my grandpa has a spare set of 3.1L heads off a burnt up 91 bird, so I;m going to have them magnufluxed and if they are ok I;m going to do some gasket matching,valve guide boss smoothing, and exhaust port polishing. Then I;m going to take the heads back to the machine shop for: .020 shaved off, stronger springs, and a good valve job. I;m hoping this will get my 7+ hp.

I was planning to sell my car(again!), but since I;ve actually saved up some money I dont want to spend it all especially since my car is paid for. Now all I need is slicks, so I can get some nice times.

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1992 black 3.1 V6, auto, T-tops. dynomax catback,3.4 headers, home-made FIPK,hypertech pulleys,B&M shiftkit,3.73's,crane compucam 2030
16flat@85.6

 

May I save you a lot of time?
When you see the heads, you will understand why I say this.
Put in ALL NEW Valve GUIDES
Get NEW HD SPrings (FROM GM Perf. Parts book - it states that these heads are good (good!) for 6500rpm with heavy duty springs).
Next, go get a 3.4 cam from the wrecking yard.
It's designed by Crane Cams (states in GM book, too). Even a FWD cam will work!
It's the hottest cam, to slip into your 3.1.
New Chain.
Back cut the valves (30-60-90 degree cut on valves).
Slap together heads.
Go get 1.52 roller tip rockers from Comp Cams.
Fits under stock valve cover.
Assemble engine real seal & leak free tight!
You'll have more HP than you thought!
Incidentialy, when you see those naked heeads, you'll understand why I state this stuff.
These heads are designed quite well.
Spend the effort on those other details & you'll make about 25 extra HP from your current engine HP rating (on a Dyno, not the factory book).
And you'll spend less time & more fun, to boot!

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Chat Soon,
KED85
Karl
1985 Firebird 2.8 to 3.4 swap project for Smog Happy LA, CA

 

... hey KED85..what do you mean by the valve cutting 30-60-90? ...

 

Well I am thinking about going to a junk yard and buying a set to experiment on myself...

 

He means basically a "3 angle valve job". These valves have cuts in them at 30/60/90 degrees.

 

When the heads are being worked upon, the machinist is cutting the seat of the valve, for sealing.
As we are thinking of porting & polishing, the valve grinding machine, does that for us, at the seat of the valve.
It makes a smoother transition, blends the air flow from the combustion chamber into the cylinder head.
This process is also known as back cutting a valve.
When you see these heads, naked or with valves, you'll get a better idea.
But, the 30/60/90 cut is done at the valve seat (by cutting, stones 3 of them) & on the valve by a valve grinding machine.
The 2.8 & 3.1 MPFI heads are identical. As is the 2.8 & 3.1 cam.
3.4 heads are better & different.
Where, unsure.
Why, larger volumn of air is moved, the 3.4 heads were redesigned.
The 3.4 long block is the best of the best.

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Chat Soon,
KED85
Karl
1985 Firebird 2.8 to 3.4 swap project for Smog Happy LA, CA

 

You'll see a raised "floor" inside the intake ports. GM added it to increase flow, so resist the urge to grind it down to nothing.


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-Tom P (Hot rodded 1986 Firebird 2.8l) from http://www.f-body.net/mailbag/3rd/3rd_mailbag.html message boards
---Think your car could be pic of the week? Visit http://www.f-body.net for details!

 

There is no diference in the heads for the 2.8/3.1/3.4 series for fuel injected motors. Here's some info on my website:

http://users.spec.net/home/emxjc/heads.html

I think Tomp is refering to the vane on the intake side of the port floor.

 

Btchin' site on the heads! Good job!


------------------
-Tom P (Hot rodded 1986 Firebird 2.8l) from http://www.f-body.net/mailbag/3rd/3rd_mailbag.html message boards
---Think your car could be pic of the week? Visit http://www.f-body.net for details!

 

THANKS FOR CORRECTING ME!
Checking my GM part book shows that the only difference truly are larger Valves (which are on the 2.8-3.1 heads) & heavier duty springs & retainers to handle the increased RPMs available due to better cam.
Sorry guys!
Karl
So start with the same heads, install new guides, new springs, new retainers, have valves grinded 30/60/90, match same effort on the head valve seat, you'll win! And use the 1.52 roller tip rockers for accuracy.

------------------
Chat Soon,
KED85
Karl
1985 Firebird 2.8 to 3.4 swap project for Smog Happy LA, CA

 

Guys,
Your experiences and knowledge about this engine is helpful for me in putting together this website.

I hope to add more info for each part of the drive train as time allows. Getting data on the 60deg and double checking/confirming what is fact or heresay can be a challenge. I use 5 reference manuals from various sources related to the 2.8/3.1/3.4 but even those do not explain 100% detail. I put this info in to help those separate what is fact from fiction, but even GM's info is so hazy.