[urq] Re: [20v] 7A vs 3B C/R

Bruce Bell bbell at surview.com
Wed May 7 12:11:48 EDT 2003

Or, the 7a head could have been milled, unlikely, but.... Do you know the
history of that head?

-----Original Message-----
From: urq-admin at audifans.com [mailto:urq-admin at audifans.com]On Behalf Of
JShadzi at aol.com
Sent: Wednesday, May 07, 2003 10:31 AM
To: "Brandon Rogers"; """20V list"""; 200q20v at audifans.com
Cc: urq at audifans.com
Subject: Re: [urq] Re: [20v] 7A vs 3B C/R

Sure, you always need to back up info..the one thing that concerns me, the
original compression differences that he listed and attributed to the head
cc are exactly the differences that I know are made up for in the
pistons...thus, I'd suspect that he has not measured and is making
assumptions, but that's _my_ assumption, so there you go  =)


>Thanks Javad.
>Frankly, the collective wisdom here holds much more credence IMO, than this
>one person, but when something like this comes up, you just gotta make
>sure - I want to make sure I put this thing together so it works properly,
>and optimally (if that's a word).
>Thanks again--
> much appreciated-
>----- Original Message -----
>From: <JShadzi at aol.com>
>To: ""Brandon Rogers"" <brogers at terrix.com>; """20V list"""
><20V at audifans.com>; <200q20v at audifans.com>
>Cc: <urq at audifans.com>
>Sent: Wednesday, May 07, 2003 9:58 AM
>Subject: [urq] Re: [20v] 7A vs 3B C/R
>Brandon, I've measured both in the past and found them to be the same, but
>usually a few cc variance between heads is common.  Have you pressed him on
>his knowledge of the piston differences?  Can he show you what he's
>referring too?  The only real difference between 7A and 3B heads is the
>water manifold configuration, cc chambers are the same, valve sizes are the
>same, etc, and as far as I know, the 7A even uses sodium filled valves.
>> I trust you based on knowledge you've shared with the list. So did you
>>measure the chambers yourself or have somebody do it or?? The guy here is
>>saying he CC's the chamber and found them to be different? This is
>>to every response I got from the list, including yours. Any further input
>>is greatly appreciated as I'm in quandary. I currently have a 7A head at
>>the machinist for rebuild so I can put it on my 3B bottom end for
>>into an urq-but this guy has made me nervous....
>>----- Original Message -----
>>From: <JShadzi at aol.com>
>>To: ""Brandon Rogers"" <brogers at terrix.com>; ""20V list""
>><20V at audifans.com>; <200q20v at audifans.com>
>>Cc: <urq at audifans.com>
>>Sent: Tuesday, May 06, 2003 9:19 AM
>>Subject: Re: [20v] 7A vs 3B C/R
>>This is not true, the compression he is referencing is the pistons, not
>>head, both the 3B and 7A have about 37cc combustion chambers.
>>>Hi guys-
>>>I was talking with a local guy who is said to know a lot about Audi
>>etc. He said that putting a 7A head on a 3B bottom would have a higher
>>compression ratio compared to normal 3B. He said it would increase from
>>9.3:1 to 10.3:1. This was not my understanding. Can anybody confirm or
>>200q20v mailing list
>>200q20v at audifans.com
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