eddy heads

[cwhubb]

I've decided to buy eddy heads but am undecided on chamber size and between e street vs rpm's, should I go 74cc or 84 cc chambers? e street or rpms? the flow on the two heads are listed as the same even though the rpm's are hand blended, I don't get that
Thanks

 

[benno440]

lower cc's is more compression, I thought the e streets were for pretty much stock engines and the rpm are the next step up

 

[67 B-body]

When I had my rotating assy balanced, the owner of the machine shop told me that he had to do a decent amount of milling to most of the Edelbrock 84cc heads just to get them down to a true 84cc. I think I would go with the RPM 74cc "providing you've thought out the rest of your engine components to support such a head".
If you have a zero deck, with flat top pistons 0cc "no valve relief", .041" head gasket with 4.5" bore, and those 74cc heads, you'll have a comp ratio of 11.78:1. Now that is pretty high, but I doubt you have a true zero deck engine.....
Lets look at .025" deck height, and a couple valve reliefs "5cc" in a flat top piston design with the same head gasket and 74cc head. This gives you about 10.5:1 comp ratio..... With your aluminum head, you'll be right at a good spot for a hot street cam, and a good induction system, along with a good set of headers. The 84cc head with all things else being the same takes you down to 9.6:1 comp ratio......
Good luck!!

 

[67Satty]

I spoke to an Edelbrock rep from the Torrance, CA headquarters who was at the local cruise night a couple weeks ago. He was a Mopar guy and knew his stuff. I asked him about the 75cc E Streets and he told me that they were still being worked on, that they weren't available yet. I've been interested in these for awhile myself, so if anyone has any info about where they are available, I'm all ears, but I really don't think they are out yet.

 

[IQ52]

Most Edelbrock techs and reps I have spoken with weren't the most knowledgeable people I've seen. I remember when they told me that the Victor and RPM aluminum heads don't lift the rocker arm shaft away from the camshaft when they warm up so you don't have to set the valve lash tighter when cold.

ANYBODY who has checked the valve lash hot and cold knows that aluminum heads require tigher valve lash when cold because the head expands and loosens the lash!

Appearently, if you give Jeg's $1,473.99 they will ship you a pair of Edelbrock 5090 75cc big block Mopar E-Street cylinder heads on Monday. At least so says their website.

 

[Cranky]

All heads expand some but aluminum expands a bit more. Also, all push rods will grow too. You just have to see what yours will do once the engine is together and running....but I tend to lean towards smaller chamber heads and if compression is too high, it's not that hard to reduce it some. It's usually much harder to raise it you're down below what you want to be.

 

[cwhubb]

you guys bring up a good point, expansion. will the expansion/contraction cycle loosen head and header bolts? I would hate to have to keep re-torqueing. Do the valves and guides leak untill the head warms up? with the expansion contraction does it create a metal fatigue problem do you have to get them milled or have the valve seats re-machined to compensate? I ask a millon questions and I appologise for the aggravation but I can only afford to do this once. Did you ever see that daffy duck cartoon where he scarfs all that dynamite and drinks a gallon of gas, lights a match then says "pay attention I can only do this once? That's me. I'm at 10:5:1 now so the conclusion I'm jumping to is if I use a smaller chamber I will get a higher compression ratio but wont have to worry about pinging because the aluminum will run cooler than iron, win win?

 

[Mopars & Missiles]

....... owner of the machine shop told me that he had to do a decent amount of milling to most of the Edelbrock 84cc heads just to get them down to a true 84cc.

I measured my RPM heads before assembly, each and every chamber was almost exactly 84cc's. No more than 0.5cc variation on mine. Guess I got lucky. Also, my CR is 11.3 with the 84cc RPM's.

 

[cwhubb]

what was the cr with the irons?

 

[Mopars & Missiles]

what was the cr with the irons?

Zero!


There wasn't any CR with irons on this engine because there were no iron heads previously. Its a completely new build with all new componets. Only thing that is stock is the block, and that has been extensively machined and modified for this build. Its a 499 cu. in. stroker that is built for 600/600 torque/HP.

 

[IQ52]

Aaaah!............If you are already at 10.5, DON'T INSTALL THE 75cc HEADS! Why do we always want to take these thinks to the edge of detonation..............or beyond? You don't gain that much horsepower with the compression unless you add camshaft to it!

 

[Cranky]

you guys bring up a good point, expansion. will the expansion/contraction cycle loosen head and header bolts? I would hate to have to keep re-torqueing. Do the valves and guides leak untill the head warms up? with the expansion contraction does it create a metal fatigue problem do you have to get them milled or have the valve seats re-machined to compensate? I ask a millon questions and I appologise for the aggravation but I can only afford to do this once. Did you ever see that daffy duck cartoon where he scarfs all that dynamite and drinks a gallon of gas, lights a match then says "pay attention I can only do this once? That's me. I'm at 10:5:1 now so the conclusion I'm jumping to is if I use a smaller chamber I will get a higher compression ratio but wont have to worry about pinging because the aluminum will run cooler than iron, win win?

