'57 4520 fi

[Wayne G.]

The '57 JM states that a 7014520 FI unit has (2) different air meters depending on HP. I've looked at many different sources trying to find out the differences, but haven't been able to find the answer. With that in mind maybe one of you with vast experience and knowledge of the 4520 unit can help me with the differences in the air meters.

Thanks,

Wayne

[Gary C.]

Re: '57 4520 fi

Wayne,

Glad you brought that up. Didn't realize there was a typo in the chart. Our bad.

Correction - should be 4521. 4520 is typo. Sorry about that.

Gary
....

[Wayne G.]

Re: '57 4520 fi

Gary,
I thought that may be the case. Thanks for the clarification.

Wayne

[John D.]

Re: '57 4520 fi

Actually a '4520 did in fact have two different air meters and variations of those.
The typical '4520 air meter may or not have a hole drilled on the pad that has the part number stamped. The low HP had a 1/8" Staight pipe thread for a vacuum takeoff. But it's still the same air meter-high HP or low HP.

The 2nd 'air meter used on a '4520 was a left over '4360 air meter. Frank Sciabica used to tell me that Rochester Products did not waste castings since they lost their butt on the fuel injections we so love.
The '4360 air meter had/has an adapter to mount the '4520 choke housing. The idle air tube on the bottom of a typical '4520 to '65 FI was not used on a '4360 unit so RP did some machine work and bubba work to install this tube via an o'ring and wild bracket bolted onto the bottom of the casting. Personally I have restored 3 of '4520's with this early air meter.
So if the Judging book states the '4520's used two air meters ( I didn't read it) then it's correct. JD

[Wayne G.]

Re: '57 4520 fi

John,
I was hoping you would respond to my question. My main concern was that there is only one stamped PN for the 4520 air meter. Gary qualified that. Your description on the RP factory modifing parts at will was interesting. We all have to remember, these were assembly line cars and parts were modified as needed.

Wayne

[Jim L.]

Re: '57 4520 fi

Your description on the RP factory modifing parts at will was interesting. We all have to remember, these were assembly line cars and parts were modified as needed.

Wayne

Indeed. I recently rebuilt a '57 "4800" Chevy passenger car unit that had a Cadillac FI air meter on it since new. It had been machined to conform to Chevy FI requirements, but the Cadillac casting number was unmistakable.

Jim

[John D.]

Re: '57 4520 fi

The latest issue of "Vette Vues" has an article by Ken Kayser on Cadillac, Buick, and Oldsmobile fuel injection. None of which made it into production.
Jim Lockwood. Did you take any pics of the Cadillac air meter???

Rochester Products was really struggling with the primitive fuel injections. You can expect most anything on the '4520's gang.
Here is our problem. We think everything went according ABC but it didn't. Frank Sciabica and I talked for many years. (on my dime). One day he hollered at me as he loved doing so. Without quoting exactly he told me that my logic on restorations was wayyyy off. For example he said in 1957 you could expect most anything of the Fi units. Mismatched castings and parts didn't mean crap to RP then. They were grasping for straws and did whatever it took to get an FI unit running.
Here is one for Lockwood and the gang here. I once restored a 57 '4520 for the original owner of the car. The owner was about an hour from my house (forget his name). His early '4520 had a reworked '4360 air meter and a '57 Pontiac choke housing on it.The owner said that only the local Chevy dealer had worked on the FI unit. That was a long time ago and I didn't know what to think. Sciabica was still living then so I called him up and told him about this. He said well what's so strange about that??? To repeat what I have told you all in the past. Frank said RP did not waste castings. If a casting was usuable but had flaws in the aluminum they epoxied them and used them in a field.
IF you are restoring a mid year FI and see some grayish/brown expoxy on the plenum it may have come that way from RP.
RP used Devcon epoxy in a yellow/black tube. I have an old tube of it buried around here somewhere.

You didn't ask but before you start discounting the originality of a '59/60 7017300 you better do your homework. RP used most any left over castings on those units. I have seen fuel bowls used on them with numbers not in any books anywhere. One day I called Gail Parsons and told him about the weird '7300 unit I had. Gail said he had the same unit in his stash and didn't know what to think. Then I talked to John Gratta and he had the same unit in his collection.
Diecast fuel bowls on a 7300 instead of the usual sandcast '57 style.
Later on I found out the fuel bowl was from a '58 Pontiac. Seems that RP had some left over unmachined Pontiac fuel bowls and machined them to fit the Corvette.
Basically the '58 Pontiac fuel bowl and the '58 Corvette are the same except for the location of the hi-pressure pump.

Sorry to hijack your thread Wayne. Yes the judging manual has a error on the air meter number. Writing one of those manuals and talking about all the numbers of FI crap is a night mare you know. JD

[Jim L.]

The "Cadillac" of air meters.....

Here ya' go, John. It's perfectly ordinary except for the casting number and some trivial differences between it and a 4520 air meter. That's a 4520 piece on the left and the Cadillac air meter on the right. The casting is very crude. The Cadillac piece lives on 4800 FI #11.











Jim

[John D.]

Re: The "Cadillac" of air meters.....

Hi Jim, The casting on the right looks like an early 'air meter from a low hp '4800 unit. What makes you think it's from a Caddy??
Who stamped the numbers on the pad. Or let me ask you a question. Where those numbers on the tag when you got the air meter??? Nice pics. Thanks, John

[Jim L.]

Re: The "Cadillac" of air meters.....

Hi Jim, The casting on the right looks like an early 'air meter from a low hp '4800 unit. What makes you think it's from a Caddy??
Who stamped the numbers on the pad. Or let me ask you a question. Where those numbers on the tag when you got the air meter??? Nice pics. Thanks, John

Hi John,

My information came from several sources:

From Brian Futo:

You have a real mystery there. I have worked on 4800 #3. It had a cast MX on the meters Can you find a MX on the parts? MX = Engineeririg development per Frank Sciabica RIP.
Back to your question I believe it to be Pontiac FI meter.I think the Pontiac has a addtional cast hole or it doesent.I don't remember.

From Ken Kayser:

I believe this is a Cadillac model casting that was used for the Cadillac Air Meter Assy 7014444 that I know one that exists today.

My guess is that the castings got mixed, this one was machined into a Chevy model and got past the inspection.

and:

The BX on the 7014053 is a B size drawing, X or first use experimental and the 5 digit number is now changed to the Production number 7014053

The AP on the 7014388 means it did not start out as an Exp number, it is on an A size with a typed description "just like 7014053 except for...." and the P is for first use Production.

From Jerry Bramlett:

I did find a Rochester drawing of that casting / part number. It is drawing number 7014445 with the title "-ASSEMBLY-, THROTTLE BODY PLUGS & TUBE". This drawing references a "model 7014391". (This number might be 7014301.) If this was a drawing for a 4800 air meter body, I believe it would reference a "model 7014801". The early Pontiac air meter was a "model 7014371". I'm not familiar with a "model 7014391" air meter (or a 7014301 air meter), but maybe that was the Cadillac or Oldsmobile air meter number.

The stamped numbers are the ones that were on the air meter when I did the unit.

For what it's worth, 4800 #38 has also been on my bench. It has the more common 7014804 air meter casting.

Jim

[John D.]

Re: The "Cadillac" of air meters.....

Neat info Jim on a mystery part. The casting is definitley not a Pontiac though. I have a 58 Pontiac unit here to restore for an NCRS member and special friend.

The air meter on it is unlike the one in your photos.
Pontiac has a hot idle compensator (like the 63 to 65 Fi's) on the air meter body. Quite visible.

[Wayne G.]

Re: The "Cadillac" of air meters.....

John,
The air meter information was very interesting. Thank you for clarifing my questions. With that in mind you may have an answer for this related question. The JM indicates that the 4520 low hp uni S/N's were all in the teens and the high hp unit S/N's started in the 2000's. Did this information come from a GM source or owner survey?

Thanks,
Wayne

[John D.]

Re: The "Cadillac" of air meters.....

Hi Wayne, I am sorry but I am going to pass on answering your question about the '4520 serial numbers in relation to HP.
But if you really want to learn about that subject then refer to my pal Ken Kayser's great book titled:
"The History of GM's Ramjet Fuel Injection on the Chevrolet V-8 etc.

I have #65 of the hard cover books signed by Ken. For reading in the bathroom I have a soft copy one also.
Kenny says all 2000 and earlier are low HP. All 2000 and higher serial numbers = HHP.
I don't know what your manual says as for some reason I don't own one. Back to work. Thanks, John

[Wayne G.]

Re: The "Cadillac" of air meters.....

John,
I would argee with you on the S/N ratings to hp. Noland Adams "Corvette Restoration" Vol 1, has an owner survey section that indicates most 250hp units had s/n prior to 2000 and the 283hp had s/n over 2000 like Ken Kayser indicated in his book. The reasons for my question is that my original '57 FI car has the original 4520 unit, but the s/n tag was removed when the owner polished the plenum. I wanted to do enough research to get the FI s/n as close to the correct one as possible. I have ordered a copy of Ken's book. Your knowledge of RP FI units and the other members of the Forum is invaluable during the restoration of ones Corvette.

Regards,
Wayne

[John D.]

Re: The "Cadillac" of air meters.....

HI Wayne, Haven't been on line for awhile. What are you going to do with the polished '4520 plenum? That's a tough one. Once the sand cast grain is gone on such a large part there is not much you can do to bring it back. Good luck, John