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my 55 bel air has these valve covers. i bought a new chrome pair at car show and finally started to install them, small block, bolt holes on heads do not line up with valve cover holes. best i can find , gm#3726086 are for 55 to 59 vette. can anyone tell me if the heads actually came off vette or are the bolt holes off set for certain heads?:
 

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pics could help. :anim_25:
 

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Corvette

I don't know why you don't want to keep the finned covers. Everyone knows they add horsepower.

Joe :sign0020:
 

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.....best i can find , gm#3726086 are for 55 to 59 vette. can anyone tell me if the heads actually came off vette or are the bolt holes off set for certain heads?:
If indeed this is the part number on the valve covers and the bolt holes don't line up, then you must have heads from a later (58 and up) model on your engine.
 

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my 55 bel air has these valve covers. i bought a new chrome pair at car show and finally started to install them, small block, bolt holes on heads do not line up with valve cover holes. best i can find , gm#3726086 are for 55 to 59 vette. can anyone tell me if the heads actually came off vette or are the bolt holes off set for certain heads?:
your heads are not necessarily from a corvette:

"Cylinder heads from 1955 through 1959 had a staggered bolt pattern for the valve cover flange bolts"
http://www.lsxmag.com/tech-stories/engine/head-history-the-evolution-of-factory-sbc-cylinder-heads-to-gen-iv/

do you know the head casting number?
 

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do your valve covers have 7 or 9 fins?

From "Tech Bench" column in the May, 2004 issue of "Corvette Enthusiast" magazine:


Although Corvette aluminum valve covers look pretty much the same to the untrained eye, there were actually six different variations of them used from 1956-1967.

1. 1956 2x4 engines used P/N 3726086: (9) fins, low (.030”) script, staggered bolt holes, and no notches in the upper seal flange.

2. Later 1956 2x4 engines with a revised intake manifold having larger runners required two cutouts to be added to the upper seal flange to clear the larger intake runners, starting about S/N 1650 (650th car built). There was no part number change, and these covers carried into ’57 production.

3. When fuel injection was introduced in 1957, an interference was found between the air meter and the upper fin on the valve cover, and the middle area of the top fin was milled off on fuel injection engines, starting about S/N 1900. 2x4 engines continued to use the “un-milled” 9-fin valve cover. Again, no part number change.

4. A new 7-fin cover (essentially the 9-fin cover with the top and bottom fins removed from the mold) was introduced on ’57 fuel injection engines about S/N 2900. The 2x4 engines continued to use the original 9-fin cover until about S/N 3900, when the transition began to the new 7-fin cover already in use on fuel injection engines. From S/N 3900 to about S/N 4500, 2x4 engines used both 9-fin and 7-fin covers, and 2x4 engines after about S/N 4500 all used the new 7-fin cover.

5. The new 7-fin low-script staggered-hole valve cover continued into 1958 production until about S/N 3600, when the molds were changed to increase the height of the “Corvette” script from .030” to .125” to improve their appearance. This cover (no part number change) continued into 1959 production until late March, 1959, when the cylinder heads changed.

6. The two lower valve cover attaching holes (and the bolt holes in the cylinder heads) were re-spaced inward to match the location of the upper two holes in late March, 1959; this new “parallel-hole” 7-fin high-script valve cover, P/N 3767493, continued in production through the end of the 1967 model year
 

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Discussion Starter #9
finned valve covers

thanks for the info. heads are more than likely to be 55 to 59. Thanks again.
 
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