2.2S pistons. 70.4mm crank. Poor running.attn Grady!

[nabilious]

A friend built a motor under my recomendation with 2.2S pistons 2.4L crank and heads rebuilt by Olies (ported and polished too). Bruce Andersons book says that this recipe actually comes out to 9.5 CR as opposed to the expected 10+CR. We used the Zenith carbs but Rebuilt them using 32mm Venturis, 140 Mains, 60 idle jets. I know everyone will say that the Zeniths are the problem but I disagree. They are as good or better than the Webers when properly set up. Just look at the specs....not the name of the carb. There is some popping in the exhaust just off idle and in the early midrange, on top it doesn't seem to pop as much at all. This doesnt seem to change whether hot or cold. It can be a bit of a wench to start when cold, lots of coaxing to needed. Most importantly, it just seems down on power across the board. it kinda comes alive in the upper rev range, but this is relative. Its just flat. feels like a stock 2.2T at best. Could the timing be too retarded?? what are the symptoms to excessively retarded ignition timing? Early on we mistook the popping in the exhaust for detonation and just turned the distributor a little bit to see if it helped. Not sure if it was ever reset correctly (car is not in my garage! not mine) Tomorrow, i'm planing on retuning the carbs to see if the idle screws can help with the popping. I'd like to set the static timing at the same time. Any insight you guys can provide would be awesome.
Thanks,
Nabil

p.s. the cams are mod-solex, 2.4L w/2.2S pistons. Ports are 35mm'ish. Dansk Sport exhaust (pea shooters), Carb jetting 60 idle, 140 mains, 32mm venturis.

[tom1394racing]

Nabil

Sound like the idle jets are either plugged or too small.

Try cleaning them and then richen the idle mixture.

[JFairman]

If timing checks good and you find the mixture is lean during the transistion phase from idle jets to main jets then smaller idle air correction jets will richen up the mixture just before and during the transition to the main jets.
you may need to go to the next bigger size idle fuel jet.

I don't know if you even get them for zenith carbs.

You can compensate for the extra fuel at idle by leaning out the idle mixture screws so it isn't too rich at idle.

If the carb is off the engine and you look in the bottom around the throttle butterfly while holding it open, you can see the idle mixture hole and 1 or 2 more small holes just upstream from it.
Those small holes are where emulsified fuel and air come out and mix with the air stream through the carb during the transition phase to the main jets.

[iq207]

I have a 2.4 built with 2.2S pistons, S cams, and Zenith Carbs. I don't know the jetting, but am working on modifying it. It runs well above 2500 RPM, but below that it wants to cut off at stoplights and is a hard start. Above 2500, it pulls like crazy all the way to the rev limiter and is a dream to drive. If you get your jets sorted, please post the info.

For timing, I have an early non-vacuum distributor and set the timing at 35deg at 6000 RPM. That ends up putting my idle timing between 15deg and 20deg. Maybe this is part of my idle problem, but I'd rather go fast!

Any suggestions on the idle problem would be appreciated. I will try to figure out my jet sizes.

[iq207]

forgot to mention - Points and MSD ignition, stock coil.

[J P Stein]

Originally Posted by iq207

forgot to mention - Points and MSD ignition, stock coil.

Use the MSD hi vibration coil, some fat plug wires (Magnecore 8.5mm) and gap your plugs to .045-.050. I don't like points but they work.......
This set up (along with an MSD 6al) did wonders for my low rpm running.

[berettafan]

Whoa now btfu.........

Set your timing BEFORE you start tweaking all over the carbs!!! Otherwise you will be tuning carbs to the wrong conditions (perhaps there is a better term?).

I supposedly (per PO) have a 2.4 w/ 2.2S pistons running on webers and i definitely would NOT call it flat.

[kenikh]

MSD and stock coil = bad idea. This can cause a lot of rough running issues. Do a search.

[john walker's workshop]

zeniths, eh? hmmmm. but you like them for some reason, so it has to be something else. at least with webers you can change emulsion tubes to fine tune the transition. try finding any performance tubes for zeniths.