Ok this is what I have, 1970 Valiant 225 super six. I got a head off of a 77 aspen wagon, I have ported the lip under the valveseats and the valve guides. next step is shaving the head. I'm not putting in a cam but like I said I have an aluminum super six intake and a BBD from a 318, I am putting 3x2x1 headers and single 2 1/4" exhaust pipe through a turbo muffler.
My question is how much do you all recomend taking off of the head to increase compression? How much can I take off and still use the stock push rods?
How many horses do you think these mods are good for?
Thanks for your advise
Phil

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Phil, i'm thinking with a supersix and BBD i wouldnt go wild on compression or anything, however if you were willing to upgrade to the larger CFM holley carbs then i'd go for it. you can take .080 off the head and still use the stock push rods, but saying you'll be getting the head machined anyways, alittle bowl cleanup wouldnt hurt as well as gasket matching if you havent already done it. (dont forget to match the head AND the intake ) if you've read Doc's head article then you'll know the expression about MAKING THEM SMILE

also i'd reccomend going with a comp cams 252S or something just slightly above stock, if done right you should yeild alittle more gasmilage (or stay the same) with quite abit more power!

Justin

We can't assume too much on your slant so you have to fill in some details before we start cutting.

We need to know how much volume your chamber has in it: smog 54cc? mid-70's 53cc? Someone already cut on it and your down to 52-52.5cc?

and which head gasket are we using:
shim .022 squash
felpro-.039 squash 'avg'

stock push rods stop about .100 off... you will want to check the cup and rocker arm interference before bolting it all together...

According to Al's Static Compression calculator and a whole 'bunch of assumptions':

Say 1977 Aspen 'BL' head with 53 cc chambers, stock deck height, stock bores (3.4"), Fel-Pro .039 squash gasket, cutting .050 out of the head will net you 9.46:1 compression. .040 get around 9.2:1

Don't forget to gasket match the ports in the head, they have loads of 'meat' to carve away for more flow...

-D.Idiot

I just went down stairs and compaired the opening on the intake runners and the openings on the head where the intake connects and the head already has larger openings than the intake. It seems to me that the intake is the one that would need gasket matching, or am I missing somthing? I really doubt that this head has had any previous work done to it. the ports were all rough cast iron and there is a lot of meterial between the base of the head and the marks where the intake/exhaust gasket was.
ID the engine has not been bored and the deck has not been altered. the head is a smog head(I'm going to have to plug the hole on the end of the head). I think I'll use the felpro 0.039 to help ensure a better seal since I'm not having the deck surfaced. What was the stock gasket thickness? wasn't it 0.019? If so would I want to remove 0.070 to gain 0.050 and result with around 9.5? I dont want to go to radical I want to retain some milage and drivablity on pump fuel I'm getting 18-19mpg now.
Justin, I'm going to reread the doc's head article thanks for the reminder
and thank you both for all you helpfull suggestions
Phil

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easiest way to do a gasket match on the head is to buy a intake/exhaust gasket, if the studs are still on the head slip the gasket over the studs and find a place to tape it down, grab a rattle can of a bright color paint (i use a lime color for this) and spray it, pull the gasket off, any paint showing up around the ports is what needs to be taken off, as for the intake/exhaust, line em up and do the same

if you really get into it you can start going into the ports further

Justin

If you can find machinist's 'bluing'(it comes in red and blue colors)( and also in brush & spray cans). You paint the manifold to head surface, and using the gskt as a template, you use a scribe to trace around the gskt's port openings. If you have some radius gauges, you can find the right radius for the port opening corners and thus choose the correct size carbide burr to fit that curvature. If you haven't already picked up a rotary grinder, choose the long 'pencil' grinder. This will give you better control. You can still use the short die grinder, too. It is just a little slower, and more touchy to use. If you lose control, the burr can start bouncing & banging around in the port and may bend the shank of the burr. A good carbide burr can be 20-30 bucks, so you don't want to screw one of them up.

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'66 Cuda 225/4spd
'66 Dart GT convertible 225/auto
'64 Dart GT 340/4spd

no no you guys arent listening my intake cant possibly flow as much as my head now. the intake runners are smaller than the ports in the head. I'm not going to get and offy or clifford and 4 barrel.
I did get a tungsten carbide cutter for my dremmel that is what I used to do most of my porting, I also used a few different grinding wheels for some of it and to allow the carbide cutter to cool. the carbide cutter worked best when it was cool to the touch. the tungsten carbide cutter for the dremmel is around $8 at walmart. sears hardware had 4 or 5 different ones but they were around $15.

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you can do the same thing on your intake manifold as you did on your exhaust . just switching intakes will not solve this, you'll have to port the intake itself to match the intake ports on the head


Justin

What would one use to port the LONG runners on the intake?
Offey's have much bigger ports than a stock super six aluminum intake dont they?
I didn't do any thing to the exhaust. I'm putting a header on it.

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Hey, '70 Valiant. You don't have to port the entire runner in the intake. What needs to get done is port matching. With the difference in sizes between your intake and head ports, there's a point at the transition that generates a turbulence area that hurts airflow. If you just make the head end of the intake runners match the head ports in size and shape, blending it back into the runner, so that everything is as smooth as possible when the airflow transits from the intake to the head, that's what you're after. You'll also want to ensure that the gasket isn't a stumbling block for the airflow, either.

Roger

AAAHHHH!! ok now I understand!! I just need to match the intake manifold port to the head port opening right?

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So would taking 0.100" off then use the thick head gasket resulting in an actual difference of 0.080" give me around 9.5to1 compression?

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Never port the intake manifold flange the same size as the head flange. If the ports do not line up exactly when installed, there will be a lip that protrudes into the port. It's better to leave the intake port a little smaller, about .010, than the head port so a mismatch won't hinder flow.

Cecil

How do you line up your intake and keep everyting straight? Since the intake has some play and can move around a bit

Rick

Pull the cylinder head, pop the intake valves, peer down the intake port and align the manifold opening with the intake port. Once this is done make a mark on the outside so you can align them up again, when doing final assembly.

The other way is to pull the head, using a T-square make align marks showing the outer edge of the intake ports.Do the same with the intake. Align those marks on final assembly.