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Idle's well but no "go"

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Mg_Bizzle

Mg_Bizzle

Senior Member
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Idle's well but no "go"

Can't work out whats wrong with my car. Its a 1979 BGT but with a big valve head, 1950cc bores, piper 270 cam, peco exhaust, 101br2 dizzy.

It idles fine and rev's up well, but when I take it out to drive it has no power what so ever even with my foot flat to the floor. It will pick-up sometimes (when going downhill for instance) and seems to have a bit of power once its goes above 3,000rpm, but most of the time it will struggle to get up to that rpm.

Iv just done the timing, iv checked engine compression. The HT leads should be ok and the coil is quite new.

What should I be looking at?
 
Re: Idle's well but no "go"

How do a check a coil and HT leads without actually buying new ones? Iv got faith in both of them as they worked fine 3 months ago with the old engine and the coil was bought new in the summer.

The rotors fine and il change the sparks tomorrow.

Having a think about it is the condenser easily effected by water? Recently my core plug leaked and the engine was pissing all over the distributer. I left it in my house to dry for a few days and thought it would be fine...?
 
Re: Idle's well but no "go"

Im surish on the timing, am I meant to set it with the vacuum on or off? (take off on the inlet manifold). I set it with the vacuum advance on. Im using a strobe-light gun thing so the timing is pretty easy to set-up.

Havent checked the fuel flow, whats the best way to check it?

I checked what I stated but ran out of daylight!
 
Re: Idle's well but no "go"

Disconnect and plug the vacuum line, yup.

The fuel pump should push out about a pint a minute. Be cautious with the flow test... We want no news of a barking MGB-GT!

"w00f!" /bcforum/images/%%GRAEMLIN_URL%%/wink.gif
 
Re: Idle's well but no "go"

Thanks. The timing isnt set-up right then. Il have another go at it tommorrow, although would not plugging the vacuum line make alot of differrence as it was set-up with out the vacuum before and had similar problems just no where near as bad.
 
Re: Idle's well but no "go"

Was the vacuum port blocked off as you set the timing?
 
Re: Idle's well but no "go"

Also, I've forgotten which induction setup you have, should be HS4 SU's. Damper oil up to level?

Just tossin' out ideas here.
 
Re: Idle's well but no "go"

The vacuum port was not blocked off (the first time I set up the timing and it ran better then what iv described here but still not right), does this make a big difference?

Oil in the carbs is fine, although I have HIF4 not HS4 (79 BGT from the UK)

I think il have to re-do the time with the vacuum all cut off and start again from there.
 
Re: Idle's well but no "go"

Unplugged vacuum line will kick the idle up causing mechanical advance in the dizzy. It's adding advance to your timing. You want it JUST ticking over at around 600~700 RPM.
 
Re: Idle's well but no "go"

As the Dr. said, disconnect the vacuum advance tube at the distributor and plug the open hose/tube. I always found a sharpened pencil or golf tee worked nicely as a plug.

Do check and set all the ignition related parts first. However, I'm betting on fuel starvation.
 
Re: Idle's well but no "go"

It was down to the timing, I sent it in for a tune up and they re-set the timing whilst they were tuning the carbs. Goes like s**** off a shovel now.
 
Re: Idle's well but no "go"

Mg_Bizzle said:
It was down to the timing, I sent it in for a tune up and they re-set the timing whilst they were tuning the carbs. Goes like s**** off a shovel now.
Click to expand...

I'm glad you got it sorted. Since the shop adjusted both the timing and the carbs it's not really possible to say whether the problem was primarily fuel or ignition related.
 
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