So im still having issues tuning this. The motor is a 12A Turbo running with 7 psi. It is supposed to be at 10psi. The intake manifold is leaking coolant out and most likely allowing air pressure to escape and cause a vacuum. ( I forgot to get the coolant passages plugged as they do not work with my current manifold.)

I have a rajay turbo and a Rebuilt Dellorto DHLA 40. The 40 seems to be giving it too much fuel. The jets are on all the way screwed in leaning it out as much as possible but it still drowns in fuel.

Can anyone tell me what my timing should be? I have read several threads saying 10 degrees advanced and locked in position. I want to print this page for the mechanic so he'll understand why it needs to be there. Currently Leading is firing at TDC and trailing 21 degrees later. The car stutters and hesitates through the entire rpm range. someone please explain the timing.
My ignition is stock but every part is new except the actual distributor.
New coils, new plug wires , new cap and new ( cold) plugs gapped at .015.

It is hard to diagnose problems when your not even sure your timing is right.

 

are you sure that your jetting is correct for the carb and the application?..also about the coolant...i bought freeze plugs from pineapple racing..but with your coolant problem that might just mean that you have shot o-rings..did you replace the ones that were on there?

 

it is not the stock manifold so it has no place for o rings i need to just get them plugged.

Any idea about what the timing should be?

 

timing should be 10 BTDC leading with a locked dizzy.

 

what are you running for spark plugs?

 

NGK B9es

Can you explain how/why it needs to be 10's before top dead center? Just so my mechanic will understand. how do you lock the dizzy?

 

pull your dizzy apart until you get down to the weights and then pull the springs off of the weights and reassemble the dizzy this is very easy but make sure when your putting it back together the little pins on the weights go back into their sliders(you will see what i mean when you pull it apart) this will make it so when your dizzy is spinning the weights will be full advance right away. i believe the advance on a 12a is 20 degrees so you retard the dizzy back 10 degrees to give you a total of 10 degrees advance or 10 BTDC

 

There is a screw on the side of the dizzy that you loosen so you can move the dizzy forward to retard or backwards to advance it. How many degrees does this adjust the timing?

What should the trailing be?

 

this is the adjuster, loosen the screw and turn it counter clockwise to retard the timing

 

the trailing should be at TDC 10 degrees split between them

 

trailing at TDC

 

thats what i was talking about. Now mine is fully retarded then. I need to adjust it back. I have mine all the way forward like yours and it fires at tdc .

How do I adjust my trailing?

 

some how in the dizzy, you loosen the screws and move the mag pick ups I am not sure what way or how much to get 10 deg split but it has something to do with the little lines under the rotor

 

To set the trailing split you move the trailing vacuum advance pot in or out. It's the one with the two slotted holes and screws. This must be done after you set the leading timing as turning the dizzy effects both the leading and trailing.

After locking the dizzy I recommend marking the pulley so you can adjust the leading exactly to 10 degrees BTDC. It's easy to do as the pulley has a circumference of exactly 360mm. So 10 degrees equals 10mm.

 

It's also sounds like you have some real tuning issues with the carb. Turning the adjustment screws only effects the mixture at idle and light throttle. To get the correct mixture under load you need the correct main fuel jets and emulsion tubes. You need someone experienced to tune it or at least give you a baseline jetting recommendation.

 

Would oversized jets really cause an exact constant stutter through the entire rpm range?