Air Cleaner Base 1970 LT-1

[David L.]

Re: Air Cleaner Base 1970 LT-1

Ron,

Enclosed is a sketch of what I believe is a 6422188 base (bottom side) with the tube angled at 90 degrees (used on the 6423907 air cleaner assembly) shown on the left side. On the right side of the sketch I always thought was the base used on the 6423272 air cleaner assembly with the tube angled at 45 degrees.

The 6423907 and 6423272 air cleaner assemblies were both used on 1968-1969 Z28's.

6423272 changed on 11/27/67 to 6423907 changed on 10/30/68 back to 6423272.

The 6423907 A/C asm. was used with the 3942518 rubber hose and the 6423272 A/C asm. was used with the 3932336 rubber hose. Both A/C assemblies use the same connector, GM # 3923260, in the valve cover. Since the rubber hoses are different I would think that the tube location on the bases would also be different.

In March 1971 a 6423907 A/C asm. listed for $34.70 while a 6423272 A/C asm. listed for $36.35. I wonder why one was more expensive if they were basically the same?

Are you saying that your NOS 6423272 A/C asm. has a base that looks like the one on the left side in my sketch?

Dave

[Ronald L.]

Re: Air Cleaner Base 1970 LT-1

Dave, the bases are identical.

[David L.]

Re: Air Cleaner Base 1970 LT-1

Ron,

Have you ever seen a base with the tube rotated 45 degrees as shown in my sketch on the right side?
I remember seeing many bases like this at Corvette Carlisle, etc., back in the 1980's and 1990's.
Paragon Corvette makes a repro that looks the same (Paragon part # 2091) but they do not give the equivalent GM part number.

Dave

[Ronald L.]

Re: Air Cleaner Base 1970 LT-1

Dave, Yes.

I saw and had one that was different a few years ago, but IIRC the tube was 90 degrees perpendicular. I fully expected when I opened the 272 box to find this pointing to the cowl, and when it wasn't .

I can only say due to how these were racked and painted, that characteristic mark of this specific piece, and that I only have had the one NOS asy, that these parts were not inadvertently mixed up somehow.

[David L.]

Re: Air Cleaner Base 1970 LT-1

Ron,

I found a page from my notebook that I have taken out to answer a question on the Nasty Z28 website about a 1970 Camaro L34 air cleaner base which uses a 6485239 air cleaner assembly. My notes indicate that I saw a NOS 6485239 air cleaner assembly at Corvette Carlisle in July 1989 and the tube was aligned in a "radial" position.
The 6485239 A/C asm. is also used on the 1971 Corvette SHP 454 as per my 1972 Corvette Parts Catalog (Sept. 1971).

Enclosed in a photo of my revised sketch.

I still want to do more research on the 6423907 and 6423272 A/C assemblies to see what the difference is.

Dave

[David L.]

Re: Air Cleaner Base 1970 LT-1

Yes, the tube orientation is quite different as well as the length protruding beyond the base edge plate.

Warren,

The tube on the base of the 6485239 air cleaner assembly is oriented in a "radial" fashion as shown in the sketch in my post at 7:19 PM today, 09/11/2011.

The 6485239 air cleaner assembly was also used on the 1970 Camaro 396 (L34 option). Enclosed are 2 photos from the 1970 Camaro assembly manual. Note the 90 degree rubber hose (GM # 3975934) and the 90 degree connector (GM # 3868842) to make the "roundabout" connection to the hole in the valve cover. The tube points back toward the firewall.

Dave

[Patrick B.]

Re: Air Cleaner Base 1970 LT-1

Ron,

I found a page from my notebook that I have taken out to answer a question on the Nasty Z28 website about a 1970 Camaro L34 air cleaner base which uses a 6485239 air cleaner assembly. My notes indicate that I saw a NOS 6485239 air cleaner assembly at Corvette Carlisle in July 1989 and the tube was aligned in a "radial" position.
The 6485239 A/C asm. is also used on the 1971 Corvette SHP 454 as per my 1972 Corvette Parts Catalog (Sept. 1971).

