Re: Rocker Arms to tight?
[Re: pgccp]
#1576794
02/10/14 08:27 PM
02/10/14 08:27 PM
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Joined: Jun 2003
Posts: 52,972 Romeo MI
MR_P_BODY
Master
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Master
Joined: Jun 2003
Posts: 52,972
Romeo MI
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Quote:
Iam reassembling my 383 had heads plained ( not very much) rockers seem to be very tight on valves when valves are closed stock shaft and rockers, rockers are riding valve tips ok. push rods are tight on closed vales. Should I install shims and how much? Push rods should be able to turn on a closed valve? Thanks Bob
I assume your talking a hyd cam.... get one of the valve on base and start pulling the shaft 1/4 turn at a time on each bolt till the push rod turns freely and count the 1/4 turns... then tell us.... if you know how much you had the heads cut we can tell
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Re: Rocker Arms to tight?
[Re: pgccp]
#1576797
02/11/14 01:43 PM
02/11/14 01:43 PM
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Joined: Jan 2003
Posts: 75,047 U.S.S.A.
JohnRR
I Win
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I Win
Joined: Jan 2003
Posts: 75,047
U.S.S.A.
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Quote:
Iam reassembling my 383 had heads plained ( not very much) rockers seem to be very tight on valves when valves are closed stock shaft and rockers, rockers are riding valve tips ok. push rods are tight on closed vales. Should I install shims and how much? Push rods should be able to turn on a closed valve? Thanks Bob
No , you do not install shims , shims are for correcting valve tip to rocker arm geometry , not making up for head/block milling.
It's a hyd. lifter not solid , the lifter should be compressed some and under that pressure the pushrod will not spin freely .
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Re: Rocker Arms to tight?
[Re: JohnRR]
#1576798
02/11/14 01:50 PM
02/11/14 01:50 PM
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Joined: Sep 2003
Posts: 2,008 Sweet Home Alabama
MRMOPAR622
top fuel
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top fuel
Joined: Sep 2003
Posts: 2,008
Sweet Home Alabama
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You didn't step up to a bigger cam did you?Best cure is to put adjustable rockers on it along with some lash caps.
"To Be The Man'You Have Got To Beat The Man"
"T/D and Pro-Bracket Racer"
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Re: Rocker Arms to tight?
[Re: JohnRR]
#1576799
02/11/14 01:53 PM
02/11/14 01:53 PM
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Joined: Jun 2003
Posts: 52,972 Romeo MI
MR_P_BODY
Master
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Master
Joined: Jun 2003
Posts: 52,972
Romeo MI
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Quote:
Quote:
Iam reassembling my 383 had heads plained ( not very much) rockers seem to be very tight on valves when valves are closed stock shaft and rockers, rockers are riding valve tips ok. push rods are tight on closed vales. Should I install shims and how much? Push rods should be able to turn on a closed valve? Thanks Bob
No , you do not install shims , shims are for correcting valve tip to rocker arm geometry , not making up for head/block milling.
It's a hyd. lifter not solid , the lifter should be compressed some and under that pressure the pushrod will not spin freely .
John is correct... no shims... IF it is compressed to far then you need shorter push rods... does any one know the dimension from the shaft center line to the push rod center line(even a close spec).. that will help also to figure out the compression of the lifter... the reason I ask is I'm not home to get any measurements or any books on hand
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Re: Rocker Arms to tight?
[Re: dogdays]
#1576802
02/11/14 03:05 PM
02/11/14 03:05 PM
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Joined: Jun 2003
Posts: 52,972 Romeo MI
MR_P_BODY
Master
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Master
Joined: Jun 2003
Posts: 52,972
Romeo MI
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Quote:
I keep thinking this: it's a hydraulic cam, right? There is supposed to be no lash in the system when the valve is closed, that's what the hydraulic lifters do. There's a spring inside the lifter that pushes the cup up. If you had slop in the closed condition the pushrods would be too short. The question is, what kind of preload are you getting on the lifters. In other words, how far down in the lifter is the pushrod pushing the cup?
R.
Correct..... the other guys are jumping the gun... if its .010 to .015 farther down in the lifter it wont matter... so why BUY rockers for no reason... yes a adjustable push rod is the easy way but if he doesnt have one then a little math works fine
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Re: Rocker Arms to tight?
[Re: pgccp]
#1576803
02/11/14 03:16 PM
02/11/14 03:16 PM
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Joined: Jun 2003
Posts: 52,972 Romeo MI
MR_P_BODY
Master
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Master
Joined: Jun 2003
Posts: 52,972
Romeo MI
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Quote:
Iam reassembling my 383 had heads plained ( not very much) rockers seem to be very tight on valves when valves are closed stock shaft and rockers, rockers are riding valve tips ok. push rods are tight on closed vales. Should I install shims and how much? Push rods should be able to turn on a closed valve? Thanks Bob
Also.... NO the push rods should NOT turn... they have pre-load on them pushing the lifter cup down in which is what the hyd lifters need to make things quiet
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Re: Rocker Arms to tight?
[Re: Thumperdart]
#1576805
02/11/14 03:50 PM
02/11/14 03:50 PM
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Joined: Jun 2003
Posts: 52,972 Romeo MI
MR_P_BODY
Master
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Master
Joined: Jun 2003
Posts: 52,972
Romeo MI
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The reason for adjustable rockers Mike is to step up to the 20th century already.............
Its STOCK.... I like spending others money also
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Re: Rocker Arms to tight?
