D0AE-N CC Head Unshrouding

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wrobinson

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My 13 year old wants to build a 1971-73 Mach 1 Mustang for his first car. We have found a Grabber Blue with white interior base model 1971 Mach 1 to start on.
Guys my question is how many CC's can be gained by unshrouding the valves, 2.19 & 1.71? I know the D0AE-N is supposed to be around 63 CC combustion chamber. I would like to be around 68-70CC's after unshrouding and polishing combustion chambers. Can this be accomplished?

 
Can I ask why you want to lower the compression? I am running CC 2V heads from Australia with around 62cc combustion chamber and run 91 octane pump gas no problem.

 
Can I ask why you want to lower the compression? I am running CC 2V heads from Australia with around 62cc combustion chamber and run 91 octane pump gas no problem.
My preference is to be around 9.7-9.8:1 compression. Higher altitudes you can get away with more compression. We are on the coast almost at sea level not as forgiving.

 
Ah got you. If you know your cam specs you can also calculate the dynamic compression ratio. There is a calculator on here somewhere for that. IMHO that is more important than static when it comes to performance and detonation. As for how much you can gain by unshrouding the valves, I am not sure. When mine were done it added about 3cc. The Aussie heads are around 59 CC stock.

 
Ah got you. If you know your cam specs you can also calculate the dynamic compression ratio. There is a calculator on here somewhere for that. IMHO that is more important than static when it comes to performance and detonation. As for how much you can gain by unshrouding the valves, I am not sure. When mine were done it added about 3cc. The Aussie heads are around 59 CC stock.
Our camshaft is a Comp hydraulic roller with LSA 110, 275/281 advertised duration, 224/230 @ .050 duration, and 569/578 lift with 1.73 rockers. I do not know the opening and closing rates though. I called Comp Cams and they no longer can pull that data for special grinds. I probably should try to spec it out with a degree wheel.

 
It should be on the cam sheet that cam with the cam if you still have it.
I do not have a cam card. All the specs I have came off of the Comp Cam box. I have watched videos on how to use a degree wheel to find the opening and closing rates. Cannot find or calculate dynamic compression without those figures.

 
On my 71 4v with the deck skimmed and heads shaved, i.e. trued up, I went with +.030" Keith Black hypo KB 148 13cc dished piston. That gives me pretty much what you're looking for, just below 10:1. These KB pistons have a compression height .020" higher than stock Ford pistons, so in my case zero deck. With 64cc GA heads and .039" compressed head gaskets, with a Melling MTF 2 flat tappet cam, the motor runs strong on 91 Shell. 

You will very likely need to rebuild and recurve your distributor especially if you have a stock Autolite or Mastercraft distributor. Clevelands seem to like about 14 - 16 degrees of initial timing with a MAX of 34 -36 total mechanical timing, vacuum plugged off then add about 4 -6 deg of vacuum advance. If you do not run a factory style dizzy, please do not use a cheapo HEI pos. Best bet would be a custom DuraSpark ,I think its from Performance Distributors or something like that.

If you want or need more info on what I did on the distributor, search for my thread or pm me

Good luck,

Geoff.

 
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Unshroud the valves for better air flow, but don't remove any more material from the heads otherwise-you'll change their quench characteristics and end up with an unknown and unpredictable outcome. Buy Cometic head gaskets in the necessary thickness to get to your desired compression ratio. Heavily modified heads have reduced value if that matters to you

 
Why would you waste a good set of heads for a street application you will never see the benefit. You have to wind the guts out of a cleveland to see the benefits of the large ports and taking compression away kills HP faster than anything else. Gas is cheap and doubt if you drive it much. We can get 105 leaded here still in NC. 

When I build the engine in my 72 will go for at least 13 -1 or why build it?  Yes if you go to 18.3 to 1 like my friend you go broke on that fuel over $20 a gallon. But it has never been beat by a Ford either is a Pontiac GTO. 

For a street driven car the Ausi heads which have 2-V size runners with 4-V valves and CC are the best. I have a 2-V head to 4-V performer and it runs great. Flat top pistons and .050" over 90 91 octane and have never had an issue. I have driven almost 1,500 miles this summer. 

