Overheat?

Are the carbs jetted correctly? (Main jets).

Jan

restoration.

You need some real world numbers to start with. Actually *measure* something, like the Oil temp. In addition, you might want to measure oil pressure.

In the meantime, perhaps run a heavier weight oil.

Also, do a GOOGLE Groups search:

Click on Advanced Search. WITH THE WORDS: overheating NEWSGROUP: (this one)

Over 2000 hits...

Speedy Jim

WAY TOO SMALL

If that's correct, then you are running way way too lean and you can expect lots of engine damage shortly. (valves)

What size are the venturies in those carbs? Something like 34-36mm?

Jet size rule of thumb: Main jet = 4xventuri size

So if your venturies are let's say 34mm, then the main jets need to be in the neighborhood of 170. Use that as a starting point and go from there, a "10" at a time maybe until you get close enough to go "5" at a time. At that point you should use an exhaust gas analyzer to measure your emissions with. You are targeting CO value of 1,5 - 2 (I'm not sure our units match so double check the proper value).

You can also monitor the mixture with a Lambda sender and voltmeter. Weld a nut on the exhaust pipe, right after the collector (Before the muffler). M18 with 1,5mm pitch. Then buy a general purpose replacement Lambda/O2 sensor that has 3 or 3 wires (Means it's the HEATED type).

The sensor takes 12V in for heating, and has one wire for measuring purposes. The other two (or one) are for ground.

Measure the voltage output of the lambda with the voltmeter, you need to be able to measure MILLIVOLTS, i.e. 0.100 to 0.900 volts. Measure only when teh engine has warmed up, and the sensor too. They need very high temperatures before they start working correctly. Thus teh heated type sensor is a must, it won't rely solely on exhaust gas heat. They are more expensive, but experience has shown me that in aircooled flat 4 engines the exhaust temperature is not high enough at teh collector for an O2 sensor.

Oh yea, almost forgot... heh.. you want the voltmeter/multimeter to read roughly 800 millivolts all through the rpm range.

Jan

WOW.... my Peugeot has 34mm venturis and a 115 main jet :)

It also has one single throat carb, two throat progressive at most.

And it certainly isn't a high performance engine :D

Jan

restoration.

Yikes. I wonder where you got venturies that small for 44 IDF's. The smallest venturies for 40mm Dellortos are 28mm. (Sometimes you hear

26).

And your Webers are 44's.

In the light of this new information, your jets may be close to acceptable size after all, in relation to the vents.

But daaaaamn those vents are small! They are severely restricting your performance in the higher rpm range. I bet it pulls great from down low though.

Replace the vents with something like 34mm and swap the jets out too for a matching set. That should really wake your engine up.... remove the breathing restrictor in the system. It may well be the root of your problem at high rpms. Or contributing to it.

Jan

Dual Throat progressive 34/34 Z2 Solex.

1905cc, a bit over 100hp.

I'm sorry, it was just a figure of speech, I was implying that the VERy small venturies and jets are preventing the engine from performing to it's potential in th eupper rpm range. Call it a bottleneck if you want.

Jan

OK I have a confession to make after reading the replies to my post i thought i would double check my reciepts for my engine parts. To my suprise the carbs are 40's not 44's as originally thought, how much difference will this make to my original problem?

Well it makes more sense, given teh rest of the engine. Good choice of carbs.

Still, the main jets sound small. Try 125-130 for starters. Just a guess.

Jan

Just for a real world example. i've just had my beetle tuned on a rolling road

1776cc engle 110 cam , Dellorto 40's : i have, 32mm venturies, 55 idle jets , 142 main jets , 9165.1 emulsion tubes. 180 air correctors, 30 pump jets

This gives me 80hp at the rollers (engine must be well over 100bhp !)

i would also advise getting the dellorto superformance book or equivallent if there webers.

hope this helps

John