Anybody know cc. S of c2.c3.and c4 s thanks
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Anybody know cc. S of c2.c3.and c4 s thanks
C2,c3, c4 etc are just the casting design numbers. Pretty sure mercury made different cc chambers in all those heads. I’ve seen factory c3’s that are 26’s, and also seen stock 38cc c3’s. Add in twenty years later and all the heads that have been cut, and the only way to know for sure is to actually cc that particular head. Obviously these are my opinions and I’m not a very smart dude lol
This is how I’ve seen it tooQuote:
Originally Posted by mach351
:iagree:
The C designation is the Squish & bowl design. The preceding numbers are the casting number. Most stock heads are 38cc from the factory. If mercury did a set of Factory Race heads I.e. 26 cc's they were stamped as such. But as mentioned above only way to tell for sure is to CC the heads.
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Can anyone comment on what CC 1996 Mariner 225 Super Magnum heads should be? 38cc? 42? I sent my heads to be shaved aiming for 36cc or so (about 145 comp), per the advice of the shop. The first one was cut (without first measuring) assuming it was 42cc to start. The shop cut enough off to reduce by 6cc or so. After cut, it measured at 31cc . Surprise. So the other head was then measured at 37cc before being cut. At this point, the second head was cut to match.
My motor had about 125 comp before any work was done. I'm in the process of assembling this weekend. Going to check compression and see where I stand. I've been told 31cc head should be way higher than 145lb. But was also told 37cc heads should be higher than 125lb which is apparently what I started with. My heads "looked" untouched before sending them off.
I want to stay with 92-93 octane gas.
The 1996 225 Super mag is the same as the 225 Pro max. Both Engines came from the factory with 18787 C3 heads at 38cc's. In good condition that combination should yield 120/125 psi compression. Your machine shop not only assumed wrong they made the cardinal mistake of not ccing the heads before cutting??? A solid motor with good leakdown numbers should yield in the 150's compression with 31cc heads and with 34 cc chambers in the mid 140's. Basic rule of thumb when cutting heads is for every .010 ths you decrease the chambers volume by .7cc. Like I said thats a rule of thumb because the C 2, 3 & 4 chambers are all configured different.
Quote:
Originally Posted by DangerNewb
Thank you. Any thoughts on max compression with 93 gas. Sunoco sells 93 non ethanol locally.
145/148 ish. Where in NC are you located?
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Originally Posted by DangerNewb
Near Raleigh. So I'm probably too high on comp for 93 octane. I'll put it together and see where I stand. The shop who cut them is OK to work with me on getting another set of heads if these are cut too far for my purposes. I'll mention that the promax motors are 38 to start. He measured my second one at 37 before cutting So maybe his measurement is a little low and maybe my cut heads are closer to 32.
If he's using a syringe to determine cc's he could be off. If hes using a Plexiglas plate greased to the Chamber face with a hole and a burette he'll most likely get a different reading on his cc's
Quote:
Originally Posted by DangerNewb
Bud, if your completely bored tomorrow feel free to drive 2 or 3 hours and help me put this thing together. Haha. Not likely... I have the front half torn apart also putting new reeds and spacer plate in. Anyway, thanks for the advice. Looking forward to getting it all put back together.
FWIW, 34cc with 1.0 gasket is 146/48 on all six on every promax I’ve done heads on.
31cc on my 2.4’s with 1.25 gasket is the same.
Yeah, I learned about the different gaskets today. The new set I got to reassemble my motor were 1.20mm. The gaskets I took out were 1.0mm. So I'm thinking I may be back to maybe 33cc's with the thicker gaskets. I used a borrowed compression gauge today and got a very low reading. I'm going to get another gauge and try again.
Curious bout results of your compression. Did u get another Guage?