Large Oval vs small oval head ID
 

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 :cool:

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

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.

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
:)

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

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 :cool:

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?

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 :cool:

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.

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 :cool:

kaama,
how do the hardened exhaust seats hold up when installed? i was kicking that idea around of having it done but was afraid they may fall out. i'm not familiar with that process. i know they are cast in from the factory.

hi BT,
i put in 2 comp cams extreme 4x4 cams this year,
int .544 exh .564 226/234 111* LSA
it was $99 from summit. i went with the edelbrock torquer springs to match the cam and no modifications were required on the heads. also used crane anti pump up lifters. the 4x4 cams make lots of torque and they sound really nice at idle. no reversion with emi thunders. rpm range is 2800-5800. i'm not trying to sell you comp cams, but i'm happy with my choice. my heads are 325cc rec. port with 2.19 x 1.88 valves with a dual plane intake by the way. my boat is 10,500 lbs. comp cams grinds those cams with a 4* advance in them so i set them straight up. good luck with a tough decision. if it were me though i'd get the aluminum heads redone and use them.
:)

Its definitly not a Max cam but with stock compression (9-1 or less) and pump gas and silent choice (Gils) its about as far as I wanted to go. I cant find my cam cards right now but I think its about 224, 232 at .050 and .527, .553 lift at 114 lobe sep. I set the #1 intake cl at 106 which is advance about 4 degrees. As always, cam break-in is critical especially since I am using stronger springs than they recommend.

Thanks Excal... what are you using for carburation?

Did you get Total Eclipse back up north yet?

BT :cool:

Ive had many 781 heads redone with hardened seats all around with bigger valves. Never had one come out. I think they are pressed in but Im actually not sure. (one of the few things I rely on a good shop)

Is that a flat tappet Formula31? If you find the cam card... do you know what the duration is a .004" lift? Dennis Moores book has taught me just enough now to be dangerous.. ;) If you don't mind me asking, how much did your shop charge for the change in valve seats... and valves if applicable.

BT :cool:

I like excals cam choice. I probably couldnt get away with it with my exhaust. The magnum choice set up puts the water in about where the stock set-up does if not sooner.

Is that a roller cam Excal?

BT :cool:

Yea, flat tappet. Duration numbers at .004 are basically meaningless, as far as I know. I know some manufacturers still list an advertised duration which is usually around .008. Ill look but I dont think they even listed that. Theres another real good bbc power book by Alex Worlordy (sp).

I doubt it at that price.

BT,
i didn't bring the Total Eclipse up yet. i sold the small one and have been busy making sure its ready for the new owner.(beating it) If you want to hear the rumble those cams make, i'll let you know when it's here.
the cam is not a roller cam. .006 tappet lift 270/278. a roller cam kit with springs and lifters is minimum $600 last time i was looking. i'm running edelbrock 750 cfm carbs re-jetted 8% richer on the main and secondary side with electric chokes.

Pardon me for my ignorance Excal, but what exactly are emi thunders? Headers, runnered manifolds, tailpipes. Looks like my choice of cams will come down to what I can afford for exhaust.

If I was to do only stainless tailpipes to mix at the transom and leave my stock manifolds, could I use the cam Excal uses?

Can I do nothing to my stock exhaust, use the cam Formula31 uses without reversion problems and get any perf increase. I now have mercruiser stock manifolds with 4" elbows exiting out the transom.

BT :cool:

If you use a set of tailpipes that dont put water into the exhaust flow till the transom (dry pipes), you can pretty much forget about reversion problems, so yes, you could use excals cam.

Yes on question 3 but a set of gils or better would help more. Not sure how much.

Its really a matter of all the components working together. Good heads and valves, intake, carb, and exhaust. Changing the exhaust alone has little effect without doing the other things. Ive never tried to do all the other things without doing the exhaust, but as long as you have through hulls you should be OK. The dryer you can keep your exhaust, the more overlap you can have. But remember, big cams need high compression and high RPM's to shine. They will hurt the performance and torque on a moderate 5000 rpm engine on pump gas. Excals cam is not what I would consider too big. Its about right and will make more power than mine with the right exhaust.

Blue Thunder,

My cousin has a pair of 454's with pocket/bowl ported oval port heads, dual plane intakes, a Comps hydraulic flat tappet cam 218*/226* duration on a 110* lobes, 8.6:1 comp ratio, stock Merc Thunderbolt ignition (no ignition box needed) with stock cast cranks turned .010", stock 3/8" rods, and cast pistons and his engines made 461hp @5100rpm and 514 foot pounds of torque @ 3500rpm on the dyno with 32* of timing. But I wouldn't run it much over 5100rpm especially with cast pistons. Of course this was done with dyno tubular headers. If you are using the stock exhaust system then you will still make the 400hp that you are looking for. Just be care of reversion with stock exhausts.

Again, he did this WITH GM oval port heads and they weren't even the 781's or 049's or even the peanut ports----these were another casting of GM's oval port heads. So I think you're on the right track bud! :)

BT,
EmI thunders are cast aluminum manifolds made by Eddie Marine. they are good for well over 500hp and a lot of guys on the board run them. they are about the same as gills or imcos. i got mine earlier this year from a guy named steve snider who advertises in the exhaust section in the classifieds for $1050 per engine complete. they have a website if you want a better look. i don't know how much if at all they would help you given that you already have 4" exhaust. i ran my motor specs on desktop dyno and came up with around 470-490 hp.