If you are going to race then race if street driven then make street driven. Most never get driven enough.

 
The spreadsheet in this thread will get you close. It uses degrees intake valve opens ABDC and has a calculator to calculate it based on information you should have from the box.

https://www.7173mustangs.com/thread-engine-and-compression-calculations?highlight=compression+ratio

2 tabs in sheet, one is static and the other is dynamic.
Well I calculated the dynamic compression on the calculator. The ABDC was 63.5 on my camshaft. Interesting enough with static compression around 9.7-9.8:1 the dynamic compression was 7.8-7.9:1. So this absolutely confirms my calculations. I am going to move forward on unshrouding the valves. I will adjust the static compression using Cometic MLS head gaskets. Thank you so much for forwarding the calculator.

 
You don't need a dynamic CR that low. That will be in the range where performance will start suffering and you'll be taking a chance that you're messing with the quench ability of the heads. Even open chamber hearts are good with a dynamic CR of 8.3:1.

 
You don't need a dynamic CR that low. That will be in the range where performance will start suffering and you'll be taking a chance that you're messing with the quench ability of the heads. Even open chamber hearts are good with a dynamic CR of 8.3:1.
+1

 
Why would you waste a good set of heads for a street application you will never see the benefit. You have to wind the guts out of a cleveland to see the benefits of the large ports and taking compression away kills HP faster than anything else. Gas is cheap and doubt if you drive it much. We can get 105 leaded here still in NC. 

When I build the engine in my 72 will go for at least 13 -1 or why build it?  Yes if you go to 18.3 to 1 like my friend you go broke on that fuel over $20 a gallon. But it has never been beat by a Ford either is a Pontiac GTO. 

For a street driven car the Ausi heads which have 2-V size runners with 4-V valves and CC are the best. I have a 2-V head to 4-V performer and it runs great. Flat top pistons and .050" over 90 91 octane and have never had an issue. I have driven almost 1,500 miles this summer. 

If you are going to race then race if street driven then make street driven. Most never get driven enough.
The build is a father and son project for my soon to be 16 year old son. Yes, it will be a daily driver with fuel injection, AODE/4R70W, and 3.50 gearing. We had four sets of 4V heads available, 3 OC and 1 CC. We chose the CC D0AE-N's because of the adjustable valve train. We have the Crane rocker conversion kit but camshaft specs are outside of its capability. If I were to start from scratch and build a set of heads it would be the small valve D3ZE open chamber. Needless to say the D0AE-N's have stainless valves, new Comp springs, locks, and retainers from prior owner. The CC heads are the easiest and quickest means to an end. No, the motor will not make extreme torque numbers but if that was our goal I would've stroked her. Furthermore E85 is available and a solution too. I appreciate your comments, thanks.

 
You don't need a dynamic CR that low. That will be in the range where performance will start suffering and you'll be taking a chance that you're messing with the quench ability of the heads. Even open chamber hearts are good with a dynamic CR of 8.3:1.
So, 10.1 static compression puts the dynamic CR at 8.1:1. Would that be better? My readings said 8.1 dynamic compression is getting close to capability of pump gas. Can you forward some reading material or data to back the 8.3:1 number?

 
The figures I used are from engine building books I have. You can search the web for dynamic compression ratio and find all kinds of articles.

Yes, the 8.1:1 is better. With quench heads or good aluminum heads you can go even higher.

 
The figures I used are from engine building books I have. You can search the web for dynamic compression ratio and find all kinds of articles.

Yes, the 8.1:1 is better. With quench heads or good aluminum heads you can go even higher.
The heads are D0AE-N quench heads with 63CC chambers. I am having the valves unshrouded and the combustion chambers polished. I think the combustion chamber will grow 5CC's maybe. The short block has a balanced rotating assembly, hyper flat tops CP555 .030, piston is .015 in the hole, and what thickness Cometic MLS head gasket to make desired static compression. I want the motor to be a reliable pump gas piece for my son.

 
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