[pretorin]

I have a 327/300 with camel hump heads out of a 62 impala and it is in need of a rebuild badly. I just need new pistons and a little better then stock cam. I also want to get a little more then 300(feels like 200) out of it, 350 would be enough for me. I was thinking about going with newer higher compression style pistons like Keith Black, or speedpro. And some new style heads like Iron dart or edelbrock. Now correct me if i am worng but will 72cc heads will make my compression go down right? Any recomendations on either would help. Yes i am new to this

 

[gpeak]

Assuming that those camel humps are 64cc, then yes, 72cc would lower the compression. But, with aftermarket heads and a better than stock cam, you won't need to raise the compression to hit 350 ponies.

 

[MI2600]

The 327 300hp factory rating in '62 was "inflated" by today's standards. Some say about 20%. It was also running 10.5:1 compression.

If the engine is in poor condition now, it probably does feel like 200hp...or less.

 

[machine shop tom]

Those heads will probably measure out to about 61CCs after a valve job and resurfacing. With a flat-top piston, you will net about 9:1 with a .039" compressed gasket. A stee shim gasket will give you about a half a point more. Using a dome will get you some more compression, but the benefits from that will be negated by interrupted flame travel. If you need more compression, you can mill the heads up to .025" for more compression and not have to monkey with the intake manifold.

tom

 

[pretorin]

The 327 300hp factory rating in '62 was "inflated" by today's standards. Some say about 20%. It was also running 10.5:1 compression.

If the engine is in poor condition now, it probably does feel like 200hp...or less..

ReallY? I thought chevy always under estimated their engine output so kids could buy them with a lower insurance cost

 

[MI2600]

A review of Chevy engine offerings, discloses a rather sharp drop in hp ratings after '72. At that time, manufacturers started to rate hp in more "real world" conditions.

I've read that it was in relation to the beginning of the smog era and because of insurance costs.

A while back, one of the mags listed the advertised hp vs actual hp on some of the older cars. I was amazed to find the 270hp '57 Chevy was only 190hp!

 

[musky2]

Chevy horsepower

I would think the 67-69 302 z28 rating of 290 horse was a little low!

 

[Robinson Robin]

A review of Chevy engine offerings, discloses a rather sharp drop in hp ratings after '72. At that time, manufacturers started to rate hp in more "real world" conditions.

I've read that it was in relation to the beginning of the smog era and because of insurance costs.

A while back, one of the mags listed the advertised hp vs actual hp on some of the older cars. I was amazed to find the 270hp '57 Chevy was only 190hp!

I've read that it was in relation to the beginning of the smog era and because of insurance costs.

A while back, one of the mags listed the advertised hp vs actual hp on some of the older cars. I was amazed to find the 270hp '57 Chevy was only 190hp! [/B][/QUOTE]


Exactly right I find there is alot of misconceptions concerning 60 era hp. The pre 72 gross hp and 72+ net hp are often mistakingly compared. Most (with some exceptions) 60 era cars when tested in modern net hp would not reach anywhere near their 60's hp rating.

 

[packratwrecker]

Horsepower ratings

Actually, a big change in the horspower ratings came when manufacturers went to SAE net horsepower.
Previously, and correct me if I'm wrong, industry standard was more like gross horsepower.
That's what I've read, and been told, anyhow.

 

[firestone]

Vortec heads ($650 with spring upgrade)
Comp XE268H cam ($160 with lifters)
Edelbrock Vortec Performer or performer RPM intake ($180 or $225 if it is the air gap)

This combonation with around 9.5-10:1 compression would put you right at 350 hp.

I would advise against going with the dart heads, the 200s are too big for a street 327, and the vortecs will flat outperform the 180s.

If you are going to go to all the trouble to get the motor torn down, and get new pistons put in it, I would bore it out to a 331.

Good luck
Adam