BTW, my cousin had hardened exhaust seats installed in the heads. This is done by a special cutter and then the new hardend seat is installed with a certain amount of "crush" and is pressed into the recess made by the cutter.

Do the hardened seats. I put the bigger valves in a set of 049's without the seats, and the valves actually worked themselves into the head. I started loosing power, and figured it was in the heads somewhere. When I took the valves out, it looked like the valve was a boring bit and worked itself in the head.
mike

Goob... I'll definately do the hardened seats if they are not already there. Thanks.

Excal... I took a look at the emi exhaust manifolds. It looks like the water mixes with the exhaust in the same place as the stock risers. Is that true? If so, I guess it would be ok to run stock exh with your cam grind and setup. Do you agree? How did you know that lsa and duration would be ok with water mixing so soon? Seems on the hairy edge.

And of course excal, the answer is YES... I would love to hear your cams in person. If you plan a run to the C&D let me know. My boat doesn't run at the moment but my truck still does and my cabin is only about 20 mins from there. Better yet... ever try the Nauti Goose?

BT :cool:

bt,
i guess that cam is close to reversion but i don't have any problems at all. the stock cams that the 400 hp cyclone engines had (my originals) were 111*LSA also with stock exhaust. the EMI's do mix in the same place as stock so i guess it would be ok for you too.
i will be doing the C&D in the next couple weeks so i'll p.m. you. what is the nauti goose?

Take note...
 

Blue Thunder,

In one of my previous posts I gave you an example of what my cousin did with his 454's with cast parts, and the type of parts he used; cams, stainless valves, Harland Sharp roller rocker arms, bowl ported oval port heads, stock Merc ignition, safe comp ratio of 8.6:1, dual plane intakes, etc. Also, he had the complete rotating assemblies balanced. Your base engines are very close to his and those are the mods he did to achieve the results he saw on the dyno---pretty valuable info....especially for what you're wanting to do. Just didn't want you to miss the posts. Have fun. :)

BTW, back in the mid 80's, we modified our 330's that had the "049" casting heads and when we did all the mods we originally did NOT have the hardened seats installed in them. We were in the learing mode and had to take the engines apart again for another problem. While we were doing this, we checked the heads out and noticed that the stainless valves were pounding the stock seats way into the head just as "goob" has described! I think it was more apparent on the exhaust side if I remember correctly.

Notes being taken Kaama... thank you very much. You have been a tremendous help!!!!! One additional question I had for you was what is"bowl porting". I've never heard of that.

BT :cool:

Bowl Porting
 

BT,

Bowl porting refers to smoothing out the transition from the port itself to the valve bowl area. Usually there are some sharp casting lines in this area from the factory, which creates tubulence and reduces flow. Also, sometimes the bosses that support the valve guide are smoothed out and reduced somewhat.

Thanks Budman. Anyone have an estimate on what bowl porting, new valves and hardened seats should cost per set - complete including machine work?

Blue Thunder, these are some rough estimates.

bowl/pocket port $225-250 per set

install hardened seats $100 per set

install bronze guide liners $85 per set

3-angle valve job $125 per set

machine for springs $45 per set

machine for seals $45 per set

You may need to have other things done to the heads like having them "surfaced", degreased, assembled, etc. Plus the cost of new stainless steel valves, springs to match the cams, retainers/locks. You could very easily have about $1200-1350 or so in one set of heads. Take it to a well known machine shop who does PRECISION machine work and that does lots of this kind of stuff. A shop that has a GOOD reputation.

All good info. I might suggest having complete bronze guides put in instead of just liners. They last a lot longer and dont cost much more.

Wow!! Serious sticker shock Kaama. Would you say it is worth doing this instead of exhaust, or visa versa. They are seeming to cost close to the same. What did your cousin use for exhaust on the 461hp dyno motor? Sorry if I missed it somewhere.

I guess a good automotive machine shop would be a performance automotive shop? I have one of those I use. Other than that, I used to use a perf automotive machine shop owned by a guy that raced outboards. Any value in using him instead in you opinion, or is a head a head?

Thanks again,

BT :cool:

Blue Thunder,

Get ahold of "Maxx"---he's a member of this board and is the one who's cutting a Bravo One drive 2" shorter project. His name is John and he lives in your area and could help you out. He's a super nice guy! He could direct you to a good machine shop in your area that could do the work and probably get you a good deal.

My cousin is using the Gil manifolds for his engines. It's up to you as far as what you want to do first. You'll need a Gil exhaust system to let the engines breath better. Doing the head mods and adding cams will help your engines produce the power, but untill you add the better than stock exhaust system it won't really break loose. You'll probably see about 380hp to 400hp with your stock exhaust with those mods. Once you add a set of Gils (or comparable) you will be in the 425-440hp range or so and the Gils will increase your rpm as well by about 300rpm or so.

Get ahold of Maxx (John) he will be happy to help you get in touch with the right machine shop. 757-739-5796

Mark/KAAMA

You are a wealth of great info Kaama!! When I get the engines on stands and have my plan defined, I'll get in touch with Maxx.

So you think I can get about 100hp per motor with exhaust and engine mods? That would be sweet. Say maybe 600-700rpm? I have a line on some 26p B1s labbed that might really work if I get that much hp boost. Running mirage 25p now at 4700. Thanks again bro,

BT (Dave) :cool:

head work
 

good work here is were I feel you have some of the most to gain. And it dose not take away from reliability. Charlie

Thanks Beerman...

BT :cool: