More poke when its hot?

[jakbob]

I recently installed a fresh 202 in my vc. I've noticed that when I drive in the city, when it runs hotter (about halfway on the gauge) it feels a lot stronger than when I drive it on the highway, when it runs cooler (about a quarter on the gauge). I'm not really sure why, but I'd rather it felt stronger all the time, rather then just in the city. I can't really enjoy the extra poke in city.
Anyone have any idea - A why it would be producing more power when its hot - and B, how I could fix it so it would make more power all the time?
I thought I could change the thermostat so it would run hotter on the highway, but then it would probably run too hot in the city.
I sort of think it should run better when its cooler, because it'll getting cooler air down its throat. But then I suppose when its hot the petrol evaporates more readily.

[VKCOMMO]

HMMMM... I'd think it'd run better when its cooler... Unless your gauge is out and it is running too cold..

[vkberlina]

change your thermostat to a warmer opening one that will get the engine at your desired heat range

cheers
scott

[VKCOMMO]

yeah.

or check your current thermo if you dont know what it is..

just get a milo tin, half fill with water, put on stove with thermostat on a piece of wire and a thermometer in there and see when it open's

[jakbob]

Yeah might try that. I had another thought, I'm taking the vacuum for vacuum advance on the dizzy straight from the manifold. Originally it had a temperature controlled valve in the top of the thermostat housing that took the vacuum from the carby just above the throttle butterflies when the engine was cold/cool, and took it from the manifold when it was hot. I think maybe when its cool on the highway, its not getting the right amount of vacuum from the manifold, and really needs to be taking it from the carby. Might see if i can get a new valve and connect it up properly. Unfortunately the old one was plastic and very brittle and smashed to pieces when I tried to remove it from the old engine.

[VKCOMMO]

That may be it.,

[VK SL 3800]

Yeah might try that. I had another thought, I'm taking the vacuum for vacuum advance on the dizzy straight from the manifold. Originally it had a temperature controlled valve in the top of the thermostat housing that took the vacuum from the carby just above the throttle butterflies when the engine was cold/cool, and took it from the manifold when it was hot. I think maybe when its cool on the highway, its not getting the right amount of vacuum from the manifold, and really needs to be taking it from the carby. Might see if i can get a new valve and connect it up properly. Unfortunately the old one was plastic and very brittle and smashed to pieces when I tried to remove it from the old engine.

Im pretty sure that Blue motors had a TVS around 104 degrees or there abouts that opens to give direct manifold vacuum to the dizzy at idle to advance timing to try to help cool the engine down and under most operating conditions just used the advance from the carby port, which also has a TVS which doesnt open until warm, so the dizzy doesnt have any advance when cold and direct manifold advance when overheating. As you stated, you really should get your advance from the proper port to get the best possible timing under all conditions.

[ari666]

all engines run better when they are hot /thread

its to do with thermal efficiency and whether the bores are either absorbing heat or reflecting it. gasses will run faster if they are excited and hot so when your bore walls and cylinder head are absorbing heat, the gases lose velocity. when the bore walls are at full temp and reflecting the heat they maintain a hot - constant flow till your headers/exhaust which is where most cars fall down cos they think that a free flowing exhaust is better, when really you need something that keeps the heat inside the pipes (not absorbs and dissapates) and keeps the gasses velocity up.

im with VK berlina on this one though, i think your thermostat is too restrictive your pump is struggling to push the water through the thermaostat, thus restricting the eninge. vac advance shouldnt really play much part in power. mind you, your advance should be connected to ported vacuum so you have a nice base timing and good overall advance.

but yeah. thermostat.

[ari666]

Originally it had a temperature controlled valve in the top of the thermostat housing that took the vacuum from the carby just above the throttle butterflies when the engine was cold/cool, and took it from the manifold when it was hot.

your looking at it the wrong way round my friend, manifold vac when cold, ported vac when hot. the reason being that manifold vac will bump up you idle when its cold to make for easier starting in the morning, ported vac is for day to day normal engine temp running.

[jakbob]

your looking at it the wrong way round my friend, manifold vac when cold, ported vac when hot. the reason being that manifold vac will bump up you idle when its cold to make for easier starting in the morning, ported vac is for day to day normal engine temp running.

Yep, that would be right, I was looking at my uncles lx torana the other day, being pre emissions it takes only ported vacuum from the carby for the vacuum advance.

[VK SL 3800]

Also being a Fresh motor you should wait until its run in a bit more and see how she goes then.

[jakbob]

Well its almost got 3000kms on it now, so I guess its not that fresh anymore, but certainly more fresh the previous one. Still, it just seems strange that there is so much more power when I drive in the city as opposed to the highway.

[ari666]

my motor only really started opening up around 6000kms, it was ok, but then one day it just started going really well. weird. my mate reckons his 383 was around 5000kms before that opened up. his theory was that the engine needed to "calm down" lol. never heard of that before but i guess the bearings and rings would need to wear out bit to loosen up.

try taking your thermostat out altogether for a couple of hundred kms and see if it helps it. itll just cost some RTV silicon as the thermostat doesnt really need a gasket. if it doesnt do bugger all then it isnt the thermostat and you ca post up and say "HA you idiot, you were WRONG, totally wrong, i cant believe how wrong you were... so wrong i dont know how you can live with yourself" ... just like most of the other users of JC do

[VKCOMMO]

lol...

ive never seen anyone say : "HA you idiot, you were WRONG, totally wrong, i cant believe how wrong you were... so wrong i dont know how you can live with yourself"

[tigervh]

try taking your thermostat out altogether for a couple of hundred kms and see if it helps it. itll just cost some RTV silicon as the thermostat doesnt really need a gasket. if it doesnt do bugger all then it isnt the thermostat and you ca post up and say "HA you idiot, you were WRONG, totally wrong, i cant believe how wrong you were... so wrong i dont know how you can live with yourself" ... just like most of the other users of JC do

Running without a thermostat is a great way to prematurely wear out an engine. The motor will never reach its operating temperature, thus it will be running excessive clearences. This will allow excessive blow buy contaminating the oil. The oil will not reach its designed operating temp and viscosity.

If the temperature is moving as much as you say it is, I would suspect the thermostat is stuck in the open position or part open position. If the thermostat is operating efficiently the guage shouldn't move once its up to temperature.

[ari666]

Running without a thermostat is a great way to prematurely wear out an engine. The motor will never reach its operating temperature, thus it will be running excessive clearences. This will allow excessive blow buy contaminating the oil. The oil will not reach its designed operating temp and viscosity.

ah ahahahahah

ok mate