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just been dismantling my 998 with 1100 innards and comparing the valve sizes of the 295, and the 202 head which i have mentioned b4 as looking like it has oversized valves..
the measurements may not be exact as my caliper is older than me .. no digi, not even an analog dial...
anyway the 295 has obviously been milled/surface ground if the 2 castings are usuallty the same thickness...if the chamber shape is similar on the 2 then the 295 has had a fair bit of meat removed around the valves, and the head planed back to adjust the compression ratio the chamber depth is 5/16 from head face to flat surface on outlet valve..it has
1 1/4 inlets
1 outlets

the 202 chamber is tighter and is 3/8 deep...it has
1 5/32 inlets
1 1/16 outlets..

both heads have1 machined 1 1/4 inlet portsthe 295 an aditional machining for those ring thingos that guide manifolds into the right place..

should the 202 have a 1 1/16 outlet???

are my asumptions about the chamber work correct ???

do you like the scrambled eggs/ cottage cheese that is caked around the thermostat??
...... 202 .......................................................................................295..

Author:	danidad [ Mon May 02, 2005 2:37 pm ]
Post subject:	valve sizes
just been dismantling my 998 with 1100 innards and comparing the valve sizes of the 295, and the 202 head which i have mentioned b4 as looking like it has oversized valves.. the measurements may not be exact as my caliper is older than me .. no digi, not even an analog dial... anyway the 295 has obviously been milled/surface ground if the 2 castings are usuallty the same thickness...if the chamber shape is similar on the 2 then the 295 has had a fair bit of meat removed around the valves, and the head planed back to adjust the compression ratio the chamber depth is 5/16 from head face to flat surface on outlet valve..it has 1 1/4 inlets 1 outlets the 202 chamber is tighter and is 3/8 deep...it has 1 5/32 inlets 1 1/16 outlets.. both heads have1 machined 1 1/4 inlet portsthe 295 an aditional machining for those ring thingos that guide manifolds into the right place.. should the 202 have a 1 1/16 outlet??? are my asumptions about the chamber work correct ??? do you like the scrambled eggs/ cottage cheese that is caked around the thermostat?? ...... 202 .......................................................................................295..

Author:	danidad [ Mon May 02, 2005 3:28 pm ]
Post subject:
also pistons are marked 040 assuming thats 40 thou over, what size displacement am i looking at roughly...998 with 1100 crank..assuming the metal removed from head has been equally compensated for by surfacing..

Author:	danidad [ Mon May 02, 2005 3:45 pm ]
Post subject:
if im correct and the 295 head has a valve lift of7.92mm then they must be pretty close to the pistons at times. also the only valve i can find at approx equal to the 202 exhaust valve at 1 1/16 is an 850 or 998 standard inlet although i havent found the 1100 sizes yet... anyone got 1100 valve sizes handy??? think im confusing myself now..

Author:	fuzzy-hair-man [ Mon May 02, 2005 3:47 pm ]
Post subject:
That's wierd why would the 202 have only very marginally larger inlet valves than exhaust valves? The 202 is supposed to have 1" exhaust valves as std. The 12G295 sounds pretty much stock Here is what I am going off for valve sizes http://www.minimania.com/ArticleV.cfm?SCatagory=CYLINDER%20HEAD&DisplayType=Technical%20Information&CarType=ALL&DisplayID=78 According to which the 202 head is supposed to have 1" 5/32 inlet valves but yours has 1"5/64 meaning the inlet valves have been made smaller What for

Author:	danidad [ Mon May 02, 2005 3:53 pm ]
Post subject:
sorry that is 1 5/32 inlet on the 202 my typo will fix the original post... thaks fuzzy ...so someone has put bigger exhaust valves in the 202..hmmmmm wonder what that was about... also still curious about the inlet port size

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Author:	drmini in aust [ Mon May 02, 2005 4:47 pm ]
Post subject:	Re: valve sizes
danidad wrote: just been dismantling my 998 with 1100 innards and comparing the valve sizes of the 295, and the 202 head which i have mentioned b4 as looking like it has oversized valves.. the measurements may not be exact as my caliper is older than me .. no digi, not even an analog dial... anyway the 295 has obviously been milled/surface ground if the 2 castings are usuallty the same thickness...if the chamber shape is similar on the 2 then the 295 has had a fair bit of meat removed around the valves, and the head planed back to adjust the compression ratio the chamber depth is 5/16 from head face to flat surface on outlet valve..it has 1 1/4 inlets 1 outlets the 202 chamber is tighter and is 3/8 deep...it has 1 5/32 inlets 1 1/16 outlets.. both heads have1 machined 1 1/4 inlet portsthe 295 an aditional machining for those ring thingos that guide manifolds into the right place.. should the 202 have a 1 1/16 outlet??? are my asumptions about the chamber work correct ??? do you like the scrambled eggs/ cottage cheese that is caked around the thermostat?? ...... 202 .......................................................................................295.. Standard valve sizes are 1.219" inlet and 1.0" exhaust for 295 head, 1.156" inlet and 1.0" exhaust for 202. 1-1/16" is a standard oversize ex valve thet you can fit when the valve seats get worn. Chamber shapes are totally different as noted. Standard thickness of both is 2.750" approx.

Author:	danidad [ Mon May 02, 2005 5:11 pm ]
Post subject:
thanks Doc .what size is a 40 thou over 1100

Author:	drmini in aust [ Mon May 02, 2005 5:38 pm ]
Post subject:
Bore of a +.040" 1098 is 65.6mm (2.583")

Author:	min13k [ Mon May 02, 2005 8:47 pm ]
Post subject:
kev i think he means pubic displace ment or is that cubic makka

Author:	drmini in aust [ Mon May 02, 2005 9:47 pm ]
Post subject:
min13k wrote: kev i think he means pubic displace ment or is that cubic makka OK, it is 1132cc. +.060" gives you 1152.

Author:	J_A_M [ Tue May 03, 2005 10:05 am ]
Post subject:
my 202 head has 1.090" exhaust valves in it. They are believed to be 850 standard INLET valves! Put these next to standard 1" exhaust valves and there is a good visual size difference. It's a nice mod with stainless seats too!

Author:	danidad [ Tue May 03, 2005 11:13 am ]
Post subject:
yeah anton thats what made me question the valve sizes from the start it sticks out like dogs balls that its a bigger valve.. i also assumed that it might have been an 850/998 inlet (mentined this 8 posts back) but apparently its the next size up on the replacement scale if your seats are knackered.. I take it this is the motor you are building for the shy car...

Author:	drmini in aust [ Tue May 03, 2005 9:06 pm ]
Post subject:
J_A_M wrote: my 202 head has 1.090" exhaust valves in it. They are believed to be 850 standard INLET valves! Put these next to standard 1" exhaust valves and there is a good visual size difference. It's a nice mod with stainless seats too! I hope they are NOT standard 850 inlet valves, those are silchrome steel, will burn out. Put a magnet on one.. if magnetic, I'd find some new valves...

Author:	J_A_M [ Wed May 04, 2005 8:59 am ]
Post subject:
danidad wrote: I take it this is the motor you are building for the shy car... shy car...... Yes it is. Kev, your info on the 850 inlet valves is duely noted.

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