I am having heat issues and I am thinking about replacing my NGK B5ES plugs with B6ES or even B7ES. Is the B7ES too cold a plug for a 1776 stocker running slightly higher comp (7.5:1)??

regards

Old Hutcho

I wouldnt be calling 7.5:1 high

Low if anything

What is the problem??
Hot oil? Head temps"

Yeah as Hypo engines go its not a Hypo. But it does run hot (Both my engines run over 100deg on mild days. The other is 1916 with a cam and about 8.5 to 1 comp) I just dont like that sort of heat on mild days. In the summer they tend to run hotter than that unless I nurse them a bit. Some reading on the Google tells me that some guys in the US are running the 7 plugs in desert heat and seem to be doing fine. Just looking to get some heat out of the system. Oil pressure and circulation is fine in both engines. Heads are all new with s/s valves and slightly bigger valves. Stock rockers in both engines.

regards

Old Hutcho

i pretty sure if you go to a 7 in ngk this will increase the head temp .....................................

Maybe I will. Thats the sort of info I am after though. Should I go the other way and drop the head temps?


regards

Old Hutcho

With NGK a 5 is a hotter plug than a 7

http://www.ngk.com.au/spark-plugs/technical-information/heat-range-explanation 

Too hot a plug will give higher combustion temps, pinging etc... just like you can get with running too lean.

What do the plugs look like if you pull them ???

As Dave said, wiith NGK 5 is hotter than 7. It's not about cylinder temps but plug temp, the plug needs to operate at it's optimal temperature. I generally use 7 when using NGK

matt is that because you use a higher comp in your motors

No, I use low comp for most, 7.5-8.5 depending on application, altho I'm tending to increasing it somewhat these days as we have awesome fuel available now.

I just fitted 5's in my 2276 again, my old plugs were only 10,000 km and are pretty shattered.. issues!!
Maybe I should run 7's? I reckon my C/R is only 8.5 ish..

OK. I have taken all the above on board. So what are we talking here. If the plug is colder does it transfer the heat from the combustion process to the head? Thereby increasing top end and subsequently oil temps? Or do we use a hotter plug and let the plug dissipate some of the heat? Is a hotter plug going to allow me to run the heads cooler?

Just for the record, I have pulled the plugs and they seem to be burning OK. Light brownish/grey residue. I dont think I am running too lean. If I go up half a jet size I have popping problems on acceleration.

regards

Old Hutcho

This is an interesting site.

http://www.ngk.com/learning-center/article/207/i-have-slightly-modified-my-mo...

Particularly interesting was the assertion that going one range colder will remove 70 to 100 deg from the combustion chamber. Thats a hell of a lot. Anybody got any experience with that?

regards

Old Hutcho

I run D6EA in my engine with its 8.6:1 compression
The 7's did not have enough heat for my engine.

Hmm, not long ago they had this forum thread here stating there was nothing wrong with running 100 degrees:

http://forums.aussieveedubbers.com/viewtopic.php?tid=101612#pid951644 

this is for oil temp.

Vassy, what sort of driving do you do. I dont get too hot around town only on long runs. My oil temp (according to the gauge) is over 100 deg on even mild days. I certainly cant hang on to the dipstick. If it didnt creep over 100 I would be pretty happy with that.

regards

Old Hutcho

105 degrees on a long run is fine (in my opinion)

105 deg is fine on a long run, I agree. But I cant push the car, specially in hot weather. 120 deg is over the top and I can get there without too mujch trouble.

I agree with Matt

I only get to 100 degrees when it is a heatwave and I have been cruising at 70mph
Most of the time I barely crack 80 degrees.

Have you checked the accuracy of your temp.gauge, Young Hutcho?

Stick the sensor in boiling water for a while, and it should read 100 degrees C. [Don't burn yourself].

Young Macko.

Has it still got the original lid that I had? From memory its the unvented one, try slicing open a tennis ball and popping it over the latch to prop the engine open a little and see if you get an improvement. Same with plugs, just try them, can't hurt.

As per Greg's suggestion about the gauge put a teabag in the boiling water as well. I prefer earl grey. Seems a shame to waste a pot of boiling water.