Intake manifold torque

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93ragtop

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About a month ago, I put the intake (edelbrock 7577) on my motor.
Yesterday, I noticed that some of the intake bolts were not tight...
I had tightened them per the FSM for 2000 dodge. With the last torque being 12ft lbs.
The only reason I can see it would happen is gasket shrinkage.
The bolts I used were just a standard hardware grade 5 with a flat washer, and oil on the threads.
Should these need to be re-torqued after a few heat cycles?
And just to clarify, its still on the engine stand if I need to change anything.
Thanks
 
The way I was taught many moons ago, was that EVERYTHING that's gasketed should be retorqued after several heat cycles. Intake, exhaust, heads, pan...
 
aluminum and cast iron expand at different rates...over time the bolts will need to be snugged...
 
Thanks to everyone for their input. But just to clarify a few things.
1. Engine is still on the stand.... Has never even had the carb mounted yet.
2. Gaskets were in a engine tech kit. But seemed to be a good quality.
3. I torqued per 2000 FSM which is in steps, but 72in lbs, then 12 ft lbs.

Not sure why, setting on a stand they seem to have loosened, esp. the center bolts.
I ordered a felpro gasket set and a sealer "Gasgacinch" to use with the gasket.
This was reccommended by Mbaird.
Intake manifold gasket sealer?

Thanks again for everyones input.
 
I think you said "'hardware grade 5". I hope those are not from any hardware store. Only automotive grade fasteners are designed to be used on autos. Rolled threads, specials shoulders etc...
What type and quality of torque wrench are you using ?
Magnum intake torque spec is 2 step. First to 16 lbs. Then torque to 23-25 lbs. This is with a Magnum bolt pattern intake.
 
Last edited:
Below is what I used when I bolted my dual plane M1 intake on. It shows 2 steps (72 in/lbs and 12 ft/lbs), but it also said to torque certain bolts in 5 steps. Center 4 bolts in order to 72 in/lbs, then the outer 8 bolts in order to 72 in/lbs, then all bolts in order to 12 ft/lbs followed with an additional check to make sure they are all still at 12 ft/lbs.

M1instructions 001.jpg


Let me know if you can't read #6 (the pertenant item) and I will zoom in on stuff and post bigger pictures.
 
I think that you stretched the bolts. I'd get rid of them and use better bolts (as per MoparLeo above). Be careful using torque specs for a cast iron manifold on an aluminum piece.... I think the directions from DionR are right on the money. I use thread sealer instead of oil on the threads to keep engine oil from seeping into the pockets below the bolts.
 
DionR said:
Below is what I used when I bolted my dual plane M1 intake on. It shows 2 steps (72 in/lbs and 12 ft/lbs), but it also said to torque certain bolts in 5 steps. Center 4 bolts in order to 72 in/lbs, then the outer 8 bolts in order to 72 in/lbs, then all bolts in order to 12 ft/lbs followed with an additional check to make sure they are all still at 12 ft/lbs.

Yes, that is basically the same as the 2000 FSM I have.
In short, start all bolts. Tighten the 4 center bolts to 12in. lbs. and keep going back in 12in. lb increases, until 72in. lbs are reached (on the 4 center bolts)
Tighten the 8 remaining bolts to 72in lbs.
Tighten all to 12 ft. lbs.

Thanks for your post.
Click to expand...
 
MoparLeo said:
I think you said "'hardware grade 5". I hope those are not from any hardware store. Only automotive grade fasteners are designed to be used on autos. Rolled threads, specials shoulders etc...
hat type and quality of torque wrench are you using ?
Magnum intake torque spec is 2 step. First to 16 lbs. Then torque to 23-25 lbs. This is with a Magnum bolt pattern intake.
Click to expand...

MoparLeo, could you tell me where you are getting this information?
The reason I ask, is that it seems to be in direct contradiction to the FSM and several post from this forum.
Not saying you are wrong, but would like to know where you are sourcing the information.

To answer your comments,
1. The bolts are hardware, (home depot grade 5) but upon doing a search for "intake bolts" on this forum, several members, including magnummopar recommended hardware bolts, and to replace the factory bolts due to breaking from corrosion.
2. The type of torque wrench was a cheap harbor freight click style for the in. lb settings. The 12ft. lbs was set with a craftsman beam style.
3. The torque ratings you stated are different then the FSM.

Thanks for your post.
 
str12-340 said:
I think that you stretched the bolts. I'd get rid of them and use better bolts (as per MoparLeo above). Be careful using torque specs for a cast iron manifold on an aluminum piece.... I think the directions from DionR are right on the money. I use thread sealer instead of oil on the threads to keep engine oil from seeping into the pockets below the bolts.
Click to expand...

Honestly, I dont see how 12ft lbs could stretch a 5/16 bolt of any grade, let alone a grade 5.
As far as I can tell, Aluminum is the only available intake for a magnun bolt pattern....
I agree, DionR is on the money, same as FSM
Never really though about sealer for the bolts.

Thanks for your post.
 
93ragtop said:

Honestly, I dont see how 12ft lbs could stretch a 5/16 bolt of any grade, let alone a grade 5.
As far as I can tell, Aluminum is the only available intake for a magnun bolt pattern....
I agree, DionR is on the money, same as FSM
Never really though about sealer for the bolts.

Thanks for your post.
Click to expand...

Aren't factory bolts TTY? They stretch by design.

Also, as you've probably sean or heard about, too much torque on a magnum intake can crack a block so the legend goes. Doesn't take much force on a magnum due to the angle of the bolts to seal it up. Don't gorilla arm it...

Regardless, we did ours per the 12fp you did and it's still running fine, no leaks. Possible your torque wrench is out of whack? If you're using a FP TW, instead of a IP TW, the torque will be suspect.

Just thinking out loud.
 
Cuda416 said:
Aren't factory bolts TTY? They stretch by design.

Also, as you've probably sean or heard about, too much torque on a magnum intake can crack a block so the legend goes. Doesn't take much force on a magnum due to the angle of the bolts to seal it up. Don't gorilla arm it...

Regardless, we did ours per the 12fp you did and it's still running fine, no leaks. Possible your torque wrench is out of whack? If you're using a FP TW, instead of a IP TW, the torque will be suspect.

Just thinking out loud.
Click to expand...

Not in my opinion they are not. The only TTY bolts I ever messed with was on a GM. You would tighten to a set LB torque, then turn an addition degree setting.
These start out in in lbs. but end at 12 ft. lbs.

I agree on over torque. Im going back at 12 lbs. (same as before) but Im adding the sealer Mbaird suggested.

Thanks to everyone for their input.
 
93ragtop said:

Not in my opinion they are not. The only TTY bolts I ever messed with was on a GM. You would tighten to a set LB torque, then turn an addition degree setting.
These start out in in lbs. but end at 12 ft. lbs.

I agree on over torque. Im going back at 12 lbs. (same as before) but Im adding the sealer Mbaird suggested.

Thanks to everyone for their input.
Click to expand...

The factory opinion would differ. The "question" was rhetorical. Good luck
 
I have probaly pulled the intake on my Magnum about a dozen times for head, cam, and intake swaps. Ive used the same original OEM bolts everytime and I have never torqued them. I snug all of them up in a criss cross pattern, and hand tighten them in the same pattern.

It is marked on the stock intake that the torque spec is 12 FT/LBS. I dont know where some of this other info is coming from. Ive also heard people say that they are TTY bolts. I dont see how 12 Ft/Lbs could stretch those bolts.
 
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