Keith,
How much compression you can run depends directly on the specs of the camshaft
you are using. In addition, when you use a "wilder" camshaft (with more overlap
& lift) you need to raise the compression to offset the cylinder pressure loss
inherent with using the wilder cam. In other words, greater engine output is
not merely a matter of using one "hot" part - it is a matter of using a set
of parts that are tailored to each other and the intended purpose. For
instance,
I use an S-2 camshaft, 10:1 compression, headers/freeflow exhaust and triple
webers on my TR6. I use 92 octane gasoline without any pinging (except for
exeptionally hot days in traffic). If I was running the stock cam, I could
probably not run higher than 9:1. Any cam supplier who knows his stuff should
be able to tell you (before you buy) what the powerband is for a particular
cam grind, how much compression you should run, and what other
engine/intake/exhaust
mods you will need to do to get the most out of the cam. If a particular cam
supplier can't/won't tell you, then walk away and find another supplier. I
have had good results from TS Imported and Elgin Cams (your mileage may vary).
Hope this helps,
Hugh Barber
Hollister, CA
'73 TR6
>
>Ok, the list got me through the great cam struggle. Thanks to everyone
>who was so patient with my questions-the three Michaels, Henry, Bobsta,
>Bud, Randall, Fred, the two Teds and some other of the usual suspects.
>Now I know enough to be dangerous to myself and others.
>
>BTW That story ends with my ordering a Babe Erson cam from Ken Gillander
>at British Frame and Engine. He's a very knowledgable guy. The so called
>"mild" specs are 287 lift at the lobe, 412 valve lift, net of .18 (!)
>lash, with 238 duration at 50 degrees. Overlap is 18. Sounded wild to me
>but I am assured it is reasonable at idle, and had plenty of power
>through the useful band.
>
>The new story is: as long as the head is off, I might as well, um, well
>you know.....
>
>I have two opening questions for those who are in the know:
>
>1. There seems to be variying opinions over what the highest compression
>using garden variety premium gas the head can handle with reasonable
>timng advance. For example, BPNW recommends 8.8:1, Goodparts uses 9.7,
>Brit Frame and Eng said go for 10 but can be talked back down to
>9.5-9.75 Ted Schumaker says go for 10. Given my new cam specs cam and
>its overlap, what do listers think is the ideal compression to maximize
>power and be assured of decent timing advance with pump quality premium?
>
>2. British Parts Northwest seems to be the only shop with off-the-shelf
>comped and reconditioned heads and their price is not a lot different
>from that quoted at my local shops for similar work on my original head.
>Anyone have experience or opinions on their product and/or alternative
>off-the-shelf solutions? ( this one can be responded to offline to
>protect the guilty).
>
>Thanks gang.
>
>It would be impossible to own this car without the help of this list.
>
>Keith Ehrlich
>74 TR6
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