Torqueing Head/Rocker Assembly Question

[tony barnhill]

So, first I loosened all the rockers off the push rods as loose as possible by backing off the valve adjuster nuts....then, I tightened all head & rocker bracket nuts....then, I torqued the head nuts to 40 ft lbs per the manual & tightened the remaining 4 rocket bracket nuts 'tight' as I couldn't find a torque for them.

Not all of the Head & rocker bracket nuts screwed completely down onto the studs - primarily towards the front of the engine - & actually allow several of the nut threads to show with the stud down inside the nut instead of sticking out of it or being level with the top of the nut.

& on TDC, my #3 valve is tight even though the adjuster has been backed off all the way.

?????

 

[v8mgbal]

did you lube the threads and consider the running torque.

 

[tosoutherncars]

Hmm, something's not right there!

Tony, is this a head (or block) that has been milled?

Have the head bolt holes been redrilled & tapped, maybe allowing the head bolts to be screwed in further than original?

(Head gasket seam looks tight & even, I assume? Similar thickness head gasket to what came off originally?)

 

[tony barnhill]

The head was milled the minimum necessary to make sure its level......head gasket seam looks nice & tight all around...Payen gasket.

I'm gonna back everything off, lift the head, remove the studs & reinsert them in the head all the way to the bottom of their holes & then back each one off about a quarter turn.

 

[tosoutherncars]

Sounds good... LMK if you need the rocker ass'y-to-head torque, pretty sure it's in my manual. (The 1500 was, and it covers the earlier engines)

 

[tony barnhill]

Head's off - studs are out of block - holes clean & threads chased (again).

I looked all through my manual & couldn't find torque for rocker assembly

Head is 40 foot pounds.

I'll reinstall everything tomorrow...maybe somebody can point me towards the rocker torque.

 

[tosoutherncars]

Tony,

Haynes (p.28) lists head @ 40 (as you did) and rocker pedestal @ 25 lb ft.

 

[tony barnhill]

Thank, Duncan - Factory manual doesn't show it...

Guess I've gotta get one of the dreaded Haynes for this little car!!

 

[Guest]

As much as I despise those Haynes books, the Haynes did get me through quite a bit of stuff. Plus I had no fear in getting it dirty. It's in 3 pieces and has survived a couple of rainstorms and full of dirty fingerprints. Served me well.

 

[Hap Waldrop]

A few things Not mentioned yet, some already mentioned, but you should alway do few things when tourquing a head.

1) always start with a lower than desire torque and work your way up, for example, 25 ftlbs, then 30, then 40.

2) always follow the manual's example of the torque sequence, if you don't have a manual, there always the same, start form the inside and work your way outward.

3) always lube the stud threar on both side with, motor oil will work fine

4) retorque after the engine has went thru a few heat cycles. Re adjust valve at this time as well.

For A-series engines, the Haynes manual is more than acceptable, but the Bentley manuals are really good.

 

[tony barnhill]

Yep - did all those things, Hap....right now I've got all the studs out & have cleaned the holes in the block, made sure the threads are fine...am going to reinstall the studs (they're new)...on an MGB block I run them all the way down & then back off about a half turn - do you do that with a Midget engine?

 

[64rocksprite]

Tony,
I'm doing the same operation this week and wanted to pick-up the correct tap..do you recall the thread off-hand? I'd like to pick one up on the way home from work today if I can.

 

[Hap Waldrop]

I missed this in reading Tony's first post, adn dang near let it by me yesterday in a phone conversation with Tony, and I didn't see anyone here address it. Tony was concerned about having all the valves adjusters backed completely off, and when torqueing the head down one or more of the rocker still having no lash on it. When I cleared my mind and thought about what Tony was asking, it hit me like a brick. No matter if Tony had the adjuster back all the way off or not, the adustment of the adjusters not greater than the valve lift, so any valve in there downward opening stroke would still be compressed even with the adjuster backed off when the head and rocker arm assembly is torqued down. Tony we discussed this yesterday, but for the crowd here, on the studs, oil lubed threads and just hand snugged will be good. I also adviced Tony that factory manul torqe is alittle on the weak side, I suggested he torque to 42 ft lbs, intially and then 45 ft. lbs for the retorque after running the engine, with ARP studs I torque to 50 ft. lbs., ans a mtter of act I will be doing this today as Drews engine, the ARP stud finally got here, and the head has been awaiting them.

 

[tony barnhill]

Think I'm just getting a little to anal on this little engine...I need to throw it together like an MGB engine & it'll be fine.

Its all buttoned up now & waiting for me to take it off the stand and attach the transmission.

 

[JerryB]

"""""Think I'm just getting a little to anal on this little engine...""""

It's called paying attention to details.

When you run the studs in the case (block) go finger tight. Do not tighten with two nuts or leave loose. Just finger tight. The bottom of the stud threads should go all the way in the case. You might have some dirt/debris in the hole(s)? Dont use a cutting tap to chase threads in the case or critical threads like main cap bolts or head studs. You want a clean up tap that doesnt remove metal just the crud. See if ARP has under 'thrad cleaning chasers" or al large macinery supply such as MSC. you really have to clean blind holes well.....a long pick/scribe and a lot of compressed air. Stiff pipe cleaners and bore brushes.

 

[Hap Waldrop]

Yep chasing threads should have been done long before assembly began, back during the block cleaning process. Tony, ask David what I used to tell him.

"no stones left unturned"

 

[tony barnhill]

I'm sure they did it - they do serious racing engines...the holes were real clean except for a little stuff in the bottom & the studs came out easily...just was a little stuff down there...& they had used oil to reinstall them.

Whatever was wrong was in my mind!

 

[Hap Waldrop]

Then just make sure you lube the threads good, anyhting you can do to cut down on friction in a fastenr with this much torque.

Tony, but there is this old saying, words to live by for sure.

Assumption is the mother of all screw ups