383 Aluminum Heads; What Works

[deputycrawford]

My earlier post is "Hydraulic Vs. Solid, I want more."  My engine specs are in it. In short I will give a few of the basics. 4:10 gear, 9 1/2 inch converter (3500 stall). 383 .040 over, stock rods and crank reconditioned and balanced, 1/2 inch oil pick up, 7qt pan. 9.5 to 1 compression with 75 cc chambers. I will go to 70 cc chambers for 10 to 1 and a solid cam for around 2800 to 6500 power band. My question is, does it matter if I go with ported Eddy's or ported Indy EZ heads. I will be running the car at MIlan Dragway as much as I can. I only drive it on the street about 1000 miles a year and don't mind having to deal with a drag style car on the street. I kinda think its cool to shake so badly at a light that you cant see straight. I do run solid mounts after I broke a "guaranteed" mount and rolled the motor over under the hood gouging it. I love all of the nasty drive habits. Oh, I have an Eddy RPM intake and a 750 Mighty Demon with an entire 1/2 inch fuel set up. What should I run for a high 11 sec or low 12 sec pass and drive it home? I think I have the rest of the engine combo ready. I just need to finish the combo.

[Chryco Psycho]

to get 70 cc chamber you need Indy EZ or Bulldogs , the small eddy is 84 cc  either will work well

[deputycrawford]

Ok, thanks for the reply. I know the question has been asked a million times and will be asked again but I thought I would put it out there. You say the Eddy's might not be able to go to 70 cc's?

[Ghoste]

Why shave new heads down to get it if there are alternatives that already have the tighter chamber?  They're probably a better head too although admittedly more money.

[deputycrawford]

That's true but the Indy EZ's come with, I believe, 78 CC chambers. I would have to shave either head. I am good friends with Autocraft Engines, my machine shop. We have beer moments at each other's house too. Shaving is no problem. I guess I would like the Indys better but am thinking about the money. $1400 vs. $2100 is a bit of a difference. I wonder what the difference would be in power between the two with the same chamber volume.

[firefighter3931]

The EZ's come in two chamber sizes...75cc and 80cc. You'll have to mill either set down to dial in the static compression you're looking for. As much as i like the e-heads, i'd have to agree with the others and go with the smaller chamber Ez's. The e-heads would have to be milled .060 just to get down to 72cc...yikes !

As for power, all things being equal....the power numbers will be pretty close. Both flow the same out of the box....give or take a few cfm. The EZ's have more potential but you really need to open up the intake ports to make em flow. The EZ is basicly designed to be a "Max Wedge" head but the std EZ comes with a stock sized 440/413 port. The EZ 1's and 295/325 cnc versions are all max wedge intake port and require an INDY intake manifold. The basic ez casting will work with your manifold and headers....allthough you might need to clearance some of the tubes for sparkplug access.

Ron

[deputycrawford]

OK, thanks Firefighter. I will save up for the Indy EZ's someday. I'm working out other bugs of the build yet and will wait till I get the car straightened out before throwing a monkey wrench into the tune up. My compression is 9.48 to1 with 906's, 75cc's, .040 thick gasket and a .040 bore and .023 deck. Of course I am adding in the 6 cc reliefs too. That should be my build if I remember correctly. I want to go to 70 cc to bring the comp up to 10 to 1. That way I can run a 260 ish duration cam at .050 and have some throttle response. How much would a "Stage 2" porting be worth in power? I'm talking about flowing the heads un shrouding em etc.

[firefighter3931]

OK, thanks Firefighter. I will save up for the Indy EZ's someday. I'm working out other bugs of the build yet and will wait till I get the car straightened out before throwing a monkey wrench into the tune up. My compression is 9.48 to1 with 906's, 75cc's, .040 thick gasket and a .040 bore and .023 deck. Of course I am adding in the 6 cc reliefs too. That should be my build if I remember correctly. I want to go to 70 cc to bring the comp up to 10 to 1. That way I can run a 260 ish duration cam at .050 and have some throttle response. How much would a "Stage 2" porting be worth in power? I'm talking about flowing the heads un shrouding em etc.

