Correct Intake Manifold bolts

[Bill S.]

I have a '66 327/350 HP with the aluminum intake and have had many discussions with all sorts of experts or so called experts and I have yet to get the same answer twice. Which is ..What are the correct letters on the intake manifold Bolts, so I can put all these people to rest.



Thanks

Bill

[Doug L.]

Re: Correct Intake Manifold bolts

Do you have a GM part number from the AIM for these bolts? If so I can compare with the P/N for the '64 bolts and if they are the same can tell you what marks my oriignal bolts have.

[Scott S.]

Re: Correct Intake Manifold bolts

I have a '66 327/350 HP with the aluminum intake and have had many discussions with all sorts of experts or so called experts and I have yet to get the same answer twice. Which is ..What are the correct letters on the intake manifold Bolts, so I can put all these people to rest.



Thanks

Bill

Bill,

I think the confusion is partly because these bolts are not called out in the Assembly Manual (intake manifold was bolted to the engine at Flint). As far as I can tell, the intake manifold bolt was the same for both 300hp & 350hp, at least for 1966-67. I don't know what the original part number was, but I think it eventually superseded to GM 9440310, which shows up in some parts books in the late 1980s. It is listed as 3/8-16 x 1-1/8", regular hex head. It should be 9/16" across-the-flats, Grade 5, with a black phosphate finish.

The 1966 Judging Guide says typical headmarks are A, M, TR, UR or FP. Any of those (or possibly a combination) should be fine.

I don't know why this particular bolt, used by the millions, is such a mystery. Joe Lucia will have a much better answer.

[Bill S.]

Re: Correct Intake Manifold bolts

I think thats why so many people have many answers of what is correct. I have had some tell me TR was incorrect I have had others say A was incorrect. I just get very upset with all these so called judges at shows who know it all and really do not know squat try to tell you what is correct and incorrect and they really donnot have a clue.

Thanks for your input

[John H.]

Re: Correct Intake Manifold bolts

I think thats why so many people have many answers of what is correct. I have had some tell me TR was incorrect I have had others say A was incorrect. I just get very upset with all these so called judges at shows who know it all and really do not know squat try to tell you what is correct and incorrect and they really donnot have a clue.

Thanks for your input

Bill -

Do you have the current '66 Judging Guide? It clearly lists the five different headmarks typically seen on L-79 intake manifold bolts; there should be no angst about what's typical and what isn't.

[Scott S.]

Re: Correct Intake Manifold bolts

I think thats why so many people have many answers of what is correct. I have had some tell me TR was incorrect I have had others say A was incorrect. I just get very upset with all these so called judges at shows who know it all and really do not know squat try to tell you what is correct and incorrect and they really donnot have a clue.

Thanks for your input

Bill,

It is my understanding from many discussions in the archives that GM had multiple suppliers for most fasteners (e.g., "TR" = Towne-Robinson, "M" = Michigan Screw Products, "WB" = Wales-Beech, etc.). The people in charge of re-supply made sure the bins full of bolts were filled with the correct GM part number. When a bin was low, it might be re-filled with bolts bearing the same headmark, or a different headmark, in which case bolts with different manufacturer's headmarks would be mixed together. The assembly line worker paid no attention to headmarks, the important thing was that the correct part was in the bin when he or she reached for it.

[Joe L.]

Re: Correct Intake Manifold bolts

Bill,

It is my understanding from many discussions in the archives that GM had multiple suppliers for most fasteners (e.g., "TR" = Towne-Robinson, "M" = Michigan Screw Products, "WB" = Wales-Beech, etc.). The people in charge of re-supply made sure the bins full of bolts were filled with the correct GM part number. When a bin was low, it might be re-filled with bolts bearing the same headmark, or a different headmark, in which case bolts with different manufacturer's headmarks would be mixed together. The assembly line worker paid no attention to headmarks, the important thing was that the correct part was in the bin when he or she reached for it.

