Big Block valve sizes - Team Camaro Tech
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post #1 of 3 (permalink) Old Apr 4th, 01, 05:40 PM Thread Starter
Tech Team
Join Date: Jul 2000
Location: Beatrice, Nebraska
Posts: 74

OK guys I need a hand I'm new to the Big Block game here. I have a set of heads that I bought from a friend at a good price. Part #3904390 GM4, and #3856206 GM5. they arent a matching set but I believe that they are identical. I'm unsure of what size valves I can put in them. the current exhaust are the 1.725 so I am assuming that the intake would be 2.065??? Is this as big as I can go? Could I have them cut larger and how big?

69 Camaro 327/Th400
Deluxe Houndstooth
Still got the protecto plate, build sheet, owners manual,inspection sheet from dealer, and a reciept for an extra key on date of purchase from dealer.

Visions of wheelstands in my head
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post #2 of 3 (permalink) Old Apr 4th, 01, 06:24 PM
Join Date: Nov 2000
Location: Pennsville,N.J., USA
Posts: 17

Those heads are physically the same in the combustion chamber,the 206 head has no provision for a temp sendng unit though. 2.19 -1.88 will work or just the 1.88 exhaust is a help.the main reason that I replied to you is to tell you that for years using these "bathtub" heads with a true
11 to 1 piston with somewhere in the area of .300-.350 dome will make contact with the head and sound just like a rod knock when running,and wil cause that also.this can be worse if things have been cut. [block ,heads].the factory 10.25 to 1 that the standard.-perf. motors used only had a .100-.170 dome .I don't know if you were even planning on running that much ,but in my years this has been more the cause of big blocks getting a bad rap ,literally. DAVE
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post #3 of 3 (permalink) Old Apr 5th, 01, 10:33 AM Thread Starter
Tech Team
Join Date: Jul 2000
Location: Beatrice, Nebraska
Posts: 74

does anybody know the cc size for these heads?
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