74 914 1.8 -

Ran OK for years with a single weber carb - the temp gauge would move about 1/8 inch when warmed up.

I've converted to dual dells - I still haven't gotten the mixture right yet, but I'm close. the stock temp gauge moves about 1/4 of an inch now when fully warmed up.

I've added a cht gauge (after the new carbs) that I got from CB performance. Now, if I drive the car for about 10 minutes or 2 miles, it's heated up to 385 degrees!

1. Is there any chance that I've installed the gauge wrong? I'm wondering if it could be off.

2. Could mixture / new carbs have caused this much of a heat increase?

Hi!

The stock gauge measures oil temp. The Cylinder head temps are always going to be a lot hotter than oil temps. I can't say for sure, but 385* seems about 20* on the warm side. Doesn't your CHT gauge indicate up to 500 or 600*?

Someone else want to chip in here?

I've gone through about every post here, and I got the impression that 400 was critical destructo temp, and 285 would be normal. I may have that confused with oil temp

My cht gauge goes from 0 to 600 though, and levels off around the middle - maybe that's a sign?

I just bought a CHT gauge for my car, but the motor is still on the engine stand and is slated to be installed this week. So I can't give you a comparative number to work off of.

Let's get someone with more knowledge on this subject to chime in. I might be thinking exhaust gas temps, lean of peak settings for the Cessnas I used to fly... that probably isn't very helpful now, is it?

That's hot.

What cam is inside?

What's normal?

I'm guessing it's the stock cam, but I can't really be sure.

Oil temp is NOT engine temp! The factory needs their asses beat for not installing a CHT gauge in these cars from day one!

NEVER USE oil temp for any engine temperature reference!!

You could have been running 385 for years and never knew it...

Now, where did you install the CHT sender and how are those dells jetted??

Here are my specs for head temps WITH THE SENDER UNDER THE #3 SPARK PLUG- no where else!!

275-325- You are running picture perfect!
325-360- Normal operating temps for most engines, no worries
360-400- OK for climbing hills for limited durations of time
400-415- Getting hot, cool it down and find WHY it's a hot runing bastard (get rid of that stock cam, crappy exhaust and give it sdome real tuning)

415+- You have damaged your engine.

Thank you for all the info! It sound like the carbs / jetting and mixture can really effect the engine temp.



Under plug 3, wire through the center tunnel, then looped and zip tied at the back of the gauge.

As for the jetting - I have no idea - The jets that came with my rebuilt carbs. Could you recommend anything?

What was your outside temperature?

I've got a 2.0l, dual weber 40's. It's been rebuilt by Joe, using the webcam 86a. I just got back from a 1200 mile trip from Tampa, FL to Biloxi, MS. Joe tuned the carbs and resynched them. I drove for 9 hrs, each way, at 75-80 mph. The CHT kept around 350 + 1 tick mark above, when hitting 90 mph. The motor now has 3200 miles on it. With Jake's comments, I feel that this is within tolerances.

-- Rob

Rob, Glad you made it home without any drama.
What kind of milage did you make on the way home?
Seems like we got the engine closer to what it need timing wise. I think your jets are a bit big. as summer comes you will need different sizes.


OK back on topic. Timing and carb jets. Got to get them right.

Stock cams make lots of heat

Stock exhaust makes lots of heat

"Friends don't let friends drive stock"

There is NOTHING that impacts CHT more than tuning! Enrichment and timing make all the difference in the world.

Of course an engine with a stock cam will run the hottest of anything- the cam was developed to build heat in the heads!

OK, sounds like I have some work to do. Is it true that the richer I run the cooler the engine will be? I'm thinking that I should run alittle richer, then attempt to set the timing.

I can't remember if rotating the distributor clockwise or counter clockwise will advance the timing (does anyone know?), but should I be looking to advance or retard my timing in order to decrease heat?

Thank you guys for all the help! I didn't realize that tuning had such an effect on heat inside the engine.

Guys,
What do you think about the air / fuel guage below. Sounds like it would really help me dial in my engine. Waste of money?

http://www.cbperformance.com/catalog.asp?ProductID=598

Narrow band. don't tell much but it will get you in the ball park.

NOW STOP WHAT YOU ARE DOING
If you are asking which way to turn a distributor to advance the you are not qualified to work on these engines. 1st get a good timing light.

Get timing corrected before you do ANYTHING else.

I am by no means qualified to work on these engines!

I have a timing light, and a dwell meter, however I get the impression that with the new carbs, the stock timing won't be accurate any more. Will 7.5° BTDC still work, or has this changed with the dual carbs?

I suppose that what I wanted to know was - does advancing or retarding the timing usually lower the temp?

It was about 65 - so the gauge read about 10 degrees hotter than actual temp

Setting the timing correctly will be the 1st step to running better.
go to Pelican parts tech articles good procedure there.
adjusting valves
Getting the carbs synched up is another major step before messing with jetting.

then working towards jetting if required.

