Whats the Difference between "73" 350 and 454 air cleaner?

[Russ S.]

Re: Whats the Difference between "73" 350 and 454 air cleaner?

I did some research back a few years ago on these air cleaners so I will reiterate what I came up with although this is not cast in concrete. 73-74 SB uses a concentric ring BB uses a offset to the rear. SB base has one large dented in area about center in the rear close to in direct line with the distributor. BB base has one smaller dented area an inch to the driver side of the SB dented area. The vent hole is also about 1 inch farther back on the BB than the SB.

75 base is different than 73-74 but the same for SB and BB except that the ring is again offset to the rear. The 75 base has two areas at the rear that are pushed in which touch each other Also the 75 base vent hole is forward farther than either the 73-74 SB and BB (which remember are about 1 inch apart) by about 3-4 inches.(depending on which 73-74 SB or BB you are comparing to)

I suspect 75 rings have different cut-outs than do 73-74 rings due to the crankcase breather hole being 4 inches farther forward. Hope this helps.

Theoretically there should be four different rings for these different applications.
73-73 SB
73-74 BB offset
75 SB
75 BB offset

If any one can add to my findings or have different findings please say so.

CORRECTION: No BB was available in 75 so only one flange ring for 75

[Russ S.]

Re: Whats the Difference between "73" 350 and 454 air cleaner?

Well if I was misunderstood, what I MEANT to imply was; THE BREATHER TUBES ARE DIFFERENT DEPENDING ON ENGINE! NOT the vent holes. I've even seen where someone managed to cram the small block tube into the valve cover and base on a big block. I've been looking at pretty much '73's exclusively for about 25 plus/minus years. I don't spout something as gospel unless I can back it up! Do YOU have a '73 A.I.M. and or the '73 parts book?

'73 LS-4 454, owned 21 3/4 years!

Otter Creek Copper Ale, now on tap

Rich, As I just posted I have 7 of these air cleaners at my disposal and of these there are three different vent hole locations in the bases. I also have a 73 purchased new in 73, AIM, and parts book. If 73-74 SB and BB used the same base I sure can't explain the three different vent locations.

PS Here may be a possibility that I just thought of as to the three vent locations:
I don't know much about the 72 air cleaner base so maybe some one can tell me whether or not the 72 base is the same physical size and shape as the 73 base.
If 72 is the same, it could be that the base I have with the third location is a 72 base???? I know it is a different part number.

PSS I just got my question answered as to whether or not my third vent hole location could be a 72 base. It isn't a 72 base because my 73 BB flange cut-outs fit the base perfectly.

[Rich C.]

Re: Whats the Difference between "73" 350 and 454 air cleaner?

Maybe one a '75? I have '73 and '74 A.I.M.'s but not a '75 A.I.M. So I have no info as to whether the part # changed for the BASE for '75. We all agree the '75 flange was different, which begs the question, why did they change the 350 flange for '75? Maybe they used a similiar base and or flange combination on other cowl induction chevys ie; Chevelle/El Caminos, etc.

'73 LS-4 454, owned 21 3/4 years

Otter Creek Copper Ale now on tap!

[Russ S.]

Re: Whats the Difference between "73" 350 and 454 air cleaner?

Maybe one a '75? I have '73 and '74 A.I.M.'s but not a '75 A.I.M. So I have no info as to whether the part # changed for the BASE for '75. We all agree the '75 flange was different, which begs the question, why did they change the 350 flange for '75? Maybe they used a similiar base and or flange combination on other cowl induction chevys ie; Chevelle/El Caminos, etc.

'73 LS-4 454, owned 21 3/4 years

Otter Creek Copper Ale now on tap!

Rich, Yes the one I have is a 75. The 75 part number (Over the Counter) for the base was 8994027. The flange changed because the vent hole is about four inches(estimate) forward of the other bases.

[Harmon C.]

Re: Whats the Difference between "73" 350 and 454 air cleaner?

I think 73-74 all bases were the same 8 1/2" to the breather hole from the snorkel. 75 base this hole was in a different location.
73-74-350 hood seal ring was on center.
73-74-454 hood seal ring was about one inch offset and easy to see it's not on center.
75-350 hood seal ring was on center and the cut out was moved to the new breather hole location.
73-74 used an (S) shaped vent tube to the valve cover on both 350's-454's
75 vent tube was a 90 degree angle to fit the 75 only base.
Russ I only knew of two vent hole locations so the third base you have may not be a Corvette part.

[Michael W.]

Re: Whats the Difference between "73" 350 and 454 air cleaner?

We all agree the '75 flange was different, which begs the question, why did they change the 350 flange for '75?

'75 was the first year for HEI, which required a different top shield, which required a different air cleaner flange. I think.

[Russ S.]

Re: Whats the Difference between "73" 350 and 454 air cleaner?

I think 73-74 all bases were the same 8 1/2" to the breather hole from the snorkel. 75 base this hole was in a different location.
73-74-350 hood seal ring was on center.
73-74-454 hood seal ring was about one inch offset and easy to see it's not on center.
75-350 hood seal ring was on center and the cut out was moved to the new breather hole location.
73-74 used an (S) shaped vent tube to the valve cover on both 350's-454's
75 vent tube was a 90 degree angle to fit the 75 only base.
Russ I only knew of two vent hole locations so the third base you have may not be a Corvette part.

Thanks Lyle for your input.

In this case, does any one have the part number(s) for the base on other GM applications? I think that would be Chevelle cowl induction and camaro. It would be interesting to know whether or not there is a different part number for these other applications.

[James B.]

Re: Whats the Difference between "73" 350 and 454 air cleaner?

Wheww! Thanks guys, and while that was all going on I did find a 73 air cleaner for a 454 off an engine with a build date the day before mine, I'm guessing it's probably the right one. Thanks again and sorry to create such a ruckus, good work gentlemen.

[Robert R.]

Re: Whats the Difference between "73" 350 and 454 air cleaner?

Don't consider it a ruckus.
This shows how we all learn from this site.
I know that I did.

[Russ S.]

Re: Whats the Difference between "73" 350 and 454 air cleaner?

There is a difference between 73 SB and BB. The BB ring is offset toward the rear. Also I believe the location of the BB vent hole as well as the pushed in area at the rear of the base is in a different location than a 73 SB

Robert, I stand corrected as a result of this discussion. It seams that you are correct in that the 73 SB and BB use the same base. Thanks for your insight. Russ

[Russ S.]

Re: Whats the Difference between "73" 350 and 454 air cleaner?

Don't consider it a ruckus.
This shows how we all learn from this site.
I know that I did.

Ditto. I also learned from this discussion. This is a invaluable resource to all of us. Thanks to all for your input.

[Robert R.]

Re: Whats the Difference between "73" 350 and 454 air cleaner?

Russ,
As stated earlier, we all learn.
I only knew of what the differences were to small blocks and had no clue as to the offeset for the 454s.
That's what I learned from this.
Bob