heads

i have 2 heads for the 200..but the combustion chambers look different..1 is round with the u shape surrounding the valves..the other just has the u shape surrounding the valves both have the same number c6de 6090 b...but one has after the b ...x12..and thats the one with just the u shape by the valves...i hope some of you will understand without pictures

Howdy mluck:

I'm not familiar with the "x12" suffix, but FYI that casting was used on both 170 and 200 engines. And several of this casting were drilled and tapped on the top of each exhaust port for the Thermactic Air Pump injection port for an EPA air pump to reduce hydro carbons in the exhaust. Take a look at the top of the exhaust ports for taps. Sorry, not much help. Let us know what you find.

Adios, David

you have described "open chamber" and "closed chamber" heads,
i'm a newbie so i can only guess at the rest.
close chamber heads are also called "quench heads", having higher compression, found on pre-74? (pre-emmision) motors.
open heads had a lower comp. ratio.

CZLN6":2tu6um6k said:

Howdy mluck:

I'm not familiar with the "x12" suffix, but FYI that casting was used on both 170 and 200 engines. And several of this casting were drilled and tapped on the top of each exhaust port for the Thermactic Air Pump injection port for an EPA air pump to reduce hydro carbons in the exhaust. Take a look at the top of the exhaust ports for taps. Sorry, not much help. Let us know what you find.

Adios, David

Click to expand...

See viewtopic.php?f=1&t=72607



See /viewtopic.php?f=1&t=71133&p=545939#p545939


The one model of C6DE 6090 B is the transition from small to large chamber, or from 52 cc closed to 60 cc open. They went to open chamber head just with the California Thermactor head. The C7 was officially (although not actually) the last of the common small chamber heads. C7 DE 6090 C2 was the rare divided exhaust head, still closed 52 cc chamber.

deciding which log head for your build whether for performance , MPG or combination it helps to start with final CR goals .

here's a DODE - 6090-A Head from a 1971 Maverick (US)170 CID manual tranny car. The 'closed' chambers measure @ 52cc's.

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Current turbo projects use an uncut D7DE 250 head with @ 62 cc chambers and typical .045" gasket for @ 7.5: SCR to keep the stock pistons inside ...

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.. the C8DE Mav' 170 block with a worked D6DE 250 head cut to 48cc chambers and steel shim head gasket is perky in a '63 wagon on 93 octane (US) and gets @ 25 MPG. Static CR runs up near 10:1 , 2bBL, Headers and T5 overdrive make a fun drive'able car for @ ten years now.

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have fun