186 heads

[Jcdubs]

I have a set of 3927186 heads I can't find any information on.
 They are date coded E278 and E298
Here is the kicker, thay are angle plug heads.

[Jcdubs]

[firstgenaddict]

I think you will find that they are plugged and redrilled... I had a set which I got with some parts back in the early 90's.
 186's use the larger flat seat plug with the 13/16 hex.

[Emo1956]

Ya someone made them that way .

[dannystarr]

So that would be May 27th & 29th 1968? Danny

[Jcdubs]

Can't imagine going through all that and leaving press in studs.
The date is odd to?
I have had these to 25 years, trying to thin out the hoard,lol

[Jcdubs]

Upon closer inspection you are absolutely right.
They were filled and drilled.
They did a nice job, for what gain who knows.

[BillG]

Header clearance mabey?

[z28z11]

If I was really energetic I would look back through my old Hot Rod mags and find the article for the company that made the kits to plug the original plug holes and redrill with the angled small plugs, which mimics the configuration that GM started in the early 70's (better flame pattern during combustion in the chamber). Screw-in inserts and a drill bushing/fixture to drill the holes, wish I could pinpoint the year and look it up. My Hot Rod subscription started in '70, still have them all (like an idiot) up until 2005, give or take a year or so. 

Regards,
Steve

[firstgenaddict]

Can't imagine going through all that and leaving press in studs.
The date is odd to?
I have had these to 25 years, trying to thin out the hoard,lol

I would have to agree on that...
The pair I had - were 292's - with screw in studs, guide-plates, doublesprings w/dampers - fully ported, and polished D-shaped Exhaust ports- gasket matched on the intakes through the throats and pockets with the chambers smoothed of sharp edges- bronze guides - Teflon seals -  2.05 intake valves, swirl polished with undercut stems, titanium retainers, & 10deg locks.

[Emo1956]

The angle plug was pointed toward the exhaust valve for better burning of the combustion chamber which made more HP. This is a set of 292 turbo heads that was run in NASCAR and then I ran on my dragster. I still have these heads. They made a lot of HP

[69Z28-RS]

If I was really energetic I would look back through my old Hot Rod mags and find the article for the company that made the kits to plug the original plug holes and redrill with the angled small plugs, which mimics the configuration that GM started in the early 70's (better flame pattern during combustion in the chamber). Screw-in inserts and a drill bushing/fixture to drill the holes, wish I could pinpoint the year and look it up. My Hot Rod subscription started in '70, still have them all (like an idiot) up until 2005, give or take a year or so. 

Regards,
Steve

One 'like an idiot' to another.. ..  I Have THOUSANDS of Car magazines (back to around 1978)  I finally stopped HRM, CC, and PHR a few years ago but all those magazines organizes mostly by year/name.  I need to let them go, but can't imagine trashing them!  Woe is me...   

[mrk69]

You might want to check with an area auto museum. Many have automotive related libraries that would welcome donations of collections like this. I gave mine to the Gilmore Car Museum in Michigan.

[firstgenaddict]

They were canted toward the exhaust because that is typically where preignition occurs- thus if you fire the plug closer to the preignition points "HOT SPOTS" -  you are less likely to have colliding flame fronts(detonation) which will destroy the engine. 
 
DETONATION is the collision of two flame fronts inside of the cylinder.
I have a book which shows photos taken by GM through a quartz lens of the entire sequence. Twenty or so photos of what happens during a pre-ignition situation illustrated in crank degree BTDC and ATDC.

[Jcdubs]

Thanks guys,
 I guess the next question is there any worth in these dinosaurs, since they have been modified?