How will Edelbrock Performer RPM heads affect my Compression Ratio?

[Great68]

I have a 68' C Code 289, and was wondering how the Edelbrock Performer RPM heads will affect my Compression Ratio. The Edelbrock heads have a 60cc chamber, and I found a website that says the 68 C code heads had a chamber size of 60.5-63.5cc, which would make me think that my compression would go up.

If this is not true, how much horsepower would I potentially lose by having my compression ratio drop a couple points?

Thanks!

 

[bnickel]

the 68 c-code should have 60 cc chambers. the 60.5-63.5 is a tolerance for manufacturing specs but i wouldn't expect that you would find your chambers to be much over 61cc at most, so you shouldn't lose any discernable compression

 

[HistoricMustang]

You should pick up some compression and you will pick up some horsepower. I run the Edelbrock RPM's on my race rod.

HistoricMustang
www.historicmustang.com

 

[68RustBucket]

i am utterly confused now ... didn't ford only manufacture 1 289 in 68, and didn't it have 54cc chambers?

 

[vobraman]

Go with those heads. I have them on my car and they work great.
Brian

 

[stangman67]

I did this on my 67 289 two summers ago. I bolted them on part#60229? RPM with 1.90" intake valves, and honestly, it made no difference. I had the RPM cam and crane rr, all the stuff, before the heads, and it ran not much better. NOT worth the $1800 total cost of the job. So thinking the compression was the problem, i rebuilt my engine last summer with forged huge dome pistons, balanced bottom end and the heads again. The pistons ended up hitting the heads during fitment, so the machine shop had to do alittle milling on them. I indexed the spark plugs, dropped it in, and it runs pretty good. At the strip i got a 13.8 for my first time ever, and im hopping to fix traction issues and drop the times. I would really recommend building a 351 with just some iron heads, i know it will feel faster on the street because my car has a loss of torque, but it runs good at 6500. If I could do it agian, this is what i would do, becuase it runs like a race engine, not a street engine.

 

[Jonstantine]

I did this on my 67 289 two summers ago. I bolted them on part#60229? RPM with 1.90" intake valves, and honestly, it made no difference. I had the RPM cam and crane rr, all the stuff, before the heads, and it ran not much better. NOT worth the $1800 total cost of the job. So thinking the compression was the problem, i rebuilt my engine last summer with forged huge dome pistons, balanced bottom end and the heads again. The pistons ended up hitting the heads during fitment, so the machine shop had to do alittle milling on them. I indexed the spark plugs, dropped it in, and it runs pretty good. At the strip i got a 13.8 for my first time ever, and im hopping to fix traction issues and drop the times. I would really recommend building a 351 with just some iron heads, i know it will feel faster on the street because my car has a loss of torque, but it runs good at 6500. If I could do it agian, this is what i would do, becuase it runs like a race engine, not a street engine.

do you think your problem is because of the large valves or because of the heat dissapation in the aluminum?

or just because your whole system is designed for highend power?

 

[stangman67]

Thats exactly it! The small cubes and RPM cam make it a screamer. I would have done a 351 with a milder cam and had more streetable performance.