Author Topic: 1970 #11 Heads for 1977 400  (Read 7409 times)

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Offline ZachAttack77TA

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1970 #11 Heads for 1977 400
« on: February 20, 2010, 07:43:04 PM »
I came across some 1970 #11 Heads for a Pontiac 400 for about $40. They're bare castings and they are 'magged', whatever that means. I was just curious if anyone has used these heads before on a 1977 vintage 400. Are these a good performance upgrade from 4X heads? What kind of compression ratio can I expect? FOr $40 buck, I figured it would be worth it even if the horsepower gains weren't substantial. My intention was just to get my 1977 400 to perform more like it's older brethern. Thoughts on this? ???

My research on YearOne(http://www.yearone.com/yodnn/tech/VehicleInfoDecoding/PontiacDecoding/PontiacEngineCodes/tabid/323/Default.aspx) says these are for for 400s in the 265 HP range. As always, thanks for all your advice. I really appreciate the time you guys take to help out a guy that's still new to all this.
« Last Edit: February 20, 2010, 09:29:42 PM by ZachAttack77TA »
1997 Grand Am
1995 Trans Am
1977 Trans Am

Offline Clint s

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Re: 1970 #11 Heads for 1977 400
« Reply #1 on: February 20, 2010, 09:55:59 PM »
"magged"  means magnafluxed,  basically it works by applying a magnetic field to a part.  This will cause a high concentration of magnetic flux at surface cracks, which can be made visible by dusting iron powder or a similar magnetic material over the component.  
I do not know how those heads flow,  but if you cut them a bit you could get over 9 to 1 and probably do quite well.  I also do not know if they have pressed in or screw in studs, they also have the smaller 1.96/1.66 valves
« Last Edit: February 20, 2010, 09:58:48 PM by Clint s »

Offline ZachAttack77TA

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Re: 1970 #11 Heads for 1977 400
« Reply #2 on: February 20, 2010, 10:22:26 PM »
"magged"  means magnafluxed,  basically it works by applying a magnetic field to a part.  This will cause a high concentration of magnetic flux at surface cracks, which can be made visible by dusting iron powder or a similar magnetic material over the component. 

Oh, duh! I knew that. For some reasn I wasn't making the connection between magnafluxed and 'magged'. Oh well, everyone has brain farts I guess. :)

Thanks for the info. I've been trying to find something on these heads and this helps a lot. Being that they are bare, what is the normal cost to assemble them? I've been adding up parts I'll need, but I'm also considering having a three angle valve job done on them for a little extra breathing. I'm not looking for a fire-breather, just a good street combo.

Do you know what normal shops would charge to install the screw-in type rocker studs? I'm going to call around and do some research.

Thanks for the help, I really appreciate it.
1997 Grand Am
1995 Trans Am
1977 Trans Am

Offline ZachAttack77TA

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Re: 1970 #11 Heads for 1977 400
« Reply #3 on: February 21, 2010, 04:39:07 PM »
Well, I picked up the heads and they have the press-in studs. I'm not really worried about going with screw-in since this car will not be raced hardcore or anything. I'll be going around to some machine shops and seeing what I can do with them.
1997 Grand Am
1995 Trans Am
1977 Trans Am

Offline Rick

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Re: 1970 #11 Heads for 1977 400
« Reply #4 on: February 21, 2010, 10:43:54 PM »
Those really aren't all that fine of a head (hate to say now, as you have them already).  The intake valve is the small 1.94" ones vs the 2.11" ones in the 4X heads.  They likely won't flow nearly as well either, unless you modify them pretty extensively.  The combustion chamber size is OK (nominally), but the pressed-in studs aren't really what you want either.  I wouldn't use a pressed-in stud -- too easy and cheap to have them threaded.  I'd have told you that sooner but I just logged in after a long weekend...

Offline ZachAttack77TA

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Re: 1970 #11 Heads for 1977 400
« Reply #5 on: February 21, 2010, 11:13:05 PM »
That's all right. Suggestions on something I can afford? What about cost to re-do the 4X heads? Can these be made into good performers?

My research on the #11 heads said they were the 265 hp variant versus the 180hp L78 I got now. I figured I'd assemble them and maybe get a three-angle valve job and a little shaved of the deck to raise compression.

I also ran across some #46 heads. Are they any good?

What suggestions would you have for getting some cheap performance out of my motor?
« Last Edit: February 21, 2010, 11:14:55 PM by ZachAttack77TA »
1997 Grand Am
1995 Trans Am
1977 Trans Am

Offline Rick

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Re: 1970 #11 Heads for 1977 400
« Reply #6 on: February 21, 2010, 11:22:13 PM »
The 46 heads are about the same, although the source I'm looking at suggests that they might be screw-in studs.  They still have the small intake and exhaust valves.

One thing you need to keep in mind is that the HP rating system used between 1970 and 1971.  Prior to 1971 the system used was highly subject to manipulation which generally overstated the true output of the engine.  It was supposedly based on "gross" HP, in which they didn't count the power taken by the water pump and alternator.  Starting in 1971 the system was based on the SAE definition of "net" HP, which was what the engine would actually make when it was installed in the vehicle.  There wasn't as much difference between that 265 HP 1970 engine and your 1977 180 HP engine as what you might think.

The biggest gains for the smallest $ are found in the carb jetting and the ignition timing.  Stock, those were set for minimal emissions rather than maximum HP and torque.  Next up on the improvement scale is the exhaust system.  The stock systems were terrible and strangled the engine's output.  A true dual setup and a switch from the stock "log" manifolds to either a set of good tube headers or a cast iron performance manifold like the RARE pieces (RAIII replicas) does wonders for the performance -- provided, of course, that you're not living somewhere that emission certifications are needed to be able to drive your car on public roads.

Those changes alone -- even without head or cam swapping -- can really wake up an engine.

Offline ZachAttack77TA

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Re: 1970 #11 Heads for 1977 400
« Reply #7 on: February 21, 2010, 11:52:12 PM »
Okay, that makes sense. Right now I have true dual flowmaster exhaust 3in pipes with no cats. It's registered as a classic vehicle so it doesn't require emissions. Since we're on the topic of headers, what kind would you recommend? Hooker? Hedman? Are some that can be installed with out removing the engine?

Also, would it be a viable performance upgrade to maybe mill the 4X heads for some extra compression? It's at 7.7:1 right now (which is ridiculous). Any way of know what kind of 4X heads they are? One has a number 4 on the right side exhaust port and the other has a 3.

My carb right now is a Carter AFB 660cfm. I know it's not original, but is this a good carb? Should I maybe get a good Quadrajet before I think about spending money on jetting a carb that may not be a good choice for the engine?

I really appreciate your all your advice, Rick. You've been very helpful to someone still trying to figure all these things out.
« Last Edit: February 22, 2010, 12:17:33 AM by ZachAttack77TA »
1997 Grand Am
1995 Trans Am
1977 Trans Am

Offline KellzBird

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Re: 1970 #11 Heads for 1977 400
« Reply #8 on: February 22, 2010, 09:41:18 AM »
the #11 heads are 80cc (or at least supposed to be) but like others have said, they have the smaller valves. If you are going to sink a lot of money into heads then I would start with a more suitable set.

those heads run pretty decent on my 1970 350, supposedly the smaller valves are just fine for that application.

I think (please don't quote me) that Mr.Pbody said something to the effect of flow trumps compression, so even though the 80cc is going to put you in the range of 9.3-9.5:1 compression, the smaller valves are too restrictive.

Offline kjkjkcjkcj

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Re: 1970 #11 Heads for 1977 400
« Reply #9 on: February 22, 2010, 01:28:36 PM »
Every now and then these heads pop up everywhere.  I wouldn't dump money into the heads either. you may be able to flip them for a proft.  try and sell them to a guy looking to boost up their performance on their pontiac 350 motor.  If you shave them down you then have to worry about matching the intake and stuff like tht. 

However if you are going to do those heads i would do these things to them
1> Extensive porting
2> Make the valve size bigger
3> Screw in studs

But those three things will cost you a pretty penny and you would most likely be better off buying a different set.
-1979 Trans Am Ws6, W72 400, holley 650, #62 heads (toy)
-Silverado 1500 (daily driver)



Offline ZachAttack77TA

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Re: 1970 #11 Heads for 1977 400
« Reply #10 on: February 22, 2010, 03:50:15 PM »
Okay, thanks a lot guys.

So what do you think of dumping some money on the 4X heads? Since they have bigger valves, is it worth it to maybe deck those and get a three-angle valve job?

I'm in the engine building phase in my classes at UTI and we're doing a buildup of a 355 that we will add performance mods to later on. It got me thinking and doing research on my motor. I really appreciate all your advice.
1997 Grand Am
1995 Trans Am
1977 Trans Am

Offline kjkjkcjkcj

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Re: 1970 #11 Heads for 1977 400
« Reply #11 on: February 22, 2010, 03:52:51 PM »
to be honest i would keep your 4x heads stock and go with an eagle stroker kit. those heads you have would be perfect for a stroker kit and it literally is bolt on power and im talkin huge power. though the kit is pricy it is the best thing you can do with these motors. i wish i bought the stroker kit instead of spending what i spent on my heads.
-1979 Trans Am Ws6, W72 400, holley 650, #62 heads (toy)
-Silverado 1500 (daily driver)



Offline kjkjkcjkcj

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Re: 1970 #11 Heads for 1977 400
« Reply #12 on: February 22, 2010, 03:53:13 PM »
the stroker kit will bump you up to like 500 hp.
-1979 Trans Am Ws6, W72 400, holley 650, #62 heads (toy)
-Silverado 1500 (daily driver)



Offline ZachAttack77TA

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Re: 1970 #11 Heads for 1977 400
« Reply #13 on: February 22, 2010, 04:13:20 PM »
the stroker kit will bump you up to like 500 hp.

Really? Does it do that on pump gas? We only got 91 Octane at the pumps out here in Arizona and it isn't really the greatest quality.

What does the kit cost? Around 1500 I'm guessing?
1997 Grand Am
1995 Trans Am
1977 Trans Am

Offline kjkjkcjkcj

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Re: 1970 #11 Heads for 1977 400
« Reply #14 on: February 22, 2010, 04:24:05 PM »
in that ball park and yes you could still run it on pump gas.  a stroker kit doesn't mean you will have more compression.  it means the stroke is longer so you will be able to pull in more fuel air mixture into each cylinder.  causing you to get a bigger explosion.  though using those 4x heads your compression will increase compared to your 400 but im pretty sure the 4x heads are ideal for the stroker kit. thats a question for jim.  he would know of the top of his head.  but im pretty sure those are great heads for a stroker.  i would def go with a stroker and save up if you don't have it right away.
-1979 Trans Am Ws6, W72 400, holley 650, #62 heads (toy)
-Silverado 1500 (daily driver)