autoluke Posted July 12, 2019 Share Posted July 12, 2019 Thread chaser cleaned out the socket, followed by careful toquingb of the plug, but can't seem to stop blow br at the plug. Would a thread sealer be advised ? Link to comment Share on other sites More sharing options...
stakeside Posted July 12, 2019 Share Posted July 12, 2019 Seems to me that the NEW copper compression washer should seal plug. 1 Link to comment Share on other sites More sharing options...
autoluke Posted July 12, 2019 Author Share Posted July 12, 2019 New copper washer did not do the trick. I am considering more torque to the plug, but am concerned with thread stripping. Link to comment Share on other sites More sharing options...
TerryB Posted July 12, 2019 Share Posted July 12, 2019 What kind of car? Is it an aluminum head? Link to comment Share on other sites More sharing options...
autoluke Posted July 12, 2019 Author Share Posted July 12, 2019 A Cadillac 346 Flathead...seven of the eight plugs are well secured, with only a problem on number two. Link to comment Share on other sites More sharing options...
Guest Posted July 12, 2019 Share Posted July 12, 2019 Perhaps it needs a Helicoil. Never ever use a thread sealer on spark plugs. Link to comment Share on other sites More sharing options...
Frank DuVal Posted July 13, 2019 Share Posted July 13, 2019 Have you tried a different plug? I have seen them LEAK! The porcelain had come loose from the steel shell. If you can get 7-10 ft lbs of hold with a new gasket, it does not need a Helicoil. Link to comment Share on other sites More sharing options...
JimKB1MCV Posted July 13, 2019 Share Posted July 13, 2019 You know, if this is a prewar 346 Cadillac it may have the notorious 10mm plugs which are known for stripping threads. It may well need a helicoil, which is not a big deal. Good luck. Jim Link to comment Share on other sites More sharing options...
Ltc4748 Posted July 13, 2019 Share Posted July 13, 2019 I have seen the sealing area's around the spark plug hole pit from rust. I had a machinist make a cutter that I turn by hand to cut the surface smooth and use new copper gaskets from a hydraulic shop. I test the sealing with a spray bottle of soapy water while the engine is running to see if it still is leaking. I have good luck getting them to seal. On one hole someone popped the starting thread and it left a recess. That one I put a thread insert in so it replaced the sealing area. Link to comment Share on other sites More sharing options...
Pfeil Posted July 13, 2019 Share Posted July 13, 2019 7 hours ago, JimKB1MCV said: You know, if this is a prewar 346 Cadillac it may have the notorious 10mm plugs which are known for stripping threads. It may well need a helicoil, which is not a big deal. Good luck. Jim My preference is a Keensert Thread repair using a keensert insert. youtube. Link to comment Share on other sites More sharing options...
autoluke Posted July 14, 2019 Author Share Posted July 14, 2019 More Facts Plug gasket recess has a very small chip, which might allow gasses to vent. ALSO noted that the R45T plug had the electrode pinned against the center anode, apparently while being struck by a valve. From my plug stock, I note that a R45S plug, although the base is wider, the threaded area is shorter, which would seem to allow more clearance to solve the problem. ( all plugs are 14mm ). Also note that the R45T has a chamfer at the base, which I suspect might add to the sealing issue Note that during the rebuilding at the machine shop, both heads were milled slightly..wonder if this might be an issue. Thoughts and suggestions will be appreciated. Phil Link to comment Share on other sites More sharing options...
joe_padavano Posted July 14, 2019 Share Posted July 14, 2019 1 hour ago, autoluke said: ALSO noted that the R45T plug had the electrode pinned against the center anode, apparently while being struck by a valve. From my plug stock, I note that a R45S plug, although the base is wider, the threaded area is shorter, which would seem to allow more clearance to solve the problem. ( all plugs are 14mm ). Also note that the R45T has a chamfer at the base, which I suspect might add to the sealing issue R45T is a taper seat plug, intended for cylinder heads designed for such a seat. It does not use a washer. R45S is an extended tip plug with a washer seal. These are two totally different plugs for different applications. 1 Link to comment Share on other sites More sharing options...
autoluke Posted July 14, 2019 Author Share Posted July 14, 2019 thank you Joe !!! Bought the 45T plugs years ago at Hershey, as the seller represented them as being perfect for the Cadillac 346. Now time to replace the remaining plugs with the correct ones. Amazing that they seem to be holding compression. Link to comment Share on other sites More sharing options...
