Thanks to all who answered my pushrod question. I will be ordering new ones
today.
Aloha,
mark
>On Tue, 22 Apr 2003 20:44:53 -0700 (PDT) mbullard <mbullard@hawaii.rr.com>
wrote.
>Bob,
>
>I'm having my head shaved on my '74 TR6 to 3.416 inches to give me around a
>9.5:1 compression. Is it safe to assume that my stock pushrods will no
>longer work?
>
>Thanks in advance.
>
>Mark Bullard
>Kailua, HI
>
>>On Tue, 22 Apr 2003 13:12:04 -0400 (EDT) "Robert M. Lang"
><lang@isis.mit.edu> wrote.
>>On Tue, 22 Apr 2003, Alan & Debbie Lindner wrote:
>>
>>> I believe my head was milled. Does anyone have a measurement
>>> of the the adjustment threads length with a narrow nut on for a
>>> standard or milled head.
>>
>>Ummm... this is one reason that you need to shorten your pushrods if the
>>head is milled. What happens is that you arrive at the proper valve lash
>>by backing the adjusting screw nearly all the way out...
>>
>>The Competition Prep Manual shows how to make a dummy pushrod to get the
>>proper pushrod length, and you then need to obtain a tubular pushrod set
>>to shorten (or you can buy them already shortened).
>>
>>Note: the Euro Spec motors ran higher compression heads from the factory.
>>so there's a euro spec stock pushrod that some folks sell (I recall BPNW
>>having them sometime in the past). The stock pushrods are not tubular
>>type.
>>
>>> Also, can I just measure the height of the head to get an idea of
>>> how much has been milled?
>>
>>Well, you might be able to, but you have to know what you started with.
>>
>>For example, I had over .110 milled of my stock 74 TR6 head and it got me
>>to about 9:1... all the late heads are 'real thick" whereas the '72 head
>>would only need less than .050 milled off to get over 9:1 (seeing that it
>>starts life as more than 8:1 and the '74 is a 7.75:1 stock compression
>>ratio.
>>
>>As a generaly rule, if you measure from the deck to the surface that the
>>valve cover seal to, you come up with a "thickness", and you can
>>approximate the compression ratio. But the only true way to measure is to
>>get a burrette and pull the head and measure the volume of the combustion
>>chamber (and don't forget that that head gasket needs to be included in
>>your computations.
>>
>>> Alan
>>
>>regards,
>>rml
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