• Hi Guest!
    You can help ensure that British Car Forum (BCF) continues to provide a great place to engage in the British car hobby! If you find BCF a beneficial community, please consider supporting our efforts with a subscription.
    There are some perks with a member upgrade!
    **Upgrade Now**
    (PS: Subscribers don't see this gawd-aweful banner
Tips
Tips

Now I'm hot

Share this page

drooartz

drooartz

Moderator
Staff member
Gold
Country flag
Online
In a classic case of DIY gone seemingly wrong, after I've fiddled with various tune-up items (new plug wires, new coil, gapped points, adjusted valves, carb) the tunebug seems to be running hot. The carbs are probably off--I was warming up the car to re-adjust them when I noticed the little guy was running at 190. It is usually at a pretty steady 180 around here.

Could I have tweaked something in the tune-up process that might cause this. Another possible consideration is that the coolant is probably out of mixture, with more water than normal. Also, I'm at 5550' elevation.

I'm trying to get the Tunebug ready for the show on Saturday, so any help is appreciated. I think I have all the bits in place, just need to get them all adjusted so he will run as well as possible.
 
And that was in your driveway, what was the temp. going down the road. Bet it was lower.
 
Drew,
Retarded ignition timing or a lean mixture will cause the engine to run hotter. Since you changed both of these we can't tell which the cause is. Start with ignition timing and then go to carburetion.
 
And that is very true as well. But then Chris if the car was not moveing 190 is not bad.
 
I was driving it around to warm it up, and noticed as I was heading back to the house that it was running around 190. When I shut it off in the driveway, it boiled over a bit. I had figured that the various settings (and mis-settings) may have effected the engine temp a bit.

I'm working right now on setting the timing, then the carbs, then I'll see how the temp is. Once I get past this weekend and the show, I'm intending to pull the radiator and have it recored/rebuilt.
 
Okies, now I understand, you were driveing it. Yep I also would bet you have the timeing and mixture off quite a bit.

You have heard the old adage, "If it ain't broke don't fix it" hehe.
 
I know, I know. /ubbthreads/images/graemlins/grin.gif

Trying to learn how all the systems and such work requires some hands on experience. I'll keep fiddling this week, and try and get it close enough. I'm considering taking it to our local LBC shop to have a tune-up done anyways, to set a baseline of where it should be.
 
If it boiled over after your drive then I would say check the mix on you "Cool"ant.

Otherwise, having overly retarded ignition would be the next greatest cause. If ignition is to far retarded, the spark comes late enough that the charge is still burning as it enters the exhaust manifold and it is not uncommon for the exhaust manifold to become so hot it glows red hot and can even be seen glowing in the dark.

The next is definitely a lean mixture. Most people know the saying "You have to be lean to be mean" which means that you need to run on the lean side to really make power, however, running too lean can burn right through the top of your pistons. That saying is a little out-dated since we now know that running at the proper stoichiometric ratio is going to produce the most power most efficiently.

JACK
 
[ QUOTE ]
Another possible consideration is that the coolant is probably out of mixture, with more water than normal.

[/ QUOTE ]

I agree with others... probably a timing issue. BTW, water is actually a better coolant than antifreeze. In other words, a car will typically run cooler on straight water than a water/antifreeze mixture, but will boil over at a lower temperature.
 
I was thinking about the coolant mix as a possible reason for the boil over. At my altitude (5550' or so) water is going to boil lower than at sea level. I probably need all the extra boil point headroom I can get.
 
At your elevation and with the hills I would agree with Zimmy and put in a 160 thermostat but still keep a 50-50 antifreeze mix to keep the rust down, and if you have any question of it not being ready it may be wise to forgoe the show next weekend if the result could be a ruined engine.
Good luck
Bill
 
I've never lived at any significant elevation but why does it matter in a closed, pressurized cooling system? I understand the principle in an open system, but a spring loaded 7 psi radiator cap should act the same at sea level or 5000’ shouldn’t it? Same principle as the pressure cooker.
 
Whoa! Perhaps I am misreading you Kurtis, but I would be careful if I were you. I don't suggest EVER running straight water in you cooling system. You're are ASKING for disaster, ESPECIALLY in a cooling system as small as a Spridget's. /ubbthreads/images/graemlins/nonono.gif

I couldn't even count the number of blown head gaskets I've seen because people thought they would just top-up with water. Just do an internet search for "Coolant boil point". You'll quickly see why you NEED an antifreeze/coolant in your system. There are certain categories/circumstances where water outperforms Ethylene Glycol or Propylene but they aren't necessarily the circumstances that the cooling system for an internal combustion engine faces.

Besides, if water were so great, why would anyone pay $8.00/gallon for the green stuff? /ubbthreads/images/graemlins/nonod.gif

JACK
 
[ QUOTE ]
Whoa! Perhaps I am misreading you Kurtis, but I would be careful if I were you. I don't suggest EVER running straight water in you cooling system. You're are ASKING for disaster, ESPECIALLY in a cooling system as small as a Spridget's. /ubbthreads/images/graemlins/nonono.gif


[/ QUOTE ]

No... of course not. But many racers do, simply because pure water is a better coolant from a temperature standpoint. However, as I pointed out, antifreeze will raise the boiling point (which is a good thing). I was merely explaining that lack of antifreeze in your coolant will not cause the coolant temperature to rise. In fact, it will have the opposite effect (at the cost of lowering the boiling point of the coolant).

Sorry if I wasn't clear.
 
[ QUOTE ]
I've never lived at any significant elevation but why does it matter in a closed, pressurized cooling system? I understand the principle in an open system, but a spring loaded 7 psi radiator cap should act the same at sea level or 5000’ shouldn’t it? Same principle as the pressure cooker.

[/ QUOTE ]
At sea level there is 14.7 psi atmospheric pressure plus the 7 psi cap for a total of 21.7 psi holding the coolant. At 5,000 ft elevation there is 12.2 psi atmospheric pressure plus the 7 psi cap for a total of 19.2 psi holding the coolant. The pressure cooker pressure & temperature will be less at higher altitude also.
D
 
question - since it was boiling at 190, are you sure your radiator overflow cap is in good shape? Sounds to me like that may be [part of] the problem.
 
It was running a bit over the 190 mark, and when I shut it off, it boiled over. I'm guessing that it shot up a bit when it was shut off, and that was enough to push it over the edge. I didn't look at the gauge when I saw the boil over. I'm guessing that was just related to the bad mix of coolant--but I'm not ruling out a cap issue either.

Thanks all for your suggestions. I've got a bunch of good ideas to take to the garage and see what I can do. I'll report back later...
 
No problem Kurtis, thanks for straightening me out. I was pretty sure there was just a bit of a misunderstanding there.

JACK
 
Back
Top