Pelican Parts Forums - 2.7 cis on a 3.0

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2.7 cis on a 3.0

I have a 3.0 transplant in my 74' 911.The orig 2.7 cis was retained in doing the transplant. The car seems to run well with this set up. I've been told I should up date to 78 or 79 cis. I have obtained a 78sc cis
It has the larger runners that will match my heads. My question is has anyone out here gone thur this and how much will I benifit from the newer cis.

Tom,

Are you running the '74 heat exchangers and muffler?

I doubt it would be worth the trouble, unless you plan on putting some more aggressive cams in it. Something like the Web-Cam CIS+ grind ... I think it is called the '20/21' grind.

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Warren Hall
1973 911S Targa

Quote:

<font face="Verdana, Arial" size="2">Originally posted by Early_S_Man:
Tom,

Are you running the '74 heat exchangers and muffler?

I doubt it would be worth the trouble, unless you plan on putting some more aggressive cams in it. Something like the Web-Cam CIS+ grind ... I think it is called the '20/21' grind.

</font>

Warren,
I have SSI and the stock 74 muffler. I know by up grading my hand throttle would be of no use due to the air regulator that is on the 78 cis. It seems the larger ports on the heads and the matching runners is a good thing. Also it appears the air meter is larger on the 78 cis. My friend told me this is a case where bigger is better...I'm just surprised that the cars runs in the state thats its in. I'll probably go thru with the up date, I hope I feel something for all the trouble I've gone thru.

Thanks
Tom