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#1 |
Junior Member
Join Date: Nov 2013
Location: Lower lake ca
Posts: 9
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I have a rebuilt motor with pistons that come 0.20 over the top deck and a best gasket with a 0.42 compressed thickness will this work with a Winfield head with no relief cut over the pistons the rods will stretch at high rpm .
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#2 |
Senior Member
Join Date: Mar 2013
Location: Australa Melbourne
Posts: 878
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No you need 0.040- 0.050" clearance to be safe some get by with less but that is a risk
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#3 |
Senior Member
Join Date: Apr 2011
Location: New Zealand
Posts: 444
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Certainly I wasn't prepared to take the risk in exactly the same situation and had the head machined using a computer program to provide clearance over the pistons
Keith |
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#4 |
Member
Join Date: Oct 2013
Location: east granby conn.
Posts: 70
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tommy it wont work as colin said. I am doing this now same thing with red head .had .035 clearance could only advance 4 deg then pre ing. go ing to cut my head tom. for .050 clearance and try that also centrificul adv dist worked better than manuel advance I have fsi ign round off all sharp edges in comb .chambers
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#5 |
Senior Member
Join Date: May 2010
Location: Santa Rosa, CA
Posts: 1,285
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Cut down the piston tops.
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#6 |
Junior Member
Join Date: Nov 2013
Location: Lower lake ca
Posts: 9
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#7 |
Senior Member
Join Date: May 2010
Location: Colorado
Posts: 235
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I had the same problem with a Thomas Head. I had the head machined to provide clearance, same a "wensum" said.
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#8 |
Senior Member
Join Date: Dec 2010
Location: FRESNO, CA
Posts: 12,560
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Have you ever seen a Model A that would REV high enough to "stretch" the rods??---Sounds like one for "MYTH BUSTERS"!
Bill W.
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"THE ASSISTANT GURU OF STUFF" |
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#9 |
Junior Member
Join Date: Nov 2013
Location: Lower lake ca
Posts: 9
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yes I have I have a 2 port riley that I have had to 5500 repeatly
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#10 |
Junior Member
Join Date: Nov 2013
Location: Lower lake ca
Posts: 9
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the head I have is aluminum so I took the head gasket and a scribe marked over pistons then took a sharpie then got my router and a carbide tip bit and removed the material and with a 90 degree die grinder polished with good results checking with feeler gauge and straight edge.
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#11 |
Senior Member
Join Date: May 2010
Location: Middletown Pa
Posts: 397
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Outstanding. A man who wants to do something will find a way; a man who doesn't will find an excuse.
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#12 | |
Senior Member
Join Date: May 2010
Location: South California
Posts: 6,190
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Good on you ![]() Having an alum super Winfield and having been in the exact same situation, I took PC/SR suggested action, i.e.- cut the piston tops off ....with a HAND SANDER ![]() |
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#13 |
Senior Member
Join Date: May 2010
Location: now Kuna, Idaho
Posts: 3,818
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Do the rods really "stretch" that much and still return to their original length, or is it the crankshaft flexing at high RM? I vote for crankshaft flex.
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#14 |
Junior Member
Join Date: Nov 2013
Location: Lower lake ca
Posts: 9
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pistons stretch with heat iron stretches when heated don't know at what rate but I needs clearance regardless.
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#15 |
Senior Member
Join Date: May 2010
Location: Long Island, NY
Posts: 4,113
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I had a Model B cylinder head cut to raise the compression ratio by eliminating the reliefs in the head for the pistons plus some more material.
Using clay on the piston tops, I determined the overall clearance (including piston protrusion above the block deck and the gasket thickness) was 0.010". I ran the motor at a car speeds of 65 to 75 mph with stock differential gears, and initially the pistons did not come into contact with the cylinder head. However, once carbon built-up on the piston tops, there came a horrible knocking sound as the clearance between the head and pistons went to zero. That ended my experiment with a shaved cylinder head. The right way is to run a cylinder head with combustion chamber shapes designed for high compression. Reliefs in the head for piston clearance are a necessity.
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#16 |
Senior Member
Join Date: Nov 2010
Location: Florham Park, NJ
Posts: 396
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My Winfield crows foot aluminum head is still working fine with no relief cut into the head. I have a standard gasket, then a 0.031" copper spacer gasket and then another standard gasket. This was recommended by a shop that builds hi-performance and racing engines. The Ross pistons came up quite a way above the deck.
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#17 |
Junior Member
Join Date: Nov 2013
Location: Lower lake ca
Posts: 9
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where did you get the spacer gasket I also have a Winfield red head that I will be putting on a motor that I plan to build in the future
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#18 |
Senior Member
Join Date: Dec 2013
Location: McCalla, AL
Posts: 181
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Innovative machine & supply makes head gasket shims.
http://innomach.com/ |
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#19 |
Senior Member
Join Date: Nov 2010
Location: Florham Park, NJ
Posts: 396
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tommy rand:
I bought my copper spacer from: Clark Copper Head Gasket 10510 Nassau Street Blaine, MN 55449 (763) 786-9590 I bought 2 pieces so I would have a spare. Thickness is .031" and is for .100" overbore. The part number for mine is PN030505-A Cost me $65 each in 2011 Good Luck Dick
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1965 Lotus Elan S2 1930 Model A Sport Coupe |
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#20 | |
Senior Member
Join Date: May 2010
Location: Mpls, MN
Posts: 27,582
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