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post #1 of (permalink) Old 05-28-2009, 12:55 AM Thread Starter
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ot--CHEVY HEADS

My first set of alum. Summit 2.02 heads on a small block chevy . What are the torqe specs?

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post #2 of (permalink) Old 05-28-2009, 06:25 PM
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Quote:
Originally Posted by Dex View Post
My first set of alum. Summit 2.02 heads on a small block chevy . What are the torqe specs?
Not off topic at all with all the Chebby engines in Jeeps now days...
MUCH more to the point and 'On Topic' than the pissing contests about this or that and the soft core porn that's passing for avitars and stuff here!
--------------------------------------------------

Same torque specs as cast iron heads,
EXCEPT...
You SHOULD NOT use BOLTS on aluminum heads,

You should use STUDS and HARDENED WASHERS with aluminum heads.

See, Cast iron won't take a fine threaded bolt without stripping the hole out.
The composition & grain of the cast iron won't allow for a fine thread to stay intact,
So you have to use 'USS' or 'Coarse' threads in cast iron.

Use a good brand of studs,
SPS, ARP, Milodon... IN that order, and torque them to about 15 Ft.Lb. into the block.
Use 'Blue' thread locker or sealer if you think they will loosen or leak, but stay away from the 'RED' thread locker on head studs.

If you tighten more than 10 or 15 Ft.Lb., you WILL crack the block in the blind holes.
If you attempt to torque to 85 Ft.Lb. or what ever the torque spec is for bolts with the stud bottomed out, it's going to crack the block, and there just isn't any two ways about it...
(I did this for 20 years, and I've seen many a cracked block where STUDS were over-torqued when they were bottomed out...)

Bolts don't bottom out, so you CAN torque them to whatever,
But with studs, they WILL bottom out, so stick with just enough to hold them in place, and some thread locker 'Just In Case'...

Personally, I skip on the thread locker and use 'Thread Sealer' Goop with Teflon.
The resistance from the thread sealer is enough to keep the stud in place,
And it's enough to seal things up without getting crap everywhere!
---------------------------------

Now, the studs will be USS thread on the bottom ends to fit in the block,
But the top ends where the heads go on will be SAE, or 'Fine' threads.

The more turns per inch of bolt, the better clamping power you can get (just like gearing, it's gear reduction with more turns per inch).

With the stud ANCHORED in the block, those USS threads don't have to rotate,
They are pulled up into contact with the block EVENLY, and they will hold MUCH MORE clamping force than if you have to turn them...

When turning them, imagine anything, speck of carbon, metal shaving, bolt sealer, ect holding the threads up off each other...
And a crack starting at the point where the load is redistributed to...
Once a crack starts in a thread, It's DONE!
There is no saving a cracked thread in cast iron! That crack will proceed no matter what you do!

If you SEAT the studs in the block, then use the FINE THREADS of the stud and nut to load the cast iron EVENLY pulling on it (no rotation),
You stand a MUCH less chance of starting a crack and having a bolt/thread failure!

So, now we have USS threads in the block,
SAE threads at the heads,
We have STEEL stud with STEEL nut as fasteners, and we have pretty much taken the cast 'Weakness' out of the cast iron...
-------------------------------

IT's time to take a look at the HEADS...

There are THREE things you have to remember with Aluminum heads on cast iron...

1. Aluminum expands roughly TWICE as much as cast iron at the same temprature.
(If it's a High Nickel racing block, expect nearly THREE times as much movement of the head than the block)

That means for every 1 Millimeter of expansion the block does,
The head will do AT LEAST 2 MM of expansion (and contraction)

2. Aluminum expands and contracts roughly THREE TIMES AS FAST as cast iron.
So, even as the block hasn't warmed up enough to move yet, the aluminum head is on the move like gangbusters!

3. Aluminum heads will 'Point Pressure' or have 'Pressure Points' where the fasteners are.

........................

Answerers to 'Issues' #1 & #3...

If you use regular nuts on the heads, as the head expands and contracts, the edges of the nut will eat into the heads,
And do HORRIBLE things to the head,
Along with making clearance in the aluminum under the nuts, usually resulting in leaking head gaskets or worse...

You need to SPREAD OUT THE LOAD from the nut on the stud...
Do this by using as large of a HARDENED WASHER as you can under the nut.
The larger the washer you can fit under the nut the more you will spread the load out on the aluminum,
AND,
The Steel Washer won't dimple or be pushed out from under the nut.

Answer to 'Issue' #3,

Use 'O' ringed head gaskets.
'O' rings will keep the head gasket from leaking as the head moves around on the block like crazy.

