New heads..
Thread Starter
Burning Brakes
Joined: Jul 2006
Posts: 833
Likes: 4
From: Mexico NY
New heads..
Is there anyway I can simply replace the heads on my 77 to get a bit more power? or will I need to do the intake/cam/carb/ blah blah...
what kind of heads do I need ?
thanks
what kind of heads do I need ?
thanks
Team Owner
Joined: Aug 2006
Posts: 24,125
Likes: 15
From: Columbia Missouri
There are so many options available to you it's almost easier for you to search this topic using the search function.
I would suggest using words like 'head' & 'swap.'
Drifting
Joined: Apr 2002
Posts: 1,716
Likes: 4
From: New Baden Illinois
Then start thinking about the intake manifold and dual exhaust.
Racer
Joined: Feb 2006
Posts: 324
Likes: 0
From: South Elgin IL
You will notice some additional power from just a head swap, but not much with that stock cam. If you have the heads off anyway, you should, at a minimum, replace the cam to take advantage of better heads. You can pick up a Summit cam for about $60.00.
Then start thinking about the intake manifold and dual exhaust.
Then start thinking about the intake manifold and dual exhaust.
If you go through the effort of making the head swap I would change the cam too. Depending upon the heads you chose (e.g. Vortec), you would have no choice but to change the intake and the air cleaner (to fit under the hood).
Le Mans Master
Joined: Jan 2006
Posts: 8,319
Likes: 7
From: Wilmington DE, Drive it like you stole it, 68 327 4 speed coupe
[QUOTE=dgruenke;1561048366]You will notice some additional power from just a head swap, but not much with that stock cam. If you have the heads off anyway, you should, at a minimum, replace the cam to take advantage of better heads. You can pick up a Summit cam for about $60.00.
1. you can modify the CR by changing the volume on the head CC (64cc vs 68 etc)
2. you can increase valve size to increase flow at the heads, also runner vol
3. you can geat heads to handle larger size cams
but to take advantage of this fully, you need to take into account
1.carb size (what cfm are you running now)
2 intake type single plane, dual plane, flow rate etc
3. exhaust, ( stock vs headers)
an engine is basically an air pump, if you increase the flow in the heads, you will see performance gains, but you will still be restricted by the stock intake, exhaust and limited by carb flow rate
I just swapped my heads from the stock iron 1.96 to a set of brodix ik 180 aluminum 2.02 heads along with hooker pipes, there is a definate improvement, and i did it in a day
I will do the cam next, and at the same tiem an intake swap, and tthrouw in a gear drive just for kicks
cheers
tim
1. you can modify the CR by changing the volume on the head CC (64cc vs 68 etc)
2. you can increase valve size to increase flow at the heads, also runner vol
3. you can geat heads to handle larger size cams
but to take advantage of this fully, you need to take into account
1.carb size (what cfm are you running now)
2 intake type single plane, dual plane, flow rate etc
3. exhaust, ( stock vs headers)
an engine is basically an air pump, if you increase the flow in the heads, you will see performance gains, but you will still be restricted by the stock intake, exhaust and limited by carb flow rate
I just swapped my heads from the stock iron 1.96 to a set of brodix ik 180 aluminum 2.02 heads along with hooker pipes, there is a definate improvement, and i did it in a day
I will do the cam next, and at the same tiem an intake swap, and tthrouw in a gear drive just for kicks
cheers
tim
Last edited by sweethence; Jul 12, 2007 at 06:26 PM.
Burning Brakes
Joined: May 2007
Posts: 945
Likes: 0
From: Ventura California
I'm not absolutely sure, but I think your stock head has something like a 76 cc chamber. (Posters, correct me if I am wrong here so I don't give bad info..) Pretty low compression. Changing to a smaller head chamber will bump up your compression and you will notice the difference. I agree with the other posters though that it is really recommended to also do intake, cam, exhaust, etc..., to get the most out of it.
Safety Car
Joined: Aug 2000
Posts: 3,711
Likes: 43
From: San Antonio TX
76cc is right for the stock head combustion chamber.
What really kills power with the factory head is an inefficient combustion chamber design and poor flowing ports.
You can pick up noticeable power with just a head swap...as long as you get the right heads. You'd want a smaller combustion chamber in raise compression and high-velocity ports. The factory intake works very well with up to 200cc intakes. Factory rams horn exhausts are actually quite efficient, but can certainly be improved on with a nice set of headers.
If you don't really want to do the cam swap -and I can certainly see many reasons why you wouldn't- then just the heads will be a good improvement. You'll notice a lot more power in your midrange. The top end won't pick up a lot since you are limited by the cam.
What really kills power with the factory head is an inefficient combustion chamber design and poor flowing ports.
