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Sun Mar 01, 2015 9:39 pm

so out cruising with the wife today and watching my gauges. Installed i have oil pressure and temp both vdo. CHT is a dakota digital. we were cruising down the highway at about 55/60 and i kept noticing the cht would climb to about 400. is this normal? my oil temp was barely 150. oil is measured off the oil drain plug. engine is stock dp 1600. svda dist. is this normal? ambient was about 55 to 60 today.

Sun Mar 01, 2015 9:42 pm

this is in my 71 bay btw.

Sun Mar 01, 2015 9:45 pm

Ever read Gene Bergs opinion on cheap gauges?

What was the difference between cold and hot oil pressure?

Sun Mar 01, 2015 9:45 pm

I wouldn't say lethal, but for that speed and ambient temperature I would say kind of high. What kind of gas are you running? Mine hates anything lower than 91 (r+m)/2.

Sun Mar 01, 2015 9:51 pm

PITApan wrote: Ever read Gene Bergs opinion on cheap gauges?

What was the difference between cold and hot oil pressure?

cold i do believe around 55 or so at 3500 rpm. hot it was around 40 and above at 3500 rpm.

the head temps are what worry me. its seemed down a bit on power today too. carb is junk i found out recently. throttle shaft is worn. idles like poop. I just did brakes on the back and had to readjust due to one dragging a bit.

As far as gas i just put 10 gallons of shell 89 octane. maybe i need some good octane booster. i may have to go find some trick octane booster (best stuff ive found, others are crap) i suspect the gas is whats the problem with power. its that oxygenated crap they sell in the winter. will try to find the non oxygenated stuff if i can.

Sun Mar 01, 2015 9:58 pm

Yea. The dirty and worn out carb would definitely shoot those temps up. that's going to cause the mixture to be very lean, which can fry an engine. Also, the precision german machines are very picky when it comes to gas. Put the good stuff in it.

Sun Mar 01, 2015 9:58 pm

drakonis wrote: PITApan wrote: Ever read Gene Bergs opinion on cheap gauges?

What was the difference between cold and hot oil pressure?

cold i do believe around 55 or so at 3500 rpm. hot it was around 40 and above at 3500 rpm.

the head temps are what worry me. its seemed down a bit on power today too. carb is junk i found out recently. throttle shaft is worn. idles like poop. I just did brakes on the back and had to readjust due to one dragging a bit.

As far as gas i just put 10 gallons of shell 89 octane. maybe i need some good octane booster. i may have to go find some trick octane booster (best stuff ive found, others are crap) i suspect the gas is whats the problem with power. its that oxygenated crap they sell in the winter. will try to find the non oxygenated stuff if i can.

If it isn't knocking your octane is fine for how you are set up. If the throttle shafts are leaking it's running lean which will hurt power. Not a lot to do---richen the idle, fix the carb.

Winter gas may have less energy but cold winter air (6oF ain't cold) will give more power.

Did you check calibration on your gauges?

http://www.geneberg.com/article.php?ArticleID=239

Sun Mar 01, 2015 10:06 pm

no i did not check calibration on the oil temp gauge. the cht gauge i bought the best i could find. rattwell recommends it. dakota digital.

my oil pressure gauge is spot on and tested against a mechanical gauge. both read exactly the same. so its good.

carbs not dirty. just did a clean out and new gaskets and valves and such. rebuilt i guess. but discovered it was bad after getting crappy idle quality. as soon as the tax money gets here im buying a set of kadrons and going from there.

maybe those will fix my lean power and hot heads problem.

Sun Mar 01, 2015 10:17 pm

drakonis wrote: no i did not check calibration on the oil temp gauge. the cht gauge i bought the best i could find. rattwell recommends it. dakota digital.

my oil pressure gauge is spot on and tested against a mechanical gauge. both read exactly the same. so its good.

carbs not dirty. just did a clean out and new gaskets and valves and such. rebuilt i guess. but discovered it was bad after getting crappy idle quality. as soon as the tax money gets here im buying a set of kadrons and going from there.

maybe those will fix my lean power and hot heads problem.

