Nope, none

No stupid questions - only slighty moronic people.

OK, my "stupid" question has to do with heat, as in cylinder head temps. The last run in the Bug - which was a freakin' week ago with all the rain since - the cylinder head temp gauge hit 355 F. My question is this: would this be considered a "normal" range in a Bug with a worked 1835cc?

Couple weeks ago the Bug sputtered a bit on the ride back home (bit of unburned gas "pops", sluggish pickup). Long story short (too late) I changed plugs, checked idle jets in the webbers (looked clean, no issue), checked timing (set total timming: 28 degrees advance) checked carb mix screws (not quite 1 1/2 turn out on each one).

I found that the distributor clamp bolt had let the Bosch 010 "walk" a bit advance. After we set the timming we made a scribe mark - the dizzy hasn't moved retard or advance of that point since.

The Holley fuel pump regulator might have played a part in the fuel delivery issues. The Mr. Gasket dial guage seems to work about every third start-up but I have fuel pressure.

Last time I drove the Bug she motored down the road just fine - no pops, spits or sputters. However, I keep wondering about that 355 number (it's about 5 degrees hotter than where it topped out before my tinkering. Oil pressure is good and oil temps never go over 190.

Should I be concerned with 355 cylinder head temps?

355 is a *bit* on the warm side, but nothing to lose sleep over. Those CHT gauges are funny though. The displayed temperature assumes the cold junction of the TC is at like 70 or 75 degrees. If the ambient temp is cooler than that, the gauge will read *high*, and if it's warmer out, it will read *low*. For example, if it's 50 degrees out, the gauge would read 75-50 = 25 degrees hotter than the actual engine temp, so if it were running at 330, it would read 355. I know it's confusing, but you get used to it and before you know it you'll make the correction in your head if the temp outside is significantly different than 75 degrees.

The idle screws need to be *tuned*, not just turned to a preset number of turns, that number is just a reference for starting tuning, which may or may not be close to where the engine needs to be.
There's a decent article here --> http://www.aircooled.net/gnrlsite/resou ... alcarb.htm on synching and adjusting dual carbs, give that a read and let us know if you don't understand any of it and we can point you in the right direction.

Thanks for the great info on my CHT question. I thought 355 seemed a bit warm. However, temps in Mich this time of year certainly fall below the 75 ambient level. It was probably in the neighborhood of mid-60s when I drove it last. Perhaps I need to keep a conversion cheat sheet in the Bug.

Regarding the idle screws being "tuned," I read the link you sent - lot of info to digest there. I had followed a tune guide from Weber Redline, but the info you sent is much more detailed. Sounds like I need to read up more on Uni-Syn procedures - I'm certainly no carb whisperer.

Could a mis-tuned condition be the reason for my higher CHT; leaner tune make things run hotter. The Weber Redline info mentioned if, after you found the best running tune, the mix screws were out past 1 1/2 the idle jet may be too lean - I think they said move up a half size.

Obviously I really need to make sure both carbs are running happy with each other or all the fine tuning is kind of a moot point.

Brian hit it on the nose when he said CHT gauges are funny. I use them as well but I do not let them give me a false sense of security. because what it reads might not really be what it is.

from the man himself Gene:

I hear daily of engines being destroyed by people relying on gauges. I have run hundreds of accuracy tests on practically every inexpensive aftermarket gauge under $125 offered. Practically all read low in the 212 to 260 degree range by 40 to 50 degrees on oil temperature and head temperature gauges in the 250 to 550 degree reading range, again being low by as much as 250 or more degrees. I tested about twenty each of most brands such as VDO, Smith, Stewart Warner, Hawk, etc., and found none without these problems.
Oil temperature gauge readings would be 212 to 220 degrees on the gauge when the true test temperature was 240 to 260 degrees. Head temperature gauges read 385 degrees with a true test temperature of 550 plus degrees. When head test temperatures were upped to 700 degrees, the reading of the gauge went up to 390 to 395 degrees. The price range of such gauges was from $60 to $125. I swapped gauges with senders and got different readings. I found nothing in that price range I would wish on my worst enemy. Not one I tested could ever be properly calibrated or relied on in any way for any valid information or even as a comparison from day to day on the air cooled VW.

