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273 commando valve clearance problem #1676413 09/24/14 09:41 AM 09/24/14 09:41 AM
Joined: Sep 2007 Posts: 641 western australia 1 1cuda OP mopar
1cuda OP mopar 1 Joined: Sep 2007 Posts: 641 western australia	i`m building a 273 commando for a 65 signet-it`s a restoration so that`s why the 273. i had stainless 1.88 and 1.6 valves put into the heads and now i`ve got valves that hit the cylinder walls-has anyone come across this before? i thought i did my homework and people on forums said only the 2.02 valves would need cylinder fly cut but after mocking up a head on a empty bore i can see the valve hits at .250 open-mainly the exhaust one. my question-it`s going to run a 470 lift cam- how far down can i cut the relief? pistons are 10.5 egge and they are .082 down the hole. they have about .200 of land above the top ring. how close can the relief be to that top ring? any help really appreciated. all the best frank.

Re: 273 commando valve clearance problem [Re: 1cuda] #1676414 09/24/14 11:25 AM 09/24/14 11:25 AM
Joined: Jan 2003 Posts: 7,131 Amarillo, Texas BBR master
BBR master Joined: Jan 2003 Posts: 7,131 Amarillo, Texas	I notched a 273 once for 1.92 valve Magnum heads. I just masked it off took a carbide in the die grinder and beveled off the edge. Worked fine. I used a coffee filter in the cylinder to catch the shavings. 8279452-abb.jpg (108 downloads) Drag Week 2011 - 77th place - DD Drag Week 2012 - 2nd place SRBB N/A Drag Week 2014 - Kapooya RMRW 2018 RMRW 2020

Re: 273 commando valve clearance problem [Re: 1cuda] #1676415 10/03/14 11:49 AM 10/03/14 11:49 AM
Joined: Feb 2003 Posts: 16,150 Mesa, Arizona D dart4forte I Live Here
dart4forte I Live Here D Joined: Feb 2003 Posts: 16,150 Mesa, Arizona	Quote: i`m building a 273 commando for a 65 signet-it`s a restoration so that`s why the 273. i had stainless 1.88 and 1.6 valves put into the heads and now i`ve got valves that hit the cylinder walls-has anyone come across this before? i thought i did my homework and people on forums said only the 2.02 valves would need cylinder fly cut but after mocking up a head on a empty bore i can see the valve hits at .250 open-mainly the exhaust one. my question-it`s going to run a 470 lift cam- how far down can i cut the relief? pistons are 10.5 egge and they are .082 down the hole. they have about .200 of land above the top ring. how close can the relief be to that top ring? any help really appreciated. all the best frank. You can also cut down a 1.88 to 1.84 and you won't have the shrouding problem.

Re: 273 commando valve clearance problem [Re: dart4forte] #1676416 10/06/14 04:19 PM 10/06/14 04:19 PM
Joined: Jan 2003 Posts: 16,376 D dogdays I Live Here
dogdays I Live Here D Joined: Jan 2003 Posts: 16,376	If you don't cut past the valve seat line... R.

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