blue thunder

Wondering if anyone can tell me how to distiguish small oval port heads from large oval port heads on a fully assembled engine? On sbc you could with the casting shape on the front of the head. Do bbcs have such an indentifying mark somewhere other than the casting numbers which I cannot locate externally.

BT

ragtop409

The casting number under the valve cover is the best wa I know how. GM made a hole page of diffrent casting numbers for BBC over the years so you real want to know what you are getting. Charlie

330864.....68-84...oval...OPEN...396, 402, 366T,
427T, 454 Truck
330865.....68-84...oval...OPEN...396, 402, 366T,
427T, 454 Truck
330866.....68-78...oval...OPEN...366T, 427T
330867.....68-73...oval...OPEN...427T
336765.....68-78...oval...OPEN...427T
336768.....73-76...oval...OPEN...427T
336781.....73-85...oval...OPEN...454, 118cc chamber, 256/114cc ports
343771.....68-86...oval...OPEN...366T, 427T, 454
343772.....68-86...oval...OPEN...366T, 427T, 454
343783.....70-76...oval...OPEN...454 Truck
346236.....75-87...oval...OPEN...454, 120cc chamber, 225/116cc ports
352625.....70-76...oval...OPEN...454 Truck
353049.....73-84...oval...OPEN...454, 122cc chamber, 255/119cc ports
366765.....74-78...oval...OPEN...427T
473328.....68-69...oval...OPEN...366T
3856206....65-66...oval..CLOSED..396, 97cc chamber
3856208....65......rect..CLOSED..396/425hp, 109cc chamber
396/375hp "Z-16" Chevelle
3856213....66-82...oval..CLOSED..366T, 427T
3856260....68......oval..CLOSED..396 Truck
3872702....65-66...oval..CLOSED..396, 427, 98cc chamber
3873858....65-67...rect..CLOSED..396, 427, 109cc chamber
3876875....77-85...oval...OPEN...427T
3904390....67......oval..CLOSED..396, 427, 98cc chamber
3904391....67......rect..CLOSED..396, 427, 107cc chamber
3904392....67......rect..CLOSED..427, Aluminum, L88, L89, 107cc chamber
3904393....68-76...oval...OPEN...366T
3908952....67......oval...OPEN...427, "M.Truck", Marine
3909802....67......oval..CLOSED..396, 427, 101cc chamber
3917215....67-68...oval..CLOSED..396, 427, 101cc chamber
3917219....68-85...oval...OPEN...366T, 427T
3919840....67-69...rect..CLOSED..396, 427, 107cc chamber
3919842....68-69...rect..CLOSED..396, 427, Aluminum L88, L89, 107cc chamber
3931063....68-69...oval..CLOSED..396, 402, 427, 101cc chamber
3933148....69-84...oval...OPEN...'69 396/265hp, 366T, 427T, 112cc chamber
3933149....68-76...oval...OPEN...427T, 122cc chamber
3935401....68-76...oval...OPEN...427T
3946074....69&71...rect...OPEN...'69 427 L88, ZL1, Aluminum, 118cc chamber
'71 454 LS6, "round exhaust port"
3964290....69-70...oval..CLOSED..396, 402, 427, 454, 101cc chamber
Large or small hex spark
plugs used
3964291....69-70...rect..CLOSED..396, 402, 427, 454, 109cc chamber
Large or small hex spark
plugs used
3965198....68-69...oval..CLOSED..396 Truck
3975950....68-70...oval...OPEN...396, 402 Truck, 366T, 427T
3986133....68-85...oval...OPEN...366T, 427T, 454 Truck
3986135....69-73...oval...OPEN...366T, 427T
3986136....68-84...oval...OPEN...366T, 427T, 454 Truck
3993820....71......oval...OPEN...402, 113cc chamber, 255/114 ports
3993820....71-84...oval...OPEN...454 Passenger and Trucks, 113cc chamber, 255/114 ports
3994026....71......rect...OPEN...454 LS6, 118cc chamber
3999241....72......oval...OPEN...402, 454, 113cc chamber

