AC Delco plugs

[Paddywhack]

The kid at the Auto Zone said the AC Delco plug 41-629 were the plug for my engine...5.7 cast iron.....they look alot longer in the threaded area than the plugs that were in there. Does this sound like the right plug to anyone? Thanks in advance.

 

[TWISTERUP]

Correct # (non platinum) AC Delco

For a 1986 the # is R43TS---I think the # you have fits in a 1987 and it is a longer plug--don't use them.

 

[Parrothead]

I work for AutoZone and after checking agree that the plug sold to you was wrong. I have submitted a error report to the company and hopefully they will get the wrong plug out of the 86 Cast Iron section and replace it with the right one. Our Znet system is pretty good but only as good as the data entry.

I am sorry the wrong part was sold to you......... We strive for accuracy and as a fellow corvette owner I am sorry you were sold the wrong parts.

 

[Paddywhack]

Thanks guys,I worked most of the night on the car and have installed the plugs, fortunatly the car started. Now, do I switch the plugs out, or leave them?

 

[Hib Halverson]

The kid at the Auto Zone said the AC Delco plug 41-629 were the plug for my engine...5.7 cast iron.....they look alot longer in the threaded area than the plugs that were in there. Does this sound like the right plug to anyone? Thanks in advance.

The "kid" at Auto Zone is just reading the data in AutoZone's computer. What's probably happened is AutoZone's listings for MY86 are incorrect. During that year, both iron head engines and aluminum head engines were used but the two heads take different plugs. AutoZone's catalog data appearently only considered aluminum heads.

If you put .708 reach plugs in a cast iron head, the plug will stick about a quarter inch into the chamber.

Cast iron heads use a .460" reach, taper seat plugs plugs.

IMO, ACD no longer makes a good plug for the cast iron, taper seat heads. I'd use the Denso ITF20. That is what I use in the one engine I have which has iron heads. Yes, Denso's Iridium Power plugs are expensive but from a performance and durability standpoint, I think they're a better choice.

 

[Paddywhack]

Thanks for the info.....pulled the plugs this morning, only one had the gap closed by the piston luckily(cyl. #4) put in the correct plugs and runs fine. Thanks for all the quick responses!

 

[bugman34202]

Thanks for the info.....pulled the plugs this morning, only one had the gap closed by the piston luckily(cyl. #4) put in the correct plugs and runs fine. Thanks for all the quick responses!

Holy Crap...I hope you didn't dent the tops of your pistons with those longer plugs. :bash