Reading old posts. One said that 64 used Y (high flow), dealers complained and RP began using X in 65. Then read another post by a real technical guy measuring engine values throught the RPM range who said his 65 had W nozzles. Can someone decode this for me. What should a 64 use? Does it depend on how you plan to drive it?
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Re: FI Nozzle Designations
Larry,
I've never heard the part about dealer complaint and nozzle change. That really doesn't make any sense. I don't know who posted that.
Nozzles were rated by flow, not orifice size. Supposedly, all of of the small disc's inside the nozzle had the same size hole (.0115") but even with the same size, they flowed slightly differently from one to the next. (same system as a Holley carburetor jet. the number isn't the drill size, it's the flow rate)
In production, the nozzles were matched to a fuel meter/pump output rate. -
Re: FI Nozzle Designations
So I think you are saying that two cars built back to back might get different flow nozzle tops depending on a reading of the fuel meter output? And, to know what to use you need to pull one from the car and then replace with the same if replacement was ever needed?
I could find the dealer comment again but whoever posted it said that the reason was because the Y flowed too much fuel.....not arguing...just telling you what I read. I guess GM was sensitive enough even back then to take feedback from their service shops but just guessing.Comment
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Re: FI Nozzle Designations
My info on the 64-65 nozzles was given to me by Frank Sciabica of RP in the old days. He said that RP was getting complaints that the 64's were running too rich. Frank said most 64's were using the Y nozzles. So he said RP went down one nozzzle size (X) in the 65's. I am just repeating what he told me.
Personal observation with no documentation is this. Most of the 64's I see have Y's. Most of the 65's I see have X's. But the last few years I have seen a fair number of '65's that have W's. Now I have no idea if these nozzles are original or if they have been changed.
Size of nozzles. W's are the smallest for midyears, Y's are the biggest. Lot of difference between a W and a Y. Not too much difference between an X and a Y as far as flow goes.
Nozzles were mostly made by Detroit Diesel. Frank said DD made the bulk of their nozzles and RP repackaged them. Not to say that RP didn't make nozzles also. Remember companies always had more than one source for parts. John
P.S. Larry, Fuel injections came with a matching set of nozzles in them. All 8 are stamped with the same number or letter.
Right below the thread of the nozzle top you will find a letter stamped in midyear nozzles. Earlier nozzles had both letter's and numbers.
More to it than that but we confused the gang enough here.Comment
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Re: FI Nozzle Designations
Thanks John. I looked and you can't see the designations while on the car so I guess I won't know what I have installed until I take the unit off for cleaning next winter.Comment
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