6272292....70-78...oval...OPEN...402, 454
6272990....70-up...rect...OPEN...454 service replacement, used on some MKIV crate engines, 118cc chamber
10045427...........rect..........Pontiac/Chevy Aluminum, 91cc chamber
Large Port, race
10049875...........rect..........Pontiac/Chevy Aluminum
Small port, race
10051128...........rect..........Bowtie, Aluminum 72cc chambers
Symmetrical ports
10051129...........rect..........Bowtie, Aluminum "raw"
casting, Symmetrical ports
10052902...........oval...OPEN...MkIV, 427T
10101140...91-up...oval..CLOSED..Gen.V 366T, 427T
10114156...91-up...oval...OPEN...Gen.V & VI 454, 118cc chamber
10141279...96-up...oval..CLOSED.."Vortec 7400", 100cc chambers
10487052...77-90...oval...OPEN...366T
12363391...96-up...oval...OPEN...Bowtie, Aluminum, Signature
Series, fits MKIV, Gen.V, Gen.VI, 110cc chamber
12363401...96-up...rect...OPEN...Bowtie, Aluminum, Signature
Series, fits MKIV, Gen.V, Gen.VI, 118cc chamber
12560241...98-up...oval..CLOSED.."Vortec 7400", 100cc chambers
14011077...69-up...rect...OPEN...Aluminum, fits MKIV, "C-port"
118cc chamber, also sold as a "solid" head
14044861...84-96...rect..........Bowtie, Aluminum, MkIV,
"raised runners", 1st design, 105cc chamber
14044861...96-up...rect..........Bowtie, Aluminum, Signature
Series, fits MKIV, Gen.V, Gen.VI
"raised runners", 2nd design, 115cc chamber
14044861...84-96...rect..........Bowtie, Aluminum, MkIV
"raw" casting of "861" MKIV
1st design
14081045...78-87...oval...OPEN...454
14081052...85-87...oval...OPEN...366T, 427T, 454 Truck, Marked "HiPerf"
14092359...86-90...oval...OPEN...366T, 427T, Marked "HiPerf"
14092360...86-88...oval...OPEN...454 Truck
14096188...70-71...rect...OPEN...454 service replacement, also used on later Mark IV LS-6, LS-7 and 454 HO crate motors, 116cc chamber
14097088...91-up...rect...OPEN...Gen.V 454/502 HO, 118cc chamber
24502585...97......rect..........Olds/Chevy, DRCE 2,
Pro Stock aluminum, for blocks w/4.900" bore centers

formula31

The casting numbers are on the head below the valve covers. I know of no other way to tell externally. There was a thread a year or so ago that listed all the good heads numbers. I use 781's (last 3 digits) and I think the other number ended with 056 but not sure. Oopps maybe it was 049, but i still like the 781's and they are plentiful.

KAAMA

Well, not sure if this will help you much, but in the mid 70's/mid 80's Merc used a GM cast iron head with large oval ports (73-84). I cannot remember which side of the casting the number was on but it was GM's "049" casting that had "open chambers", 2.06" intake valves, 1.72" exhaust valves and I think the chamber size was something like a 122cc. 049 were the last three digits of the casting number. Ragtop, has it listed as "353049". It was a very good head. Merc used these on their 330hp engines back then. A friend of mine had a 1979 Scarab with these engines/heads and when he modified them in the mid 80's he took the heads to a hi-perf shop and had the larger 2.19" intake valves and 1.88" exhaust valves installed, hardend exhaust valve seats, bronze wall guides, machined for larger diameter springs and bowl ported with a hi-perf valve job. He used them on his modified 330's and added some hi-perf exhausts with great results----something like 450-475hp. These heads were used until Merc started using some even smaller oval port heads that are sometimes refered to as "peanut port" heads(casting #346246). The peanut ports are good but not as good as the "049"s.
Casting # 336781 was a good head too----very simular to the "049" but I think the "049" had the edge and was the better oval port head of them all---for a GM head that is. The Merlin oval port heads are the way to go these days. They come with hardened seats, larger valve spring pockets/seats, and with the larger 2.19"/1.88" valves and they have larger ports. However, if you have a 454 already, and have the "049"s and want a little more power while sticking with the stock valve sizes, just have them pocket/bowl ported and use a cam that is somewhere right around .500" to .550" lift and about 218*/228* of duration @ .050 and I think you will be happy with the power increase from these mods. You will still have to add stainless steel valves and the hardened exhaust valve seats for them, and may have to machine for larger spring seat pockets. I would also consider broze wall valve guides. Adding the larger valves to these GM heads is where the cost will go way up----and if you're going to do that you might as well buy the Merlin oval port heads. I may not have answered your question as well as you wanted, but I hope you might have gained something at least.
Best wishes

audacity

shouldn't you be boating!!!!???...or working on your boat!!!!??? you just love this ****, don't-cha KAM!LOL....

blue thunder

Thanks for the input guys. That is a ****load of info Ragtop... hope you didn't have to retype all of it. Thanks. I tried to find the casting number when the vavle covers were last off, but I didn't recognise any. I'll look closely when I get the engines pulled.

