Weber/timing help

[Szia]

82 720 with automatic transmission. I installed a weber and deleted a lot of vacuum lines. My problem is when I set timing I get a ping under load. So I retard the timing, now no power. Seems to be a lot of vacuum at idle. During warm up it acts great. When it gets to operating temp is when pinging and shuttering starts. Anyone have this problem with there conversion?

[datzenmike]

Well that might depend on where you have set your timing. You don't say, but it should be 3-5 degrees BTDC.

 

You also don't mention what size or where you got your weber. Is it new or someone else's problem? Runs fine when cold could be that it the extra rich fuel mixture from having the choke on. When warmed up, possibly the carb primary is a bit lean for theZ24. Lean will run hotter and may cause pinging.

 

What brand of plug and what number exactly. Nissans like NGK plugs. Other makes are not a good match.

 

High vacuum at idle is normal, good in fact.  

[Szia]

So disconnected vacuum line, plugged and set to 5 degrees. When I reinstall vacuum line, timing jumps off gauge to like 30 degrees BTDC. I installed a 65 idle jet. Biggest I have on hand is a 70. I thought that might be to much, but I can give it a try. I have NGK plugs in now. I pulled them out on intake side and #1 and 4 were on the white side and 2 and 3 were on dark side. The weber is a progressive 32/36. The motor is the z22. It seems if I leave a vacuum leak it kinda runs better? Thanks for the quick reply.

[Tinman]

Timing vacuum has to be ported vacuum, not manifold vacuum.  You should get NO vacuum on your distributor at idle.

 

At least with a weber.   A stock system works a little different.

[Szia]

32/ 65 idle jet. 140 main jet. 180 air corrector.

36/ 55 idle jet. 135 main jet. Didn't pull out yet.

 

Going to increase main jets and see if that helps. It should be running a lot higher on idle circuit, can only get about 850 rpm. Then when I put into drive it stalls out. So then I open idle adjustment which exposes vacuum at port.

[OneFreakyMF]

If I remember right, there is a thermal vacuum "switch" that could be an issue depending on which vacuum lines were removed and which vacuum line is running to the distributor. When I installed my 38 Weber I deleted every vacuum line except for one running to the distributor and have had zero issues. Had to plug a few things and such but it worked great!