'70 LT1 intake manifold bolt torque

[Kenneth H.]

So I'm going to replace the ignition shielding brackets on my LT1. In order to do this I need to remove the intake manifold bolts holding them in place. I don't want to mess this up and want to tighten these bolts correctly. Does anyone know the correct torque for these bolts, or can someone give me an idea where I can find this information.

I've checked the archives, looked at the A.I.M. and checked the Service Manual, without luck.

Any help would be appreciated. Thanks.

[Joe L.]

Re: '70 LT1 intake manifold bolt torque

So I'm going to replace the ignition shielding brackets on my LT1. In order to do this I need to remove the intake manifold bolts holding them in place. I don't want to mess this up and want to tighten these bolts correctly. Does anyone know the correct torque for these bolts, or can someone give me an idea where I can find this information.

I've checked the archives, looked at the A.I.M. and checked the Service Manual, without luck.

Any help would be appreciated. Thanks.

Ken----


It's 30 lb/ft for all intake bolts.

[Kenneth H.]

Re: '70 LT1 intake manifold bolt torque

Joe, thanks for the info.

[Stuart F.]

Re: '70 LT1 intake manifold bolt torque

If you can't get on it with a socket and torque wrench, it's one "eugh!" with a box wrench.

Stu Fox

[Kenneth H.]

Re: '70 LT1 intake manifold bolt torque

Thanks, Stu. The ignition shielding, distributor cap, air filter and air filter base are off (as well as some hoses) and it looks like I'll be able to reach it OK. Wish me luck.

Thanks.

[Larry M.]

Re: '70 LT1 intake manifold bolt torque

Thanks, Stu. The ignition shielding, distributor cap, air filter and air filter base are off (as well as some hoses) and it looks like I'll be able to reach it OK. Wish me luck.

Thanks.

Ken:

Some of these intake manifolds require that you fabricate a special extention to be able to use a torque wrench. I have made (or had made) one for myself using a decent quality box end wrench, cutting it in half, and then welding a 1/2" drive socket to the cut off end. Works well.....and you only have to do the extra work once....just keep it in your toolbox to use later or loan to friends. You also must slightly decrease the torque value due to the extra length....typically around 3-4 lb-ft lower torque (ie use 26-27 lb-ft) for the intake mainfolds bolts. The exact number is rather easy to calculate once you have the new extention length.

Good luck. Larry

[Jack H.]

Re: '70 LT1 intake manifold bolt torque

Joe's on the money, as ususal, 30 ft-lbs is the spec. You won't find it in the AIM as the engine came to the final line as an assy with the intake already installed.

Check out your copy of the Chassis Service Manual, Specification section at the rear, Engine Torque chart under 3/8-16 fasteners...

[Stuart F.]

Re: '70 LT1 intake manifold bolt torque

Sounds like a good idea that Larry posted. I wonder if you could do something similar with one of these new short wrenches which have a box end and open end, and are only about 3" long. If the bend /offset is not enough at the box end, you could do a heat, bend and chill process to make it work. Both ends would be 1/2", so a 1/2" extention might snap right into the open end. Uuuumh, I'll have to look into this.

Stu fox

[Kenneth H.]

Re: '70 LT1 intake manifold bolt torque

Guys, I must be missing something. That's probably because I haven't thought the process thru yet and also because I'm a novice at this. I understand the part about using lower torque because of the extension, but I don't understand the concept or practical application of the special tool. It appears, on the surface, that all I need to do is attach the correct socket to the proper length extension for clearance, and then attach this combo to the torque wrench and turn. What am I missing?

[Larry M.]

Re: '70 LT1 intake manifold bolt torque

Ken:

You are absolutely correct, no special tools are required IF YOU CAN GET A TORQUE WRENCH AND SOCKET ON EACH BOLT. Many intake manifolds are not this way. That is why I mentioned the special wrench. I have had to make/use for a number of intake manifolds over the years. I made an assumption that one would be needed for the aluminum LT-1 intake.

Larry

[Stuart F.]

Re: '70 LT1 intake manifold bolt torque

Ken;

Those of us who have changed intake manifolds on Chevy V8's over the years have run into difficulty finding either the right torque wrench, or combination of extensions and sockets to engage all the mounting bolts to execute a proper torque on them. The best promise is when all attachments and accessories are off the manifold. Unfortunately, that sort of ideal scenario seldom presents itself during normal on car maintenance. I guarantee if you were trying to re-torque all your intake manifold bolts on the car you would run into some you could not do with the tools most of us have in our tool box. As an example; I used to change out complete manifolds with dual quads installed at the drag strip. I could never have used a torque wrench in that endeavor so, like many others, I have developed my hand into a human torque wrench using a box end wrench. I can tighten those bolts by hand so close to 30 Ft-lbs that the engine will never know the difference. Call it "back yard mechanics" or whatever.

As you stated, you have removed many items you see will be in the way, so perhaps you will do fine and I do wish you luck. Just having the plug wire brackets in place should be ok.

Stu fox

[Kenneth H.]

Re: '70 LT1 intake manifold bolt torque

Stu and Larry,

I think I know where my confusion lies. I can see where it would be very difficult to remove most of the intake manifold bolts. I'll leave that to the professionals. The only two bolts that I'm interested in removing are the two that hold the ignition shielding brackets in place. I'm replacing the two brackets with the ones that are correct for my LT1. From what I can see, I think that they can be torqued with a standard torque wrench and an extension. Is that correct?

Thanks.

[Wayne K.]

Re: '70 LT1 intake manifold bolt torque

Ken:

Some of these intake manifolds require that you fabricate a special extention to be able to use a torque wrench. I have made (or had made) one for myself using a decent quality box end wrench, cutting it in half, and then welding a 1/2" drive socket to the cut off end. Works well.....and you only have to do the extra work once....just keep it in your toolbox to use later or loan to friends. You also must slightly decrease the torque value due to the extra length....typically around 3-4 lb-ft lower torque (ie use 26-27 lb-ft) for the intake mainfolds bolts. The exact number is rather easy to calculate once you have the new extention length.

Good luck. Larry

Ken,

This link will help if you need to make an adjustment to the torque wrench to compensate for additional length of and added extension. Also you should know if the bolts your dealing with go through a water jacket.

Wayne

http://www.belknaptools.com/extcalc.asp

[Joe L.]

Re: '70 LT1 intake manifold bolt torque

Stu and Larry,

I think I know where my confusion lies. I can see where it would be very difficult to remove most of the intake manifold bolts. I'll leave that to the professionals. The only two bolts that I'm interested in removing are the two that hold the ignition shielding brackets in place. I'm replacing the two brackets with the ones that are correct for my LT1. From what I can see, I think that they can be torqued with a standard torque wrench and an extension. Is that correct?

Thanks.

Kenneth----


Yes, that's all you need to do. If you use a standard extension on the torque wrench no torque value correction is necessary. If you were to use a CROWFOOT or TORQUE ADAPTER, then a correction is necessary. However, you should not need to use these for the bolts you're referring to. A crowfoot or torque adapter are needed for other manifold bolts, particularly the two "center" bolts on each side.

[Kenneth H.]

Re: '70 LT1 intake manifold bolt torque

Thanks Joe. Concerning the extension, I went to the link that Wayne posted and I think I understand wher the extension confusion comes from.

From the picture it appears that the extension in question is horizonal to the handle of the torque wrench. In that case one would need to compensate. But in the case where the extension is perpendicular to the handle you wouldn't need to modify the torque. does that sound right?