My stroy goes like this. Both original 454 mags (1988s) died terrible deaths due to valve failure (I think). I now have two remanned marine long blocks built by a place called Sequel Engines. They were to make 330hp min. I want more at this point, probably in the low to mid 400hp range. I want to do much of what you suggest Kaama, but need to decide between the heads that came on the remanns, or the aluminum rect port edelbrocks I have. Much of that decision has to do with if the ovals port cast heads are good power makers. I have new edelbrock intakes for the oval port heads and only old beat up mercruiser intakes for the rectangle port heads. They won't be being used. Two of my four edelbrock heads have experienced lost exhaust valve heads under them and are in need of serious rework.

I really lean toward the cast heads because the aluminum heads were nothing but problems. I believe the crank and pistons to be cast in the remanned engines and it has 4 bolt mains. Any additional suggestions would be appreciated.

BT

KAAMA

Blue Thunder, I would stick with the oval port heads---especially for a 454" engine. The cast cranks are fine to about 5500rpm--no more. Even if you have to have the cranks turned .010" they will work---just make sure whoever turns them puts good radius's on the throws/journals. The 3/8" rods are fine too. Have them shot peened to relieve the stress (might cost about $50 per set), recondition if needed and use use the ARP Wave Lock rod bolts. Check the main saddles and make sure they're close to perfect as you can get---if not, have them align honed. Use either hyperutectic or forged pistons---for your naturally aspirated engine the hyperutectics should be fine. Have the COMPLETE rotating assembly BALANCED. Have all this done by a COMPETENT machine shop with a good reputation.

I think you'll be bucks ahead with the oval port heads. To me, it sounds as if you have the "peanut port" heads being that you have the 330hp engines with the 4-bolt mains, but I could be wrong. The peanut ports should put you close to the 400hp mark. Have them pocket/bowl ported---I think the peanut ports already have the hardend valve seats vs. the "049" castings so you will be bucks ahead there. Have the bronze wall valve guides and stainless one piece valves installed too. Those heads with a decent cam and good exhaust will make some neck snapping torque.

What kind of cams were you thinking of using? Hydraulic rollers, hydraulic flat tappets or solid flat tappets?

blue thunder

Kaama,

I wasn't planning to do anything to the rotating assembly because these are basically new (rebuilt) long blocks. I'm hoping the cast piston will be ok to the 5100 rpm level. Other than that, I was going to try the Competition Cam 11-234-3 recomended by Dennis Moore... 212 @ .050 on intake and 218 @ .050 on exhaust with a .480" lift. Flat tappet hydraulic. Not really sold on that, just the best suggestion I have to date. I am really looking for maximum power that if treated right will be fairly reliable. Also looking for maximum rumpetty rump at idle. This is purely an ego thing, cause I love that sound.

Was planning to go through the heads to make sure the seats are hardened and the valves inconel. I need to look at the valve springs/guides as well. I am pretty sure I have the large ovals, not the peanuts going from memory of when I put them on in June.

Exhaust is the wild card at the moment. I know what would work best (headers), but I am on a tight budget. I was thinking decent runnered manifolds with stainless elbows to reduce back pressure and prevent reversion. More ideas here would be greatly welcomed.

Thanks for the help Kaama,

BT

formula31

Everyone has there own opinion and Im sure youll hear plenty of them. I think that cam you listed is the stock cam or even smaller. Dennis liked my choice of cams too. Edelbrock Torker 2. Roller's are nice but not as reliable and very expensive and not really needed for a moderate engine. The Edelbrock comes with lifters for about $139 and works really good with large oval port heads to around 5100 rpm. No reversion.

blue thunder

Maybe I missed it somewhere Formula31... what was the cam you used? I remember reading about it. I think I want to stay with flat tappets... but definately want max performance. Any suggestions would be welcomed.

BT