How much to mill Edelbrock heads

[Rapid]

Taking my new heads to be milled Monday. They have 60 cc chambers. Planning to take them down .020 to make them 56cc. Sound right??

 

[Fast63]

I wouldn't mill them at all if I were you unless they were warped and needed some straightness. Are you just trying to raise compression?

 

[Rapid]

I'm trying to keep it the same. Edelbrock advised me to mill them but did not suggest how much. My stock heads are around 55 ccs from what I can gather.

 

[rbohm]

i also would not mill the heads. 5cc is only .1-.2 worth of compression, so an engine that had 9.5:1 drops to 9.3:1. not enough to worry about since the added airflow and larger valves will vastly more than make up for any horsepower lost. but if you are set on milling the heads, then yes about .020 should get you where you want to be.

 

[calpolymustang]

why not use 58cc?

I'm in the same boat... I want to replace my stock 54.5cc iron heads with AFR 165cc. I have a 2-barrel engine that only has 9.3:1. If I go with the 58cc head, I'm expecting to go down to 9:1 or maybe 8.9:1. Eitherway, I dot want to modify the heads because eventually I might want to run a stock 5.0 bottom end.

It apears that the 60cc Edelbrock heads are geared more towards engines that already have 60-64cc chambers, which is common on the 5.0s.

 

[Rapid]

I am not really set to do anything, hence the surch for advice. Just trying to make sure while I'm doing this that I do the best job I can. If I stand to gain 40 with the better head and lose 5-6, I can live without the hassel of having the heads milled. I have not seen any dyno results gained by swapping stock 289 heads to Edelbrock with the 60cc chamber. If anyone knows of some, I'd like to look.

 

[Rapid]

Decision,

Not milling. I can do that later if I want to. I have a dyno baseline and will report what happens.

Thanks!

 

[calpolymustang]

Your dyno results would be appreciated.

Could you also include the detailed specs of your engine before & after?

 

[Rapid]

Yes. I'll figue out how to list them like yours or ad them in the reply.

 

[D.Hearne]

If anything have them cc'd first before making a decision. A .020 mill isn't going to hurt anything. And if it does net a 5 cc decrease, that's a big jump with a 289 cid motor. Smaller the motor the more a change in chamber volume affects the comp ratio. As for using them later on with a bigger displacement engine, you can always tailor the build to fit the heads. I ended up milling my Canfields .060 and have never regretted it. They were supposed to be 58 cc heads and ended up being 64's. The .060 mill brought em down to 57.

 

[Helmantel]

i also would not mill the heads. 5cc is only .1-.2 worth of compression, so an engine that had 9.5:1 drops to 9.3:1. not enough to worry about since the added airflow and larger valves will vastly more than make up for any horsepower lost. but if you are set on milling the heads, then yes about .020 should get you where you want to be.

It will change the compression ratio a bit more than that. Reducing 5 cc from the heads on a 302 with 9.5:1 CR will increase the CR to 10.15

If that's worth the trouble is of course another discussion and depends on the situation and the goal. The gain will be modest at best, but on the other hand, that can be said of many performance parts/modifications.

 

[SadbutTrue]

i also would not mill the heads. 5cc is only .1-.2 worth of compression, so an engine that had 9.5:1 drops to 9.3:1. not enough to worry about since the added airflow and larger valves will vastly more than make up for any horsepower lost. but if you are set on milling the heads, then yes about .020 should get you where you want to be.

Also gotta disagree with that, I just had my Trick Flows milled .030 after calculating out the difference in compression (assuming I'm at 8.8:1 now, with 60 cc chambers, after milling I will be at 9.3 or 9.4:1). Took a lot of algebra, but I'm pretty sure its right