Scott-----


That's how it was. As far as fasteners go, there were usually more than one supplier for any particular part number. Therefore, if one knows the part number of a particular bolt, that provides no definitive information as to what the headmarking should be. In fact, some of these bolts under the original part number are still available from GM to this very day. Don't buy one and think you're going to get an original headmarking. Most of the time, you won't even get a "period-correct" headmarking----you will get a headmarking of the company that CURRENTLY manufactures the bolt for GM.

[Scott S.]

Re: Correct Intake Manifold bolts

Joe,

Do you know what the original part number was for the 1966-67 small block intake manifold bolts, and why such a widely used bolt isn't listed in the parts books (or is it)? GM 9440310 may be the current (or at least more recent) part number, but I suspect a bolt part number beginning with "944" is not the original part number from the 1960s.

[Michael H.]

Re: Correct Intake Manifold bolts

I thought black "NAT bolts were also very common for 66 and 67.

[Craig O.]

Re: Correct Intake Manifold bolts

I thought black "NAT bolts were also very common for 66 and 67.

I have a very early 67 and the bolts are NAT. black, but show signs of silver paint
overspray.

[Joe L.]

Re: Correct Intake Manifold bolts

Joe,

Do you know what the original part number was for the 1966-67 small block intake manifold bolts, and why such a widely used bolt isn't listed in the parts books (or is it)? GM 9440310 may be the current (or at least more recent) part number, but I suspect a bolt part number beginning with "944" is not the original part number from the 1960s.

Scott------

I do not know what the part number was for the bolts used in PRODUCTION for the intake manifold application. For one thing, the same bolt was not necessarily used at all intake manifold-to-cylinder head bolt positions. Some positions used a different length bolts depending upon what other parts the bolt might be used to retain.

In any event, these bolts were a standard parts item. Standard parts items are usually not carried in specific parts groups although, occasionally, they are included. In this case, if the bolts were included in a specific parts group it would have been group 3.275 and none are.

Bolts with 7 digit part numbers beginning with "94" were used in the 60's. However, bolt GM #9440310 was definitely not the bolt used in PRODUCTION as it does date from a latter era. From what I can tell, the original bolts used in PRODUCTION probably were never available in SERVICE. The original bolts were 1-1/8" long and SAE grade 5 but the only bolt GM offered in SERVICE of this length in the 60's was an SAE grade 8. This is common since GMSPO decides that a grade 8 bolt will work for all applications requiring a bolt of a particular length and the fact that it costs a few cents more is not a problem in SERVICE.

[Patrick H.]

Re: Correct Intake Manifold bolts

Mostly M on our late April 66 327/350.

[Ron G.]

Re: Correct Intake Manifold bolts

I have to agree with all of the replies as GM (and John H. & Joe L. would probalby agree) what I refer to as the "family of hardware" that was used not just on Corvettes, but all GM vehicles manufactured of the era. However, my own personal experience with the few 66-67 300 & 350 horse powres cars I have owned mostly had the aforementioned that our Corvette counter parts already said. Mostly "A", "M", "TR" and as Mike Hanson mentioned "NAT". I have a copy of this if you are interested.

[Terry M.]

Re: Correct Intake Manifold bolts

Not an answer to the OP's mid-year question, but an example of the fastener diversity common to all engine assemblies. There are seven different styles (including headmarks) on the intake manifold of my 1970 LT1. One is a stud, and one a washer-head bolt for the lifting bracket. Neither of those would be on a mid-year though. The two fasteners that hold the distributor shield supports have different headmarks than any other intake manifold fasteners.

When I judge, I make a minor deduction if all the intake manifold fasteners are the same headmark. The odds of that happening in production are greater than those of you winning the lottery; but the odds of that happening if you buy an intake manifold fastener kit from one of the Corvette supply houses is about 100%.

[Timothy B.]

Re: Correct Intake Manifold bolts

I have a '66 327/350 HP with the aluminum intake and have had many discussions with all sorts of experts or so called experts and I have yet to get the same answer twice. Which is ..What are the correct letters on the intake manifold Bolts, so I can put all these people to rest.



Thanks

Bill

Bill,

My September 1966 built 67 convertible with 327/300hp engine (cast iron intake) has NAT bolts used on the intake manifold.