You can pick up noticeable power with just a head swap...as long as you get the right heads. You'd want a smaller combustion chamber in raise compression and high-velocity ports. The factory intake works very well with up to 200cc intakes. Factory rams horn exhausts are actually quite efficient, but can certainly be improved on with a nice set of headers.
If you don't really want to do the cam swap -and I can certainly see many reasons why you wouldn't- then just the heads will be a good improvement. You'll notice a lot more power in your midrange. The top end won't pick up a lot since you are limited by the cam.
Drifting
Joined: May 2007
Posts: 1,491
Likes: 2
From: North Royaton Ohio
I believe this would be a great option for you. I'm planning on doing this upgrade in a month or so, and I know of a few other people on this forum that have already done it.
http://www.sdparts.com/product/SD806...RPMAirGap.aspx
They're upgraded GM Performance Vortec heads, and an Edelbrock Performer Vortec RPM air gap intake. Recommended by the carb guru on this forum, Lars, and the all knowledgable Glensgages, was a Holley 770 carb and a Comp Cams XE268H Hydrolic lift cam.
Here's a page with dyno'd results. Scroll down to number 99.
http://www.ryanscarpage.50megs.com/combos13.html
Quite a little combination
http://www.sdparts.com/product/SD806...RPMAirGap.aspx
They're upgraded GM Performance Vortec heads, and an Edelbrock Performer Vortec RPM air gap intake. Recommended by the carb guru on this forum, Lars, and the all knowledgable Glensgages, was a Holley 770 carb and a Comp Cams XE268H Hydrolic lift cam.
Here's a page with dyno'd results. Scroll down to number 99.
http://www.ryanscarpage.50megs.com/combos13.html
Quite a little combination
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Le Mans Master
Joined: Apr 2006
Posts: 5,403
Likes: 95
If you have a L/48 cam get rid of it, 195/202 at .050 duration,
390/410 lift, you will never go anywhere with your car for
perfomance with this cam. But if the heads are all you want to change
no cam or intake, the summit head is reasonable in cost. SUM-152123.
www.summitracing.com
390/410 lift, you will never go anywhere with your car for
perfomance with this cam. But if the heads are all you want to change
no cam or intake, the summit head is reasonable in cost. SUM-152123.
www.summitracing.com
Last edited by Little Mouse; Jul 12, 2007 at 09:49 PM.
Le Mans Master
Joined: Sep 2001
Posts: 7,739
Likes: 630
From: Unreconstructed, South Carolina
A good used or new pair of ZZ4 aka L98 aka 113 (GM P/N 12556463) aluminum heads will work well without changing intake/cam/carb ... their 58cc chambers ... & GM P/N 10105117 head gaskets ... will push your 77's scr up to about 9.7:1. You don't have to but a cam change to something inexpensive like summit's sum-K1103 would go real well with those heads. Before any heads or cam, and if possible in your locale ... replace the 77's factory exhaust w/true duals.
Race Director
Joined: Mar 2001
Posts: 11,322
Likes: 1
From: Living in the Hartland
I am running a set of zz4 heads with the summit k1103 cam along with 1.6 rockers mated to a T5 trans; combo is a good all around performer yeilding good low end torq and shoots up to 5000 pretty nicely. Def not a screamer but nice low $ combo.
Found the heads local second hand but new doing a google search.
Thread Starter
Burning Brakes
Joined: Jul 2006
Posts: 833
Likes: 4
From: Mexico NY
How do I Know that all my accessories will still bolt up?
Say I know a guy that used to build race car engines and he has several shelves of 350 chevy engine parts...
How do I know that a certain heads will work?
I want to retain all my factory option brackets....
are there any numbers to look for?
thanks
How do I know that a certain heads will work?
I want to retain all my factory option brackets....
are there any numbers to look for?
thanks
Le Mans Master
Joined: Feb 1999
Posts: 8,351
Likes: 75
From: Tampa Bay FL
Your carb may require a re-jet/recalibration with a change in cylinder head size/flow (aka. a carb refresh by Lars). And, don't forget a good performance ignition curve to fully realize the improved performance. If you do opt for a carb refresh, be sure to provide as much info about the car/engine so that your rebuilder sets it up right.
I went with the 72cc DART IRON Eagle 180cc intake runner cylinder heads. However, if I had a do over, I would have opted for the 65cc heads and the added compression.
I went with the 72cc DART IRON Eagle 180cc intake runner cylinder heads. However, if I had a do over, I would have opted for the 65cc heads and the added compression.
Le Mans Master
Joined: Feb 1999
Posts: 8,351
Likes: 75
From: Tampa Bay FL
Without an ignition recurve for performance and carb recalibration, you won't feel much difference with heads alone. In my opinion, the carb recalibration is critical to prevent damage from lean-out conditions that higher cylinder flow may introduce. And, a good performance recurve will unleash hp/tq that you may not have realized as the stock curve focus is emissions over performance.
