Just trying to find out some details on some "supposed to be" DZ heads.

There are some casting marks on the heads themselves that I'd like some info on.

Under the "2" on the hump picture there is "1692" stamp. It is on the opposite side (the side with 1 acc hole) on the other head.

On the outer edge of both heads is stamped FJ23 in a tiny flange.

The GM stamps on the valves with a "T" on the opposite edge.

No visible relief on the intake valves lead me to believe that they are indeed real 186 2.02 heads. Any way to find out if they came on a DZ motor? They are supposed to have the "grumpy" treatment as well, by some renowned racer..but no details are given other than the story. They have some porting and polishing (looks very well done actually, as well as the spring seats).

Any ideas? I plan on using them on a 302 I am building.

The chamber wall around the intake valve looks like the factory style unshrouding of the 2.02 heads. Are these straight plug? The picture of the chamber looks like the spark plug is angled. Of course they have aftermarket springs reatiners and what looks like different studs.

They are angle plug heads.

Josh,

GM never installed an angle plug head on a production engine.

186 heads were straight plug heads, so somebody has modified those, which was done back in the day . . . . how about a picture of the outside where the spark plug goes in ?

It also looks like someone has installed screw in studs. They are the "repair" type of stud, not the performance ones.

The funny thing is the "humps" look more like the ones on the 292/492 heads, which were angle plug heads available over the counter.

Something "screwy" about the whole deal.

Looking closer, they have been modified (under some carbon) someone did the angle job, very nicely I might add, you can't even tell where they welded it.

Was it commonplace for racers to do that kind of modification ?

Was it commonplace for racers to do that kind of modification ?

Not common at all. Most likely was done by somebody like Jenkins, who was "cutting edge" at the time.

Or by someone who had nothing better to do with thier time and had the equipment to do it with :)

By the way, they probably did not weld it. Usually a plug was made to plug the original hole, then a new hole drilled and tapped right through the plug.

Interesting, thanks for the info Bill, any idea of the stampings purpose? I was hoping someone would chime in with a "my original DZ heads have that there" ....

No matter really, from all the info garnered so far, these seem to be real, and if indeed the story adds up that "grumpy" actually mod'd these then they should flow like a sumbich!

And we all know that the real DZ heads really...really make a destroked SBC go well.

I had a friend growing up who had a real one, man that thing was incredible...nothing gets me going like the sound of a 302 going at 7700RPMs!

Here is one of my favorite Z Vid's...just love that sound!

This is a 302 cu in SBC Z28 engine in action... - YouTube

Is it possible the screw in repair studs were the "upgrade" at the time considering that 302's had hardened rockers?

Just wondering why someone would have gone through all the trouble to flow these and angle the plugs and not install plates and guides.

Josh,
The numbers are probably just job numbers for the shop that did the work.

As far as flow goes, this might be sacralidge, but I would almost bet dinner that the Vortec heads on my 99 Tahoe probably flow pretty close, if not better than those will :(

Not sure why someone would have just used those screw in studs. The heads might have been done for a racing class that only allowed certain mods to the heads. The rules might have stated "no guide plates" etc.

You never know what guys were thinking when they did some of that stuff.

HAH!

I know very well that the Vortec heads flow well, A local renowned builder uses them exclusively and to much success (Bob Joehnck).

However....I beg to differ on this in particular. I have personally seen many of these motors in local hotrods, they pull like no one's business to about 6k, then fall flat on their faces.

I'll take the 3-8k pull of a destroked 302 with 186 heads on it anyday. At least the real ones worked well, as we both know there at thousands of 1.94 heads out there, reworked in someone's shed, that lay waste to the mythical "camel hump heads" mystery. :hurray:

I love old iron tho, nothing beats watchin my friends 283 with real 2.02's on it smoke these guys at our local spot...and those vortec motors cost 3x what you can build a destroker for...

Anyhow, thanks for the info Bill ! :beers:

Is it common to make the exhaust outlet port perfectly round, when porting ? I ask because weren't those a D port in stock form ?

Pictures remind me of Crane Fireball heads made from '492 castings, as BillK states.
Awesome head for the time they were made. They would have 'CRANE' stamped on the ends. If no stampings, I would say these would be a reverse engineered set of heads.
Not original production head, only bought over the parts counter.
Use the same header tube diameter as the exh port shows, 1-5/8 inches I bet.
Aftermarket coolant temp adapter in the head, I would say for a SW mech gauge with a Bourdon tube, also period correct.
I beluieve the intake side would take a Fel-Pro 1205 gasket, large port.

They sold Jan 69 casting 186 2.02's over the counter?

I thought all the over the counter stuff was 292's?

3890462....66-67...302/327/350..Camel hump,no accessory holes,64cc chamber

3917291....67-68...302/327/350..Camel hump,no accessory holes,64cc chamber
Jenkins also worked these Heads

3917292....68......327/350......Camel hump,64cc chamber (This is the HOT Item to Get - But not a DZ Head)
The Port Floor Angle was better then the 291's
One of Grumpy's Favorite Head Castings

3927186....69-70...302/350......Camel hump,64cc chambers,accessory holes
Can't say they had the Hot Port Floor Angle

3947041....69-70...302/350......"Right angle" casting identifier, 64cc chamber, accessory holes, good HP head

3947041X...69-70...302/350......"Right angle" casting identifier, 64cc chamber, 165cc intake port, accessory holes, good HP

340292.....70's.......Over the counter, angle plug, 64cc chamber

All the Heads listed above are great heads for either a 302 or 327 where aftermarket really can not do any better for the Small Displacement Hi-Revving SBC.

Grumpy was a 327 Man. I'm very familiar with Jenkin Specs as I did a lot of Head Porting back in the day. From your PIC's I can't not see his recommended Chamber Modifications and he did not recommend opening the Exhaust Port to a Round Circle in order to match headers.

Here's an Example of 291's done to Jenkin Spec's.

http://farm4.static.flickr.com/3407/3638727769_c0a7fedc8a.jpg

http://farm4.static.flickr.com/3333/3639537426_38b7d8b068.jpg

http://farm4.static.flickr.com/3406/3638727897_57368a58a6.jpg

Thank you very much for the info Ron, I knew someone would know !

They still look very nicely done however, I'll post up a vid of them when I get the 302 done, see how they run :thumbsup:

I think you guys are pretty right on about Joehnck or Jenkins doing the angle plug conversion. IIRC long ago there was a magazine article about converting straight to angle plug spark plugs. I even did a set using a custom made cast iron plug epoxied in and then redrilled and tapped in the angle plug location. The "Crane Fireball" heads were the poor mans store bought heads that made decent numbers. I know they used the 462 and I suppose also the later 292, 492 and 186 castings

Hey Bill, I see you own your own machine shop, any recommendations to seal the heat passage?

Hey Bill, I see you own your own machine shop, any recommendations to seal the heat passage?

Josh,
Some guys will use melted aluminum to fill the passage but for a street / strip engine all you really need is a thin piece of steel sheet to block it off. We used to cut a piece off a tin can :) A lot of the gasket sets come with block offs. If the intake you are using does not have the passage then it really does not matter anyway.

Thank you very much Bill, just wondered if the block off's in the gasket set were up to it :D

And another thanks to everyone passing along info, You guys are great!