Frank DuVal Posted July 15, 2019 Share Posted July 15, 2019 I have no idea what "No Hotlinking Allowed" means but here is an AC chart I posted a year or so ago. T suffix is a "new" one, i.e. in the last 40 years or so. They are like the 18mm plugs on Fords, no washer, just taper seat that seals to taper cut into head. No way is your Cadillac head cut for taper seat plugs, unless a machinist got carried away with it! 1 Link to comment Share on other sites More sharing options...
autoluke Posted July 15, 2019 Author Share Posted July 15, 2019 The heads are indeed cut to receive a flat washer, and apparently a flat plug. While not being familiar with the intended final fit, it was my error to assume that the taper was meant to fit within the gasket ring. We live and learn. Link to comment Share on other sites More sharing options...
autoluke Posted July 18, 2019 Author Share Posted July 18, 2019 NEED MORE INFO.. The heads on my 346 flathead are threaded to receive 14mm plugs, but can not correlate the plug number with the various suppliers. I was under the impression that my engine was 1941 vintage, but suspect that it is of earl;ier production, which might account for the 14mm plug. Would appreciate knowing the correct 14mm plug number for my application. Phil Link to comment Share on other sites More sharing options...
joe_padavano Posted July 18, 2019 Share Posted July 18, 2019 On 7/15/2019 at 12:03 AM, Frank DuVal said: I have no idea what "No Hotlinking Allowed" means but here is an AC chart I posted a year or so ago. When you first posted this, I had no idea what you were referring to, as the chart was still visible in my post. Now it isn't and I get the "no hotlinking allowed" message. What's up with that? Never seen that before. Link to comment Share on other sites More sharing options...
PFitz Posted July 18, 2019 Share Posted July 18, 2019 17 minutes ago, joe_padavano said: When you first posted this, I had no idea what you were referring to, as the chart was still visible in my post. Now it isn't and I get the "no hotlinking allowed" message. What's up with that? Never seen that before. Joe. About "hot linking" and why some sites don't allow it. https://www.urbandictionary.com/define.php?term=hotlink Paul Link to comment Share on other sites More sharing options...
joe_padavano Posted July 18, 2019 Share Posted July 18, 2019 1 hour ago, PFitz said: Joe. About "hot linking" and why some sites don't allow it. https://www.urbandictionary.com/define.php?term=hotlink Paul Thanks, Paul. I merely inserted a .jpg from another site, which I've done hundreds of times here. The Insert Other Media function on this forum allows it. As I said, the really weird thing is that for the first couple of days, the jpg showed up in my post, though that may have been due to the cache in my browser. Link to comment Share on other sites More sharing options...
PFitz Posted July 18, 2019 Share Posted July 18, 2019 (edited) I've seen lots of things posted on here from other sites and I've never come across that hotlink warning, either. I suspect that it may have been the site that the jpg was borrowed from that squelched it ???? Right clinking on the No hot linking symbol and picking properties shows it's from the sparkplug.com website. So I doubt AACA blocked your original jpg link. Anyway, good on you for trying to help. Paul Edited July 18, 2019 by PFitz (see edit history) Link to comment Share on other sites More sharing options...
Bloo Posted July 18, 2019 Share Posted July 18, 2019 It is not so common now to ban hotlinking. The issue is that the picture is on another website, and their bandwidth is used to host it, but the people who see the picture never visit their website. Maybe they lose advertising money, or maybe they just don't want to pay bandwidth for some other site. It is less likely that some site like the AACA would make a noticeable difference, but a picture could be hotlinked to some a site that a huge segment of the population sees. The administrator of the site with the picture could get an unexpected bill for a whole bunch of bandwidth, or he might exceed his monthly limit, and his site might go down. The server does not know the difference, and if the administrator has configured it to disable hotlinking, it probably disables it for all other sites. Disabling hotlinking was more common a few years ago than it is now. Downloading a copy of a picture and posting it elsewhere solves the bandwidth problem. That is called "rehosting". There can be and often are copyright issues. IMHO today rehosting is more likely to cause ire than hotlinking. YMMV. Link to comment Share on other sites More sharing options...
joe_padavano Posted July 18, 2019 Share Posted July 18, 2019 1 hour ago, PFitz said: Right clinking on the No hot linking symbol and picking properties shows it's from the sparkplug.com website. So I doubt AACA blocked your original jpg link. Ahh, that makes much more sense. Ironically, I've "hotlinked" that particular spark plug graphic on many sites. I guess I never went back to check. I'll download it from now on. Link to comment Share on other sites More sharing options...
joe_padavano Posted July 18, 2019 Share Posted July 18, 2019 So just to follow up, it turns out that the problem actually comes from whoever sparkplug.com hotlinked from. When I go to their site, I can no longer access the graphic. Interesting. In any case, here's the same info, directly from AC Delco for future reference. https://m.acdelco.com/content/dam/acdelco/north-america/usa/mobilesite/en/home/Parts/Spark Plugs/02-PDFs/acdelco_spark_plugs_numbering_system.pdf Link to comment Share on other sites More sharing options...
stakeside Posted July 19, 2019 Share Posted July 19, 2019 Btt Link to comment Share on other sites More sharing options...
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