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MG MGB GT V8 Factory Originals Technical - Webber Tune up help

I have just finished re-building my 3.5 with a new Webber 500, Mallory dizzy, Dual Plane manifold and twin SS block hugger exhausts.
Can anyone recommend a tuner preferably with a rolling road? I live in Milton Keynes (M1 J14)
My last request to a local tuner was to be told he did not think my carb/manifold/engine combination was correct!
All I would like is to get the best out of what I have got and a rough idea of the output power.

I have 160 +/- 5 psi on all 8 cylinders. Is this pressure OK for a std SD1 head, 9.75:1 pistons and tin gaskets?

Your help would be appreciated.

Regards

Dave
D M Tetlow

Dave,

Your carb and manifold are fine, however you do need to re-jet the carb as it will run very rich with the standard jets and needles fitted.

You need 1441 Rods and 1421 Jets and these have been proven to give good mixture control across the rev range.
They are available from Real Steel or RPI.

Something else that is worth checking is that your timing marks are accurate, mine certainly was quite a bit out, to check raise N0,1 piston to Top Dead Centre and check how this relates to the pointer and front pulley. If it's wrong you can simply put a dot of paint on the pulley or bend the pointer if it's not too far out. Your cylinder pressures sound about right to me.

Power outputs vary even with standard engines. if you assume a standard SD1 produced 155BHP at the flywheel
so with a small increase in compression and the new inlet set up, you should gain a few BHP.the major restriction is the heads which need the throats behind the inlet valves opening up to match the seat size, and then port matching the manifold to the heads using an inlet gasket as a template which is what most people call Stage 1. These simple mods can produce another 35BHP or so. Don't expect the block huggers to increase output because they are designed to fit the car rather than increase performance RV8 manifolds will however release an additional 10-12BHP.

As I live in kent, can't help you with a recommendation for a rolling road facility, but I'm sure others may have suggestions.

Kevin



Kevin Jackson

Kevin
Thanks for the help I appreciate it.
Regards
Dave
D M Tetlow

This thread was discussed between 14/12/2006 and 19/12/2006

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