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Jun 26, 2007 | 01:30 PM

Stoney57

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Spark plug threads

I just bought some bosch fusion platnum 4505 spark plugs for my 1995 aerostar 3.0, the threads seem like they will go in deep. The spark plugs that are in there now (motorcraft platnums) don't have as much thread as the bosch plugs. Will it be ok to use these plugs? It looks like they will go quarter of an inch deeper into the cylinders.

Jun 26, 2007 | 02:19 PM

VanGo

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From: Wichita

You better make sure they are applicable to your engine. You don't want them to hit your pistons.

Jun 26, 2007 | 02:33 PM

Bear River

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From: Salt Lake City, Utah

Return the Bosch plugs and go get the correct Autolite or Motorcraft plugs. There are many threads on this forum regarding which plugs to use. Any non-OEM plugs may be of the wrong heat range, or cannot withstand the combustion temperatures of these engines. I would take those plugs right back and go get the best. For the Aerostars, and I assume several other Ford models with the 3.0L and 4.0L nothing beats the factory plugs and wires. The proper gap and heat range Denso Iridiums are also suitable. They may last longer than the OEM. But they will not outperform the factory plugs and they cost more.

Jun 26, 2007 | 02:43 PM

96_4wdr

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From: Washington state

your 95 3L has the EDIS non distributor system. these are more critical on spark plug design and heat range. many have reported problems using anything other than Autolite or MC double plats or iridium/plat

my problem with the Autolite/MC double plat conventional ground electrode plugs is that the gap opens up so much from use especially towing...to over 0.100"...does make it hard starting....no success regapping....new plugs only

the part number is correct according to Bosch site. if the retailer won't exchange or refund, then try them

Honda and Acura user forums scream about using only NGK OEM plugs but I've had good success using Bosch +2s and they are somewhat longer tipped than the NGKs

report back what you put in and how they work
good luck

Last edited by 96_4wdr; Jun 26, 2007 at 02:51 PM.

Jun 27, 2007 | 01:38 PM

Stoney57

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I got them from advance auto, and according to their web site, and their store they are correct for my 95 aerostar 3.0. My 95 has a distributer and looks just about identical to my old 89 aerostar. These pics I took answer my question. The Bosch plugs just have threads up higher, but will only go in as deep as OEM. I'm going to install them along with new 8mm autolite professional wires here in about a week and let you know how they work.

Plugs Pic 1

Plugs Pic 2

Jun 27, 2007 | 01:49 PM

96_4wdr

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From: Washington state

your old plugs look great...good for another 50k

Jun 28, 2007 | 08:43 AM

Bear River

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From: Salt Lake City, Utah

I agree, there is nothing wrong with those old plugs. The extra tips on those bosch, combined with the longer threads may increase compression slightly, which will increase the combustion temperature slightly which in turn increases tour chances of pinging. I have not tried that particular series of Bosch plug, but if you read one of my previous posts on the subject of plugs, I mentions how in 15,000 miles I went through 2 sets of Bosch Platinums.