which plugs now?

[gotmud]

I took the heads from my grandads 68 c10 w/stock 307 to a machine shop to be redone. What I got instead was a set of replacement heads that fit perfectly. All the holes line up etc. He said they were heavier duty and had larger valves in them. Ive gotten everything hooked backup now (except the distributor) and just started to put the plugs in. They appear to have the right size threads but there arent enough threads to get them in more than 1/4 turn. Anyone know how I can figureout what plugs go in these heads? Machine shop owner isnt much help.
Thanks again.
Glenn in Atlanta

[Cat Fuzz]

Did you ask for these replacement heads or did they just swap them out? I'm a bit suspicious. I'm thinking your heads may have been something more desireable for them and they gave you some common heads guessing that you aren't going to care.

[Longhorn Man]

307s didn't really have "desirable" heads though.
Whats the casting numbers on the ones you were given?

[70ChevyLongbed]

Originally posted by Longhorn Man
307s didn't really have "desirable" heads though.

Ain't that the truth!

I'm at least lost with the story, and maybe a little suspicious too...

[1972C10]

Possibilty they sat with no plugs in them and got a little rust in the holes,

Alot of parts houses have thread chasers for clean out spark plug holes Sometimes i run into this problem i try sprayin wd-40 or something similar in the hole turn the plug a little then back it out

If that dont work i have a small wire brush that they sell for prepping 1/2 copper fittings before you solder them .. you can get them anywhere like home depot etc they work realy well to go into that hole and brush out and debris / rust.

Hope this helps Pretty much all the older model small block heads use the same plug like a r45ts or r44 Seems like only the real newer model stuff uses the longer thread ones.

[gotmud]

where do I find the casting numbers?
The plugs that were in the old heads would fit if the threaded part of the plug were longer. It looks like these new heads have a deeper well in them before the threaded part starts. This deeper well is a smaller diamiter than the larger part of the plugs have.
Glenn in Atlanta

[gotmud]

I pulled the valve cover off and found the following numbers in different spots:
333882
D*30
5
D
A
GM12


Does this help???

[gotmud]

I just found this info on a web site (http://www.mortec.com/castnum.htm):

333882.....74-80...350/400......76cc chambers

This makes it seem that the heads are from a 74-80 year model 350\400ci engine. Is this so? What does the 76cc chambers mean? Is this good or bad? Any idea how to now figure out the plug options and which would be good with my pertronix points replacement module?

UGH!
Glenn in Atlanta

[gotmud]

This web site says they are off of a 1974 vette:
http://corvetteactioncenter.com/specs/1974/74id.html

[cdowns]

since nobody has asked what sparkplugs do you have ???

[gotmud]

Bosch Platinum WR9FP were on the origional 307 heads.

[Longhorn Man]

With just the casting number and no date code or anything, they could be off of anything from a truck to a vette. No telling.
882's are a decent head considering they are smoggers. Most are a lightweight casting, but as long as you don't overheat them too much, then there will be no problem.
They have a bad rep for the overheating, but these ones you have has made it through 30 years, so they can't be too prone to cracking. Plus, I overheated mine up to about 260-280 degrees and they are still perfecly fine, so don't let anyone tell you that you need to junk them. (common quote when you say you have 882's)
As for plug choice...I am unable to say. If your engine is pretty much stock, try a stock plug and check them in a couple weeks and try to 'read' the deposits, then you will know which way to go.
As for getting your plugs in, coat the threads of your plugs with some anti-seize compound (as you should always do installing plugs) and gently force them into the hole, backing them out every couple turns and cleaning the threads. If it takes alot of force, I would call the shop that sold you the heads and raise h*ll.
If the threads on the heads end up being trashed, you could rethread them, but I think I would just as soon rip them back off and get a refund (What did you pay for them anyways?) and look for later model 305 heads. They will be set up for unleaded fuel, (as your 882's are) and you would end up with a better compression ratio. The 305 heads are ideal for 283 and 307 engines that are stock or have a mild cam, not to mention they are so common and cheap, you would be hard pressed to have to pay more than 50 bucks for a good set you could just toss on there.

[kwmech]

With a later model cyl head, you will need to buy the later model spark plugs such as a delco R44t and gap it to .035 you are trying to install the flat gasket type plug into a taper seat hole, threads are the same, but the sealing suface is different

[1972C10]

882s are real good heads compared to the late 80s heads alot of people use.. If you upgraded to petronix might as well go ahead get an r45ts and gap them 45 the 44s are really for points 45s are just a tad hotter. and 882s will use a r45ts style plug.

The 76 cc chamber is the largest chamber offered it will work find with flat top pistons You will probally see around 9-1 with f/t pistons

[Cat Fuzz]

Originally posted by 1972C10
.. If you upgraded to petronix might as well go ahead get an r45ts and gap them 45 the 44s are really for points 45s are just a tad hotter. and 882s will use a r45ts style plug

The gap doesn't depend on if your using points or solid state ignition. It depends on the output of the coil. If he's using a stock coil that came with the points dist. they should still be gapped at .035.

[gotmud]

The ignition is the stock distributor with the Pertronix Ignitor breakerless ignition dropped in and the Pertronix 40,000 volt Flame-Thrower coil. The wires are stainless braided 8mm.
Does this help?
Glenn in Atlanta

[Longhorn Man]

Go ahead and open the gap up a little.

[1972C10]

I was pretty certain that the petronix system would be used with a hotter coil dont know first hand not having any expeirence with pertronix I always use msd or hei's

[Cat Fuzz]

Originally posted by gotmud
The ignition is the stock distributor with the Pertronix Ignitor breakerless ignition dropped in and the Pertronix 40,000 volt Flame-Thrower coil. The wires are stainless braided 8mm.
Does this help?
Glenn in Atlanta

Yeah, you'd want the wider gap with that set-up. .045

[gotmud]

I got the 45s last night. Funny asking the parts guy for a set of plugs for a 75 vette to go in my 68 truck...anyway they fit. Hopefully this weekend will tell me if they work!
Thanks for the input.
Glenn

[SWEET7T]

So what plugs did you put in it?!
I was going to suggest Autolites AP145 (or similar plug). Maybe I'm wrong, but they are the same style plug, but are skinnier 13/16 instead of 5/8.

[gotmud]

I put in the ACD r45ts and gapped at 45.