Loaded Question About Heads...Need HELP
Thread Starter
Melting Slicks
Joined: Jan 2006
Posts: 2,664
Likes: 1
From: Nashville TN
Loaded Question About Heads...Need HELP
My uncle gives me this set of heads and acts like they are gold. I am appreciative but not sure what they are and how they will help my horse power situation.
casting #'s 3927186
One head has GM 30 Stamp, other has GM 47 but same casting numbers
From looking them up this is what it says but im not sure which one I have?
302/327/350
68-72
1.94/1.50 OR 2.02/1.60
64cc Doubble humps Bolt holes
I have a 72 convertible with base 350 numbers matching 4 speed with these heads in it now:
Casting # 3973487X
350
68-73
1.94/1.50 2.02/1.60 76cc
(X cast adds 10cc's larger intake port)
Do I take and put the heads my uncle gave me on the car during the rebuild and bag the originals to keep or stick with the original because the horsepower isnt that much different?
Thanks guys and if this is a newb question please feel free to flame me.
casting #'s 3927186
One head has GM 30 Stamp, other has GM 47 but same casting numbers
From looking them up this is what it says but im not sure which one I have?
302/327/350
68-72
1.94/1.50 OR 2.02/1.60
64cc Doubble humps Bolt holes
I have a 72 convertible with base 350 numbers matching 4 speed with these heads in it now:
Casting # 3973487X
350
68-73
1.94/1.50 2.02/1.60 76cc
(X cast adds 10cc's larger intake port)
Do I take and put the heads my uncle gave me on the car during the rebuild and bag the originals to keep or stick with the original because the horsepower isnt that much different?
Thanks guys and if this is a newb question please feel free to flame me.
Racer
Joined: Nov 2004
Posts: 432
Likes: 0
From: Granbury TX
I googled 3927186 and got this site.
www.nastyz28.com/sbchevy/sbch.html
1968-69 3927186 302 2.02 1.6
1968-69 3927186 327 2.02 1.6
1970-72 3927186 350 2.02 1.6
www.nastyz28.com/sbchevy/sbch.html
1968-69 3927186 302 2.02 1.6
1968-69 3927186 327 2.02 1.6
1970-72 3927186 350 2.02 1.6
Race Director
Joined: Apr 2000
Posts: 17,676
Likes: 201
From: Who says "Nothing is impossible" ? I've been doing nothing for years.
3927186..69-70...302/350......Camel hump,64cc chambers,accessory holes
3973487X...71-72...350..........75cc chamber
Years ago camel hump heads were gold, now they are old technology, they would be better that the heads you have now as they would raise the compression and probably flow better
3973487X...71-72...350..........75cc chamber
Years ago camel hump heads were gold, now they are old technology, they would be better that the heads you have now as they would raise the compression and probably flow better
Pro
Joined: Jan 2002
Posts: 624
Likes: 0
From: Marietta ga
those heads are "3927186....69-70...302/350......Camel hump,64cc chambers,accessory holes."
They are great stock heads. If you want to keep a stock appearing engine bay, ie iron gm heads, I would use these anyday over yours. They have a smaller 64cc combustion chamber, yours are 75cc, which will give you hight compression depending on your deck height and pistons. You will also be able to run a slightly larger cam with these heads. If you keep them I would recomend a comp xe268 or xe274 or similar in another brand. Try and keep the durration under 236 or so.
I might be jumping the gun, what are your plans? What carb are you running? How will you be using your car? What intake are you using or will use? Headers? Auto? Stick?
If you do not care about orginality or at least stock appearance, I would invest in some nice aftermarket heads. On the other hand, these are good heads and they will save you some money.
They are great stock heads. If you want to keep a stock appearing engine bay, ie iron gm heads, I would use these anyday over yours. They have a smaller 64cc combustion chamber, yours are 75cc, which will give you hight compression depending on your deck height and pistons. You will also be able to run a slightly larger cam with these heads. If you keep them I would recomend a comp xe268 or xe274 or similar in another brand. Try and keep the durration under 236 or so.
I might be jumping the gun, what are your plans? What carb are you running? How will you be using your car? What intake are you using or will use? Headers? Auto? Stick?
If you do not care about orginality or at least stock appearance, I would invest in some nice aftermarket heads. On the other hand, these are good heads and they will save you some money.
