Rembrant Posted January 15, 2022 Share Posted January 15, 2022 Gentlemen, This may be a dumb question, I don't know...but I started Googling answers and I ended up going down a rabbit hole and now I'm more confused than ever lol. I love my 302's, but the major downside to them is that if you try to search for ANYTHING you will invariably end up sorting through 10,000 Mustang threads looking for answers. Anyway... Engine is a 302/5.0 with roller cam/lifters, and the same SBF stamped steel rocker arms that have been used since the late 70's. So my question is: When does one need to be concerned with shimming them during re-installation on a rebuilt engine? Or does one need to be concerned at all? I thought the whole point of these things was to just stick 'em on and torque 'em down. I understand if you mill your heads 0.030" to boost compression and have the blocked resurfaced and run a thinner head gasket then OK, you'll have to shim the rockers or get shorter pushrods. But what if you just had basic clean-up resurface work done? The bare minimum to clean up a set of heads, and take 0.005" off the decks on the block? Or 0.010"? Lets say that the worst case scenario is 0.020" material removed between the heads and the block, and then you install a head gasket that is supposedly 0.007" thicker than stock. That leaves 0.013" difference, on the high side. Surely the stacked manufacturing tolerances of the heads and block varied by 5 or 10 thou, no? What IS the procedure for installing the factory rockers? And does that procedure change on a rebuilt engine? Link to comment Share on other sites More sharing options...
85lebaront2 Posted January 15, 2022 Share Posted January 15, 2022 There is a lifter collapsed clearance spec on any of the torque to stop rocker setups. Using a 1994 5.0L the following specs are given: Allowable limits 0.071 - 0.171 in Desirable limits 0.091 - 0.151 in Link to comment Share on other sites More sharing options...
Rembrant Posted January 15, 2022 Author Share Posted January 15, 2022 There is a lifter collapsed clearance spec on any of the torque to stop rocker setups. Using a 1994 5.0L the following specs are given: Allowable limits 0.071 - 0.171 in Desirable limits 0.091 - 0.151 in Ok perfect, a spec, thank you! Where do I measure? I snuggled down two rockers on cylinder 1, and one of the lifters squishes, and the other doesn’t. Link to comment Share on other sites More sharing options...
mat in tn Posted January 15, 2022 Share Posted January 15, 2022 Ok perfect, a spec, thank you! Where do I measure? I snuggled down two rockers on cylinder 1, and one of the lifters squishes, and the other doesn’t. i often use an old method, of course i am assuming the cylinder is at tdc after the comp stroke (both cam lobes at base circle) tighten the rocker bolt to the point where the pushrod achieves zero slack/tolerance. from that point you should tighten the bolt and it should only take 180 degrees more to do so. many times, I have used shorter pushrods or even pedestal shims to achieve this. to add to the issue i may also be using higher strength valve springs and that "loads" the lifters even more Link to comment Share on other sites More sharing options...
85lebaront2 Posted January 15, 2022 Share Posted January 15, 2022 Ok perfect, a spec, thank you! Where do I measure? I snuggled down two rockers on cylinder 1, and one of the lifters squishes, and the other doesn’t. There is a Ford special tool that is used to compress the lifters one at a time and there is a sequence given in the service manuals (which depends on the firing order). I have actually never had to do anything on a later Windsor engine, the newest one I had was a 1970 1/2 Falcon that originally had positive stop studs with the "rail" rockers but ended up with a set of 1965 289 4 barrel heads with adjustable rockers. Other than that I had a 260, 312, 390 and two 429s and one 460. Link to comment Share on other sites More sharing options...
Gary Lewis Posted January 15, 2022 Share Posted January 15, 2022 There is a Ford special tool that is used to compress the lifters one at a time and there is a sequence given in the service manuals (which depends on the firing order). I have actually never had to do anything on a later Windsor engine, the newest one I had was a 1970 1/2 Falcon that originally had positive stop studs with the "rail" rockers but ended up with a set of 1965 289 4 barrel heads with adjustable rockers. Other than that I had a 260, 312, 390 and two 429s and one 460. Cory - I have the '95 FSM. Would it help to post the section on that engine here? Link to comment Share on other sites More sharing options...
Rembrant Posted January 15, 2022 Author Share Posted January 15, 2022 Cory - I have the '95 FSM. Would it help to post the section on that engine here? Gary, if there's anything in there regarding rocker installation that is different from the previous trucks I wouldn't mind seeing it, but the 1984 FSM just says to install and torque, nothing more. I know in the 1995 they had roller cams, but the hydraulic lifters, rocker arms, and pushrods would all be the same thing really...so the procedure should be the same all things considered... Link to comment Share on other sites More sharing options...
Gary Lewis Posted January 15, 2022 Share Posted January 15, 2022 Cory - I have the '95 FSM. Would it help to post the section on that engine here?Gary, if there's anything in there regarding rocker installation that is different from the previous trucks I wouldn't mind seeing it, but the 1984 FSM just says to install and torque, nothing more.I know in the 1995 they had roller cams, but the hydraulic lifters, rocker arms, and pushrods would all be the same thing really...so the procedure should be the same all things considered...Let's see if this section of it helps. And if you want more just let me know. Link to comment Share on other sites More sharing options...
Rembrant Posted January 16, 2022 Author Share Posted January 16, 2022 There is a lifter collapsed clearance spec on any of the torque to stop rocker setups. Using a 1994 5.0L the following specs are given: Allowable limits 0.071 - 0.171 in Desirable limits 0.091 - 0.151 in Ok, I am finally getting back to this. Some of the lifters are easy to compress and I can bottom them out by hand. Some of them move a tiny bit, and others are hard as a rock. I guess this is why you need the tool to bleed them down (by applying pressure?). Anyway, on the ones that I can easily collapse and bottom out, it looks like my clearances are in the 0.110" to 0.115" range, which is well within spec above. If I run the nut down slowly until all the slop comes out of the pushrod and rocker arm, it then takes about 1/4 turn to hit the stop, and then another 1/4 turn to tighten it (with a little 1/4" ratchet). That 1/4 turn is collapsing the lifter a tiny bit. If I go by the distance traveled of a 5/16-18 nut, that converts a 1/4 turn to 0.014". I assume it is OK that the lifters are collapsed 0.014"-0.020" at rest with the valve closed? Link to comment Share on other sites More sharing options...
Rembrant Posted January 16, 2022 Author Share Posted January 16, 2022 i often use an old method, of course i am assuming the cylinder is at tdc after the comp stroke (both cam lobes at base circle) tighten the rocker bolt to the point where the pushrod achieves zero slack/tolerance. from that point you should tighten the bolt and it should only take 180 degrees more to do so. A quick check looks like it takes 1/4 turn to hit the stop from slack, and then I can turn it another 1/4 turn before it's tight, so that's 180 deg. I have only tried a couple so far, but that's where I seem to be. Link to comment Share on other sites More sharing options...
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