AndyB

Need some help on head choice. I am building a mild budget 383 with a cc305 cam for my ImpalaSS clone and have a choice of two different heads

Either a unported set of LT4 heads with different springs or a set of mildly ported Iron lt1 heads with 2.02/1.60 valves. The iron heads have a mild intake port job, pretty decent exhuast port job, flash cleaned up in the combustion chambers and 3 angle valve job. Pics can be seen here

http://www.jbelectric.us/ot/ImpalaSS/heads/

Porting the lt4 heads right now is not an option due to my budget limitations. My goal is to have a very torquey and daily drivable 383.

Any thoughts?

96z

There is always next year so the LT4's would be a good investment. To go along with that is a good deal of weight savings. How much do the Iron heads flow?

AndyB

No flow #'s on the iron heads. My guess would be similiar to the lt4s.

And would just stock lt4 heads be a good choice for a torqey 383 with a cc305? I would be more than happy with 350rwhp out of the motor.

96z

LT4's no question than. You will need the intake also.

Z95m6

LT4's does anyone port iron heads? At least i know some of the better porter's won't touch them.

AndyB

I think CMS still does iron. The ones I have were done by a local porter so they are nothing fancy. Just a typical port job like that on 11ty billion sbc running around.

OldSStroker

You already have the iron ported heads. How about having an intake and exhaust or two flowed, maybe also with intake mounted. Then compare to stock LT4 heads before you make a decision. I'm not sure of LT4 head cost, but a new LT4 intake is about $220 + frt. from Scoggin-Dickey.

Try the cheap route first.

grygst76

Funny thing is the iron head version of LT1 flowed better and produced more power then the aluminum counterpart!! if the price is right grab the iron ones unless cost for cost the lt4 ones are equal or less, then grab the lt4 ones either way you will be happy

AndyB

Actually the price of them where the same

$600 for the pair of Lt4s
$600 for the ported Irons.

I think I am going to sell the iron ones and stick with the Lt4s. Any recomendation for valve springs? Since I havent put the heads on yet should I have them machined for a different sized valve spring?

96z

What cam are you going to run, thatll play a big part in spring selection.

AndyB

CC305 with 1.6 rockers

FacelessZ

porting iron heads would be good to support spray...but they're a B I T C H to port and they don't come out as well as...say....aluminum heads...

AndyB

BAck to the top for valve spring suggestions

Ai

I'd agree with OldSS first... if you're trying to save $, it might be worth $20-40 to find out what the iron heads flow presently since they've been worked over. It wouldnt take much to get them to flow better than an untouched LT4 casting.

Stock, I've seen the impala stuff in the 22X peak cfm range, vs. the LT4's low 23Xcfm peak flow on our bench . If the iron castings are stock (flow wise), I'd probably just pick up LT4's & save $ to have them gone through in the future. $600 seems cheap though for a pair, unless you're picking up used castings online somewhere .

As far as springs for a cc305, I'd probably just put a set of 987's on them. Since they're off the car, it's no big deal to machine seats for a proper locator. That and if you have them worked over in the future, they'd probably end up opening them up anyway.

Regarding porting iron... Filthy & time consuming, I won't even do it anymore. Then again, I am a bit overly particular about at times

FacelessZ

and if you don't want to worry about extra machining to the seats...just get the 612 springs...