Hey guys, A few questions, I was wondering what I kind of heads I can put on my 355 to get some good bottom end power. I'm not sure what size of combustion chamber I need to run pump gas. 87-91 octane
Will new style ( 90's + up) LS-1 or Lt-1 heads

The set up I have now is as follows:
1979 350 bored .30 over. flat top hypereptic pistons
old vette 882 heads (slight porting to match gasket )
comp cams 268AH-8 cam (.464 gross valve lift & 222 and 226 dur.)
Edelbrock performer alum intake topped with a Q-Jet

I'm thinking about vortec's, but not sure what the differance in intake runner length will do to bottom end torque?

 

Welcome to the boards!

Neither the Lt1/4 or the LS1/6 heads are a direct bolt on. Well, to be a bit more specific, the LT series head bolts up, but it requires modifications to the coolant ports due to the fact that the later LT series engines are reverse cooling. The LS series engine, well for the sake of bolt ons, they really dont share much with the Gen. I SBC. Heck, they really don't share much with the Gen. II.

But you're on the right path wanting to get rid of the 882 smogger crap heads. They have large 76cc chambers that kill compression. Look in the classifieds for either 305 heads such as the 601's, 416;s or 081s. the 083's from the L98's will also work. Avoid the TBI heads. They have a flow impediment that hinders the intake flow at anything over around 3500 RPM. They (GM) calls them the swirl port design. They are castings 187 and 193 (305 and 350 respectivly). Any of the above castings that i suggested can be ported with good results. You have a faily modest cam so clearance shouldn't be TOO much of an issue. But still check the clearances.

Vortecs. That's a whole new can of worms. Try clicking this and doing a search for Vortec heads. They are a WIDLY discussed topic. <A HREF="https://www.thirdgen.org/techbb2/search.php?s="><IMG SRC="https://www.thirdgen.org/techbb2/images/smilies/search.gif" BORDER="0"></A> (It's a clickable smiley).

Once you have read over the many topics about Vortec heads, come back with any remaining questions and we will be glad to answer them.

Do you have headers and a good exhaust system?

 

Thanks for the advice. This site is excellent!
My Exhaust is a bit lacking. I have hedman shortys into a custom y-pipe. the rest of the exhaust is stock sadly. I would like to run around 3inch single or 2 1/2duels this winter when I take the car off the road.
The part I'm not sure is the runner length? What does the length determine( high end or lower end, hp or torque)

Any ideas of non-Gm heads that you get good performance for a decent price?

Or just get some vortecs and buy an Edelbrock Vortec carb intake

 

T/A,
what compression ratio do you have now,
what compression ratio do you want?

contactpatch

 

I'm told that the compression ratio of this engine is about 10.5 :1
I'd like to change heads to something that make good torque and I can still run regular or mid grade fuel. Thanks

 

Then you were told wrong.

Assuming zero deck height, a .018 steel-shim gasket and 7cc valve reliefs in the pistons, your CR is about 9.3-9.4:1. That's the upper limit.

Assuming stock deck height (.025"), the same 7cc valve reliefs and a stock thickness head gasket (.039"), your CR is around 8.5:1. That's the lower limit.

I'd guess your CR is somewhere in between 8.5:1 and 9.3:1. Probably closer to 8.5:1.

You need 64cc heads.

Vortecs would be OK; or any of the various aftermarket heads such as Edelbrock, TF, Dart, AFR, etc.

Budget?

 

According to David Vizard, a closed chamber style head is worth about 20ft.lb of torque everywhere over an open chamber head (882). I don't think you can go wrong with the Vortec head...

 

Question: Where did you get the idea that a vortec head had a different length port runner?

The runner length is the same as any other common small block chevy head.
The vortec heads have a slightly "raised port" and a different intake bolt pattern that requires a vortec manifold.

A set of vortecs would go a long way to wake up your motor. After bolting on a set with a vortec manifold you will swear ya just gained 100hp. Actualy you'll see about an 80hp gain from your present 882's.
You will have tons of new found torque too.
Right off idle to 5500+rpm. They work very well.

 

General Motors has just come out with a new aluminum Vortec style head. They are making big claims with this head installed as is. They say not to make any changes to it and just bolt it on. There have been some recents posts. You will need to do a search. By the way it will take either the perimeter style valve covers or the center bolt type. Allen

 

Are you talking about the Fastburns, if so, those are a little too big for a mild 350?

 

Also, they are near $1200 for a pair. Not exactly a "budget" head, assuming you are talking about the Fastburns.

Also, if talking about the Fastburns, they have been out a while and require some massaging to reach full potential. For that price, i would rather front up and get AFR's.

 

I went to www.gmgoodwrench.com and looked up the heads. They are the aluminum fastburns part number 12464298 with 62cc combustion chambers. You guys may be right. I was reading the write up and I thought they were new the way the it was written.