72cc or 76cc heads
Yeah, I guess so. It did seem to work fine, motor seems to have plenty of power, but I still have torque converter issues to work out before I really know just how well it's performing. I do know that if he had just stuck those heads on right out of the box with the 76cc chambers, it would have been a real dog with the compression so low.
Hello, hope you don't mind me butting in here. I just got my Edelbrock's for my 390 today and I'am kind of excited to get them on and I have some question's. The instruction's say rocker arms- adjustable 1.76:1 required. Do they mean I have to have an adjustable rocker arm assy. or are they talking about the ratio or what? Did you have any problem with piston to valve clearance? I'am using the Speed-pro forged piston's @ 9.5:1 comp. ratio. And then there's the rocker geometry. I understand that- guess i'll cross that bridge when I get to it. Upon reading your post about heads coming in at 76 cc's vs. 72. Should I worry about this? I'am not building a hot rod but would like to stay as close to 9.5:1 as I can. I did buy the rocker assy. stud kit as well as the head bolt stud kit. Thank's for any help. Someone told me there is no dumb question so sorry for all of them!
The adjustable valve train means you will need to get adjustable rockers. The orinal equipment was NOT adjustable. Without adjustable rockers you woul have to check each lifter to rocker dimension and get a pushrod the right length for each one. Someone else here can probably explain it better than I. I got the complete adjustable rocker assys with spacers from Dennis at DSC Motorsports. And by the way, the only dumb question is the one you don;t ask. The people on here are awesome and extremely helpful with all your questions, trust me.
Thanks Az guy. I'll be waiting for some more input from these guy's. You are right. This is a great forum, I've learned alot reading here during my rebuild. How much did you have to come up with for the adjustable rocker assy? By the way, I just bought a set of rod's through DSC last week.
To tell ya the truth, I think it was around 250 or so, maybe 300 with the spacers. I am on the road and in Los Angeles right now so don't have my stuff to check. Call DSC and Dennis will give you all the help you need. I got the push rods from him and some other stuff as well. Good luck with your build. I should have put the engine in when I got it done. Now I am looking at it in the stand and wanting to make some changes. Hee hee, nothing like a build to use the spare change on before the lady gets it.
Edelbrock head compression
As stated above, the 72cc Edelbrock heads were actually 76cc? Whats the cc's for their 76cc heads? Wow, this can really screw up a custom engine build, dog, performance or detonation? Be careful and do your own math as manufactures only want your money. Trust no one!
Carl....=o&o>....
Carl....=o&o>....
I agree with Carl, get them cc'd and go from there. You may want to look at the Dove heads (or Blue Thunder if they are available yet) but they could be the same way. I would call Dennis at DSC and chat with him.
JC
JC
To Woodsrider
I went through this a couple of years ago. If you have a standard deck height then the edlebrock heads will work fine with the stock non adjustable lifter setup. The deck height of the heads is the same as stock if you add the thickness of the splash guards, which are not used on the edlebrock heads.
You have to add shims to the rocker shaft to space the rockers to the slightly increased valve spacing on the new aluminum heads.
You can use the stock pedestal bolts if you get washers to limit their length or get them cut down at the shop, cause the ports are a little higher and the bolt holes are not as deep. Make sure to use the reduced shank bolt in the correct hole that has the oil supply route in it.
Put the pushrods back in the same holes they came out of in the same direction they came out of.
You can use the same head bolts if you take a socket to a grinding wheel so that it fits in the boss.
I went through this a couple of years ago. If you have a standard deck height then the edlebrock heads will work fine with the stock non adjustable lifter setup. The deck height of the heads is the same as stock if you add the thickness of the splash guards, which are not used on the edlebrock heads.
You have to add shims to the rocker shaft to space the rockers to the slightly increased valve spacing on the new aluminum heads.
You can use the stock pedestal bolts if you get washers to limit their length or get them cut down at the shop, cause the ports are a little higher and the bolt holes are not as deep. Make sure to use the reduced shank bolt in the correct hole that has the oil supply route in it.
Put the pushrods back in the same holes they came out of in the same direction they came out of.
You can use the same head bolts if you take a socket to a grinding wheel so that it fits in the boss.
large valves in 72cc heads
Randy, you can not install 2.19 and 1.73 valves in a 72 cc general production 390 heads. The spacing of the valves on 76cc LR heads are the same as general 72 cc 390 heads but they run 2.09 and 1.66 valves. Now if your talking about the 76cc MR or HR heads, the valves are spaced farther apart which allows for 2.19 and 1.73 valves. Also different rocker stands and shafts.
They will not fit on 4.05 bore blocks.
Carl....=o&o>....
They will not fit on 4.05 bore blocks.
Carl....=o&o>....
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