CHT

I know Stan monitors the cht of all 4 cylinders, but for most people just #3 is adequate. As Stan has menioned, when something is wrong he immediately knows which cylinder it is, so there is value in knowing at a glance the state of each of the 4. The VDO cht gauge is not temperature compensated (will read as much as 30 or 40' low when the ambient temp is above 70'F and high when ambient is below), so it's not the best choice.

I think a cylinder head temp gauge is essential with any bigger, modified VW aircooled engine in a confined engine compartment such as a Speedster and will definitively tell you your engine's state of happiness. Cht, if monitored from under the spark plug has the advantage of telling you what's going on right now. Oil temp, while also valuable information (and needs to be kept under control), is the result of what happened a minute or 3 ago, and can lead to a false sense of security, as an additional cooler will keep the oil temps under control under almost all conditions while the heads can be so hot they're slowling destroying themselves (and the rest of the engine). The thing will die (usually somewhere out in the middle of nowhere) with no warning and you'll be left scratching your head muttering "what the h*ll happened?".

Someone on the Samba advocates monitoring the air temperature inside the engine compartment, the idea being anytime it is noticeably hotter inside than outside there is not enough airflow into/through the engine compartment to be removing all the heat, and some of it is being recirculated back into fan and carburetors, which (when you think of it) is exactly what you don't want! The recirculated air just gets hotter and hotter...I think this is something a lot of guys don't pay nearly enough attention to.

When stuffing a larger engine that makes 2, 2 1/2 or 3 times the original horsepower into a car we have to remember that we're now the engineers in charge- we're in uncharted territory, as the airflow and cooling requirements of a larger, more powerful aircooled engine are completely different than those of a stock 15 or 1600, or even lightly warmed over 1776 or 1835. Although our cars and original 356's are the same general shapes, we can't look to Porsche for ideas either, as that's where the similarity ends, as no stock 356 engine (other than the 4 cam series) never made more than 90 hp (which is about the output of a mild 1835 or 1915).

Where we can find information is vintage racing, where guys are trying to make high strung 356 engines making anywhere from 130 -160hp last as long as possible. Some cut the underneath of the engine lid up for as much air movement as possible, and at least 1 team ducts air into the engine compartment from the front through a tube a foot or more in diameter. In a world where engine life is sometimes measured in racing sessions (not seasons), does it take much to figure out what they've discovered? 

_{The secret is air!}

Btw- threads are locked after a certain time of inactivity (you'll have to ask Theron for an explanation).

PS- Sorry Tebs, couldn't keep it to 2 paragraphs!

As Al mentioned, I monitor all 4. The real value is in immediately knowing  when an idle jet is plugged, or my carbs are going out of sync for some reason.

It is a pain when changing spark plugs, as the rings always want to float away from the holes, and getting them lined up back up is no easy chore.  However, I find that it is completely worth it to me. 

As far as an analog vs digital: that's a question only you can answer. Digital is quite a bit more accurate, but looks really out of place (at least to me). 

Richard: I don't have any CHT visibility, going on the (potentially misguided) assumption that "ignorance is bliss".  I'm running a stout 2,110 but I'm also running an external oil cooler (Yeah, Al, I know that's 3-4 minutes too late) but I've also done all I can to get as much air into the engine compartment as possible and totally sealed the top from the bottom.  Seems to work thus far.

As far as digital versus analog, I totally agree with Stan - Digital is way more accurate but looks out of place, and while it is mesmerizing to watch the analog A/F needle swinging around as I drive along, fortunately, thus far, I haven't been too distracted that I've hit anything.

Here's my digital heater thermostat, next to my analog A/F gauge.  I added the digital bit just to piss off the Porsche Purists, but it's as out of place as a Tornado in a Trailer Park!!

BTW:  Who's the "Junior Pit Crew" member in your Avatar?

Happy Holidays!

A bit of background. The motor l ran before was a 1911 type4 with a Dtm and l just went by the oil temp as a guide, like you say ignorance can be bliss Gordon.  Now I'll be running is a fresh built type4 2270 dry dump motor. See picture.  Just finishing a few details before it goes in.

I did read in some old threads that you monitor all four Stan. I understand the logic but can't help think the more gauges I'll have, I'll be to busy monitoring them rather than putting my foot down. Will it become a mission to get all gauges to read roughly the same temp across the board as I'm sure they will differ from each other. As a man from experience do you always find yourself glancing at the dials to much Stan?? Or do you go by the sound of the engine before you start looking at the dials to to give you an indication were the problem maybe??

