I just finished up installing my edelbrock 3711 intake on the engine stand using edelbrock bolts. Lubed them all with engine oil and torqued them down in sequence per the FSM. Second to last one (behind the choke stove) let go getting and clearly stripped, but I stopped as soon as I felt it going. It's still way more than finger tight, but no where near 40 ft/lb. How concerned should I be? Probably the bolt or the head? This is a stock low compression motor so nothing crazy like boost to worry about, but the exhaust crossover is right there. Should I leave it or order a thread chaser or tap set and see if I can repair it? Still have the factory bolts of course. thanks in advance for your input!

 

A longer bolt may work to pickup some deeper thread, if not, then I would use a heli-coil to repair it.

 

I seriously doubt the bolt striped. Like Eric says try a longer bolt to get to some deeper threads in the head. If not I would be thinking about pulling that baby back off and repairing the threads, and maybe look for any others that appear borderline.

 

pull the offending bolt out and take a peek.

if the bolt is necking down then it was about to snap and is defective. I have never had a factory intake bolt fail.

If the bolt is fine, verify its length, there are 3 or 4 short ones that go where the intake is less thick. Should not be possible to mess that up.

Then we get to the treads in the head. Chasing the threads couldn't hurt. Longer bolt might be tricky to get the length exactly right to get more thread engagement but not bottom out before coming tight. A stud would solve that issue at the cost of altering the appearance. Do 'em all in studs! Boy would that be a pain to remove the intake later.

 

I agree with all above:

Pull the screw and have a good look at it.
Get a tap in there and chase the thread.
Make sure you've got the right length screw.
If the threads really are stripped, Heli-Coil it, which will require removing the intake (or drilling out the intake hole bigger).

The likelihood that one of these holes in the cast iron head is stripped is very unlikely, though.

Did you chase all the threads in the head before you assembled it? Hmmmmmm???

- Eric

 

And if at all possible use a thread chasing tap, not a thread cutting tap. Use just a little bit of thread lube.

 

I'm not sure if you should be torquing an aluminum manifold to stock iron specs.

 

You should. There is no difference in the torque spec.

 

Thanks for the tips guys. Pulled the bolt out this morning and found this:



Tried fingering the factory bolt down in the hole and it stopped moving after a few turns. Went on a hunt for a 3/8-16 thread chaser. Let me tell you, as hard as you might imagine it would be to find one in Okinawa, Japan, it's worse. Several hours later I returned with a tap (all I could find) and ran it in with my fingers as far as I could. Seemed straight, so I went a little further with hand tools, pulled it out, and now the factory bolt spins right in. Ran out of time before work so I didn't have a chance to install it permanently and torque it to spec, but it seems like it will be fine.

On a side note, the factory bolts are longer than the edelbrock ones. As many thread as you see missing is about how much longer the factory bolt is. Guessing that was the cause. Seems odd and I worry slightly about the other bolts, but they all made it to tq spec, so I'll leave them.

 

I'd use the factory screws if I were you. Don't use screws that are too short (and not hard enough), or they'll do the same thing.

So they're a little rusty. So what? They work.

- Eric

 

That's what I figured the bolts are too short. Take a wire brush and clean your stock bolts and use them.

 

Yeah, probably will, at least with the 3 short bolts. The long ones were all the same length as factory. I wonder if it's worth even complaining to edelbrock about.

 

Edelbrock says torque to 25 ft lbs


http://www.carid.com/images/edelbroc...structions.pdf

 

Whoops. Well, they are all at 40 now. I guess if it was going to hurt anything, it would have already and no point in taking them back down to 25, right?

 

Thank you!

 

I wouldn't worry about the over torque. Check to make sure your not pushing out the front and rear manifold seals.

 

I'm not entirely sure what the rationale for less torque would be in this case.

- Eric

 

Aluminum expands more than iron when heated. Maybe it's for less load on the bolts when the manifold gets hot?.
I don't know, just my reasoning.

Roger.

 

I believe because the Elderbrock manifold comes with a composite gasket.

 

Factory aluminum manifolds are torqued to the same levels as iron. Unless E-brock is using the world's worst quality aluminum in it's manifolds, there is no reason to reduce the torque, especially if you are using a factory style intake gasket.

 

I have cracked/chipped an Ebrock around 35ft lbs. however if your already torqued to 40 I'd probably leave it too

 

If you did, there was some other cause than the torque. The tension force for a given torque can vary by over 2:1 just based on the amount of lube or rust on the bolt. That variation is far greater than the difference in tension force due to torquing to 40 ft-lbs instead of 25 ft-lbs.

For example, assuming dry, clean bolts, the tension in a 3/8" bolt is about 4,000 lbs at 25 ft-lbs and about 6,400 lbs at 40 ft-lbs. If the bolts were dipped in motor oil before torquing, per the CSM, those tension loads would be 8,000 lbs and 12,8000, respectively.

The compressive yield of an A356 aluminum casting is about 28,000 psi.

A standard 3/8" washer has an ID of about 11/32 and an OD of about 7/8, so the net area is about 1.67 sq in. Even at the fully lubed 40 ft-lb case, that's only 12,800/1.67= 8,000 psi, which is less than ONE THIRD of the compressive yield strength of the casting. There is no way this caused the problem.

Sorry, but math and physics says your torque ISN'T what damaged the manifold. More likely there was something not flat or not seated properly, or a pre-existing crack, or a grossly out of spec torque wrench.

 

The only point i was trying to make was that a fellow CO member might have made the same oversight as i, since the manufacturer does call for 25 NOT 40 ft lbs
I do appreciate your knowledge but not the patronizing "sorry" as much