Until your engine can cruise down the interstate at 75 MPH at IDLE, DO NOT set the timing at idle!!! Set the timing at "Full advance", above 3,200 RPM...

Hammy has a good point. What CHT gauge did you get and what was the temp outside?

I thought that was the procedure for a 1.7 or 2.0. I grabbed this from pelican's site:

That pelican info is for stock FI.

Set the timing to 28 degrees full advance. You'll either need to get an adjustable timing light or take off your cooling fan and mark 28 degrees.

update -
On the ride home, I stopped by the local harbor freight and bought a laser temp gauge, warmed the car up. I turned it off, popped off #3 plug wire, and lasered it up

I found that when the CHT gauge (VDO I got from CBperformance) reads 335, the laser gauge reads 310 - while the outside temp was in the lower 70s. I'm going to say that the gauge is close enough to accurate for me.

I took a quick check, and my dwell is set to 80. I'll work on setting that and the idle tomorrow after work.


Thanks again to everyone here - I'm really learning alot!

Just wanted to thank everyone - I found the problem while I was setting my timing.

Looks like these 3 paper towels were sucked into the fan, and clogged it up.



She now runs around 340!

Yup, waste of money. Want mine?

--DD

So Dave...let's hear why you think they're a waste. Are you talking about a narrow band gauge or are you including the wideband meters as well??

If you are including all air fuel gauges in the same "waste of money" category, do you prefer tuning to the "sound" of how the engine runs and how it runs??

Dave...Do you really want to get rid of yours...how much?
Mark

Narrow band == all but completely useless. They're inexpensive, and there's a damn good reason for that...

Actually, they're fine if you want to make sure your catalytic-equipped closed-loop modern EFI car is operating in its "happy zone". But for actual tuning of any real kind? Useless.

Wideband, on the other hand, seems pretty good for tuning. IF you know how to use it effectively. (Which I will still likely be learning for the first few years after I install mine....)

--DD

The laser temp guns are worthless for reading head temps! By the time you get the engine to temp, stop, shut it down and get a reading the head temps have already changed!

Terry, do a valve adjustment on that engine, things have more than likely moved around with the heat..

Now, remember what that sounded like, things that are sucked into fans have their own weird sound, famialirize yourself with it.

Setting timing at idle puts the dizzy in total control of the full advance, don't trust it! Only set timing at full advance.

O2 sensors narrow or wideband are practically useless for a guy with carbs unless they really know what the F they are doing, and you won't find many of them here on he board. There are a few, but not many. I am not one of them either. they can be used to monitor things, but don't try to setup your carbs over a long period of time with them. To many variables.

Carbs, tune them for the following:

Drivability - point blank if it is a street driver, tune it for the drivability that is all you really car about. You will not notice a 1-3 HP difference. Save the money you will spend on the AFR gauge and 02 sensor, and spend it on a set of jets or a book on your Dells. Before I did that I would buy a good EGT ( Exhaust Gas Temp) gauge and a better CHT gauge. Nothing wrong with the VDO CHT gauge you got as long as you understand the short comings. As eluded to in the post, VDO is non-temperature compensating. So your readings change as outside ambient temperatures change. The hotter it is the lower it reads head temps, the colder it is outside the hotter your head temps will be. It is all relative.

CHT and EGT are all functions of A/R and timing, cam etc.... Its a combination. Oil temp is important, but you can run a super cold oil temp and have a head temp through the roof. To many variables here to know with out pictures and data.

So knowing you have a VDO and it was about 70 degrees outside, your CHT temps where a little low. Now that should alarm you, but you need to run the thing and get an average temp, finding those pieces of towel lead me to believe, I would drop the engine take of the shrouds and fish out the rest. Bare minimum, pull the spark plug boots and see if you have towel shrapnel left over on the engine. I could have it in and out in a day, well worth the effort not to toast the car as the temps get warmer and your CHT gauge reads lower, than actual temp.

I just cleaned my fan a few weeks ago. 20,000 miles.

Sprayed it with Purple power while the engine was running. then let loose with the water hose. and run the speed up to about 2 grand or so.

It's enlightening at all the places air leaks out of stock tin. Going to address it when the new motor goes in.

Anyway the motor just sounds happier with a clean fan and what ever else washed out. Lots of crud. Runs a bit cooler now too.

Sucked a heater hose in the fan once. was not re-useable for sure.

Last time I had my engine out I noticed 3 female threads around the front of the fan intake housing. It looks like there was the intent to be able to bolt on some sort of screen to help keep things like papertowels or heater hoses out of the fan. Anybody make something like that?

Yes you can find the screen on Busses, since the fan was right there, VW, must have thought it was a good idea to add to keep stuff from getting sucked in while you work.

If I was adding something to my fan opening it would be a velocity stack, for it and not a screen.