Rocker adjusting screw question

S

slimjimandtherats

Active member
Hey, so I have a concern and i havn't found much of an answer "on the line". I've got a 61 falcon wagon with a lil 170cid. My question is aimed at setting valve lash. My concern is with the adjusting screw. From where I'm standing, my motor did not have a set screw, or jam nut to secure the adjusting screw after valve lash has been set.
[image]http://image.mustangmonthly.com/f/24920116+w750+st0/mump_0910_26_+rebuild_200co_six_engine+shaft_mount_rocker_arms.jpg[/image]
Just to clarify, i found this picture as its similar if not the same as what I'm working with. So to get down the meat and potatoes, am I missing any hardware to help snug down the adjusting screw?
I've had plenty of experience with little honda twin motorcycles but this is a slightly different beast. A manual is on the horizons, but this has been bugging me for quite some time today. Cheers
 
That's the way stock Falcon six'es with adjustable rockers are. The adjusting bolts are to have an interference fit with the rockers and they are suppose to hold them tight enough they won't back off. If they don't then they will need to be fixed or rebuilt so they will. Good luck :nod:
 
What do you mean exactly by interference fit? Some of the adjusting screws are a pain to tighten down or loosen, while others could be hand tightened to achieve valve lashing.
 
Hi, interesting photo of a rocker shaft installation. Plenty of pre lube on the valve stems and push rods but none on the rocker shaft. Bubba is right, just set the lash to factory clearance. Good luck
 
If I pull the 170's adj rockers off (1 spare motor) & put them on my freshly machined 250…
will the push rods (needed due to the cup - end for the adjustables) fit?
250s block is not decked…

Thanks ~
 
slimjimandtherats":3f4twjpk said:
What do you mean exactly by interference fit? Some of the adjusting screws are a pain to tighten down or loosen, while others could be hand tightened to achieve valve lashing.
Click to expand...

An interference fit means that one part is going to be slightly smaller then the other or it could also be Egg shaped to cause some resistance in turning. i.e. The rocker arms threaded hole vs the adjusting bolt. This is the same idea as is used with self locking nuts. The rockers that are a pain to tighten or loosen are working as they should. Good luck :nod:
 
chad":3nvx2ub2 said:
If I pull the 170's adj rockers off (1 spare motor) & put them on my freshly machined 250…
will the push rods (needed due to the cup - end for the adjustables) fit?
250s block is not decked…

Thanks ~
Click to expand...

Chad you would need a new set of custom made and lenght push rods to fit since none of the 250 ever had adjustable rockers. Good luck :nod:
 
Hi, 170 or 200 push rods will be too short. I don't know how Ford 6 adjustable rockers could be made to work on your engine. You may need to look at a performance rocker set up. good luck.
 
bubba22349, thanks for clarifying, I'm curious if I could place a thin locknut on the underside of the rocker arm and give them a good tightening with proper valve lash(to get by for now). Looks like i may swap around the adjusting screws to find out if the issue is with the screws or maybe the rocker arms are tired. Crossed fingers that it's the screws and not the rocker arms. Cheers
:beer:
 
B RON CO":2wbuz29x said:
Hi, 170 or 200 push rods will be too short. I don't know how Ford 6 adjustable rockers could be made to work on your engine. You may need to look at a performance rocker set up. good luck.
Click to expand...

All sb I6s heads are dimensionally the same concerning the rockers. Only longer cupped rods are needed.
 
X2 absolutely and on the late 200 and 250 heads and rockers in the same year group's (for example heads from about 1975 to 79 and 1980 to end of production) they are both identical i.e. The log size and chamber CC. :nod:
 
slimjimandtherats":k4wxq97p said:
bubba22349, thanks for clarifying, I'm curious if I could place a thin locknut on the underside of the rocker arm and give them a good tightening with proper valve lash(to get by for now).


:hmmm: "Maybe it all depends how much of the threads are showing and clearance you have. Personally I think it may fit better and be easier to put them on the top of rocker arm though that's how Ford did the adjustables rockers on their previous engines like the 223 six and 292 Y Block V8's. "


Looks like i may swap around the adjusting screws to find out if the issue is with the screws or maybe the rocker arms are tired. Crossed fingers that it's the screws and not the rocker arms. Cheers
:beer:
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:thumbup: Sure there's a real good chance it's the adjuster bolts have been worn enough to be a little loose. It's also easy enough for you to pickup a few new ones to try out in their places. Good luck :nod:
 
Hi, you should need to give the adjuster screws a good twist to turn them in or out. If they are too easy to turn they will not hold the adjustment. I guess they may be too loose but I've never seen that. I thought about a jam nut (good) or maybe even locktight (?) on it. I wouldn't be afraid to try that.
 
bubba22349":2n83qav8 said:
Chad you would need a new set of custom made and lenght push rods to fit since none of the 250 ever had adjustable rockers. Good luck :nod:
Click to expand...
So @ 9 5/16 inch where do I tell them to make the cup?
OR
would the top (lip, not cup bottom) of the cup end @ that hight?
 
Do I remember reading in the 6 book that big block FE ( 390/428) pushrods were the correct length for a 250 with adjustable rockers ?
DannyG
 
yeah, 390 ci
/OR/
Compcam: CCA 7533-16 (order an FE motor 332-428ci)

hummm - well all ways said I like stock...
 
Right on! well as it turns out, there are about 8 adjusting screws which are needing replacing. I swapped them all around and it turns out the adjusting screws are indeed worn out.
After a quick search, i failed to find a solid source for them.
Secondly, the thread pitch on the adjusting screws are slightly off what the local hardware had on hand. I believe the 20tpi (forget what size screw. 3/8 maybe?) was what was closest, but bound up right as it cleared all threads. I tried the jam nut on several other adjusting screws, but the nut bound up on all. I am planning on just using blue locktite after shes warmed up to get my final lash.
Would anyone happen to have the specs on the adjusting bolts? I may try to massage the bolt threads back with a rethreader if i can get the stock thread pattern.
I'm gonna spend the day getting a start on the exhaust
[image]https://scontent-sjc2-1.xx.fbcdn.net/hphotos-xap1/v/t1.0-9/13043315_10154222859839430_5545373435538371195_n.jpg?oh=88ff2fd79e1fafbb2e34d14dbbc2839a&oe=57728099[/image]
Anyways, give me your thoughts and concerns.
:beer:
 
Hi, remember that loctite works best on clean dry threads. Also there is stronger loctite you can use. Red will hold better. I would squirt the thread, adjustst the valve, and let it dry. Good luck
 
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