I used the Ross Piston calculator and came up with 9.35:1 with the dimensions you posted above. If you go to a 72cc chamber and a .020 steel shim head gasket....you'll be at 10.02:1 static compression. As for porting to stage 2....that depends on what stage 2 means. If the heads are basicly stock, then get yourself a set of the MP porting templates and go to it. This will wake up the low and mid lift flow quite a bit....up to about .500 valve lift which may be all you really need.   If all is right and depending on how "stock" the heads were before the porting templates....you could see a 40-50hp increase. The stock heads flow in the 220cfm range and after the MP template treatment usually go into the mid 240's or so at .500 valve lift. The flow numbers will also fatten up all the way through the curve as well.

Ron

[Steve P.]

A few things just popped up in my little mind reading this.

First, I seam to remember that we took at least .060 off Mike's E-heads with no trouble and E-brock told us in advance that it was no trouble at all.

Second, if you are going to aluminum heads you reallllly want to step up closer to 11:1 CR. That is if you have pump gas that will take care of iron heads at 10:1!! 

[deputycrawford]

I think Firefighter was thinking about money savings for all the milling. I heard I don't want to go to a steel shim gasket when changing to aluminum heads. Thats why I planned to go to 70cc to make up the difference. I do have a ton of valve clearance even at 75 cc's now. something like .180 intake and .210 exhaust. I was going to keep the comp around 10  to 1 for pump fuel anyway. I should have a decent quench already. I am also thinking of using a really high .500 lift solid cam with around .020 lash. I want around .560 to .575 after lash and around 260 duration at .050. I'm leaning toward Hughes. I know the "Stage two" can mean many different things. I meant that I want it ported like my 906's are now. They have had everything done but hogging them to within an inch of their lives. I will do the same to the new heads.

[Steve P.]

Setting up the mill is the expense. Aluminum is cheeeeeeap to mill. The Eddy's are $700.00 cheaper and the thing about 11:1 is due to the aluminum dissipating the heat so much faster than iron, you kind of need to raise your CR a point to reap all the benefits. I'm sure others can explain this better than I..

[Ghoste]

You still gotta keep a little fire in the hole don'cha?

[Steve P.]

What, is it close to her birthday??

[firefighter3931]

I think Firefighter was thinking about money savings for all the milling. I heard I don't want to go to a steel shim gasket when changing to aluminum heads. Thats why I planned to go to 70cc to make up the difference. I do have a ton of valve clearance even at 75 cc's now. something like .180 intake and .210 exhaust. I was going to keep the comp around 10   to 1 for pump fuel anyway. I should have a decent quench already. I am also thinking of using a really high .500 lift solid cam with around .020 lash. I want around .560 to .575 after lash and around 260 duration at .050. I'm leaning toward Hughes. I know the "Stage two" can mean many different things. I meant that I want it ported like my 906's are now. They have had everything done but hogging them to within an inch of their lives. I will do the same to the new heads.

Just to clarify, i was referring to your iron heads when i suggested the steel shim and 72cc chambers. I made this assumption based on your response pertaining to new (Indy) heads at a later date.

I'd agree that an aluminum head and steel shim are a bad match. You should be trying for 10.5:1 minimum to get the most out of those heads (aluminum) performance wise. If you really wanted to optimize the combo, zero decking the block would bring up the static compression and give you better quench. With .023 deck and a .040 gasket you're at .063 assuming a closed chamber head....which is outside the effective quench zone. An open chamber head only compounds the problem.

Milling the e-heads .050-.060 really isn't a problem but it doesn't leave you much room for future "cleanups". The smaller chamber will also influence future build options once those heads are milled. I prefer to keep them close to "as delivered" as possible so that there's something to work with in the future.

Ron