540ish Hemi rebuild

[Paul G]

This engine is in my 69 Road Runner convertible. It has a 46rh overdrive behind it with 4.11 gears. I bought this car as another rescue. it was running pretty sour and needing lots of TLC. The engine was down on compression in three cylinders, broken ring lands in all three, scoring on the cylinder walls. Short block is with machinist now. Probably be there for months.

Not just a 540 Hemi, there is an F1 Procharger   on it with a water meth system. Why someone would build this in a convertible is beyond me. Cant race it, wont meet NHRA tech with a convertible and no cage. But it does have a drive shaft loop  .

Now, how to build this engine the right way. I think they added the water meth because of the high compression, but I dont think it worked. Probably ran out of water/meth and toasted the engine, my guess anyway.

The combo;
Block - 426 Mopar block, bored .030" over stock. Needs another bore to clean up the scratches. Machinist says it should clean up with another .010" Would put it at 4.290" bore.
Crank - 4.500" stroke, 2.200" journals, BBC crank, needs a polish.
Rods -  Eagle H beam 7.1" good shape.
Pistons - I measured 1.35" compression height, no other markings on them. The pins are up in oil ring. Need replaced
Cam -  It has a bad lobe, there numbers on it I will put a pic of, but I have not found out what it is. Needs replaced anyway.
Lifters - Solid rollers that look good. The roller on the bad lobe has no visable damage. But, I found a hydraulic lifter plunger laying in the bottom of the oil pan. Where did it come from?  
Push rods - Their big boys, all straight and look ok.
Heads - Indy 426 Legend

The bearings are not good. Lots of lines in them. Metal has most likely gone through the engine at some point.

I want to keep the Procharger since they had sliced up the inner fenders a little to get it in there. Keep the water meth too. But I want it safe even without it.  

What I want this to be is an easy to drive street combo while still using the Procharger. I would like to use as much of what I have as possible.

My biggest question is, how much compression and how to get there? Custom pistons are in my future.    

[heyoldguy]

Aaah I think..........Camshaft looks like Comp Cams ZT series solid roller high rocker ratio endurance application like NASCAR Camping World Truck Series

4819 intake lobe/4817 exhaust lobe on 110 LSA, 300/296 @ .020", 268/264 @ .050", .411"/.409" lobe lift. Recommended valve springs are COMP #26099 or #26091

[metallicareload99]

Those must be custom pistons to begin with? Not trying to nitpick, but I'm coming up with around 518 CID by my math Even with small domes I figure that thing is already near 10:1+ compression. Paying close attention, this sounds like fun with the ProCharger

[Challenger340]

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[Challenger340]

I will echo Jim's ID of CompCams 4819/4817 Lobes, and it appears as though someone may have initially been thinking 'Turbo" application ? with the smaller Exhaust profile/higher Exhaust pressure commonly used to drive the Turbo harder ?

No matter...
how much power are you targeting ?

Your Call, but IMO, you don't need the water/meth injection.
My rationale being the more there is ?..... the more there is to go wrong !

And with pretty low boost 91 Octane compatible pretty easy to get a TON of power anyways ?

For example only here: we just did a 572 KB/Stage V with 10-71 BDS that bumped 1200 hp at 8-9 psi ?
and just say'in....
so I can't see how even a no-brainer 6-8 psi 540 can't easily give you 800-900hp with UTMOST driveable reliability, however, I would LOSE anything Camshaft-wise that requires 550+ V/Spring rates(the Cam you currently have) in favor of what's called a STREET Mechanical Roller Camshaft...... that is designed for extended STREET driving/usage