Flat spot

[panalvan]

Hi after some advice my friend has a 72 crossover and it has a huge flat spot pulling away in first and when you change into second only way to get it to pull away is rev it and slip the clutch .Apart from that it drives really nice gave it a full service this morning all ignition parts and oil change hoping the new ignition parts would sort it but I'm now thinking it's a air leak issue it's a1600 twin port. Strange thing is is you rev it when it's stood still it will rev really nice but as soon as you put it under load it bogs down .Its the first time I've been stumped so any advice would be great fully received
Cheers chris

 

[StuF]

What carb and dizzy is he running? Mine bogs down a bit but that is due to the rubbish repro carb and I have learned to drive to its limitations!
Might go to twins at some point in the future from eurocarb!

 

[panalvan]

It's running an original solex carb and a 009 dissy

 

[StuF]

When my timing was done we had to advance the dizzy to remove as much of the flat spot as possible.
Get a timing light and see what its set at - might just need a tweak

 

[Johnny69]

Put an svda dizzy on it - makes a big difference I found

 

[jonboylaw]

And the accelerator pump is working properly, with the correct amount of fuel being squirted out per stroke ?
If he fitted an alternator the accelerator pump may foul on the alternator body...


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[StuF]

Put an svda dizzy on it - makes a big difference I found

Are they the "best" dizzy for the aircooled motors? Might change mine in the future and will try and fit the best I can

 

[67westy]

Put an svda dizzy on it - makes a big difference I found

Are they the "best" dizzy for the aircooled motors? Might change mine in the future and will try and fit the best I can

Made mine a lot nicer to drive when I ditched the 009 for one

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[lasty]

Two points really ....

I ran a 009 for 20 years but never could get it spot on - best improvement was to set the quadrant on the accelerator pump to maximum squirt .

Second point being I fitted an accuspark SVDA last week and it TRANSFORMED the low to mid-range . No fiddling with the carb , just reset the quadrant to middle .

Voila - no more flat spot . 60 quid on ebay , absolute bargain .

 

[Bluesnailman]

3rd vote for an svda distributor with electronic ignition. Best £60 spent (well, on the ignition system at least.)

Also, if you persist with the 009, it could be that you need to statically 'time' the engine, depends on engine number...

 

[mr fish]

009 don't work very well because they rely on revs to bring in the advance but advance is need to get to that point in the rev range and hence the flat spot.

With a SVDA dissy the vacuum produces advance before the revs increase so the revs increase a lot quicker and more smooothly.

It is a common fix to increase the accelerator pump CC which helps over come this. This obviously comes at a cost where as vacuum is free.

A well set up SVDA dissy will pay for its self quite quickly in saved fuel so worth the investment.

The only real advantage of a 009 is that its completely independent of the carb so if non stock carbs are fitted the advance will always be the same.

Its also not advisable to static time a 009 as they seem to vary a lot. Always time with a light at max advance (3000-3500 rpm) between 28-32 degrees although most people prefer not to go over 30 when used in a van. My van currently has a 009 in it (temp measure as the old dissy failed) and measures 0 degrees static with 30 max. But i've set others up that measure 10 static with 30 full advance.

 

[K@rlos]

I use 009's on everything, never had this dreaded flat spot :|

 

[bananacustard]

I also run a 009 with twin 34s and accuspark and it's as smooth as you like. No apparent flat spots.

 

[panalvan]

Strange how the 009 has such a bad reputation now as I've used them for years and at one point everyone was using them I will reset the timing see what happens

 

[K@rlos]

I used an 009 on a stock 1600, 1600 with twin 36's and now my 2110 with twin 48's. Never been an issue for me.

 

[madmike]

009 and a Pict34 carb just don't go together :roll: as said get a vac can dizzy,you won't believe difference!!!!
and you guys that say they work good for you?,,Go buy a Lotto ticket,, your just 'Lucky' :lol: :lol: :lol:
Like the POS progressive carbs,one out of ten work :roll: