[Burningbird]

Hi! Just ordered a 501 shortblock-kit from Butler with their 325cfm RPM-heads (CNC-chambers). The engine is for my -65 Bonneville. This car will mainly be driven on the street, but will also be raced @ the track maybe once or twice a year just for fun. Here are some of the specs and parts I planning to buy, please let me know what you think.

*455 0.060" over, Ross flat top pistons, Eagle 4.5" forged crank, Eagle 6.800" H-beam rods, Billet 4-bolt main caps, Butler crank scraper.
*Edelbrock/Butler 325cfm RPM-heads 87cc, 11:1 compression ratio.
*Lunati Voodoo HR (20510713) with Lunati lifters.
294/302 adv, 243/251 @ .050, 616/622 lift with 1.65 rockers, 110 LSA, 106 ICL (Already purchased through Butler).
*Scorpion Race 1.65 alu. rockers.
*New HEI distributor with BOP polymer gear.
*Mad Dog 1 7/8" round port headers, 3" mandrel bent exhaust with X-pipe.
*KRE Northwind intake, Quick Fuel QS 950 Street Carb. (I also have a Performer RPM and 800cfm Q-jet I want to try).
*Stock style fuel pump with RobbMc Power surge system.

Car has 3.55 gears with posi, TH-400, Hughes 3000-stall converter (GM30HD) and weighs about 4200lbs.

[tempest1964]

Sounds really bad-a$$!

[1968GTO421]

There's a member here (who's also on the GTO forum) who was on last years Power Tour and had his Scorpion rockers fail on him around the pushrod holes. Like a bad cam lobe he's having to go through the whole engine. Locally I've heard both great responses on Scorpion rockers and many who've had failure.

With the $$$$$ you're putting in this engine, I'd spend a little more and get the Crower stainless rockers. I've only heard good things here about them (except price) but they won't leave you needing a rebuild and clean-out of debris either. Otherwise, your choices sound great. Love those Voodoo's.

Sounds like you're going to have one mean stomping engine and Bonneville when all is done. Great to hear you're using a "big" Pontiac for your build!

[grivera]

Cliff posted pics of Scorpion rockers that were cracked in this thread:
http://forums.maxperformanceinc.com/...light=scorpion

[Steve C.]

Compression ratio is too high. My .02


Many years ago when I was planning my previous 462 build with Edelbrock aluminium cylinder heads I contacted Dave Bisschop about compression ratios. At the time based on his dyno testing he was recommending a maximum of 10.25 compression with the 87cc Edelbrock chamber design as cast and 10.5 compression with the 72cc Edelbrock chamber design as cast. This was a general recommendation for engines leaving his shop to be used under all types of driving conditions, unknown gas quality, unknown camshaft pararmeters, and not knowing how the end customer would tune and operate the combination. Obviously under the right conditions it could be higher but like many proffesional engine builders there not going to suggest pushing it for most people with a lot of unknowns.

Keep in mind this statement, "The design of the combustion chamber influences the performance of the engine and its anti-knock properties. The layout and shape of the combustion chamber has a bearing on the thermal efficiency and performance as well."

In these compressiion discussions some will suggest a certian compression ratio with the KRE aluminium d-port chamber design, often pushing 11:1 ratio. Not apples-to-apples with the older Edelbrock chamber design. The unmodified as cast older Edelbrock chamber design can dictate a differant amount of static compression. The use of the KRE d-port head can help push the compression envelope, as would the newer design Edelbrock chambers with the better design similar to the KRE head. (other things also factor in, it's more than just the chamber design)


.

[steve25]

I think you need to start thinking about the drive train needed to survive behind this motor!

[Burningbird]

Thanks for the "heads up" about the Scorpion rockers. I'll ask Butler which rockers they recommend for my combo. The Crower's is probably best, but is quite expensive.
Steve C, these heads have the new CNC heart shaped chambers. I live in Sweden were we still have 94-octane at the gas station and it rarely gets above degrees 80°F in the summer. I hope this reduces the risk of detonation. My previous engine, a 400 (406) with ported iron heads and 10.1:1 comp. run fine without any problems. I have tried to "copy" some of your engine combo with this build, but a little milder version than your's.
steve25, I hope the drivetrain will hold up, not too sure about the 295 Cooper Cobra's in the rear...

[steve25]

If you still have a one leg differential you might as well have a 350 cid motor in there as that 501 will not provide much more than high speed fun!

