
#17
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Posted 17 March 2007 - 11:00 PM
Check first that the roller is rolling across one side of the valve tip to the other, and being about the middle of the tip on half lift. This is where pushrod length comes into play.
If the valves are being held open then this is where pedestal height comes into effect.
Are you comparing the standard lift from the standard rockers as to the rollers which may have a higher lift ratio?
Another, but unrelated to your question piont is that yella terra shaft mount have a slight different arrangement from pre efi to the efi heads. i.e. the shaft sets (inlet/exhaust) come in two lots for the earlier heads with 4x having a different offset to the other 4x set. So looking at a head you would fit two the same to the first two inlet/exhaust pedestals and the opposite two sets to the last two pedestals.
Later heads just use the one type. Using the old style on VN on heads may mean some of your rollers may not be true on center of the valve tip.
As stated this only applies to shaft mount race style YT rollers.
What is your mate using?
If the valves are being held open then this is where pedestal height comes into effect.
Are you comparing the standard lift from the standard rockers as to the rollers which may have a higher lift ratio?
Another, but unrelated to your question piont is that yella terra shaft mount have a slight different arrangement from pre efi to the efi heads. i.e. the shaft sets (inlet/exhaust) come in two lots for the earlier heads with 4x having a different offset to the other 4x set. So looking at a head you would fit two the same to the first two inlet/exhaust pedestals and the opposite two sets to the last two pedestals.
Later heads just use the one type. Using the old style on VN on heads may mean some of your rollers may not be true on center of the valve tip.
As stated this only applies to shaft mount race style YT rollers.
What is your mate using?
Edited by ALX76, 17 March 2007 - 11:01 PM.
#18
_brett_32i_
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Posted 19 March 2007 - 01:55 PM
bolt on type.
yes they are a higher lift, but nothing stupid. so i reckon them being held open is therefore due to pedestal height?
i suggested getting some 5/16 washers and throwing them under to see what affect it has.
yes they are a higher lift, but nothing stupid. so i reckon them being held open is therefore due to pedestal height?
i suggested getting some 5/16 washers and throwing them under to see what affect it has.
#19
_bodallafella_
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Posted 19 March 2007 - 05:51 PM
Hi Brett, you adjust the pedestal height to correct the rocker geometry at the valve. If this is correct and the valves are being held open you need shorter pushrods. The geometry is correct when the rocker is at 90� to the valve at half lift.
Your best bet is to take the pushrods out to set the pedestal height and then use an adjustable pushrod to work out what length you need.
For more info see here:
http://www.mid-lift....nstalled-G1.htm
Your best bet is to take the pushrods out to set the pedestal height and then use an adjustable pushrod to work out what length you need.
For more info see here:
http://www.mid-lift....nstalled-G1.htm
#20
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Posted 22 March 2007 - 02:50 AM
A very interesting read bodallafella as i was going off Yelle Terra's recomendations but i think i will have to read it several more times before it sinks in lol.
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