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Discussion Starter · #1 ·
Hi guys. I've got a '68 t-bird w/ 429. The engine was rebuilt, so says the previous owner. Older guy. Seems trustworthy, but I got such a great deal on the car, it wouldn't matter if it wasn't even running. There's still the c8 block in there but I see the latter, what? like '70 heads I guess they are? Dove-C they're stamped on them.

Anyway, fast forward a few years with going through the car and rust repair, body work and paint, interior work etc.etc.etc. I finally got to the point where I had to pull the engine, to do some rust repair on the firewall. So I figured, why not put a good sounding cam in, while the engine is out. I'm not looking for crazy hp or anything, just something mild, so I decide to got with comp cams mutha thumpr. Perhaps more bark than it's bite? but that's ok. Just a good street cam. So any rate, I install the cam, degree it in (I got the 102 CL cam degrees to 103 center line but I had to use the A mark on the cam gear, O and R were all way too far off) so it's still got like 4 degrees of built in advance anyway, I believe, so I considered this close enough for this cruiser and occasional tire shredder. ;)

Anyway, install the rockers, adjust a half turn after zero lash, so the research tells me, and then snug the second locking nuts on top down to 20 ft lb. Well, 3 studs top nuts stripped.

So no big deal right? Just google to see what rockers I need, but wait. That doesn't seem to match what's in there. If research is correct, I'm supposed to have 7/16 studs top and bottom, right? Course thread on bottom, fine thread on top, I think, right?

But I have course thread 7/16 on bottom, however tappers down to 3/8 fine thread for my top threads. If my research is correct, are these not small block ford rocker arm studs?

Are they ok? Should I just replace the 3 stripped out ones with the same, and not be concerned about it? Should I replace them all with the proper 7/16/ 7/16 studs if that is in fact what they're supposed to be?

There's not a clear and obvious reason why an engine builder would use them on the '68 block with the '70's dove-c heads is there? I'm not going to mess up the geometry of anything either way right? With either size stud, nothing changes as far as those goes right?

But I'm wondering, if ford used a constant size 7/16 stud for the big block, they must of figured the engine needed the extra strength over the small block tapered down to 3/8 studs, right?

Am I worried for nothing, or is it: Oh heck no don't run those!! and it's a good thing I decided to do a cam swap and had a few threads strip out on me, so I caught a failure before it happened and I have to swap them all out for the correct studs before I break the cam in?

Am I just wrong and worried for nothing and these are in fact factory big block dove-c rockers with 7/16 base and 3/8 thread tops and I'm seeing what I'm supposed to be seeing. I'm thinking not based on what summit is showing I'm supposed to be seeing in my engine.
 

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1990 Ford Mustang LX 351M powered!! Project Cherry Bomb!!
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Yeaaaahhhhhh, I'd wait just a doggone minute there... I've got a set of D0VE heads out in the building and to the best of my recollection the bottom is a 7/16 course (technically a j thread that Ford used) and fine on the top... What you've got don't quite sound kosherized... I'd wait till a few more chime in on this just to confirm what's what...
 

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OEM bottle neck rocker studs are 7/16" bottom and 3/8" top. Though they can be converted to adjustable with Mr. Gasket kits the OEM rockers tend to chew up the valve stem tips with an oem cam.

We convert to proper 7/16" studs top and bottom, guide-plates, roller rockers and proper length hardened push rods.
Steel rockers will fit under oem valve covers.

Fortunately that lift on the thumper cams is pathetic so topping guides is not necessary but better springs are a good idea.

The A slot on some timing sets is actually the early straight up position. Keyway / tooth / A all in line at noon.




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Discussion Starter · #5 ·
Ah. That explains things. Both the current studs and why I had to use the A slot to degree in my cam. Yeah, the thumper cam doesn't have much of a lift compared to some other cams designed for the comparable powerband does it? It appears to be much better than oem and even the comp cams I just took out - extreme energy xe256h.

I didn't research how much I could go before I needed other supporting components. I know the rabbit hole can really suck you in hahaha and I didn't want to get crazy.

You know, I was researching some roller rockers or just some roller tips and it seems like a good upgrade for just a couple hundred bucks or so. I've been working on restoring the car for years now though and I just want to get behind the wheel and start enjoying it a bit.