Burning Brakes
Joined: Jan 2004
Posts: 1,043
Likes: 4
From: Va
casting # 3927186 Small “camel humps” 186, 492 Later hi-perf or “fuelie” heads, some 186 (‘69 & later) & all 492 have accessory bolt holes; 1.94/1.50 or 2.02/1.60 valves; 64cc chambers; ‘70 LT1/Z28 use 492; avail as PN3987376 , verify these heads have hardened seats before you install and use unleaded fuel.
casting# 3973487 ‘71, 76cc, like 441 but better chamb, hard seats, acc bolt holes Big chamb needs domed pistons to get hi-comp
casting# 3973487 ‘71, 76cc, like 441 but better chamb, hard seats, acc bolt holes Big chamb needs domed pistons to get hi-comp
Thread Starter
Melting Slicks
Joined: Jan 2006
Posts: 2,664
Likes: 1
From: Nashville TN
I am open to any ideas on carb and intake manifold, plan on putting the originals in a bag with the rest of the original parts im not going to use. Im building it for me but keeping the matching numbers stuff together in case I ever decide to part with it.
Its a fun/weekend/I need some "me time" car, not a daily driver for sure.
I plan on using headers and it has a 4 speed muncie tranny. I have two sets of those heads now and think im going to use one of them on this build just because my uncle gave them to me (its not like my uncle to do anything like that). I am not looking for the monster super high HP car but I dont want to be taken by any rustangs or not be able to hold my own when messing around with my cousins and their hot rods.
Im stupid when it comes to engine tech stuff, I can put one together and do it right when someone just hands me the stuff but when it comes to picking out the right parts I have to rely on others.
Thanks!
Jake
Its a fun/weekend/I need some "me time" car, not a daily driver for sure.
I plan on using headers and it has a 4 speed muncie tranny. I have two sets of those heads now and think im going to use one of them on this build just because my uncle gave them to me (its not like my uncle to do anything like that). I am not looking for the monster super high HP car but I dont want to be taken by any rustangs or not be able to hold my own when messing around with my cousins and their hot rods.
Im stupid when it comes to engine tech stuff, I can put one together and do it right when someone just hands me the stuff but when it comes to picking out the right parts I have to rely on others.
Thanks!
Jake
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Thread Starter
Melting Slicks
Joined: Jan 2006
Posts: 2,664
Likes: 1
From: Nashville TN
no idea on rear end, no idea on RPM power range, had the original carb on and two extras (holly and rochester) came with the car but all are off right now as its being stripped/motor pulled.
Thanks for your help and again im sorry for sounding like such a newb to your questions...
Thanks for your help and again im sorry for sounding like such a newb to your questions...
Pro
Joined: Jan 2002
Posts: 624
Likes: 0
From: Marietta ga
Originally Posted by LittleJake
no idea on rear end, no idea on RPM power range, had the original carb on and two extras (holly and rochester) came with the car but all are off right now as its being stripped/motor pulled.
Thanks for your help and again im sorry for sounding like such a newb to your questions...
Thanks for your help and again im sorry for sounding like such a newb to your questions...
If you are going to use any of those carbs you need to know what size they are.
Pro
Joined: Dec 2002
Posts: 560
Likes: 1
From: Mooresville NC
From the pic, these do not look like the 2.02 intake of the "Fuelie" heads everyone talks about. The space between intake and exhaust valve seems like a lot. No offense to your your uncle, they are probably worth more to someone doing a NCRS project. But they are free ... 
Instructor
Joined: Feb 2005
Posts: 215
Likes: 1
From: Belton Missouri
There were different variations of the 186 head:
Some had 1.94/1.50 valves, 64cc chambers, pressed rocker studs, no guide plates. Used on lower HP models.
Others had 2.02/1.60 valves; 64cc chambers, screw in rocker studs, and guide plates . Used on higher HP models.
And apparently based on your photos, they had the 1.94/1.50 valves, 64cc chambers, screw in rocker studs, and guide plates version also.
Great old heads, they can be machines for the larger valves. They were only made 2 or 3 years, and used to build some of the hotest small blocks during their time. 69-71?
Audie
Some had 1.94/1.50 valves, 64cc chambers, pressed rocker studs, no guide plates. Used on lower HP models.
