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mercruiser 4 cylinder 3.0 head vs 2.5 head

7

77 gt

New member
Hi all,

Could anyone tell me if i could use a 1977 mercruiser 3.0 140 hp head on a 1971mercruiser 2.5 120 hp block? The only difference I can tell is the valve size, since im going from a bigger head to smaller block displacement, it should be ok right?
 
thanks for the info. the 3.0 I have is a 1977 140 hp (which is the head i want to use) and the 2.5 is a 1971 120 hp bored .30 over. The 3.0 block is cracked and I have a rebuilt 2.5 ready to go in. I plan on using the 3.0 head and exhaust to bolt on to the 2.5 so exhaust ports shouldn't be a problem. the head gaskets and ports all line up to the block. I just wasnt sure how the larger valves would effect the engine. The main reason im using the 3.0 head and exhaust is because I dont have the throttle linkage that connects to the 2.5 exhaust as it is different than the 3.0.
 
77 gt said:
thanks for the info. the 3.0 I have is a 1977 140 hp (which is the head i want to use) and the 2.5 is a 1971 120 hp bored .30 over. The 3.0 block is cracked and I have a rebuilt 2.5 ready to go in. I plan on using the 3.0 head and exhaust to bolt on to the 2.5 so exhaust ports shouldn't be a problem. the head gaskets and ports all line up to the block. I just wasnt sure how the larger valves would effect the engine. The main reason im using the 3.0 head and exhaust is because I dont have the throttle linkage that connects to the 2.5 exhaust as it is different than the 3.0.
Click to expand...

Ayuh,.... That'll run, just Fine,....
 
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