Opinions wanted

[halg]

As most know I am building a supercharged 1608 in a 1969 coupe. I am looking for opinions on using the block mounted or external thermostat. Originally I was going to use the external one because of the bypass issue raised in a earlier post. Since I now know there is a bypass built in I am torn between the two. I do know there would be significantly more water flow with the thermostat closed with the external one. I of course have installed a much larger radiator to handle the extra heat load of the supercharger(2 1/2" core). Of course during warmup the supercharger will be deactivated. Since everything will be custom anything goes.
Hal

[So Cal Mark]

unless you want to install helicoils in the head for the water outlet bolts, I'd stick with the external stat

[halg]

Do you really have to change the thermostat enough that the bolts holding it would be the deciding factor in which system to use???
Hal

[ventura ace]

I'm not sure what the helicoils would be for, unless your head is stripped out where the water outlet bolts attach. I would just give them both a try, and take notes to see which one you like the best. It seemes to be a pretty easy swap. I like the internal thermostat because it's simpler, and less effort to bleed. If you do try them both, please publish your results here.

Alvon

[halg]

I am more than willing to do the swapping, but with all the posts about external thermostats I assumed that someone had already done it. ACE you know very well once your car is running it is unlikely that you will take it apart to try something that might make a difference(or not). I hope you had an uneventful cross country trek, and everything was fine at the other end.
Hal

[mdrburchette]

I've got a 71 with the internal and 72 with the external. I can't determine a difference between the two. I've even checked the head with an infared thermometer and both are even with heat distribution. I will tell you I had a hard time bleeding the car with the internal t-stat vs the external though.

[engineerted]

One main advantage of the internal thermostat, is that you can get a wide range of tempature choices from 160 to 195, plus they are also cheep $$.

Ted

[ventura ace]

Hal,
I understand what you mean by not wanting to change something on your engine once you've got it running good, especially if it is a change that is not easy to reverse. However, this is a fairly easy change, and easy to reverse, so I would be happy to make the comparison myself if I had the parts and the time to make the change. I don't have the water passage adapter for the external thermostat (the neck and the 'T'). I do have the hoses and an external thermostat, so I may try to get my hands on the other parts one of these days and do the comparison test myself.

As I mentioned earlier, I have noticed with my 1.8L engine, that the water temperature seems to rise higher than I like under some operating conditions, and I crack open the heater water flow to keep the tempature gauge reading the desired range. I never had that issue with my 1438cc or 1608cc engines. I'd be interested to know if the external thermostat does away with that little aggravation.

Alvon

[manoa matt]

Ace,

If you are running mild cams, dual carbs, and a 1.8 motor and trying to cool it with a 1438 or 1608 radatior then you will run hot. You need a bigger or more efficient rad.

[mdrburchette]

Alvon, I've got a bag full of those water necks/tees. I'll try to dig something up and send it to you.

[So Cal Mark]

if opening the heater valve drops your temp, then your radiator is the problem.

[ventura ace]

Thanks for the offer Denise, and for your inputs as well, Matt and Mark. You indicated that the 1970 radiator (for a 1438cc or 1608cc engine) doesn't provide adequate cooling for the 1.8L engine with mild cams and 40 IDF carbs. I didn't leave myself enough notes back at the time that I built this engine, but I don't recall having any 'run hot' observations until after I swapped radiators. My original 1970 radiator seemed to run normal temps under any operating conditions with this 1.8L engine combination. I changed out the radiator, though, because it had a tiny pinhole leak that I could not get repaired. It was a very small leak that apparently only occured at pressure and temperature. The radiator shops witnessed the leak when the radiator was on the car, but they were never able to duplicate the leak with the radiator in their dunk tank, so they couldn't fix it. After taking the darned thing out 3 times to have repaired at 2 different radiator shops, I finally said enough and bought another radiator. The 'new' radiator looked much, much better than my old one, and was certified by the seller to be clean and functioning properly. It looked practically brand new (from a '71 or '72, I believe). However, with the 'new' radiator, I started to notice the running hot pattern, but only in cool weather. No problems in the hottest of days under the most demanding driving and climbing, but starts running hot when the weather is cool outside.

I took the 'new radiator' to a shop and had them check it out. They gave it a clean bill of health. I paid them to take off the tank and rod it out anyway. They did so, and reported back only minor fouling, if at all. I reinstalled it, and just live with it. If the engine starts to run a little warm, I just open the heater water valve to keep things cool. I may just put the old radiator back in one of these days to see if the running hot problem goes away, but before I do so, I should try the experiment with internal and external thermostats to see if there is a noticeable difference in temperature control.

Alvon

[manoa matt]

When I removed my heater core and connected the heater tube at the back of the pump to the port on the head I noticed my running temps dropped by a few deg. Creates a better flow around the back of the head and block and evens out the temps across the cylinders.

Of course I don't need the heater here even on a cold day (low 70's). Only time I would need heat is when it rains hard and I have the top and windows up. The inside of the windshield condensates from my body heat so I just open the cowel flap, turn on the blower motor, and draw in cool outside air that elimenates the condensation on the inside. You may need your heater core up in Ventura. How cold does it get there?

[halg]

Since my car will be anything but stock changing between the two systems would be more difficult than yours ACE, using stock parts. If you really want to do this let me know if I can be of help, since I will get the benefit.
Hal

[ventura ace]

I'll be glad to run the swap test for you. I found a water neck in my collection of parts, but I don't have a 'T' to connect to it. If I could get one of those, between you and Denise, I could do a thermostat swap to note any differences. I have all the hoses and the external thermostat.

I would also like to put my old radiator back in, eventually, to see if that makes a difference, also. To do so, I need to weld the side bracket back on to the radiator (I borrowed them off my old radiator to put onto the 'new' radiator, since the side brackets are different on the '70 and the later years' radiators). I have acquired a second set of the side brackets, so they could be welded (or soldered) onto the radiator at any time. Do you have the equipment and skills to put the brackets back on for me?

A