[Re: Thumperdart]
#1576807
02/11/14 03:59 PM
02/11/14 03:59 PM
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Joined: Jun 2003
Posts: 52,972 Romeo MI
MR_P_BODY
Master
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Master
Joined: Jun 2003
Posts: 52,972
Romeo MI
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I get it BUT Isky iron or a cheaper version takes the guess work out and you can even play w/preload like we used to at Pettis on the stockers.............
No I dont think you do get it... its STOCK... we dont even know if he will EVER hit the track to see what it might do..... I think you should buy a dana.. because your 8 3/4 MIGHT blow up... get my point... we love spending someone elses money
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Re: Rocker Arms to tight?
[Re: Thumperdart]
#1576809
02/11/14 04:13 PM
02/11/14 04:13 PM
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Joined: Jun 2003
Posts: 52,972 Romeo MI
MR_P_BODY
Master
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Master
Joined: Jun 2003
Posts: 52,972
Romeo MI
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Quote:
You`re stuck in your ways and me in mine. ANYTIME a head is milled or valves sunk from valve jobs, the pre load`s out of wack period and shimming makes the already sucky small block`s sweep worse so adjustable rockers are the only LOGICAL solution...........I`m gonna go work out now..............
Never mind... I quit... you tell him what he needs
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Re: Rocker Arms to tight?
[Re: Thumperdart]
#1576814
02/11/14 04:31 PM
02/11/14 04:31 PM
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Joined: Jun 2003
Posts: 52,972 Romeo MI
MR_P_BODY
Master
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Master
Joined: Jun 2003
Posts: 52,972
Romeo MI
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Not trying to be right but "been there done that" many, many times and I stand behind my "opinion" %100000000................I don`t EVER guess on ANYTHING car related but also understand I`m a nobody and that`s cool by me...........
Well your guessing right now.... we have very little facts about the build... no one said valve job was done... was it .002 taken off the heads or .020.. it he measures first he will have a idea.. instead of just throwing dollars at it
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Re: Rocker Arms to tight?
[Re: Thumperdart]
#1576815
02/11/14 04:34 PM
02/11/14 04:34 PM
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Joined: Oct 2006
Posts: 427 Sweden
Mopar Guy
mopar
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mopar
Joined: Oct 2006
Posts: 427
Sweden
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Quote:
Not trying to be right but "been there done that" many, many times and I stand behind my "opinion" %100000000................I don`t EVER guess on ANYTHING car related but also understand I`m a nobody and that`s cool by me...........
Thumper im no expert of any kind and im not trashing anybody just have an opinion and im still learning from my mistakes like i always have and guy´s like Smokie in his best D garage is the guy´s i try to learn from
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Re: Rocker Arms to tight?
[Re: dvw]
#1576818
02/12/14 12:33 AM
02/12/14 12:33 AM
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Joined: Jun 2005
Posts: 6,257 gulfport, ms, west mi
rowin4
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master
Joined: Jun 2005
Posts: 6,257
gulfport, ms, west mi
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Quote:
Why not remove the intake and measure the preload? Bend a couple pieces of thin wire 90* at the end, various thickness. Use them as a go/no go gauge between the retaining ring and lifter piston. For what its worth I've shimmed plenty of shafts due to milling. Have 3 cars running around right now. Big block with a small .460" hydraulic a 7000 rpm small block with a .540"/.570" @ 245* solid. For that matter my rocker stands for my T&Ds are shimmed .125" cause I was to cheap to buy another $400 set of pushrods. No issue with that one either. I actually mapped out the geometry change, we're talking about .010" difference in sweep across the valve at .800" lift. Doug
Shimming rocker stands is one thing, shimming shafts is another. The rocker shaft is made to fit into the shaft mount, putting shims under the shaft will make the bottom of the shaft bigger therefore upon tightening spreads the shaft mount and splitting it.
it's ok to butt heads, just don't do it with a butthead
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Re: Rocker Arms to tight?
[Re: rowin4]
#1576820
02/12/14 01:44 AM
02/12/14 01:44 AM
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Joined: Mar 2006
Posts: 9,849 MI, usa
dvw
master
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master
Joined: Mar 2006
Posts: 9,849
MI, usa
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Quote:
Quote:
Why not remove the intake and measure the preload? Bend a couple pieces of thin wire 90* at the end, various thickness. Use them as a go/no go gauge between the retaining ring and lifter piston. For what its worth I've shimmed plenty of shafts due to milling. Have 3 cars running around right now. Big block with a small .460" hydraulic a 7000 rpm small block with a .540"/.570" @ 245* solid. For that matter my rocker stands for my T&Ds are shimmed .125" cause I was to cheap to buy another $400 set of pushrods. No issue with that one either. I actually mapped out the geometry change, we're talking about .010" difference in sweep across the valve at .800" lift. Doug
Shimming rocker stands is one thing, shimming shafts is another. The rocker shaft is made to fit into the shaft mount, putting shims under the shaft will make the bottom of the shaft bigger therefore upon tightening spreads the shaft mount and splitting it.
I've used these for builds over the last 25 years. http://chucker54.stores.yahoo.net/rocshafshim.html Have never had a shaft crack or split. There is as much sectional area of the shim as there is of the pedestal. Therefore the load would be supported the same. Is the rocker geometry perfect,no. However availible small block rocker arms don't have perfect geometry either. Ideally with more lift the shaft should be lowered with a shorter pushrod. We're not talking Pro Stock. Will shimming work if the pushrod is a little long from milling or valve job, absolutely. Cab has the right idea to check it. Go from there. Doug
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