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MG TD TF 1500 - XPAG Supercharged

I had to rebuild my engine. So I bought custom pistons & rods along with a Cortina Clutch & Flywheel from Manley Ford, Roller Rockers from Len Fernelli, & a Mirage Grarge supercharger. What a transformation. One small fly in the ointment. between 30 & 40 rpms it seems starved for fuel. I's worse before being warmed up. I can push the peddle & its fine >40K. I guess I have it tuned on a Dynamiter. My wife clocked me @ 70 on the bridge over LA Harbor.
KX Bielinski

Lean mix with a blower is bad ju ju. Good idea to get it on a rolling road or install a O2 sensor and see whats happening.

Have a link for the blower used?
MG LaVerne

Definitely sounds like weak mixture / wrong needles. Hard to say for sure without seeing it of course. Try richening the mix until the problem goes away.
Steve Simmons

Your carb might be a bit small for 40000 rpm!
mog

It's one of our superchargers, and it has a 1-1/2" carb. I strongly suggest having the distributor rebuild by Jeff Schlemmer, and running the car on a dynamometer. As LaVerne wisely notes, a lean situation is a recipe for disaster.

KX - please contact me off-line, as I have other suggestions.

Tom Lange
MGT repair
t lange

Tom, I remember working on dynos in test beds, they would struggle to get the engine up to 40000 rpm
mog

The last engine I had on a dyno was run up by the operator to 6,000 RPM to be sure it was strong enough. Like Gloria Gaynor, it did survive...

Because he himself had recently "rebuilt" the distributor the owner refused to send it to Jeff Schlemmer; the springs turned out to be stretched and the weights were sluggish, drastically affecting the timing. Had he continued to run it like that he would have burned a piston due to lean condition.

I STRONGLY recommend Jeff Schlemmer's rebuild for every supercharger (and regular) distributor, and a dyno test.

Tom Lange
MGT Repair

t lange

40000 that is 40 thousand rpm Tom.

Agreed by the way, sort out plenty of needles and get it down the rolling road.
mog

Kaz, 90% of all concerns of fuel problems end out to be primary or secondary ignition, not fuel mixture.
You of course have installed one of my S/C roller cams in addition to my roller rocker arms.
Let us know what you find.
Len Fanelli

Kaz, you might change the dash pot oil to 90 wgt gear oil if you haven't already done so. It will make you mixture richer on full throttle application. Heavier piston springs will also have the same effect. Of course you will only be guessing as to what is happening unless you get some time on a rolling road with an O2 sensor up the tail pipe or install one in your car.
MG LaVerne

Springs can affect mixture, but oil will only affect mixture during throttle changes. At steady throttle there will be no difference!
Steve Simmons

At the least you want to ensure the mechanical advance is operating smoothly on the distributor. Sticky advance and/or incorrect timing can cook an engine, as can needle(s) not rich enough. What kind if ignition setup are you running? Points/condenser or electronic?
D mckellar

This thread was discussed between 03/01/2016 and 08/01/2016

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