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427 heads and cam

I love my Chevy Chevette!
Posts: 10
Joined: 06/13
Posted: 08/05/14 02:14 PM

Hi , Im sure old news and this has been discussed many times but some advice would be appreciated.

I have a 427 bbc , hedders , dual exhaust , holley vac 2nds , manual 4 speed in a 73 camaro.
It has an xe262 flat tappet cam (218/224 at 50 with even 510 lift) which I may also change but more on that later.

First question:
I am wondering if a simple change from the current heads to some replacements Ive found would give a noticeable increase in performance. More interested in torque than top end HP as its all about acceleration from a moderate rpm for me- street car.

The current heads are 3933148 which are semi closed chamber either 112 or 122cc chamber ( depending on where you look - weren't measured sadly) with a 225 cc intake runner. List as 265hp head truck.With my pistons I would have at 112cc chamber 9.5:1 CR or at 122cc 8.5:1 CR.

I have sourced some v.good condition iron heads 3917215 , which Ive measured have a 104cc chamber giving me about 10:1 CR. List as 396/427 375/400hp head.They have a 260cc intake runner and have been polished and ported. Would these give me a noticeable increase in performance on their own? Cant afford Ali heads.

Also would changing from 2.06/1.72  to 2.19/1.88 be worth doing. Bearing in mind the heads have been worked and I don't want to get near a waterer jacket ruin them. Is this likely?

Car has a low rise iron intake , presumably going to an edelbrock performer or similar would give me a noticeable gain but with the head change a very noticeable gain.I cannot fit anything taller btw.

Last Point:
If Im doing all this Im taking the engine out. So maybe changing to a hydraulic roller cam as well.On its own will I see a performance increase? and with all heads and intake changed…?
I wouldn't go past 6500rpm and rarely hit 6k. I drive round town a lot and like to m obey along at a lower rpm and then hit the gas and take off. I thought something like a lunati 221/229 at 50 with 575/575 and 112lsa. Or is this too big. Want big low to mid acceleration but also power up to 6k.
Next one down is 211/219 and 550/550 with lsa 112.

Rear end is 3.08 but will go to 3.55 or 3.73 if it gives me back some torque I might lose with the bigger cam.

thanks in advance.  


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