DO NOT use hard setting sealers!
Use Fel-Pro Head gaskets with the 'Blue' Teflon surface coating so they allow the head/block to move independently of each other,
But still seal up the water passages.

Those head gaskets have Copper Cored, Stainless Steel 'O' rings built into the head gasket so the cylinders won't leak.
They work GREAT, are reasonably priced, and soak up a BUNCH of the problems associated with heads we used to have to 'O' ring groove, and use copper wire in to seal up the cylinders.

--------------------------------------------

Good set of 'O' ring head gaskets,
Good set of studs with washers,
And some care when you put things together should make for a good, and long lived, install!

You wouldn't believe how many broken and/or useless heads/blocks I've seen ruined by people using plain bolts or studs/nuts without HARDENED washers!

The other thing is,
Before you install the studs, Run a SHARP tap through the block bolt holes to clean them/straighten them out,
And flush the holes with something like brake cleaner,
Then dry throughly before you install the studs...

Factory block threads leave something to be desired...
They were usually cut by a dull tap, so they aren't FULLY formed,
Most of the time they are 'Warped' or 'Wobbly' and they are ALWAYS full of crud.
The studs will be FULL thread engagement, and they will have STRAIGHT, usually ROLLED threads on them,
And the cleaner and straighter the threads in the block are,
The more contact area you will have.

DO NOT use choke/carb cleaner, it leaves a residue that will effect the usefulness of the sealer or thread locker you use.

Go easy on the sealer or thread locker, and apply it to the STUD THREADS ONLY...
You don't want a liquid in the bottom of the hole that can 'Hydraulic' and interfere with the torque reading, or even crack the block!

Any questions?
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post #3 of (permalink) Old 05-28-2009, 09:59 PM Thread Starter
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OMG wow wee

yes i do have studs, but that is the most best answer i have ever got , hey man your the greatest, thank you for your time an very good help

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post #4 of (permalink) Old 05-29-2009, 09:30 AM
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No problem Dex, just killing time, and glad I could help with a Jeep tech question.
Let me know if there is anything else I can help with.
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post #5 of (permalink) Old 05-30-2009, 02:15 PM
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Quote:
Not off topic at all with all the Chebby engines in Jeeps now days...
MUCH more to the point and 'On Topic' than the pissing contests about this or that and the soft core porn that's passing for avitars and stuff here!

Man you really like to beat the dead cat don't you.... People like you can ruin a forum... I'd rather read all the B.S. on Pirate....
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post #6 of (permalink) Old 05-31-2009, 11:28 AM
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Quote:
Originally Posted by SilentBob2 View Post
Man you really like to beat the dead cat don't you.... People like you can ruin a forum... I'd rather read all the B.S. on Pirate....
While TR's bedside manor can be a bit rough at times....and he and I have not always seen eye to eye.....his response to the OP's question was very good.....

I'ts your kind of response that perpetuates the on going problem with some of the OT posts......there was no need for it.....

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post #7 of (permalink) Old 05-31-2009, 08:03 PM
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This is what I'm talking about...
Crap instead of usable information.
--------------------------------------------------

USABLE KNOWLEDGE OF THE SUBJECT PLEASE!

Like, Make sure you champfer the top thread of every block threaded hole before you install bolts or studs,
SO the top thread doesn't pull up and keep the head/head gasket from sealing.

Use only thread locker or thread sealer on the block sides of the studs,
But don't forget to LIGHTLY LUBRICATE the fine threads on the head side before you torque the head into place.

Run the torque pattern from the center out, working in expanding circles to chase any air pockest out, and to work any 'Wrinkles' out of the aluminum head as you go.

Start with about 35 Ft.Lb., run the pattern, and give the block/heads about 15 minutes to settle out before running the torque pattern again at about 65 Ft.Lb.
Give the block/heads about 15 more minutes,
then run the torque up to within 5 or 10 Ft.Lb. of the FINAL torque goal...
Run the pattern yet again and let the head/block/gasket settle out and any trapped air to migrate out of the joint before you do the final torque pattern at full torque value.

NEVER, EVER Torque heads on a block that DOES NOT Have the main caps torqued in it!
Some of the head bolts are threaded into the main webs that service the main caps, and torquing heads on first can cause real main cap alignment problems.

You may not believe this,
BUT!
Cast Iron is SOFT & FLEXIBLE, and you can distort it fairly easily!

Go easy and torque the studs/bolts in STAGES, letting the cast iron block settle out in between torque sessions.

Especially if you have a Chevy engine with 4 bolt mains.
4 bolt main blocks had higher nickel content, which lets them handle heat a little better, but nickel is SOFT, and likes to move around some...
(Likes to 'Smear' when you polish it too!)