Also don't forget that the cars fuel system needs have just gone up big time, you now need a fuel system that can in free flow dump out a Gallon of fuel in 40 seconds!

['ol Pinion head]

Just a few thoughts... then someone can crucify me for bringing it up

An .060 455, I'd be concerned about cyl wall thickness. Would not a proper short fill of hard block, folllowed by block machinework, & an oilcooler make sense w/ any stock block with one of these 4.5" stroker cranks? 6.8 rods with 4.5 stroke is going to result in a 1.51 R/S....short skirt design custom piston, quicker cyl bore wear.

[Steve C.]

Burningbird- Thanks for the update, I was not aware the RPM version was avaialble with heart shaped chambers. I thought only the new d-port version had them.


.

[grivera]

Originally Posted by Burningbird

Thanks for the "heads up" about the Scorpion rockers. I'll ask Butler which rockers they recommend for my combo. The Crower's is probably best, but is quite expensive...

These Harland Sharp heavy duty are nice and don't break the bank: http://www.jegs.com/i/Harland+Sharp/...FUeHswoduccJsA

[gtofreek]

Sounds good, but does that kit come with 6.8" rods? I ask because most 4.5" stroke kits have 6.7" rods, as the 6.8" rods make the piston really short. 1.17" compression height.

Also, I would spend the extra on Crowers. It's only $250-$300 more. When looking at the total cost of building an engine like this, $250-$300 is nothing.

I love the Voodoo cams. I use a lot of them. I installed the one you got in a 455. It ran like a scalded dog! I would install it on a 104° ICL, though, not 106°. These Voodoos really need to be 6° advanced. That ought to pretty much ward off the detonation.

If you're going to use the Lunati Lifters, you need to grind a small groove in the lifter bore to lower the oil feed hole 1/4". Otherwise the oil groove in the lifter will not line up with the oil hole when on the base circle. This will result in the lifters slowly bleeding down until they are empty, then they won't be able to fill back up, and they will be noisy. The oil groove mod, allows the lifter to fill on the base circle, when it's supposed to. I did a lot of testing with this to figure out what was happening with all the noisy HR lifter complaints. The lifter bodies are Chevy bodies and don't have the oil band in the right place. You can do a search for "noisy Hydraulic roller lifters" on here, and I started a thread about that, and have pics of the mod.

If you need help at all, I have a friend in Sweden who is a very good engine builder, and has experience with Pontiacs. His name is Peter Lindberg, and is part owner of PPM Racing. He might be a good resource for you over there.

[Steve C.]

'ol Pinion head has brought up a good point about block fill.

In part from Jim Butler in a related Q&A topic- March/April 1997 PE magazine....

The Pontiac block has thin cylinders, and there not supported or reinforced in the lower part of the water jacket. Most friction is produced as the piston starts up the cylinder from BDC. The longer the stroke and shorter the rod, the more angle the rod has relative to the direction of piston movement. The pressure or load on the outside of the cylinder increases with the longer stroke. The cylinder wall starts to distort from the outward force caused by the rod angle as the piston stops and begins the upward movement. The force on the piston and cylinder is drastically increased at this point over any other part of the stroke or cycle. The rod angle and pin location in the piston can effect the amount of pressure the piston has on the cylinder.

I would think the longer 4.500" stroke contributes to this situation.

The force caused by the rod-to-stroke angle can cause the cylinder to distort, which produces friction, since it does not match the shape of the piston moving against it. The problem has been solved for quite some time by filling the lower part of the water jacket. Jim built two engines for his son's street car. Both engines had 455 blocks. One was filled and the other wasn't. The filled block ran 10 to 15 degrees cooler than the unfilled block. Upon tear-down and inspection, the cylinder walls on the unfilled block were seen to be scratched and scored from excessive friction. When measured with a dial bore guage, they were found to be out of round. The filled block was smooth and the bore round. You do lose significant coolant capacity by filling the block. However, the difference in the amount of friction produced is much improved. I'd certainly consider it knowing this.


.

[77 TRASHCAN]

The 6.8 rod has bitten at least one 4.5" stroke engine, that I know of...I would not do that...

Have you checked cylinder wall thickness, yet? 455 blocks can be very thin, but are seldom more than minimal @ .060. as stated the 4.5 stroke crank puts more stress on the cylinders...

11:1 may be too much. Many steps have to be taken to make this compression ratio work.

