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Username Post: 333882 Cylinder Heads        (Topic#180000)
57 boxman 
Senior Member
Posts: 650
57 boxman
Loc: N. Texas
Reg: 03-14-04
01-18-08 10:08 PM - Post#1346235    

I looked up my cylinder heads today on Mortec.com. I have 333882 heads. Motec told me they were made during years 74-80, used on 350/400 cubic inch engines, has 76cc chambers, 1.94 intake and 1.5 exhaust.

I have been told they were good heads for the smog years, true or not true?

I wonder how much more power I could get from a set of 2.02s or after market heads?

Anyone have a link to some good informational reading about cylinder heads?

What is the chambers? My friend had some 10239906 heads off a 95 and it has 64 cc chambers. The other numbers are the same. Which is better 76cc or 64cc?
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fritz1990 
Dedicated Enthusiast
Posts: 6411
fritz1990
Age: 53
Loc: Kansas
Reg: 02-16-03
01-18-08 11:11 PM - Post#1346246    
    In response to 57 boxman

Here is some flow charts for heads. Have to start at top and scroll down slow.

http://users.erols.com/srweiss/tablehdc.htm#Chevy


http://www.purplesagetradingpost.com/sumner/techin...


Regards, Jeff
1998 K1500 6.5 Coal burner
1965 C10 with 498 BBC AFR Heads
1964 C10 Ran 348W for 6 years, now SBC.

Corvettes owned: '74 '77 '78 L82 Silver Anniversary, 2002 LS1

Don't have a nervous come together!

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Edited by fritz1990 on 01-18-08 11:18 PM. Reason for edit: No reason given.

 
craig32 
Frequent Contributor
Posts: 1253

Age: 52
Loc: PA
Reg: 08-05-07
01-19-08 03:51 AM - Post#1346288    
    In response to 57 boxman

  • 57 boxman Said:
What is the chambers? Which is better 76cc or 64cc?


Chamber is 'combustion chamber', the cutout in the head where the valves are. 64cc is a smaller chamber which would mean higher compression. The heads you have are the modern equivalent to the old 461, 291 and other 'hot' heads od days ago, except for the bigger chamber. SOME of the 461s had 2.02" intake valves, others had the 1.94" Engines from the 60's had flat top pistons, small chambers, big valves, high lift cams, high compression, more HP. As insurance companies started getting antsy about covering cars with said engines, pistons became dished, chambers became bigger, compression went down, lower lift cams, HP went down. De-tuning is a good way to put it. And, GM changed how they rated HP, so it 'appeared' lower than it actually was.
Newer heads also had 'access holes' when A/C and other things that run off of a belt became more common. All of the older cars I had only had an alternator (or generator) and that was it.
Just my opinion, I could be wrong.

Craig
http://www.cardomain.com/id/chevysgalore
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Edited by craig32 on 01-19-08 03:53 AM. Reason for edit: No reason given.

 
Rick_L 
Honored Member
Posts: 25843

Loc: Katy, Tx, USA
Reg: 07-06-00
01-19-08 05:59 AM - Post#1346338    
    In response to 57 boxman

"I have been told they were good heads for the smog years, true or not true?"

I've always been of the opinion that the 487 head was the "best" head from the smog years. Its ports are virtually the same as the old camel hump heads - the difference is the bigger chamber. Unfortunately the 487 heads are very prone to cracking in the exhaust valve seats.

The 882 heads are also prone to cracking in the exhaust ports. I think the reason this is common on both heads is that the 70s engines were set up with lean mixtures and retarded timing to get the exhaust temperatures higher for the early style catalytic converters.

While from the charts the 882 is "not too bad" for flow compared to other iron heads, I think you have to take those numbers with a grain of salt. Even some minor grinding work can help a lot on some heads, and you don't know from those lists which heads had what done to them. The 882 has an odd shaped "shelf" in the intake port which has to affect its potential, though I'm not sure how much.

I think you're far better off with those 906 Vortec heads. Probably to the tune of 30-40 hp over the 882 heads, and the potential for more. Note they did not come on 95 models though - they started in 1996, but obviously a head for a 96 model could have been cast in late 1995.

 
57tim 
Valued Contributor
Posts: 2764
57tim
Loc: Cameron, Wi, USA
Reg: 11-09-01
01-19-08 06:51 AM - Post#1346364    
    In response to Rick_L

I have been told that the camel hump heads with 1.94 valve would be best for normal street driving vs the 2.02 heads. This comes from a fairly knowledgable source.
57 Bel Air 2dr Ht
327 700r4
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498 chevy 
"6th Year" Gold Supporting Member
Posts: 367
498 chevy
Age: 63
Loc: hayward ca.
Reg: 09-28-07
01-19-08 10:11 AM - Post#1346468    
    In response to 57 boxman

hi I had many sb 400's with these heads. they are a good low end head. You also have to keep the cam small 256 degs and .440 lift. If you want a little more on mid to top end i used world with 2.02,s and it worked great. All the newer head will out do the stock casting. ron
http://www.picturetrail.com/webe


 
Mike55 
Super Senior Member
Posts: 4393
Mike55
Loc: Lou.Ky .....
Reg: 03-20-02
01-19-08 01:58 PM - Post#1346584    
    In response to 57tim

I always understood it that it would a set of lights to note the difference. I always ran 194's and had good luck. 2.02's are just so you can say you have 2.02's IMHO.
My memory's not as sharp as it used to be. Also, my memory's not as sharp as it used to be.


 
bamaboybwoody 
Forum Newbie
Posts: 45
bamaboybwoody
Age: 59
Loc: Gardendale,Alabama
Reg: 10-23-07
01-19-08 03:28 PM - Post#1346631    
    In response to Mike55

Far as I can tell those smog year heads are not very good for performance or gas mileage. I have used them and then changed to vortecs, it is like a whole different motor.

Joe

 
MikeB 
Senior Member
Posts: 9523
MikeB
Loc: Plano, TX
Reg: 08-28-03
01-19-08 08:42 PM - Post#1346781    
    In response to 57tim

  • Quote:
I have been told that the camel hump heads with 1.94 valve would be best for normal street driving vs the 2.02 heads. This comes from a fairly knowledgable source.



1.94 valves can actually flow better in a bore smaller than 4", but I don't see any advantage to using them with a 4" bore. And if your bore is 4.030 or larger, I would definitely use the 2.02 valves, even with a small cam.

That said, GM uses the 1.94/1.50 combo on many of its crate engines, including the ZZ4 and HT383.

1982 C-10 SWB pickup -- Unmolested, original paint, 250 six, 3-on-the-tree
(Soon to be 350 w/Vortec heads & TH350)

Sold my 55 sedan in June 2014, having owned it 11 years.


Edited by MikeB on 01-19-08 08:46 PM. Reason for edit: No reason given.

 
Steves32 
Ultra Senior Member
Posts: 10811

Reg: 12-22-99
01-19-08 08:48 PM - Post#1346786    
    In response to MikeB

Since when are 882's anything special?
I always thought they are thin castings prone to cracks.
The hot ticket when we were running early heads- we ran 291's. We'd have them extrude honed, machined for huge springs, set up for screw in studs, bunch of bowl work, slap as set of 2.02/1.60's in it & go racing.
Today- that would be cost prohibitive.


 
DZAUTO 
Senior Member
Posts: 7572

Loc: Mustang, OK, USA
Reg: 12-25-99
01-20-08 06:55 AM - Post#1346927    
    In response to Steves32

  • Steves32 Said:
Since when are 882's anything special?
I always thought they are thin castings prone to cracks.




That is exactly, completely 100% correct.
I was hoping someone would step in here sooner regarding these heads.
So, I'll provide some additional info about PRODUCTION SB heads.
READ THE FOLLOWING CAREFULLY.
The heads on 1974 and earlier PRODUCTION SB engines are the only heads worth using. Beginning with 1975 PRODUCTION SB engines, GM started cutting corners to save weight as well as more aggressively reduce emissions. Thus, in 75 the production SB heads were a little thinner and they got twin exhaust crossover passages. This became a receipe for more heat, more cracks and a shorter life for the head. By 1977, production SB heads were paper thin junk. Yes, it is VERY true that you may be able to find a good, rebuildable set of 75-later heads that are not cracked------------------ -yet. But there is a genuine risk that after rebuilding and investing you money in them, they very possibly will develop a crack. I would strongly encourage anyone to stay away from 75-later SB production head castings.
I keep mentioning production heads. These are heads that were installed on engines that went into cars sold to the public. The over the counter performance heads, such as Bowtie heads, are NOT in this catagory of thin head castings.

