46 replies to this topic

[Starcon88]

Well here ya go Art. I don't think the BPR7HS's will work. I don't happen to have a factory plug laying around to stick in the head to get a picture of so I don't know how far the factory plug sticks in the combustion chamber.

http://oklahomaspeed.com/pics/BPR%20in%20Marnel.JPG

Kurt

[artinist]

hmm, is there any way you can get a hold of a stock plug to have something to compare it with. that seems to be a little farther in than what I remember. i have had these BPR7HS's on for about 6 months now and took them out to inspect them a few days ago. everything seems normal but its worth to find out if there is different castings of the marnel.
the stock plug surely stuck out a good 1/4" on my head. lets see if its the same on yours.

[jr_ss]

Here's a picture of the stock BUR6ES spark plugs in the stock j/v head I have here... This head is off an 86 with mech rockers and hydra lifters (not that any of that makes a difference).

[jr_ss]

Here's a link to the NGK webpage for our cars, it'll show you everything available for our car....

http://www.ngk.com/results_app.asp?AAIA=1208225

The NGK plug recommended for our car has a reach of 3/4". The same reach between the platinum, iridium, and regular spark plugs.

[artinist]

we need a pic of the stock plug in the marnel, not the stock head. the stock plug fits the stock head fine.

[importwarrior]

that is great info.i never thought about it but the pics explain alot!

i will have to check the thread depth when i change my head gasket.

[4NMOPAR]

yeah awesome info guys, I learn something new each day I'm here !

[Banky]

What do you folks think of these? 3 electrodes:

[artinist]

when it comes to spark plugs its good to be racist. bosch for germans and NGK/ND for japs.

[B.K.]

I HAVE A BRAN NEW MARNAL HEAD THAT I WILL BE PUTTING ON THE QUEST I WILL CHECK IT OUT, I AM GOING TO BE USING THE IRIDIUM NGKS

[Richie_Rich]

Please post a pic with your Marnal-AMC head if that's the one you have.

I forgot about this thread when I had MrDodge's engine apart.

Here's a picture of the Marnal-India head.
It looks pretty good as far as the spark plug projection.

[artinist]

yea, that combusion chamber is way different that the AMC

[bad2theBone]

what type of marnel head is the best made, is it from india, usa, brasil, spain, South America, China or anyother country made, its that true the best quality and endurance material is the one from spain, please correct me if i'm wrong.

Is it possible using the Marnel head from spain, with the Stock Starion or conquest TBI Injection system for the moment as daily driving

When I get the marnel head in here can i just make the Porting job or its also very important to have the polish job as well.

How much is the retail price for a porting and polish job done. or at least just the porting. Doing the polish job on the marnel head after porting, it will make any difference, i'm just asking because i only read that many people is doing the porting job but i haven't see at this moment anyone doing the polish job as well on any head. i just want to know whats the deal with that, in not doing the polish work, may be is more expensive +++$$$ in doing the polish work.

[TurboRaider]

I dont think the shroud or the plugs threaded end run very hot at all.  Look at the exhaust valve, nice tan collor becuase it gets hot.  Look at the intake valve...  dark because it stays cool.

Same with the shroud and the plug body, if they were gettging hot you would seem them turn a lighter color.

Kevin

[Technology]

I dont think the shroud or the plugs threaded end run very hot at all.  Look at the exhaust valve, nice tan collor becuase it gets hot.  Look at the intake valve...  dark because it stays cool.

Same with the shroud and the plug body, if they were gettging hot you would seem them turn a lighter color.

Kevin

or is it because they are made of different metal.

everything is hot in a combustion chamber, it doesn't have to be discolored from heat to be hot enough to cause premature detonation.

i'm gonna check this out.. Art - what does a port job like that do to the compression, quench zone, etc. ?  does it thin it out excessively around any water jackets?

[artinist]

not much material was taken out the combustion chamber. just the sharp points were removed mostly.

anothing thing with the exposed threads. if carbon builds up on those threads, it could easily damage the threads  on the head if you remove the plug.

[TurboRaider]

I dont think the shroud or the plugs threaded end run very hot at all.  Look at the exhaust valve, nice tan collor becuase it gets hot.  Look at the intake valve...  dark because it stays cool.

Same with the shroud and the plug body, if they were getting hot you would seem them turn a lighter color.

Kevin

or is it because they are made of different metal.

everything is hot in a combustion chamber, it doesn't have to be discolored from heat to be hot enough to cause premature detonation.

i'm gonna check this out.. Art - what does a port job like that do to the compression, quench zone, etc. ?  does it thin it out excessively around any water jackets?

Its the combustions deposits that turn differant colors as the get hotter, not the metals.  Once you have a few miles on a motor there are not many bare metal surfaces.

So if the plugs threaded section is dark with some oiley deposits on it it it not getting hot enough to burn the oil away.  

A good example of this is the valves.  The exhaust valve runs hot and you wons see any dark oily depostis on it.  The intake valve runs a lot cooler and looks darker and oil and fuel can cake onto the backside.

Basicly its like reading plugs, white deposits = hot, dark = cold because it never got hot enough to burn the oil off.   If the part is not hot enough to burn oil off of it its not a big factor for detonation, at lest compared to the exhaust valve thats hundres of degrees hotter.

Cooler running exhaust valves can redcue octane requirments.  Since octane is a limiting factor for the amount of boost and HP  you can can make finding a way of lower its temperature may help.  

I wonder how sodium filled valves would work?

Kevin C

[Technology]

well, i tried the stupid method for measuring plug depth into the head.  i took a short peice of coat hanger and bent the end 90 degrees and held it in the plug hole and pulled back so it was against the edge inside.

then i held my finger against the base on the outside, then took it out, and measured that against the spark plug. it was the same length, but i have no idea if i'm holding the hanger peice in the right spot for a semi-acurate measure.

my head is on my car though. i have an AMC head and i think it's ok.  but i'd like someone else to try or just tell me the smart way to do it, and i'll do it.

[AUstarion VR4]

Ahhh, we had the same problem here in Australia on our race car, turned out it B7ES plugs R the correct units, they R full reach but the centre electrode isn't exposed, NGK web site has more info on BCP*...B7ES etc.

[tsiconquest88]

i somehow missed this whole post along the way lol but i have been using the bpr8es's in every plug change over the years in my cars, unfortunately i never looked at this BUT i can say one thing all the threads are clean as the rest no carbon so i would assume that the plugs have never been close into the chamber, and i have been using marnel AMC heads all along. just some 2.6 cents on this post that has been dead a while lol

Edited by tsiconquest88, 02 April 2009 - 06:35 PM.