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What spark plug to use in Supercharged 454?

bigsbetter

bigsbetter

Active member
What is a good plug to use in a 454 with a small 177 supercharger installed? The engine is stock 330 horse. It now has Champion RV15YC4. I compared these to some A/C delco r43ts and the champions have a longer ceramic piece and stick down in the cylinder farther. The supercharger instructions say to go 2 steps colder on the spark plug. Should I take the Champion's out and put them in my lawnmower where they belong??? Sorry Dodge guys....but please help
 
The plug reach down into the cylinder is critical.. this will drastically chage the heat range of the plug during operation, and is determined by which head you have.. normally the 330 hp engines used short reach plugs.. this needs to be verified..

when i can, i use my o2 , sensor to read how the engine is performing, and to be on the safe side, i like to run 14.7 and idle and about 12.8 at wot.. we then read the plugs, and ajust heat range accordingly.. of course we just assumed the responsibility for that particular engine..

I have found that some engine will use the ac// 41 heat range, while others do just fine at the 43 heat range.. youl'll have run tests, and read the plugs to dial this section of the engine in.. thus said I cannot reccomend a particular plug, but can try to steer you in the right direction
 
Ok I installed NGK plugs. The heat range is comparable to an ACr42. I also installed #93 jets in the secondaries. The primaries still have the stock 60's. I ran it today pretty hard for a long time at full boost, then pulled a plug. They are as white as can be! I can't believe a 93 jet in a 800 cfm carb is not big enough. How long do I need to run it before the plugs will turn tan like they should be? I have some #77 jets should I put them in the primaries?
 
There is no way that carb should have 60's in the primary and 90's in the secondary. You should be alot closer on the primaries. If its running lean under boost, you are 1 step away from meltdown. Be real careful here. I would recommend that the carb should be boost referenced by a real carb specialist like Dean or Brad Nickerson. They built me a 1180 Dominator for my NA 540. It runs so well, you would think the engine is injected! It was worth every penny I sent them.
 
I have to agree with Vinny on this one. I just got back from trying out my Procharged m-1 5 p.s.i. on my 454 mag with a Nickerson carb on it and I am running 78 primary jets and 94 secondary jets. Plugs look good and great performance. I am using NGK plugs as well. I think the stock # was 3249. Brad and Dean Nickerson were very helpful with technical support when I needed it also. Good luck.
 
OK I called Holley and he said the reason I'm running lean is because my power valves are never even opening. I have to boost reference my carb by running a small vaccum line from the intake around the supercharger and into a port on the carb. I understand it now. The power valve is held closed by engine vaccumm. When vaccum falls as you accelerate the valve opens and gives more fuel. On top of the supercharger the vaccumm never falls so the power valve never opens! And I have 2 power valves in this double pumper so I should relly feel a difference. I'm so excited and can't wait to recieve his fax and do this procedure and test run it and watch my plugs finally change color!
 
so what did holly say about running a 60 jet in the front and a 93 in the back???? I really would love to hear this answer??? once you move your vaccume line???? then what??? what power valves are you using?? I'm willing to bet that that carb should be squared off and around a 74 jet, w/ a 6.5 powervalve.. .. so what did holly say??
 
The stock jetting from holley in this 4165 spread bore is 60 in front and 85 in rear. It is a double pumper with 2 power valves. I'm guessing the reason the jets are futher apart in sizes than most holleys is because the front primaries are so much smaller than the massive rear secondaries. My original thinking when I just changed the rear jets was that the boost does not kick in untill I'm into the secondaries so I'll keep the small jets up front for economy since it ran perfect before with a great plug color, and I'll just put some bigger ones in the rear for the boost. That was my thought before I learned the problem. I told Holley what I did with the jetting and he just said that I'll never get it jetted right without 'manifold referencing the power valve'. When he sent me the fax,it was only for modifing the primary power valve. I called him back and asked what to do about the secondary power valve and he said to just take it out and install a block in the hole and increase the jets up about 7-8 sizes to compensate for the lack of a power valve. I don't think the numbers on the power valve (as in 6.5 or 4.5 or 8.5) are rates of fuel that that valve flows. The numbers are how much vaccum it takes to hold the valve closed. That's why if you have a real radical engine that lopes hard it will have very low vaccum at idle and if you dont choose a low enough power valve then it will stay open all the time and load up with fuel at idle. Anyways back to my carb jetting...I did the modifing on the carb. I just have to drill a hole in the intake and tap a port in it for a fitting. I think what I'll do as far as jetting is to run it just on the primaries real easy and then pull a plug and see what it looks like. If it's lean then I'll go bigger on the primaries. I talked to a 1/4 mile drag racer and he said they install new plugs and make 1 pass and check them and they turn brown in 1 pass. I'm just glad that after all that lean running I didn't burn a hole in a piston. I cant wait to go out and beat that Baja that got me yesterday!
 
