Just wondering about changing sparkplugs in an Aluminum head. Should the engine be cold, warm, or at operating temps before changing/removing/installing the plugs. I know a bit of anti-seize on the threads never hurts. Just concerned about the steel plugs and aluminum head. What's the best advice?
Hi Larry, I know I have not had a problem changing the plugs on my Stage 2 heads with the motor cool.The only reason the engine was cool was to protect my tender little pinkies!! I use just the slightest amount of never seize on the plugs as well.Plugs run out or in with hand pressure except for final tightening(or loosening). Rod
I have never pulled plugs from a hot late model alum. head because sometimes it can pull the threads with it (mechanics have had this happen).
I have removed plugs hot on the alum heads many times during dyno sessions. Never had a problem. Jim Burek
Motorcycle mechanics say preferably cool. Exception like tuning are OK, but not the preferable method for long-life. I think JW mentioned some time ago that a NGK school he attended recommended no anti-sieze for their plugs as they are coated for that purpose. Maybe he can confirm that or you can find it in a search?
So it's best to remove and replace the plugs when the cylinder head is cool. I remember some dealerships having a problem with some of the newer Corvettes that had aluminum heads. I recall the problem occured when the plugs were removed from a hot cylinder head, but I wasn't sure. JB says he has done it without problems. That's good to know. I think I'll err on the side of caution, and remove them with the head cool. Thanks Guys.
The only time I have had problems pulling the threads out of a cylinder head was when some zagnut crossthreaded them in.I am a ASE cert technician and do it everyday. I also pull them out at the big end after a big hp nitrous pass with no issues. When it all comes down to it just be careful and you won't have problems
Cold plugs I'm an advocate of pulling them cold unless they don't wan't to budge.. Then I'll try warming up the engine. As for "coated plugs" and no anti-seize I got to live that nightmare one time on my quad-4 about 12 years ago (only time I have not put anti-seize on spark plugs in an aluminum head) and it froze up BIG TIME. It wasn't even nice enough to pull the threads out OH NOOOOoooo the shell of the Champion plug SNAPPED and the threaded part of the plug stayed in the head. Being in a hole 6in deep mean I pretty much had to pull the head, ever pull the head on a quad-4???? (its a muther). My advise, anti-seize is awfully cheap insurance!!! regards
Of Course, I drove it back from Rob Chilenski's. Only problem was it ran at 145-150* Guess I need to put a 180 stat in it. It feels great. I wasn't really able to lay into it in rush hour traffic, but it pulls really nice. I'm sure I'll have to tweak the timing and see what it likes. And the stock Stage1 pump may not be enough for it. I'll find that out at the track. If it lays down at the top end, the Rob Mc 110 pump is ready to go in. We will see.
Larry, The stock Stage1 pump is NOT going to be enough! Why ruin a day at the track with an unnecessary lean-out at the top end? Your car will start coughing and sputtering at 1000 feet. Been there and done that with my '70. Just trying to save you the aggravation. If I had it to do over again, I'd have installed an electric pump as soon as I got into the twelves. Instead, I kept driving it with the motor protesting at the top end on every pass. Not good.
Doug, You are absolutely right. I have planned for this. I bought the Robb MC mechanical 110 pump awhile back. http://www.v8buick.com/showthread.php?t=78743 The stock Stage1 pump flows 35 gph@5 psi. The Robb Mc pump flows 65 gph@ 5 psi, good to 560 HP That should do it. I'll have it in before going down the track.
I've never heard of that one. Is it a direct bolt-in replacement for the stock pump? The numbers you mentioned (65 gph!) should certainly carry you through with no problem.
This is correct. Studies have shown that anti-seize reduces the dissipation of heat from the plug into the head. On aluminum heads, only use plated plugs.. plain steel plugs require anti-seize, which in fact inhibits heat distribution from the plug into the head, and can cause as much problem as it is trying to solve. Champion, AC and Motorcraft are out for these heads. If you have to use plain steel plugs, then you must use anti-seize. Use plated spark plugs, with nothing on the threads, tighten to the correct torque for the plug type. Also, NGK makes a 5/8 Hex plug that fits that TA head, I forget the number off the top of my head. Fits better than the 13/16 plug. JW
Jim, That is good to know. The plug you are referring to is the NGK FR-5. Same plug as the UR-5, except it has the flat gasket seat, and required 3/4" reach. I actually supplied Robby with these plugs, but he didn't realize it, and he put in a set of AC R43XLS's. Guess I better get those plugs out of there.
How many guys at the track wait for their engines to cool before they pull the plugs? That should answer your question.
I don't think I'd ever have occasion to change my plugs when the engine was hot, just because, I don't want to burn myself. From what I've read, changing them when the engine is cool is my best bet. I'll go with that.
Hi Guys, I prefer cold....because if you REALLY think about it, aluminum has a much lower melting point than iron and those aluminum threads get softer as the temp rises. Even if you don't pull the threads out each time you remove plugs when hot, don't kid yourself...those threads are "moving" somewhat and are weakening each and every time. Why tempt fate???o No: