Team Camaro Tech banner

1 - 10 of 10 Posts

·
Registered
Joined
·
1 Posts
Discussion Starter #1
I have a 454 bored .60 so I am thinking she's now 496. I'm really only concerned with big torque for 0-60/70 times. Planning on this going into my 72 SS Clone backed up with a M21. I have a pair of heads from 71 402 Chevelle. Casting 3999241. These any good or am I better off with a set of decent aluminum heads. Pretty much looking for a stop light runner with nice highway speed. My 72 has a 3:55 axle I'd like to keep in her... Also have a 77 Z28 I plan on using 1 71 Vette CJL 4-speed 350 in. I have a pair of 68-69 Camaro factory heads 3947041. Got flat tops in it, hope these heads provide a decent CR not too high and I want to keep my A/C in her.
 

·
Registered
Joined
·
2,289 Posts
A 454 bored will not reach 496 unless you swap out the crank and pistons for a stroker kit. I run Merlin Cast roval ports on my 496, maybe someone can chime in about your heads.
 

·
Registered
Joined
·
4,848 Posts
3999241 heads are basically the same head as a '781. Both will support 600 horsepower with installation of 2.19"/1.88" valves and some pocket porting. The '241 lacks love because they were used on smog motors. As such their power rating was way down due to NET HP rating and use of dished pistons to kill compression instead of a pop up domed piston used on the earlier heads. People love horsepower and assume the lower power rating is due to a bad head.

Casting number '241 was an open chamber Passenger head used on the Impala, Chevelle, Camaro, and the Corvette in 1972-'74. It was cast to replace the '781 that even after being a redesigned version of the '041 head still had some cracking issues.

On a 454 it was rated at 270 NET HP, while in 1970 it was rated at 365 gross hp. Equipped with small steel flat faced 2.06"/1.72" valves with a 118 cc combustion chamber.

Big Dave
 

·
Moderator
Joined
·
14,281 Posts
Although some cast iron heads are ok you’ll always be better with a good set of aluminum heads.
 

·
Registered
Joined
·
4,848 Posts
Agree with John!

Cost to pocket port is about $65 for cartridge rolls and wear and tear on burs and your compressor as well as the grinder (your labor is free).
Price of Manley valves is $288

https://www.jegs.com/i/Manley/660/11528-8/10002/-1

https://www.jegs.com/i/Manley/660/11527-8/10002/-1

and new hardened exhaust valve seats $120

https://www.summitracing.com/oh/sea...Default&SortOrder=Ascending&retaillocation=oh

Then there is the big ticket item to upgrade the heads (this labor you can not do unless you own a machine shop). Expect to pay $380 to get your hardened seats installed, and $260 for a valve job (five angle), another $60 to pressure test the head and $130 to hot tank it and Mag-na-flux for cracks, then there is the cost of milling the head if it isn't flat (most are not), which is another $115 per head if needed). Add up all of the prices and you are approaching the cost of a good set of aftermarket heads. Need further incentive? You still have your old worn 3/8th inch cast iron valve guides. Bronze ones in a smaller friction reducing 11/32th inch size are expensive to machine and buy, but when you are buying valves you would buy the smaller stem size at the same cost.

I buy aluminum heads solely for the weight savings. Stock LS5 heads (complete): 73 lbs each. Edelbrock Performer RPM heads (complete): 40 lbs ea. Total weight savings 66 lbs. off of the nose of the car. INstall aluminum heads, water pupmp and intake and you are running the same weight as a SBC over the nose once you move the battery to the trunk. Swap out heavy copper brass radiator for aluminum and you take off even more mass.

Big Dave
 

·
Super Moderator
Joined
·
32,611 Posts
Agree with Dave - less weight is more horsepower, as the old saying goes.
 

·
Premium Member
Joined
·
703 Posts
1 - 10 of 10 Posts
Top