The trick flow heads I was planning on getting went up another $120, it's starting to get out of my reasonable budget. I know a guy who will give me a deal on machine work, what kind of potential do the L48 heads have and what parts will need to be replaced to complement a new cam and higher compression, also do L48 allow you to use thinner head gaskets to bump up te comp ratio?

 

i would get new heads. Even if u dont get the trickflows there are world castings, dart, edelbrock, holley. Any of these heads will be better than a 30 year old design. The head is where all the power is made regardless of cam. For street purposes any new head design would do. Even the worst new design would flow a lot better than the old heads.

my 2c

 

szercer,

What about using iron Vortec heads? P/N 12558060 used on several GM crate motors. Not a lot of money and reports seem to indicate they work well


[Modified by mapman, 10:22 PM 1/11/2003]

 

Vortecs are great cast iron heads for a 350. I think the only stock Chevy head that outflows them are Fastburn heads. You'll get 30-40 hp just by bolting the heads on. They require centerbolt valve covers and a special intake, Edelbrock sells several different intakes in their Preformer line, but you can also get a TPI or TBI manifold if you want to go fuel injection route.
Desktop Dyno shows that Vortec Heads, Comp XE262 cam, Quadrajet, dual plane intake, and headers with mufflers will produce 353 HP at 5000 rpm and 403 lbft of torque at 3500 rpm.
Those are ZZ4 type numbers for under $1200.00!
The Vortecs cost about $450 a pair new complete with valves, but you'll have to have new springs put on and the valve guides cut down and spring seats widened to handle the bigger cam. Stock springs are only good for .450-470 lift and give up completely at 5000 rpm due to being very weak.
Scoggin-Dickey, Jim Pace and Salley Chevrolet all sell them for about the same price, and one of the places actually will sell them to already modified with LT4 springs.
I'd suggest using 1.6 GM roller rockers with them, since they are self guiding, if you go with another kind you'll have to have pushrod guide-plates installed. With this combination you'll have a very nice engine. Chevy High Performance used a $1200 GM Targetmaster crate engine and built it up using similar parts and got over 400hp at the flywheel.
I think you could realistically get the whole setup for around $1100-1300 in parts. Currently I have a ZZ4 in my car, but I have all the parts to build a Vortec based 350 out of my old 350. Maybe one of these days I'll build it and stick it back in my car. Then I can put the ZZ4 in a 53 Chevy truck I have my eye on. :D

 

AFR 190s are good. I think I'll bolt those onto my dad's old 327/350 (crate motor that replaced the stock one in his '64 Corvette) after with rehone the cylinders. 11:1 compression with 64cc heads will come down to 9.7:1 with those 76cc heads. I believe for every point of compression you get 4% more horsepower. So if you can run aluminum heads, you can run a full point greater compression resulting in 4% more horsepower. This coupled with the increased flow of aluminum heads (you've got to get your money's worth!) you would get a pretty good sized gain.

 

I got a set of heads off E-Bay (laugh if ya want to!) for 350 bucks from a rebuilder who sells on there regularly. They are casting # 14014416 w/2.02 & !.6 valves and 64cc compression........Half the price of a set of World Torquers (all new moving parts BTW, swirled stainless valves, etc). :yesnod:

 

i bought these and love em! $650 a pair at sumitt... http://store.summitracing.com/partdetail.asp?part=22688

 

For the price,the Vortec's would be a real deal. I saw a build up with Vortec's and a Comp XE-268 cam pull 390 hp,and 430 lbs running 87 octane gas. For the money Bubba would charge to grind your heads,you can't go wrong with the Vortec's.

 

the vortec's need self aligning roller rockers, and I have a weiand intake that will work with the q-jet... I want to avoid having to buy a new carb/intake, but I'm hearing that the L48 heads aren't worth putting money into though. I'm also concerned about putting new heads on a 80,000 mile engine...

 

Don't waste your money on rebuilding smog heads. Their combustion characteristics are poor. I was quoted $660 to have my old smog heads rebuilt. Aftermarket heads can be found for near that price. Or if you can still find the pre-smog factory performance heads, those would be great for a budget build-up.

 

Get the Vortec heads with a performer RPM intake. Use your current carb. If you get serious, I can give you the casting # you need to get these from a salvage yard (if you're gonna cut them to put bigger springs on, might as well start used).
Todd :D

 

szercer...

Contact a cylinder head shop in your area and give them the casting #'s to see if they can be machined to 2.02/1.60 valves. If not, then you are limiting any performance aspects. If they can... at the least you will need to:

1)Magnaflux the heads to make sure they are worth dealing with.
2)Have someone machine the heads to accept 2.02/1.60 valves.
3)New valves
4)Double valve springs w/ dampers.

If you are on a real serious budget... reseat the valves you have and go to double springs w/ dampers. You can still pump up the HP to 300+ with the original heads.