Sealer on the block side of the studs, 10 to 15 Ft.Lb. install torque.
You don't have to worry about the crank being in when you are only torquing to 10 or 15 Ft.Lb. since the studs are pulling on anything (Torque Plate or Head yet)

Double nut the studs and install them by the binding nuts rather than getting a hold of the shank of the stud with vice grips or something equally damaging...
Stud installer tools are nice, but not many people doing one time installs buy one...
So double nut, jam one nut against the other, and use a ratchet or torque wrench to install,
Then separate and remove the nuts.

Most good quality studs will have EXTRA threads sticking up past your heads. This isn't because 'One Size Fits Everything' with good studs,
This is the 'Install End' that you are supposed to torque on...
If you over tighten the nuts or hammer too hard with a stud installer, it's supposed to be on the VERY END of the stud, so you don't compromise the load bearing part of the stud.

Some of the top quality studs will have smaller diameter socket heads formed into them so you can use an 'Allen Wrench' to install the studs.

Some will have a smaller diameter 'Hex Head' so you can use a common socket to install/remove the studs.

These are REALLY HANDY, but expect to be in top fuel racing before you see any of the really good stuff!

Remember what I said about SPS, ARP, Milodon.
I simply WILL NOT use any of the others.
Too many failures with the 'Economy' stud kits that cost MUCH more than just replacment studs!

As for INTAKE BOLTS...
If you heads don't already have steel inserts cast into them,
Consider drilling out, threading, and installing a HELI-Coil type product in the head bolt holes of the aluminum head.

Same with bolt/stud holes for carb in aluminum intakes.

Replacing aluminum threads with steel Heli-Coil right from the start is a GREAT way to do things! Saves you a lot of 'OH CRAP!' moments when the aluminum threads turn lose and ruin your afternoon!
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post #8 of (permalink) Old 06-02-2009, 10:36 PM Thread Starter
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u da man good answer

ok on that 350 86' i got the tiny ridge out but now i need to run a bottom TAP before i get it cleaned up at the mach shop and do a ring gap test on all cyl's so i can do studs what size TAP??

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post #9 of (permalink) Old 06-02-2009, 11:37 PM
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Sure, TR's post is long, but FULL of good information. It never hurts to hear it again, we all forget sometimes.

Those that don't understand it, or think they already know everything can revert back to what they do know, or should know. The switch on their computer labeled "Off" saves alot of their time.
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post #10 of (permalink) Old 06-03-2009, 10:19 PM
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Quote:
Originally Posted by Dex View Post
ok on that 350 86' i got the tiny ridge out but now i need to run a bottom TAP before i get it cleaned up at the mach shop and do a ring gap test on all cyl's so i can do studs what size TAP??
The Chamfer at the tops of the bolt holes is to keep the top thread from pulling up when you torque the heads down.
Only happens once in a while, but it DOES happen, and it WILL KEEP YOUR HEADS FROM SEALING....

Chamfer - Wikipedia, the free encyclopedia

Chamfering tool is just a small cutter with blades about 45°, and ANY machine shop will have them or you can order them from places like 'Fastenal'...

This is a REAL issue with aluminum heads since if the head doesn't seal, the hot gasses from that cylinder can ruin the aluminum head's deck surface.
(That's why I recommended the Chamfer in the first place, it's a good idea on ALL blocks, but MANDATORY in aluminum blocks!)

As for the tap, take a head bolt into any machine shop or supply store and throw it on the counter,
As for a BOTTOM tap that fits the head bolt size.
It can't be any more simple that that!
----------------------------------------------------------

Quote:
Originally Posted by RRich View Post
Sure, TR's post is long, but FULL of good information. It never hurts to hear it again, we all forget sometimes.

Those that don't understand it, or think they already know everything can revert back to what they do know, or should know. The switch on their computer labeled "Off" saves alot of their time.

Yup, the 'OFF' switch will work WELL for them!

I give COMPLETE information, I don't know what the skill level is of any user on the forum, so I start from scratch and work up from there unless I'm familiar with the user name.

This guy was NEW, had a low post count, and seemed a little lost, so I started from scratch and built up from there.

The OP seemed quite happy to have the information, and I'm sure some of the guys that had to make snarky comments would have learned something if they had read the OP and the response in full.

For one, I don't know why they bothered to waste the time posting up!
Nothing to add to the conversation, just padding their post number I assume. No other logical reason for them to stick in a comment that I could see...

Besides, with Auto Shop in high school going the way of dinosaurs, and no real clubs or OJT or anything to pass on the information, This is about the only way to learn anything anymore for some people.
Glad I could help the OP, and to the others.... Oh Well... I'm not loosing any sleep over what they *think*!

Last edited by TeamRush; 06-03-2009 at 10:26 PM.
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