Novice engine builder seeking advice

[RAC95054]

Hey, everyone.  I have a '70 GTX with the original 440, intake, carb, heads, exhaust manifolds... but when a previous owner rebuilt it, he put in new pistons, crank and cam.  The cam is aggressive (an older Crower, 509, other specs I forgot off the top of my head), and I need race gas to prevent pinging because of it (I've tried lots of carb adjustments, backing off the timing, etc, but at the cost of less HP).  It does come to life nicely at high RMP though.    

In any event, I was debating putting on a set of aluminum heads to help with the pinging, and try to get the HP up a bit.  My questions are:

1) Leaving on mostly stock equipment, will the heads help performance that much (i.e. without headers, etc)?

2) Once I get the heads (after having them cleaned up/checked), is it as simple as removing the old ones, and putting on the new ones (with new gaskets, bolts, etc of course), and reusing the rod and the original rockers (in the order removed)?

3) And if #2 is basically that simple, are there any special tools needed beyond a nice torque wrench?  Do I need an engine lift to remove manifold, or anything else?  Any gottchas to watch out for?

Thanks! 

-Russ

[c00nhunterjoe]

manifold's lift right off and only weigh a few pounds.

heads are not too bad either.

the cam alone will not cause you to need race fuel, compression ratio along with total cylinder pressure will. if it is pinging on 93 octane then you probably have pretty good compression ratio, sounds a bit odd though as i run an 11:1 motor with a decent cam (.510 lift, 292 adv duration) and i run all day long on 93 octane with 38 degrees of total timing.  

you need to find out what kind of pistons are in the engine before you go ordering new heads. i would suspect based on what you describe that you have a pop-up domed piston. you need to find out for sure the pistons and cam specs so you know about valve clearance. again, i suspect that if you want to drop compression to allow for normal gas that you will go with an 88 cc head to drop it down some, but again, we are guessing until you know what is in your engine currently

[RAC95054]

Thanks for the reply.  I believe my cam is also a 292 (or maybe 295), and just doing a pressure test of the cylinders, I was getting about 185 psi is each (which seemed on the high side to me).  It has the stock heads/rockers, so I assume the pistons are not domed.  They are supposedly TRW gapless rings being used. 

Just to be clear, it still pings with 100 octane.  With 110, it seemed to stop (as long as I didn't have too much advance... 38 degress or less).  So yes, compression must be high (11ish:1), but not sure if the heads were milled, or the block deck, etc, but I don't believe they were. 

Thanks again.

[c00nhunterjoe]

perhaps cam timing is off? pinging on 100 octane is odd.

[Challenger340]

I agree that the best course of action, is to initially remove one of your current Iron Cylinder heads, "verify" the current Compression Ratio/Piston combo as the cause of the Pinging, then Purchase/Install a set of Aluminum Aftermarket Heads to address the Issue, if C.R. is found to be too high.

Edelbrock RPM Heads ?
Stealth Heads from 440 source ?

There are many Aluminum Heads available on the Market, in various CC configurations, with the added benefit of the Aluminums heat dissapation characteristics, which is like dropping 1 pt in Compression Ratio for Fuel Octane requirement.

Most work with stock attachments & parts, and require only basic tools/knowledge/equipment to install, possibly a few "tips" from here.

Best C.R. range for an Aluminum Head running on Pump Fuel, is to shoot for 10-10.3:1 with 225-230'ish @ .050 Camshafts.

Pretty much all the Aluminum Heads available aftermarket, should provide a Performance Increase from your Iron Heads, even with the lower effective C.R.

[RAC95054]

Thanks again guys for the input.  Yeah, it sounds like at a minimum, I need to pull a head and see where I'm at from there, but would likely then put on a set of RPMs or cleaned up Stealth heads after doing so (since half the work would already be done in doing so).  I suppose a cam swap is another option, but a bit more involved.  So many options, too little time. 

[Chatt69chgr]

The Edelbrock 84cc heads are closed chambered but unless you are running a .040 to .055 piston to head clearance then you would not achieve Quench and so the 88cc Edelbrocks would be just as good to get to the recommended final static compression ratio.  It's going to depend on the pistons you have and whether the block has been decked.  Assuming you do buy aluminum heads go with the Edelbrocks.  The Stealths have had problems with too valve guide clearance being too tight, valves not seating properly, and valve lock/retainer issues.  Now you will still need to have any set of aftermarket heads including Edelbrocks taken apart and valve guide clearances checked, spring pressures checked, and valve seating checked.  You cannot just bolt them on.  You can also do a certain amount of adjustment of the CR with the thickness of the head gasket.

[flyinlow]

No headers ?

Without a free flowing exhuast you will limit the benifits of the better heads.

It is the old story. The engine is an air pump. The most resrictive part of the system,from the cold air intake to the exhuast tips will be your limiter.

Pick matched components for the power level you want.