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 Post Posted: Tue Dec 13, 2011 4:34 pm 
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Location: Tell City, IN
We are in the process of upgrading my uncles motor from a flat tappet cam to a solid roller.
He has a set of 3/8 stud roller rockers and no stud girdle.
The spring I am looking at putting in it are K-Motion K-800 which have 165Lbs on the seat
and 471 Lbs with the valve open with the cam we are going to run.
I am thinking we may be ok just adding a stud girdle to his current setup.
The motor will be under 7,000 rpm.
Thanks in advance for advice...

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 Post Posted: Tue Dec 13, 2011 5:25 pm 
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how big is the cam =; ..
I am also thinking your going to need different push rods..

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 Post Posted: Tue Dec 13, 2011 5:49 pm 
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Are these 3/8" SCREW IN STUDS?? If not, then forget it! O:) A press in or even a pinned 3/8" press in is still junk for a roller, especially since I've seen them pull out on a solid flat tappet.

If they are screw in then there's no reason not to change them while the engine is down for a cam change. That and 7/16" roller rockers are pretty cheap now a days too.

FYI, I've broken a couple of 7/16" screw in studs with a stud girdle on a 23* head with a cam that is 268/272 and .660 lift.

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 Post Posted: Tue Dec 13, 2011 9:23 pm 
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Just my opinion, I would go with at least 225 lbs on the seat.

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 Post Posted: Tue Dec 13, 2011 10:27 pm 
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Several comments ...

* If the cam only needs those spring pressures you can probably get by with 3/8" studs (if they are screw in like Ken said), with a stud girdle on it.

* I assume he wants to save money by not buying new rockers and studs, but I would never buy 3/8" to begin with.

* With the information given there is no way to know (or even speculate) the amount of spring pressure needed.

* In my friend's 355 I did a spring check to find most springs as low as 175# and some as low as 160. We changed to new 210-220# springs and it didn't pick up at all. Cam was Herbert 268/275 .650ish lift with 1.6 rockers shifted at 7200. Most people are running excess spring IMO, just to be safe.

Rick


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 Post Posted: Tue Dec 13, 2011 11:53 pm 
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Location: Tell City, IN
We are going to get the 7/16 rockers and maybe also the stud girdles.
The Cam I am looking at again..

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6.11@110 Gas
1.3718 Sixty Foot with the rear wheels Gas

6.07@110 on Alcohol Injection with a 4-link 4-6-12
Best 60' 1.2537 Alcohol Injection 4-29-11
Thru the Mufflers!!


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 Post Posted: Wed Dec 14, 2011 8:45 am 
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Jody that is probably the best thing to do. I have broken 3/8 with a stud girdle with a 519/523 cam. Then went to 7/16 ARP and a gidle and don't even think about it. I have a new set of Harland sharp 1.7's for a big block. ;-) Only 20 minutes on them. =;

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 Post Posted: Fri Dec 16, 2011 4:15 pm 
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Well scored some comp cams 7/16 Stud Girdles today in great shape for $50
Also a set of 7/16 Rockers for $60 I think they are Lunati's but not 100% sure.
Also looks like we have a set of studs already. So that is a real cheap upgrade! \:D/ \:D/

_________________
6.11@110 Gas
1.3718 Sixty Foot with the rear wheels Gas

6.07@110 on Alcohol Injection with a 4-link 4-6-12
Best 60' 1.2537 Alcohol Injection 4-29-11
Thru the Mufflers!!


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 Post Posted: Fri Dec 16, 2011 5:22 pm 
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Just for grins my 23˚ 427 has 3/8" studs and stud girdles, never an issue over 7500 with K-900 springs and a 285/295@.050 cam. Intake lift just over .700 with 1.6 rockers. At the time I put it together I had the rockers and could not afford the change, but never an issue with them.


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