Hello, all.
The 'B (she hasn't told me her name yet) ticked over 110K miles the
other day. I've known for a long time that she'll eventually need
open-heart surgery, even though her oil pressure is still 70-75 psi and
power seems good. (I'm actually looking forward to the project...)
I've been reviewing Scott Fisher's recent narrative (of 6 Jan)
describing his MGB lump, and I think I'd like to do something similar.
Scott uses a '73 18V block with early, angled-big-end rods and early
8.8:1 compression pistons. Two questions come to my mind:
1. Is there actually any benefit to the angled big-ends? In thinking
about the four strokes of the four-stroke engine, I've convinced
myself that the angle of the rod bolts shouldn't matter too much.
On the intake stroke, the bearings see almost no load; on the
compression stroke there is some load (I haven't calculated how
much), but it's all borne by the upper (rod side) bearing, and the
lower (cap side) bearing is just along for the ride; the power
stroke produces the most load on the bearings, but again, this is
borne primarily by the upper bearing; on the exhaust stroke the
bearings get a rest. Since the lower bearing sees far less load
than the upper, do the angled big-ends provide any real benefit? Am
I assuming too much; are there any wierd transient oscillations
going on?
2. If I should choose to retain my 18V (straight big-end) rods, will a
swap to the earlier pistons provide me with the 8.8:1 compression
ratio? In other words, are the effective lengths of the 18G and 18V
rods the same? Are there any problems with swapping the gudgeon
pins?
In other news, the garage (with the house attached) is coming along
nicely...
--
Todd Mullins
todd@nutria.nrlssc.navy.mil On the lovely Mississippi (USA) Coast
'74 MGB Sport Tourer patiently awaiting some TLC
"A life lived in fear is a life half lived."
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