Enclosed in a photo of my revised sketch.

I still want to do more research on the 6423907 and 6423272 A/C assemblies to see what the difference is.

Dave

Dave:
If I understand your post correctly, the 6485239 A/C you saw at Carlisle was mis-boxed. If that 6485239 had the pipe at a 45 degree angle to the firewall it will not fit an LS-6. My LT-1 had the base with the pipe angled 45 degrees to the firewall. I put a ZL-1 427 with an LS-6 manifold (to fit the LT-1 hood) in the car in 1982. I tried to use the LT-1 A/C on it, but it would not fit. I had to buy a 6485239 from the dealer in 1982 to make it work. Subsequently, I put an L-88 hood and stock high rise maifold on it but kept the same LS-6 base. That base is in my photo in an earlier post of the BB in the car, and the pipe is aimed directly at the valve cover. The hose is a little cockeyed when it has to point down from the high rise manifold rather than straight across with the flat LS-6 manifold.

[Patrick B.]

Re: Air Cleaner Base 1970 LT-1

The first two photos show the air cleaner base from my 1970 LT-1 ser# 14297 built July 3, 1970. It points toward the firewall at an angle like the air cleaner base in Paul's first picture. I am sure this is the original air cleaner. I bought the car from the original owner in 1972 when the car had only 8,000 miles on it.

The third picture shows an air cleaner base that looks like the units that point toward the valve cover. It is a service piece for a 1971 LS-6 that I bought from the Chevy dealer in 1982. You can see why it works so well on a big block - the tube points straight toward the breather opening in the valve cover. When I put this engine in the LT-1 in 1982, I tried to use the LT-1 base but I could not bend the hose to make it fit the big block. So apparently the LS-6 bases will work on either an LS-6 or an LT-1, but one type of 70 LT-1 base will not work on a big block. Maybe that is why the firewall oriented base does not appear in 1971.

David and Warren:

Excuse me for adding confusion to this issue with my previous post. I believe I lost track of which of the a/c bases in my photos came with my 70 LT-1 and which I bought under the LS-6 part number 6485239. I looked at an old M.F. Dobbins Vette Vues Fact Book that showed good pictures of LT-1s, LS-6s, L-88s and a ZL-1 all taken in the late 70's and early 80's when these cars were not that old. The LT-1s, L-88s and ZL-1 all had the pipe pointing to the valve cover like the base in my third picture with the ZL-1 engine in my car with a L-88 hood. The LS-6s in Dobbins book had the base with the pipe angled toward the firewall like Dave's sketch and observation of an NOS unit at Carlisle. It is like my first 2 pictures that I had stated were from my LT-1 (apparently incorrectly). When I first put the ZL-1 engine in my car in 1982, I used a low LS-6 manifold on it so I could make it clear the LT-1 hood. That was when I discovered that the LT-1 a/c base would not fit, and I had to buy a new 6485239. When I replied to this thread I found the old box with my LT-1 smog pump, LT-1 a/c top, LS-6 a/c top and one base. After looking at Dobbins pictures I believe the loose base I had was really the LS-6 service base rather than the original LT-1 base. I put The ZL-1 manifold and a L-88 hood (to clear it) on the car in about 1985 and I must have put the LT-1 base back on then because it looked the same as an L-88 base.

So the bottom line is that my 70 LT-1 had an a/c base with the pipe pointing toward the valve cover and it is the base residing on the big block in my third picture. However, I still believe some 70 LT-1s had the base with the pipe angled toward the firewall. Dobbins book shows a 70 350-350 with the angled base that I now associate with the LS-6 service a/c.

[Terry M.]

Re: Air Cleaner Base 1970 LT-1

1970 LT1 end of January build: Gosh I should have cleaned it at least a little first.

[Terry M.]

Re: Air Cleaner Base 1970 LT-1

They pointed to the firewall/heater box.