[Cliff R]

501 CID and 11 to 1 compression will manage pump fuel w/o issues, however the cam is a tad small and tight LSA, both of which work against you when it comes to using pump fuel with high compression.

My 455 is 11 to 1 compression (10.99 exactly), and it does fine on pump gas. Cam specs are 289/308, 236/245 on a 112LSA with the ICL at 109.5 degrees........for comparison purposes.....Cliff

[gtofreek]

Cliff, I used that cam in a 455 and it manages pump gas just fine. It was high tens on compression. These aren't Comp lobes, so the same laws don't apply.

[Burningbird]

Thanks for all the wisdom and help given in this thread, appreciate it! I will try to clarify some things. The block, rotating assembly and heads is bought from Butler as a ready to assemble shortblock kit. According to their website the rods in the kit is 6.8" long. From Butler's website:

"462-501 CI short block kit
*Complete Internally Balanced longrod rotating assembly & high-performance prepped block
*4.000", 4.210", 4.250", or 4.500" stroke cast or forged crank (4-Bolt Billet Mains Caps recommended for 4.5" stroke)
*Internally Balanced
*Ross Racing Pistons (Bore 4.181 - 4.211)-Flat Top (Dish or Dome/additional charge)
*H-Beam Rods
*File fit rings
*Performance Rod bearings
*Performance Main bearings
*455 Performance Prepped Block
cleaned
*magnafluxed
*sonic tested
*completely deburred
*bored and honed with torque plate
*line honed with ARP main studs
*deck squared
*cam bearings and brass freeze plugs installed
*ready to assemble"

I will contact Butler and see if they the can short fill the block with Hard Block which seems like a good idea. Thank you for the information about the Lunati roller lifters Paul! I will definitely make the modification you suggested. The timing set is a 9-way so I will install the cam with the ICL @104°. If the engine can't take the 11:1 compression without knocking I will follow Cliff's advice and try another cam, perhaps the Road Paver with 114LSA?

steve25 - The rear end is being rebuilt with Fabcraft's 3:55 HD gear and a custom posi unit from Jeff at Engineered Performance. The TH400 trans will get a Hughes performance rebuild kit and HD sprag. The carb will be supplied through a RobbMc Power Surge system rated to 900hp @ 7psi.

[gtofreek]

You''l be fine with that Voodoo cam. I use a lot of them and it'll be fine.

[Cliff R]

Paul, agreed, for sure that cam would be fine in a 455 with some compression in it on pump gas, but this engine is 501cid and a solid 11 to 1 compression. Pound for pound it's smaller than my OF cam in my 455, and tighter LSA. I'm not sure if it would be pump gas friendly or not, since it's territory I've not been in yet, but at a glance it raises a flag from where I'm sitting.......Cliff

[gtofreek]

I guarantee you that cam will make power well past 6000 rpm, and the point at which hydraulic lifters meet there limit. How fast does one want to spin a 4.5" stroke? Don't know how you figure it's smaller than your OF cam. The 231/239 Voodoo pretty much matches the OF[within 2°]. This cam is quite a bit bigger than OF. IIRC, it was bigger than the RP at .200" also. If it is installed at 103°-104° ICL, I wouldn't be worried at all of it detonating. There is a lot more to detonation than just the intake closing point. Contaminating the intake charge with exhaust gasses is a bigger cause of detonation, than intake closing point. Less exhaust gasses in the charge, means a faster burn rate of the A/F in the chamber. Get that A/F burned before max cylinder pressure occurs, and it won't detonate. The only VooDoo cammed engine that I built that has detonated is a 428 with 10.8:1 Compression with #62 iron heads. That engine has the 233/241 HFT Voodoo in it, on a 110°, and it only detonates in the heat of the summer here. During the cool months, it's fine on 91 octane. Key is getting these Voodoos advanced. Harold did things to these lobes that no one else has ever done[and it's not just the non-symmetrical lobes, there's a lot more to it than that], and that's why his 110° LSA lobes have the power band of others 114° lobes. Remember the 413 I recently did, and posted results for here? That engine made over 400 ft. lbs. of torque at 1500 rpm, and made peak power at 5300, but carried that same power out to 6000 RPM. That's a 4500 RPM power band on a 110° lobe in a 400. That was on 91 pump gas too, at 10.1:1 compression. No detonation. That thing had to be making a ton of cylinder pressure to make 415 ft. lbs. at 1500 RPM. I bet this 501 will make well over 500 ft. lbs. at 1500 rpm with this cam.