Al, I'm still sourcing getting someone to punch some Louvres in the inner wings and lower engine tins to help with getting fresh air into the engine compartment. I was only going to go with say seven 5" Louvres adjacent to the carb, although I'm now thinking the more the better will help??

l like the digital with the benefit of having one gauge to monitor all four CHT's but like you say will look out of place. So lm leaning towards old school anolog. 

I did see someone with a steering column clamp that houses x2 gauges but can't remember who makes them?? Has anyone got one fitted to your car?? 

The junior pit crew member Gordon is my youngest. I can't go in the garage without him by my side. I'm thinking he'll need his own tool set soon... 

Just do number three. I used Dakota Digital and mount up under the crossbar behind the dash. It needs to be in the shade to see it during the day.

I too, use the Dakota Digital units for oil and CHT. Initially I used a rotary switch from radio shack to monitor all four CHTs and 6 different oil temp. sender locations. Here's some  pics of the gauges in use and what I feel is the best location for the oil temp. sender. 1st choice is the block-off plate for a type 3 on the universal case........Bruce

Thanks guys. Decisions decisions. Seems Digital is the way forward if not in looks, a lot more options with just one gauge. 

Bruce l take you still need x4 thermocouples upto your rotary switch to monitor one at a time??

Bruce you mention you struggle to see the Dakota during the day. Take it, assuming its with the roof down only. Do you have the same problem Bill. Is this a downside to the digital gauges when the sun is out and the roof is down??

Yes, I did have four thermocouples to the rotary sw. I have since then,reduced it to just one on #3.  I also monitored oil temps. at four different places as well and am back down to the one location now.

The Dakota gauges are pretty bright and the only time I had to shade them with my hand is when the top is down and the sun is on my back. I'm happy with them BUT I would rather not have ANY extra gauges on the dash.  It's just a necessary thing I put up with. I really like the simplicity of the dash....3 switches and two gauges.  I should point out to you that eventually corrosion on the contacts of the rotary switch would/could change the accuracy of the readings. Depending on the ambient conditions in your area this may (or may not) happen and who knows how long it would take. Perhaps a hermetically sealed rotary switch would help.....Bruce

Idea: mount the Dakota readout up under the dash, too high to be seen. Attach it to a servo-actuated thingy which lowers it under two different conditions. Condition 1: a button you press. Condition two: the temp reading you deem notable. 

Et voila! 

RichardMaxwell posted:

Thanks guys. Decisions decisions. Seems Digital is the way forward if not in looks, a lot more options with just one gauge. 

Bruce l take you still need x4 thermocouples upto your rotary switch to monitor one at a time??

Bruce you mention you struggle to see the Dakota during the day. Take it, assuming its with the roof down only. Do you have the same problem Bill. Is this a downside to the digital gauges when the sun is out and the roof is down??

No, I put mine on the cross brace behind the dash...Perfect day or night.

I have a Dakota Digital CHT mounted beside the steering column. I have no trouble seeing it during the day, other than it is kind of blocked by the steering wheel.

I also have an Innovate air/fuel gauge.

Even though they are digital, when the car is parked they go black so other people don't see the digits.

Thanks for the feedback. The Dakota guys, what colour did you go for?? Blue/Teal.

Im going back some ((15-20?) years and recall seeing an article in a Porsche magazine with a guy from Cali called Pascal with a original Speedster that had auxiliary gauges between the speedo, tacho and fuel/temp gauges just above the steering column. Looked really cool and didn't look out of place?? Searched the www but not find anything on the article. He must have had small gauges to get them to fit. Anyone tried that?

Could it have been an early one?  They had the arrangement that you describe except that there were only two large gauges.

I think I went with Teal to match the Innovate air/fuel gauge.

I used an Airkewld billet mount but they don't seem to available now.

Blue, cheap mount from NAPA 

Michael McKelvey posted:

I have a Dakota Digital CHT mounted beside the steering column. I have no trouble seeing it during the day, other than it is kind of blocked by the steering wheel.

I also have an Innovate air/fuel gauge.

Even though they are digital, when the car is parked they go black so other people don't see the digits.

With the top down and in the sun, I could not see mine. Could be the polarized glasses. Moved it under the cross brace behind the dash and it's perfect.

Bill also has the problem that his only source of shade in his Speedster, his Hawaiian straw hat, keeps blowing off in the wind at speed.  

He might have to go for a Life Guard hat with the chin strap.

Lane Anderson posted:

Could it have been an early one?  They had the arrangement that you describe except that there were only two large gauges.

Lane deffo had x3 big gauges and x2 small auxiliary. 

Anyway after lots of searching l found the magazine l mention above. It was June 2000, l did say it was a few years ago. So I've purchased it of the net, just waiting until it lands on my doorstep to get to have another look at the article.