Yes, even the oil pressure gauges were just as bad. I found good accurate gauges range from about $250 to $350 and few people would buy them. What was needed was a device that gave the information required and was reasonably priced. That was the reason for the GB 227 in the first place. It is specifically made and calibrated to provide an accurate reading in the ranges of the VW air cooled engine. Originated by Hal Brown in 1972. Made in the USA.

Note: If you must install an oil pressure gauge use GB 264-1/8 tee fitting and GB 265-1/8 pipe nipple to install the factory (Bosch VWA021-919-081B) light sending unit and the gauge together as the factory sender and light are over 100 times as fast to tell you if you run out of oil. Never use any sender that has the pressure and a light combination as they are extremely slow and you lose the rapid action that the factory light sender provides.

Warning: If you want gauges as a decoration fine, but never rely on them. After all, if they provided reliable information I would be selling them to make a profit just like our competition.

Thanks for the advice - although now I probably won't sleep very well tonight thinking about what Gene said.

Sounds like I need to make sure my tune is accurate and not overly reliant on the ol' gauges.

So if it was in the mid 60's, your actual CHT was probably more like 345...
Don't get too hung up on the exact number, just look more at trends, and do the corrections in your head to get a ball park. So if your CHT is around say 340 normally (actual temp), and it's 40 degrees out, you can expect the reading will be somewhere in the ball park of 375. If it's +/- 5-10 degrees of that, don't worry about it. But if on that 40 degree day it's reading 390 or 400, it's time to get concerned!

The mixture absolutely does affect CHT. Again though, the 1.5 turns is just a ball park. Mine are only out about 1/2 a turn and it idles at 11.2:1, and cruising on the idle circuit it's about 13.5 to 14:1, which is where I wanted it. In my experience the idle jet has very little effect on the idle mixture, that's primarily controlled by the mixture needles, and then the idle jet controls the mixture once you get into the progression holes. likewise, once you get into the progression holes, the mixture needle has very little effect. So unless you make the idle mixture screw pig rich, the mixture when cruising around on the progression holes is mostly a function of the idle jets. You could try to go up a size on the idle jets and see how it reacts, but rather than rely on the CHT for tuning the carbs, you need to read the plugs, or use a wide band O2 sensor. I would say before you do any of that though, make sure the carbs are properly synched and the idle mixtures are adjusted properly. Practice adjusting the linkage and tuning the idle circuits and synching them before you mess with jets, cause if all that stuff isn't perfect, you could be chasing your tail for ever.

I disagree with a lot of what Berg had to say, including his hatred of gauges. To me, some information is better than none... Even if the absolute value of what your gauge is displaying is off, you can still see trends or changes if something goes wrong. The good mechanic though does rely on his ears, his "butt dyno", and his smell to determine how his car is running from day to day, in addition to the information from his gauges. This is one reason I would never put a radio in my bug, I am constantly listening to the engine to determine its state of tune. Besides, the sound of 180+ aircooled horsepower is sweeter music to me than anything on the radio...

Hey mr garret I'm glad youade it on the board. I miss that sled everytime I open my garage. Keep those pics coming and you have my number if you need more help.

Thanks for all the great tune info. I'll print it out and keep it next to my "How to Keep Your Volkswagen Alive."

The plugs weren't bad when I changed them out, looked a bit on the rich side (#1 cylinder in particular). I get the tail chasing advice - I won't touch the idle jet until I'm sure the carbs are absolutely in sync and that the idle mixtures are right on.

Hey John, how's it going. Yeah, I finally nerved up and put my noob-self out there.

I saw the Super Bug thread - needs some photos of your, I mean your "friend's" project.

If the rain holds off I'm going to take the Bug to a car show tomorrow at the local college's automotive dept. I'll post some photos Saturday after the show.