Intake Manifold Washers 72 LT-1

[Les W.]

I am trying to find out the size (thickness and OD) and finish for the washers that go under the 9/16 bolts, that make contact with the aluminum intake manifold. Can anybody help?

[Joe L.]

Re: Intake Manifold Washers 72 LT-1

I am trying to find out the size (thickness and OD) and finish for the washers that go under the 9/16 bolts, that make contact with the aluminum intake manifold. Can anybody help?

Les-----


Washers were not originally used. However, I recommend them or flanged head bolts for all small blocks, aluminum manifold or not. In a retrofit of washers and where judging standards are also concerned, you want to use 9/32" ID washers with the smallest possible OD so that they are as non readily apparent as possible. Of course, such washers defeat part of the functionality since the smaller the OD the lesser the clamping force is spread.

[Patrick H.]

Re: Intake Manifold Washers 72 LT-1

I believe that they're called "AN" washers.

http://www.speedwaymotors.com/Stainless-Steel-AN-Washers-Pack-of-50,4817.html

[Terry M.]

Re: Intake Manifold Washers 72 LT-1

Les-----


Washers were not originally used. However, I recommend them or flanged head bolts for all small blocks, aluminum manifold or not. In a retrofit of washers and where judging standards are also concerned, you want to use 9/32" ID washers with the smallest possible OD so that they are as non readily apparent as possible. Of course, such washers defeat part of the functionality since the smaller the OD the lesser the clamping force is spread.

Joe,

Some 1971 and all 1972 LT1s used either a washer or a bolt with a built in washer on many of the intake manifold positions. I have never had one apart, so I don't know which it is, but there is definitely something under the head of the bolt to bear against the aluminum intake. You are however right about 1970 and early (don't ask what "early" means) 1971 LT1s having no washer under the bolt head.

[Sal C.]

Re: Intake Manifold Washers 72 LT-1

I agree with Terry. And I have had many of them apart. Every original one had bolts with an integral (flat and relatively thick) shoulder. These were not installed at the engine lift hook or spark plug wire support points.

[Sal C.]

Re: Intake Manifold Washers 72 LT-1

Oh, and nice talking with you Les.

[Les W.]

Re: Intake Manifold Washers 72 LT-1

Joe & Patrick,

From what I have read in Corvette Restoration Guide 68-82, the 9/16 hex head bolts, which is a 3/8-16 bolt, have washers under the bolts that contact the aluminum manifold. GM started using them in 1972. I don't know about the 'AN' washers, but Paragon has SS washers that measure 3/8 ID and a little under 9/16 OD. I have heard that GM used a bolt with a fixed washer. Any photo's would be helpful. Thanks.

[Terry M.]

Re: Intake Manifold Washers 72 LT-1

I agree with Terry. And I have had many of them apart. Every original one had bolts with an integral (flat and relatively thick) shoulder. These were not installed at the engine lift hook or spark plug wire support points.

As I was typing my response I was thinking "Sal would know." I almost typed it, but I didn't want to put you on the spot. See you in Florida?

[Sal C.]

Re: Intake Manifold Washers 72 LT-1

[QUOTE See you in Florida?[/QUOTE]

Absolutely

[Kevin G.]

Re: Intake Manifold Washers 72 LT-1

Wes,

Here is a picture of the flanged head bolt on the lifting eye. I have some pictures of the regular bolts with washers but they are not very clear. I'll try to shoot some for you.



Heck here's a blurry one .............

[Sal C.]

Re: Intake Manifold Washers 72 LT-1

Here is another. Photo by Gary Bosselman

[Ron G.]

Re: Intake Manifold Washers 72 LT-1

As far asI know, all 70 and most 71 LT-1's did not have the washers under the intake bolts, there were bolts with built in washers if it was attached to a part such as the photo kevin Goodman provided for us. Hi Thal.

[Joe L.]

Re: Intake Manifold Washers 72 LT-1

Here is another. Photo by Gary Bosselman

Sal------


Interesting. I was not aware of this. I am glad that GM finally figured this out. As I've mentioned before, they should have used washers or flange head bolts (like they did for big blocks) on all small block manifolds, aluminum or cast iron.

I wonder if they continued the use of washers for the aluminum manifolds used on many 1978-82 Corvettes?

[Dave S.]

Re: Intake Manifold Washers 72 LT-1

Sal------


Interesting. I was not aware of this. I am glad that GM finally figured this out. As I've mentioned before, they should have used washers or flange head bolts (like they did for big blocks) on all small block manifolds, aluminum or cast iron.

I wonder if they continued the use of washers for the aluminum manifolds used on many 1978-82 Corvettes?

71 LT-1 #16798 did not have any washers or washer head bolts on Intake.

[Kevin G.]

Re: Intake Manifold Washers 72 LT-1

Two more.