Next time you change oil, check your oil temp gauge at 212F.

I doubt ratwell knows other CHTs. Where is he anyway? maybe get a thermocouple plug to put on your wire (if you don't have one in the engine compartment) and check the temp on a fluke 51 or 52. You can find them used for $50 or so. If you are using a ring type pickup under a plug you can check that at 212F also.

Sun Mar 01, 2015 10:24 pm

yeah using the ring thermocouple. guess ill be making a pot of boiling water in the garage. lol.

Sun Mar 01, 2015 10:31 pm

How is the ring sender under the plug?

Sun Mar 01, 2015 10:33 pm

sender ring is against head. then plug washer and plug. in that order. all brand new btw. just installed last week.

Sun Mar 01, 2015 10:48 pm

harbor freight has those IR guns for pretty cheap. I use it all the time. I think Colin is always using it too, and he never uses any gauges on his buses.

When you use cheap gauges, you have to find whats normal for you. Especially freaking VDO gauges. Your CHT sounds right to me, but then again I don't use gauges.

Mon Mar 02, 2015 12:20 am

I own a raytek temp gun. I used to race gas rc offroad. bought for that. still have it almost 15 years later. still works great. I do trust it. ill use it ont he heads and see what readings i get. maybe pull the dipstick and check its temp when hot.

Mon Mar 02, 2015 4:55 am

Have you checks your timing?

I would suspect as mentioned above that you may be running lean. A dumpy idle is one symptom that suggest this.

Mon Mar 02, 2015 7:08 am

Check points?
Timing like ^ he said :wink:
prolly carb though?
Please don't do the K-duds, fine some nice 40 IDF's 10 times the carb,then kadrons(no bushings to wareout :wink: )

Mon Mar 02, 2015 7:16 am

The Dakota Digital gauges are actually pretty good. That Berg write up is quite dated, although certainly applied back in the early 70's.

I would be sending that carb off to have the throttle shafts rebuilt if it were mine. Also keep an eye on the entire cooling system to make sure it is everything it can be.

Correct timing based on your distributor please, after checking the dwell angle of the points. Keep an eye on the valve adjustments.

Unless you have some sort of high compression set up 89 grade is not really helping you any. This thing should run fine on 87 octane.

That laser thermometer won't tell you much about the CHTs.

Mon Mar 02, 2015 8:38 am

If you have even a minor combustion gas leak past the ring terminal your gauge will read very high even when your CHT's are normal.

Mon Mar 02, 2015 10:18 am

I like the part of this thread where OP buys a very good CHT gauge and everyone beats up on him about having a cheap gauge.

Anyway, my head temp gauge stays around 340-350 most of the time, but I've seen it climb into the 400 range on mountains or if I'm really pushing it on the interstate at 70mph for a long time.

I would make sure your fan isn't blocked by something and check your flaps before you leap to engine problems. Best to start the process of elimination with the easy stuff, anyway.

Mon Mar 02, 2015 3:05 pm

well as far as cooling goes. im going to buy the correct tins and veins and all the internals so it cools correctly. right now the flaps are wired open as i dont have a thermostat. it came that way. i dont drive it much so right now its not too big a deal. im going to fix it right. as for the carbs i cant spend too much. i like the k-dogs but i may go with 40mm webber/hpmx type. right now its a 1600 but soon it will transform into a 1915 or a 2054. most likely a 2054. for right now im going to concentrate on the correct tins for cooling and the t stat. The carb situation im not sure a set of 40mm hpmx carbs would work well. im thinking it alot of carb for just a 1600. after i build a new bigger engine then i could see it working well. more thoughts please. and dont beat me up about a gauge being cheap. The dakota digital was not cheap. lol.