OK, so now, what kind of heads are good heads to use? Admittedly, the 71-74 big chamber (~76cc) heads are not the most ideal. But, they certainly can be very good heads for a nice street performance engine. It WILL cost some $$$$$$$ dollars to make good heads from 71-74 heads, but it will still be cheaper than aftermarket heads. If you are a conservative person, and know how to shop around, you can build a nice set of heads for $400-600----------------- -----ready to bolt on.
First, production 71-later heads had induction hardened exhaust seats---------------but the induction hardening is only "skin deep". But still, you should be OK with a valve job, or, even if you choose to open up the intakes/exhausts to 2.02/1.6 valves, you should be just fine. With all the engine experiences that have occured in the past 35+yrs, I am now satisfied that valve seat recession on the average, daily driven, street-performance engine is a NON-ISSUE. So, don't spend unnecessary $$$$$$ having hard valve seats installed in the heads. I DO RECOMMEND buying and installing stainless valves. If you shop around the mail order sources (Summit, Jegs, etc), you can make some pretty good buys on stainless valves and springs that are good for up to .510 lift which fit the stock spring pocket.
If a healthy 350-larger engine is to be built, I'd certainly engourage the installation of 2.02/1.6 stainless valves. If 70-earlier (461, 291, etc) heads with 1.94 valves are opened up for 2.02/1.6 valves, you also need to have the machinist cut a relief in the combustion chamber wall next to the intake valve, as was done at the factory on production 2.02 heads.
If you are installing 2.02/1.6 valves in 71-later heads with the biger 76cc chambers, this relief in the chamber wall is not necessary.
the place to spend your $$$$$ on this type of head is to have port matching done to the intake ports and have the bowls lightly cleaned up.
If you plan to use a cam with a lift ABOVE .450, it would be essential to convert the studs to screw-in. When adding screw-in studs, it would be very good to also install guide plates.
There are going to be several people say that if you're going to spend this much money on a set of 30+yr old heads, then for just a few hundred more dollars, you could have some brand new, ready to bolt on heads with all the above features. And this is very true. But for some folks, especially those on a limited budget, it may be important to just do a good rebuild to a set of stock heads.
Tom Parsons


 
57 boxman 
Senior Member
Posts: 650
57 boxman
Loc: N. Texas
Reg: 03-14-04
01-20-08 11:22 AM - Post#1347105    
    In response to DZAUTO

Thanks for all the info. I will have a lot to think about in the coming year. I plan on motor upgrades for my next years winter project.

A couple of more questions. How do you read a flow chart? It reads like a racing form. What is No Pipe/pipe?

I have a mid 14 second car. I just want a low 13 second car. I want to get out of the street muscle car class and race in the king muscle class in the Texas Muscle Car Series. I'm tired of getting beat by the same people. I guess I want to get beat by a new group.
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Steves32 
Ultra Senior Member
Posts: 10811

Reg: 12-22-99
01-20-08 01:13 PM - Post#1347167    
    In response to DZAUTO

Great post Tom!

For a minute there- I thought I was alone.


 
sedandelivery55 
"8th Year" Gold Supporting Member
Posts: 2736
sedandelivery55
Age: 54
Loc: Moore, OK
Reg: 02-20-02
01-20-08 04:24 PM - Post#1347260    
    In response to Steves32

Tom, I've been on a budget since I got this car. I did exactly as your post on a set of '72 heads, cast #3973493, ported to the intake with both matching the gaskets. I did a clean-up in the valve bowls, also. I could tell a difference right away. The heads had been milled to 72 CC by the previous owner and still has the 1.94/1.50 valves.
Lee

http://www.picturetrail.com

The '55 is home again!
92 GMC Sierra short/stepside
4.3 V6, 5 speed





 
DZAUTO 
Senior Member
Posts: 7572

Loc: Mustang, OK, USA
Reg: 12-25-99
01-20-08 05:03 PM - Post#1347285    
    In response to sedandelivery55

Here is the combustion chamber of a 1.94 head (461) that has never been touched (I knew I had photos somewhere). Notice the raw cast finish of the chamber wall next to the intake valve.


This is the same set of heads after having 2.02/1.6 stainless valves added.

NOTICE HOW THE SIDE OF THE COMBUSTION CHAMBER WALL HAS BEEN RELIEVED NEAR THE INTAKE VALVE. This is what was done at the factory when head castings were machined for installation of 2.02 valves.


This is also a comparrison of before and after having screw-in studs and guide plates installed on the same heads.



Tom Parsons


 
MikeB 
Senior Member
Posts: 9523
MikeB
Loc: Plano, TX
Reg: 08-28-03
01-20-08 05:22 PM - Post#1347291    
    In response to Steves32

Tom, could you be a little more specific?

1982 C-10 SWB pickup -- Unmolested, original paint, 250 six, 3-on-the-tree
(Soon to be 350 w/Vortec heads & TH350)

Sold my 55 sedan in June 2014, having owned it 11 years.


 
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