Rick,
Sorry that I can not give a constructive answer, but there is something way
wrong. I run a standard 3.5 rover v8 with optronic ignition, 2 SU's. idles
so
soooomthly at bang on 500 rpm, under acceleration(except when I experience
fuel
vaporisation) much much smoother than B series, much quiter, hydraulic
lifters!
My exhaust blows a bit at the manifold, but dont affect the smoothness
My back axle (3.07 with Quaife LSD heehee!) although rebuilt whines around
60-70
so top down most of time , then no noise!
Mpg around 27.5 overall last measured on trip to LE mans last year ...
Suggestions:
if it were ign. set up motor would just be sluggish, but check this FIRST!
sounds like carb may need tuned to engine...dont know a thing about anycarbs
except SU's!
Cam may give lumpy idle but motor should pull clean over idle
Aw the best
Derek
74B
Subject: Rough Running
Author: "Rick Huber" [SMTP:102221.1716@compuserve.com] at Internet
Date: 3/16/99 11:56 AM
Hi V8 ers,
I've got about 425 miles on the monster B now, still holding it to about
3500 RPM until 500 miles. Glorious weather the last couple of days, in the
40's and 50's, so I'm not too concerned without a temperature gauge while
waiting for an MGB sending unit to arrive. Since I'm pretty new at this
stuff, I've got a few questions. I hope you don't mind.
Rover 3.5, Carter 500 necked down to 400, Buick intake manifold, mallory
electronic ignition distributor
Rough idle - I tried to turn down the idle yesterday afternoon from 1200
where it's a little rough running / lumpy, to 800, but it got much rougher
and coughs and wheezes that low, so I turned it back up to about 1100 where
it seems to run a bit smoother. I've tried the disconnect one plug at a
time, and they all seem to be working. My next idea is a vacuum leak.
Does that seem plausable? I guess it's time to go around spraying WD-40 on
potential leak sources. Is that the best way to check for vacuum leaks ?
Could it be the cam, which is a bit hotter than stock ?
The gas mileage is pretty terrible too, like 15 mpg. I was expecting well
over 20. I know the 3.9 rear end is causing some of it, but it's much
worse than I thought it would be.
The engine doesn't seem to run smoothly while accelerating, I can hear /
feel a thump it seems like with every turn of the engine. (like fluttering
your tongue to make a strong acceleration sound). Is it the exhaust sound
I'm hearing / feeling and thinking it's the engine ? It feels plenty
powerful, but just doesn't sound / feel as smooth as I expected. I'm a bit
afraid of opening it up thinking I might damage something.
I've got a little ticking sound at idle, like a sticking lifter, on the
right side of the engine.
I've got a differential whine between 45 and 50 mph. Not bad with the top
down, but quite loud with the top up. It's the original 3.9 MGB
differential, but no clunks.
I'll be out on the highway again today, thoroughly enjoying myself and
thinking about some of these little things.
Thanks for the help,
Safety Faster,
Rick
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