Also Warren the car I viewed had that little hole below the screw hole on the drivers side for the coil bracket. Right below where the screw head is located.

Paul 18046

I didn't take a picture, but I am pretty sure my coil bracket has the hole you are referring to. I can look if it is a big deal. LMK, Paul.

[Terry M.]

Re: Air Cleaner Base 1970 LT-1

Not to confuse the discussion, but a 1972 that has been restored. I have no clue how original the base and hose are, but the dark elbow into the rocker arm cover looked original.

When I was taking the picture at the Wisconsin Chapter Meet someone standing around said "That is for the LT1 air cleaner base discussion on the tech board." We may be more popular than I thought.

[Warren F.]

Re: Air Cleaner Base 1970 LT-1

David and Warren:

Excuse me for adding confusion to this issue with my previous post. I believe I lost track of which of the a/c bases in my photos came with my 70 LT-1 and which I bought under the LS-6 part number 6485239. I looked at an old M.F. Dobbins Vette Vues Fact Book that showed good pictures of LT-1s, LS-6s, L-88s and a ZL-1 all taken in the late 70's and early 80's when these cars were not that old. The LT-1s, L-88s and ZL-1 all had the pipe pointing to the valve cover like the base in my third picture with the ZL-1 engine in my car with a L-88 hood. The LS-6s in Dobbins book had the base with the pipe angled toward the firewall like Dave's sketch and observation of an NOS unit at Carlisle. It is like my first 2 pictures that I had stated were from my LT-1 (apparently incorrectly). When I first put the ZL-1 engine in my car in 1982, I used a low LS-6 manifold on it so I could make it clear the LT-1 hood. That was when I discovered that the LT-1 a/c base would not fit, and I had to buy a new 6485239. When I replied to this thread I found the old box with my LT-1 smog pump, LT-1 a/c top, LS-6 a/c top and one base. After looking at Dobbins pictures I believe the loose base I had was really the LS-6 service base rather than the original LT-1 base. I put The ZL-1 manifold and a L-88 hood (to clear it) on the car in about 1985 and I must have put the LT-1 base back on then because it looked the same as an L-88 base.

So the bottom line is that my 70 LT-1 had an a/c base with the pipe pointing toward the valve cover and it is the base residing on the big block in my third picture. However, I still believe some 70 LT-1s had the base with the pipe angled toward the firewall. Dobbins book shows a 70 350-350 with the angled base that I now associate with the LS-6 service a/c.

Patrick,
I've been away a few days so I didn't catch this posting until today. Thanks for clearing up the confusion. If you decide to sell the LS6 base plate or assembly I would be interested in it. I have one car with a badly banged up tube.

[Patrick B.]

Re: Air Cleaner Base 1970 LT-1

Warren: If I had an extra one I would be happy to sell it to you. Unfortunately, I'm planning to put the LS-6 manifold and LT-1 hood back on this winter, and I'll need the LS-6 a/c again. My drag racing days are over, and I'm putting the original parts bach on my LT-1. However, I'm not quite ready to give up my home-made "LS-6" with an aluminum block. The LT-1 was my fall back choice when I was looking for an LS-6 in 1972. I had seen one (a green convertible I think) at my local dealer the year before and had no idea that they were so scarce. I'm glad I settled for the 8,000 mile LT-1 when I came upon it because I probably never would have found an LS-6 back when they were just used cars.

[Warren F.]

Re: Air Cleaner Base 1970 LT-1

Patrick,

I understand. I've been searching for more than 5 years now for an air cleaner base. I'm very fortunate to have the two cars I do, there's no way I could afford to buy them presently.

[Ronald L.]

Re: Air Cleaner Base 1970 LT-1

Dave,
Just today I happened across one of the bases in a pile of parts someone had for sale, with the tube at a 45 degree angle. The tube is a different profile-form than the LT1 427 "188" base.

Warren - is that the base you need???


Terry, I see your finger prints!