Others had 2.02/1.60 valves; 64cc chambers, screw in rocker studs, and guide plates . Used on higher HP models.
And apparently based on your photos, they had the 1.94/1.50 valves, 64cc chambers, screw in rocker studs, and guide plates version also.
Great old heads, they can be machines for the larger valves. They were only made 2 or 3 years, and used to build some of the hotest small blocks during their time. 69-71?
Audie
Le Mans Master
Joined: Feb 1999
Posts: 8,351
Likes: 75
From: Tampa Bay FL
My '69 L46 with 11:1 CR came stock with the '186' castings. With my recent carb/distrib rebuild/repair/blueprint, it runs very strong; and they accomodate my domed pistons.
I checked into vortecs and with my OEM domed pistons, the vortec's won't accomodate (different shape to the chamber). If I ever have cyl head work done, will probably just refresh as I'd like to keep the stock pistons.
Looks like your '186's head surfaces need a good resurfacing but otherwise look good. If Have they been rebuilt? They look 'new'.
I checked into vortecs and with my OEM domed pistons, the vortec's won't accomodate (different shape to the chamber). If I ever have cyl head work done, will probably just refresh as I'd like to keep the stock pistons.
Looks like your '186's head surfaces need a good resurfacing but otherwise look good. If Have they been rebuilt? They look 'new'.
Last edited by TedH; Mar 1, 2006 at 09:49 AM.
Race Director
Joined: Sep 1999
Posts: 11,360
Likes: 382
From: Plano TX
As far as stock iron heads go, these are about as good as they get. They can be machined for the larger valves.
However, only reason I would ever run them is if I needed to compete in a racing class that required factory heads. Aftermarket aluminums will outperform the ported double humps out of the box. Plus you drop a bunch of weight.
Sell the double humps to someone that wants them and buy a nice set of aluminums. AFR, TFS, Edelbrock, Brodix etc all have really nice units. Many go for under $1k complete.
However, only reason I would ever run them is if I needed to compete in a racing class that required factory heads. Aftermarket aluminums will outperform the ported double humps out of the box. Plus you drop a bunch of weight.
Sell the double humps to someone that wants them and buy a nice set of aluminums. AFR, TFS, Edelbrock, Brodix etc all have really nice units. Many go for under $1k complete.
Thread Starter
Melting Slicks
Joined: Jan 2006
Posts: 2,664
Likes: 1
From: Nashville TN
TedH wrote:
Yes, they were rebuilt about four years ago and then stored in two plastic bags. I opened them up yesterday to take the pics and saw all the surface rust. I guess I will need to get them rebuilt again?
Thanks for all your help with the heads, will check the budget and might go with new aluminum heads and save these for the Chevelle.
Thanks!
Looks like your '186's head surfaces need a good resurfacing but otherwise look good. If Have they been rebuilt? They look 'new'.
Thanks for all your help with the heads, will check the budget and might go with new aluminum heads and save these for the Chevelle.
Thanks!
Le Mans Master
Joined: Feb 1999
Posts: 8,351
Likes: 75
From: Tampa Bay FL
You can probably have a quick resurface done and then coat them in oil before you re-seal the bags (OR you could see if your uncle will approve selling them now...).
If you decide to sell them down the road, drop me a line. I can always use a spare set of 186's.
If you decide to sell them down the road, drop me a line. I can always use a spare set of 186's.
Last edited by TedH; Mar 1, 2006 at 11:30 AM.
Le Mans Master
Joined: Mar 2004
Posts: 7,474
Likes: 1,495
From: Little Rock AR
Those heads are valuable to restorers and maybe some stock class racers. I estimate $400 and up for unmolested 186 core pairs with desireable dates. The small valve versions are not as desireable as the factory equipped big valve versions so they go for less. I have not seen any (factory equipped) big valve 186's for sale in quite a while and they would not be cheap.
They are good stock heads but only for a resto or if you already have them free. Aftermarket is better for performance and the prices are close if you figure in the core value plus the prep. Even then they will not be as good as afermarket.
-Mark.
They are good stock heads but only for a resto or if you already have them free. Aftermarket is better for performance and the prices are close if you figure in the core value plus the prep. Even then they will not be as good as afermarket.
-Mark.
