That sounds a little low for a pre-smog B engine. Theoretically the HP
peak was 98 @ 5400rpm, and the torque peak was 107 @ 3500 (1966). This
more or less concurs with my experience. The power increases steeply up
to 3500rpm, and hangs on until 4500 or so, when it seems to taper off.
(Someone commented recently that a loss of power at the top end (in a
stock motor) could be attributed to lack of exhaust back pressure. I can
believe this since my front muffler must be 20 years old). But one
doesn't shift at 3500 just because it's the torque peak. You want to get
to high enough revs so that when you shift to the next gear, the revs
don't drop below the power band (at least 3000rpm).
The 71 B was rated 92HP @ 5400, and 110ft/lbs @ 3000, so it probably does
have a lower shift point. But shifting at 3000 would definitely drop you
out of the power band, and therefore retard effective acceleration
significantly. These engines are relatively torquey, but like all small
displacement engines, need reasonably high revs to develop maximum power.
You may be right about the cam wear, in your case.
IMHE...
BobMGT@aol.com had this to say:
>I just got my TD back on the highway after a partial engine rebuild
>(pistons,
>rings, valves, and lifters). After 2K miles I think it's still breaking in,
>because it reves a little better each time I take it out. Now the old XPAG
>doesn't have a lot of power, but I notice that it does increase with rpm.
>The
>higher the rpm the stronger it seems to pull. Looking at the power curve
>published in an old magazine, one would expect this. Now my MGB, on the
>other
>hand, seems pretty flat. There doesn't seem to be any advantage shifting at
>4K over 3K. It's willing to rev, but nothing exciting happens over 3K.
>Several of my B owner friends have the same impression. Is the actual power
>curve of the B series engine flat at the high end, or is this the sign of a
>cam that has seen it's better days?
>
>Bob Donahue (Still stuck in the '50s)
>EMAIL - BOBMGT@AOL.COM
>52 MGTD - under DIY restoration NEMGTR #11470
>71 MGB - AMGBA #96-12029, NAMGBR #7-3336
>
--
Max Heim
'66 MGB GHN3L76149
If you're near Mountain View, CA,
it's the red one with the silver bootlid.
|