LeMans Pete

Instead of going the aftermarket route, I'm interested in using an old set of GM head on my 355. What I'm trying to figure is which head to use?

From what I've read, I should look into 186s, 291s, and 462s in that order. Would you agree with this list and order?

Also, I was planning on running about 10:1 compression, anyone have a problem with pump gas and these iron heads at this ratio?

DZRick

I believe the 492 2:02/1:60 was the performance head to have.

mrvette

#113 aluminum off a L98,

10.5 comp, true the valves could be larger, if that big a deal, get them enlarged.....

almost as good as any head out there, and better than iron, ...

now this is with a cost/benefit ratio taken into consideration....

150-200 for the complete head set, then another 2-300 for a complete overhaul, which I got new springs for that included....

and a few new valves....

63mako

Here you go, More info than you will need. You can port the old heads big time. We used to get close to 600 HP out of the old double hump castings back in the 70's. Look at the intake to exhaust ratio and flow @ .400 numbers to make a wise choice.
http://users.erols.com/srweiss/tablehdc.htm#Chevy

LeMans Pete

Good suggestion, these are 58cc right? What the intake runner size? I'll admit, I was looking for 64cc with bigger valves, but thats a good option too.

Thanks Mako, I think you're right though, that might be more information than I was looking for. I really wish he did a better job of putting that site together, its a headache to look at and try to figure out what all the numbers are. I'll sift through it though, thank you.

Peter

DZRick

I thought he was looking for an old GM head

mrvette

Well, they first appeared 22 years ago on the '87 verts....

THAT olde tyme enuff???

DZRick

Old enough for me but not nearly as old as the 186, 291,or the 462. I figured he wanted iron heads.

LeMans Pete

I was/am looking for old iron heads, I forgot about the L98s. Though they are pretty small.

2000FRCZ19

the double hump 462,461 heads can be ported to flow very well. i had a set of nicely ported 461's on my last 383 and it ran very well. the comp ratio was over 10 and i did get detonation sometimes.

LeMans Pete

So which order would you guys rank these? I'm heading to the swap meet this weekend, and in case I get a choice (with condition, valve size and price equal) what is the pecking order here?

492
461/462
113
186
291

63mako

The 461, 462 and 291 have no accessory holes.
As far as flow The Chevy Turbo heads are the very best old iron. The part # is 340292 The I/E ratio is 88%. Flow is 201 int 177 ex @ .600 lift. This is as good as any modern aftermarket head with a similar port size. They are rare and were a GM over the counter performance head. If you can find a set buy them.

The 492 is next @ 209/141 @ .600 lift

The 186 and 041 is next @ 188/140 @ .600 lift

In comparison the AFR 195 eliminator flows 286/215 @ .600 lift
See why they make big HP numbers!

LeMans Pete

Ya I was planning on AFR, but the price is rediculous. I agree that its worth the cost if you want high HP, but with this engine, I'd be happy with a solid 350 HP at the flywheel.

Plus, I cannot comprehend those flows since I won't be anywhere near .600 lift, more like .495/.502.

Thanks for the info Mako, always appreciated.

Peter

gkull

Price out Dart iron heads. Modern chambers and higher flow. I spent a thousand getting 186 and 292 castings all Zouped up back in the 80's only to give them away because I got tired of looking at them on the shelf when I went to aluminum

About 200 cc is the max practical on 355 ci with a Weiand stealth intake. Modern 180 cc at a minimum

The 292 casting were one of the best when ported and using 2.055 / 1.6 valves. They were also angle plugs for superior flame travel

bashcraft

I put a stock set of these on a '70 LT-1, along with a cam and intake change, that little motor made 450 hp. Trap speeds were 112-113 mph.

TERRY CLARK

Vortec Aluminum.......

Fishndude

I went this route once and will never do it again.. I had an old set of 291's and by the time I was done doing it right (spring pockets opened up, new springs, new valve guides, pocket ported, gasket matched, new valves, new hardened valve seast for unleaded fuel, valve job, screw-in studs, etc.) they cost me more than a better set of aftermarket bolt-on heads. After soaking all that money into them I ended up buying a set of Dart Iron Eagles and by just bolting them on, I knocked almost .7 off my quarter mile times slip (from 11.60's to 10.90's)..

If your going to attempt any porting you need to know what your doing because yu can decrese performance. You also may not want to polish the runners because it will reduce fuel/air atomization and can also cause fuel puddling when ideling. All-in-all I would only install old heads if I were trying to keep it all stock..

jackson

If your lift's in that ~.500 range ... best look at heads' flow at around ~.400 ... that'll be more representative of what your lobe profile will actually be flowing thru the port for any significant length of time (most .XYZ lift lobes have very little duration at same .XYZ lift). Also ... .495/.502 looks like a comp XE retro roller ... those are typically a cheaper quality cast iron roller core selling for inflated$ ... if going roller, suggest look elsewhere for billet steel core. Maybe Doug Herbert or Howard's Cams. GMPP has steel roller close to your spec but I think it's not a retro.

FYI ... look inside any OE ironhead vortec 350 truck motor (aka L31 VIN R) circa1996-2000... all have an OE mild roller cam but they're all billet steel ... not cast.

Solid LT1

My list for production iron heads: Vortec 906, 492, 186, and 041 the 291 and others are left off because they have no end holes for accessory mounts. This being said, unless you have "free" machine shop access, the rebuilding of most of these heads will run more than a set of aftermarket cast iron heads and for $150 more you can have Brodix IK, Canfield, or Trickflow aluminum heads which will support future modifications (think LONG TERM! not "next quarterly statement" like American MBA's do.)

LeMans Pete

Dead on Jackson, I had a Comp cams catalog laying around and liked that grind. But when comes time to buy, I will be making sure to get a quality cam.

Peter