Michael McKelvey posted:

I think I went with Teal to match the Innovate air/fuel gauge.

I used an Airkewld billet mount but they don't seem to available now.

Been thinking of Teal (green) thinking it would match the other dials more myself if l go that route.

Question;

I've got the Dtm already fitted etc. Can l fit the thermocouple to the No3 spark plug and drop it in from above and tighten it up? Or will l need to remove the Dtm again to dremal out the spark plug hole for clearance for the thermocouple??

Whilst searching I've seen various thermocouples on offer made from copper, aluminium and stainless. Should l be steering towards either??

Heres the magazine l mention earlier.

and here's the dash layout with x2 auxiliary gauges squeezed in

May try the same layout. Will need to get my ruler out. 

Has anyone used Westach gauges?

I also feel a drastic need to have a more accurate reading on the oil and heads.

I can get two, 2 inch dual gauges in my dash in the space either side of the tach.

I can moniter the CHT on both sides and Oil temp and pressure.

They might not match the cheesy china gauges, but I'm not really going for show anyway.

CG

Those are what I'm running. 2 of the dual CHT Westachs. 

So I take it that they're decent enough.

Which temp range and thermocouplers did you use?

Thanks,

Actually, I was wrong. I use these:

from Aircraft Spruce.

I had North Hollywood Speedometer put them in chrome bezels, and had the "L" and "R" replaced with numbers "1-4" for the cylinders. They're supposed to be temperature compensated, but I have a cold joint in the wiring, so I think not.

they work well, look the part, and are pretty inexpensive.

When Henry switched out my fuel injection, installed Webers, and put the engine back in the IM he took out the CHT gauge.

He said he never put CHT gauges in his cars and I didn't need one.  

Now I've got a nice Westach CHT gauge to put in my buggy.  Installing the gauge is fairly easy, but holding that damn metal ring in place while tightening down the spark plug is a PITA.

^ Yes it is.

Should be A LOT easier with my buggy.

Following the direction a few of you guys have made, l decided to follow suit and hit the purchase button. Now they've landed l can crack on installing. Not looking forward to fitting the sender under the spark plug bit though.. any tips

RichardMaxwell posted:

 Not looking forward to fitting the sender under the spark plug bit though.. any tips

Yes. It would be helpful to have eyes on the ends of your fingers.

Short of that, if something feels "funny" it's wrong.

Trying to keep the ring in one place while tightening the spark plug is a real pain.

I can't remember-do you guys that have CHT gauges take the spark plug washer off when installing the CHT sender ring?

I leave mine on. 

 I bought a thermocouple  and gauge from another supplier then went with the Dakota gauge and thermocouple. Both stated in fitting, to remove the spark plug ring but one also stated on higher horses engines it maybe necessary depending on the thickness of the thermocouple end.

l took mine of anyway.

I managed to fit it under the plug and run the thermocouple up front, now just waiting for the gauge holders to arrive to hook up and play.

Ron & Richard- have a look at this-

Cheers Al

I've already had the time and pleasure of doing that. Pain in the ass, had to take the shroud all off again to get access. Putting a small recess into the side to accommodate the thermocouple ring washer. Something l should of done when l had the heads on the bench instead of doing it with the engine all built up. It scared the crap out of me having to pull the plug and plug the hole to stop any aluminium chippings from the dremal going down the bore.

Lesson learnt anyway...

After much thought and purchasing various gauge holders to go under the dash (Hence why I got the black gauges). l took the plunge and drilled some holes. 

Been in touch with Dakota and they're sending me some Chrome Bezel's to match the others.

Actually, Richard.......  After you get over the dread of drilling two holes in a perfectly good dash, I think they're gonna look Wicked Awesome!  I had to go out and sit in my car and see if that huge steering wheel hub was in the vision way (it wasn't) so I think that location is perfect - especially for something you might want to glance at when cresting a hill (or half way up a mountain - which you don't have a lot of in your part of the UK).   Waiting to see the finished look!

Hi guys a quick question regarding the Dakota CHT gauge.

l managed to get it all wired up this weekend and working. Question is, should it read Zero on a cold engine?? Mine is reading 57F as soon l switch on the ignition. Are they really that sensitive?

Mine never reads 0.

Yup, they're really that sensitive.

Richard.....Both my gauges (CHT & oil) read the same cold. They are reading ambient air temp. This morning our air temp was 58 F and the two gauges both read 56F. Yes they are pretty accurate.  I have checked my oil temp gauge against a very accurate test thermometer down the dip stick and they were within 2 degrees as well...Bruce