I do have a performer intake and holly 750 (vac secondaries) on it too. Put in a 2500-2800 higher stall and shift kit in the C6. Ditched the one wheel peel, 2:80 hwy gear out back for a trac lock 3.25

It smoked that tire with ease with the 2:80's and that extreme energy cam though! hahaha I can't imagine how it's going to feel now with a bit more cam and some more gear. Getting exited. Just a nice little (if you can call a 68' t-bird little haha) mild, cruising car, turned hot rod. I've only driven it a few times in between working on it. She's almost done! Done as in, I'll be driving it while tinkering it with from here on out. ;)

Ok. So I think I'm going to grab 3 studs that match for now, since I know they're factory and ok. Get the cam broken in, get the car finally on the road and drive it for a bit before snow comes. Then I'll upgrade the studs and rockers and then get a valve spring compressor and a pushrod length checker. Probably over the winter while the car is up or next spring.

So am I correct in setting these style stamped steel (oem I presume) rockers on this style stud? (course 7/16 base as common but fine 3/8 top) in that I turn the main nut while spinning the pushrod, feeling for resistance and once it starts, turn another half turn and then set the top nut? I searched how to do this, but as I'm seeing now, I don't have the most common style stud I guess but these instructions still apply to me, right?
 

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Discussion Starter · #7 ·
Yes, just make sure you’re on the base circle of the cam when you’re adjusting the valves.
Yeah! Thanks for making sure I knew that. I did in fact, find that while researching the instructions too. Appreciate it.
It was easy without the intake on, as I could look to see but no biggie. I'll just hold the end of the pushrod and turn the engine over until I feel it bottom out and turn a little extra for good measure. Should be just as easy, I'm sure.


So I just got out my tape and verified what I've got.

7/16-14 base thread (pretty sure, 99% this is the only option here for all options anyway)
3/8-24 stud/top thread

base thread is 3/4 = .75
top stud length is 3/4 = .75
overall length is 2 5/8 = 2.625
effective length is = 1.875 (yeah, I had to do a quick google to find where this measurement was taken from haha but a photo popped right up for me.Basically, as if measured from the bottom of the head, as if the stud were fully inserted in the head, is all.)

So I ordered 3 trick flow TFS-51400613-1

Thanks guys!

I'll research latter on what (roller/ roller tips) rockers for a budget $200ish price range I should upgrade to latter. Then I'll have to get matching upgraded 7/16 studs. Looks like using a push rod tool is pretty simple. I've heard about the "rope trick" rather than compressed air to hold the valve up for swapping in a test spring, which looks simple and safe to do too. I'll mess with this over the winter when the car is up anyway. For now, time to get her out there and burn some tires.:D

I haven't played with an old school gas engine like this in over 20 years. I'm sure it's obvious I'm very novice haha,. I appreciate the help guys! Very grateful.
 

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Discussion Starter · #8 ·
Oh, and yeah, I have already checked out a video, showing how to check that the rockers stay and ride in the center most of the valve tip there. His video showed how to mark and and even make sure to hold a roller (tip) still also, while making your witness mark but I'll check things out more when that time comes too. If anyone else can think of anything a novice like me needs to know, or recommends a roller and stud set, feel free to let me know. I don't want to do something stupid after getting the car on the road after all these years haha
 

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I've seen the "rope trick" done with small vacuum hose on YouTube, looks like it may be easier than trying to push it full of rope when it's at bottom dead center.. as far as the rockers, the steel ones that Scotty J recommended will fit under your valve covers the best.

 

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Discussion Starter · #10 ·
No worries there. I've got some tall aluminum valve covers to go on, once I set the engine and trans back in this Monday. I had ripped the A/C out of the car, so while the engine was out to repair the firewall, I finished removing the whole HVAC box with A/C guts and made a custom box just for the heater core and tube over to the blower motor. Cleaned her right up real nice under there and freed up all kinds of room, so grabbed some tall covers, really just for the appearance of it but I did have in mind a roller rocker upgrade too when looking for something that wont rust out. Had some low profile chrome ones but they rusted, so with the extra room, this can open up my options for rockers.
Looking them here....... They're 3-3/4" tall.
 
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