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Old 11-26-2011, 01:52 PM
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Originally Posted by wild_man84
Im going to be working with stock 4 bolt main 454 Gen IV bottom end.. ( in vehicle) I have a set of stock 781 heads.... I'm ready to send the heads off to a machine shop for work ( if needed/recommended) for new parts to match cam and for port&polish job.
Don't say port&polish. It's a term from decades ago that no longer applies. These days, you want the exhaust ports polished, but you want the intake ports rough, like a fingernail file. This helps to keep fuel in suspension.

Originally Posted by wild_man84
Ive been searching and it looks like the cc's of the 781 are 115-118 cc's.
You will have no idea unless you pour them yourself. I'll refer to a previous post on the subject....
Building a motor that will make power for a length of time requires doing the same drill every time. It ain't rocket surgery, but it does require that you know what you're doing and that you pay attention. All the parts must be figured out ahead of time to work with each other and generate a product that will do what you want it to do.

I'm constantly amazed at the fellows who come on here and tell us how they don't have a clue what's inside the motor, but they're gonna install a world-beater camshaft in the motor.

Start a log and record all the parts that you use, part name, description, manufacturer, part number and dimensions that you, yourself have taken off the part with your own precision measuring equipment.

Part of the blueprinting process that you must do if you intend to build the motor correctly is "pouring" or "cc-ing" the combustion chambers. Most shops, I think, will charge around 100 bucks to do 8 chambers. You can invest the 100 bucks into equipment and do it yourself. That way, you have the equipment to do another motor down the road or to make a little money pouring heads for friends. I might be thinkin' 60 bucks for a set of V8 heads, 50 bucks for a set of V6 heads, 45 bucks for a straight 6 head and 30 bucks for a 4-banger head. Just doin' a few jobs for friends would pay for the equipment. After that, you'd be makin' pocket money. You would need the heads to be clean and complete with valves and spark plugs. You will not need springs, retainers or locks.

You could also cc dome pistons if you have a cylinder to slide 'em into. If you're interested, I can explain the procedure to you. This cc equipment is very light and could be hauled over to someone's garage to do the measuring (for instance on a block that would be hard to haul around).

Buy this cast iron base....

This 100cc acrylic burette....

This piece of plexiglas....

And these cylinder head work stands....

Originally Posted by wild_man84
The cam im looking at recommends CR to be 9:1+.
Can I and how do I get my CR up without bottom end work?
You're making the classic rookie mistake of choosing a cam before knowing anything else about your motor. At least you realize that there is a relationship between SCR and cam timing. I suspect the stock SCR is somewhere around 8.5:1, so short of changing the crank and/or the pistons, you're stuck with it and should choose a corresponding cam grind.

Originally Posted by wild_man84
Should I get the bigger valves 2.19 and 1.88?
Larger valves will help on a set of heads such as these. If they're not already fitted with larger valves, you may consider cutting the seats and installing the larger valves.

Originally Posted by wild_man84
What should I tell the machine shop to do with my heads ( mill? cc? P&P )
First, cc them at home and mark the volume beside each chamber with a Sharpie. Then take them to the shop and discuss what needs to be done and how much it will cost. Begin by magnafluxing them for cracks. You may find that the amount of work and the money involved will come close to or even exceed the cost of a new set of heads that are ready to go out of the box, such as the RHS 320 cast iron heads.

Originally Posted by wild_man84
Should I use 0.020" shims (read that) Port match gasket?
If you're asking about head gasket thickness, that will be determined by the piston deck height. You want PDH and gasket thickness combined to be around 0.050" to 0.060". Larger diameter pistons than a small block allows the edge of the piston to come up further in the bore as they swivel on the pin, so allow a little additional room for the squish, over a small block.
I don't port match unless it is a max effort motor where every little thing counts. Most times, the grinding is not carried back into the port far enough and it appears in cross section to look like an Anaconda that swallowed a pig. The increased volume at that point will slow down the mixture as it travels the port and may allow fuel to drop out of suspension, giving you tuning headaches that you may not be able to fix.

Originally Posted by wild_man84
The cam recommends 2 different valve spring sizes, how Would I determine the answer. so in the future, I can figure it out for myself instead of having to ask. here is what it offers/recommends for the cam...Single Outer Valve Springs: 1.524" O.D., 1.110" I.D. OR
Dual Valve Springs: 1.509" O.D. Outer, .697" I.D. Inner On a guess, Id say the Dual valve springs BC of High RPM and my cam is .51 lift int & exh. and my rocker ratio is 1.72? is that right
If there is any doubt of what spring to use, call the grinder and talk to them. This is too important not to get the exact right answer. Factory stock BBC rocker arm ratio is 1.7:1. Because of the acute angles on the valves and pushrods, I would not use anything more radical.

Originally Posted by wild_man84
Not a daily driver.. Looking to get high tq. rpm range (2200 to 5800)
I would begin with this piston or one like it in forged. With a 119cc chamber, they will make 10.2:1 SCR. Then you can match up a cam that will pull hard, something like this roller....
Dynamic compression ratio with this cam is 8.53:1....
Or, if you want a little more cam....
Dynamic compression ratio with this cam is 8.36:1....
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