What do you guys think about me wanting to keep smaller jets up front? I know most Holley's have maybe 6-8 sizes between the front and rear jets but this is not a normal 4150 or 4160 Holley. It is a spread bore 4165, so the rear jets are going to be much larger than the fronts since the rear 'butterflies and venturies are about twice the size than the fronts, and plus I dont need lots of fuel if I'm just in the primaries since there isn't any boost. I wish I had lots of money so I could send it to the place Vinnyp reccomended, but I'm sure that costs at least a couple hundred and a few weeks of down time.
 
ok... so your duplicating the old merc 420/460.. and back in the day was called go and blow.. it was never a reliable setup..

i do have a couple of old smokin boats that still run them... i use 4 corner idles, 73-75 squared and they boost about 2.5.. and holding from 150 to 200 hrs now.. (better than the 40 to 50 they used to get)... lean out/wash out was always a problem
 
What do you mean by lean out wash out? Do you mean it runs lean on the little primaries and then washes the cylinders out on the secondaries?If running the jets closer together is better then I'll do that.
 
lean is mean... so the racers say... wash out is when too much fuel is delivered, not so much as to flood the engine but enough to choke here down while she's running.. wash out occures at lower rpm... idle to around 1500
 
I did the modification and ran a line to the intake bypassing the blower. I put #98 jets in the rear. I gained 2 mph from this procedure. I then swapped the hydromotive 28 to a Bravo 1 26 on the river and gained another 2-3 mph,so now I'm at 68 gps mph. I let it cool down and pulled a plug......still lean as can be! I'll try some 70's or 80's on the front side next. The Bravo prop feels great...
 
here is an issue that hasn't been considered w/ your carb set up... your power valves will never open correctly on a blower moter with a progressive carburator ...

reason #1... there is a low pressure formed below your blower, and the top of your intake.. vaccume must be take from below the carburator... or the carb reworked and remove the power valves alltogether

holly should have told you that... they make a carb for blower applications...
 
The power valves will open as long as they are reading the vaccum in the intake(under the blower). They won't open if they are reading the vaccum on top of the blower. Vaccum holds the power valve closed. At idle most engines have about 15 inches of vaccum and that is what 'sucks' the valve closed. As you accelerate even if there becomes boost it doesn't matter the power valve will still open when the vaccum falls below whatever powervalve you have say 6.5. Any way how the heck do you spell vaccum? vaaccuumm?vacuum? vacumm?>???? I don't know???
 
and here is where it goes.. where does the 4165 read pressure... under the blower or at the carb.. and please don't be silly and tell me the carb is under the blower.. there is a vortex under the blower at induction into the intake. which doesnt allow proper powervalve operation.. this is due to phy sicks.. (get it) a natural low appears there... and power valve operation doesn't function properly... thats why we pull the power valves out.. and plug them.. do some drilling.. and a couple of other things.. and low and behold.. we can rejet and get what we want out the motor.. so vacccccccuuummme can be sold... as is... and call holly... they sell a carb set that way for blower moters.. so vacum ,vacation. or get blown away by a properly set up blower moter.. or is that not so running mota
 
Happy, settle down...,. You're excactly right about the vacuum on top of the blower and under the blower. Have you not read the previous post?? I called Holley and performed the proper modification to the carb. It's called 'manifold referencing the power valve'. For a stock carb, the power valve gets its vacuum from under the carb/on top of the blower, which will not open the power valve. After you do the modification inside the carb, you run a vacuum line from a port on the carb to the intake so the power valve gets its vacuum from UNDER the blower which WILL open the valve....do you agree? Where's vinnyp???....He'll understand.
 
i understand too.. and even if you do that.. you will not fucntion efficiently.. i'tll work better.. but not right.
 
On a 4150 i jetted all four corners the same ..took the PV's out and it runs great..and plug color is good...Just a hair darker brown than perfect..but safe..Might have left a little on the table but....did plugs checks from 3000 to WOT and all readings look really good..just my 2 cents..im sure someone wont agree with this setup but it worked for me and im happy
 
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