All metal fatigues after many heat cycles and yes, valves and guides can leak a bit when cold but it's nothing to worry about. As for the head bolts, I like to torque mine to the maximum and usually never have a problem and aluminum does dissipate heat faster than iron. Your dynamic compression will dictate if you have ping issues but usually anything over 190 cranking pressure might cause you problems.

 

[bigblock]

Aluminum heads have been around for 60 years. Might have to replace a HG every 100k, but so what? Also drops the CR about 1 point so calculate that into the build. I had an early set years ago and the specs were all over the spectrum,I'm sure they have sorted all that out by now. DO NOT USE THE VALVE SPRINGS. Order springs to match your cam,and if you're wise you will use a roller cam due to the piss poor oil these days.

 

[67Satty]

Most Edelbrock techs and reps I have spoken with weren't the most knowledgeable people I've seen. I remember when they told me that the Victor and RPM aluminum heads don't lift the rocker arm shaft away from the camshaft when they warm up so you don't have to set the valve lash tighter when cold.

ANYBODY who has checked the valve lash hot and cold knows that aluminum heads require tigher valve lash when cold because the head expands and loosens the lash!

Appearently, if you give Jeg's $1,473.99 they will ship you a pair of Edelbrock 5090 75cc big block Mopar E-Street cylinder heads on Monday. At least so says their website.

I'll do ya one better, I called Summit and they said have them in stock and they'd ship me a pair for $1249 - no shipping charges, that's down there near Stealth-price territory! But you're right, the Edelbrock guy at the show, whose only job is to know what products they have for sale and to help promote them to guys like me, was clueless about the E Streets.

Still really curious about the 75cc E Streets.

 

[cwhubb]

thanks for all the advice everyone, I'll go with the rpms

 

[Cranky]

Aluminum heads don't actually drop CR but since they dissipate heat so rapidly, it acts like you have lower compression. Heat is energy after all. With a tight quench and the right cam etc, 11-1+ CR is possible on pump gas and 10.5-1 is easy. Do your homework if you plan on going more than 10.5-1 on the street.....

 

[Sweet5ltr]

I keep on telling everyone who will listen, that it is near impossible to run 10.5:1 with a carbed application on today's ethanol infused pump gas, let alone 11:1. Modern ECU's adjust timing (which can be done in our cars, with a retard box) but they do this in milliseconds and also have ten if not twenty other variables and factors that can impact when they retard timing (which in effect, drops power). Do yourself a favor, stick with a REASONABLE compression ratio of 10.25:1 (which would more than likely require 84cc Eddy's) and call it a day. You will be making more power, by actually being able to optimally tune your engine to the compression ratio, other than de-tuning it to live on pump gas.

 

[cwhubb]

The car came with 10:5:1, fresh rebuild so I'm not touching the internals other than going to a solid cam, my 6,300 ft elevation makes it a bit more sh#t gas friendly, I live in los alamos nm, the nearest track is 5,200 ft, so I'm trying to get the most out of the car as I can and still drive it on the street, This is my thought process here... since the air is less dense at altitude I'm trying to increase my power by enhancing air flow, good heads, higher lift cam, bigger carb, I figured if I'm going to get aluminum heads I might as well explore the possibility of the smaller chamber. I'll go with the 84cc's, I might even use a thicker head gasket to de tune a bit

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@ mopar and missles thats a beautiful motor

 

[Sweet5ltr]

The car came with 10:5:1, fresh rebuild so I'm not touching the internals other than going to a solid cam, my 6,300 ft elevation makes it a bit more sh#t gas friendly, I live in los alamos nm, the nearest track is 5,200 ft, so I'm trying to get the most out of the car as I can and still drive it on the street, This is my thought process here... since the air is less dense at altitude I'm trying to increase my power by enhancing air flow, good heads, higher lift cam, bigger carb, I figured if I'm going to get aluminum heads I might as well explore the possibility of the smaller chamber. I'll go with the 84cc's, I might even use a thicker head gasket to de tune a bit

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@ mopar and missles thats a beautiful motor

Yeah, I am not saying you can't run 10.5:1, but my engine is borderline (without mystical' quench effect) at 10.25:1 with a massive solid camshaft @ sea level. I would try and get as close to this ratio as possible for ease of tuning.

 

[67 B-body]

Gosh guys,
I have .140" domed pistons in a 440 with 72cc chambers.... I can run 93 octane!
It will run on a bit if in neutral with a higher idle speed.... Of course this goes away with some AV Gas...... but doable.....