Eriks85Rx7

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.

Fuel is a SE pump the line is splits off with a T to limit flow pressure to the carb.

Carl Byck

I don't have your answer, but I know some guys that have a similar set-up. I will print your page and see if I can get it to them. I would try posting on some Austrailian forums as there are alot more of these set-ups in use there.

Good luck, Carl

moremazda

iTrader: (4)

Timing could be set to 15 deg with an 8deg split, plugs should be bur9eq.

What is this "T" thing you are talking about for the fuel supply... You need to have a rising rate fuel pressure regulator with base pressure around 3.5psi.

Have you blocked off the choke passage on the Dellorto?

sand121

iTrader: (3)

I have a setup similiar to yours and I'm running 15 degrees before TDC, the trailing is 10 degrees before TDC. I used to use a locked dizzy, but it really hurts driveability and causes the turbo spool up slower. What I did was weld stops in the dizzy that limit the amount of mechanical advance. I also put in softer springs to make it reach full advance sooner. Now its around tdc at idle and then advances 15 degrees at about 2.5k. For you I would recommend starting out with your timing at about 10-12 dergrees before Tdc, when you feel more comfortable that your carb is tuned correctly, you then can try to advance the timing a little more.

Are you using a wideband A/F meter to tune you carb? If not, go get on right now. Its a must if you are messing with turbos and rotarys. It doesn't take a whole lot to shatter a apex seal, destroy a rotor housing and the turbo.

What kind of fuel pressure regulator are you running? Is it a rising rate regulator?

As for the T-fitting, I don't think you should be using one side as the feed and the other as a return. Otherwise its just going in one side and coming out the other. Meaning the carb might not see the fuel pressure it needs because the fuel is just bypassing it. Now if you had the fuel pressure regulator on the return side then you'd be ok.

Dragtek

I will ask some of the local racers here that use Your simmilar set up and see what answers I can come up for You.