Head advice on BBC
 

This is my fist post but I have been on this site several times looking for advise. I have a BBC 489 Stroker motor in a 1994 Baja 236 Cuddy.
Flat top KB pistons .030 over
Forged crank 4.25
Forged rods stock length
Holley MPI 950 with oval ports
EMI exhaust (long)
Lunati hydraulic EFI cam with .540 and .550 lift and .230 and .235 duration @ .500
Comp Cams Roller Rockers
Roller timing chain
HEI computer controlled ign.
Now here is my weakest link.
GM oval port Heads ported and polished with Manley SS valves 2.065 Int and 1.725 Exh casting 10114156
I am looking to upgrade my heads but if I switch to Rec Port I will have to switch my Holley MPI intake at $450.
I have read good things about the L29 heads. Has anyone tried them on a setup similar to this one. I am ready to port @ polish them and install bigger valves, better spings, rockers and guide plates.
Thanks,
Jeff

Re: Head advice on BBC
 

Jeff,
Welcome to OSO. There has been alot of discusion here about this engine. Do a search in the Tech section on it.

I run a pair of 454 strokers with the Merlin Dart "Grumpy" Heads. These are the raised exhaust port casting and they work great! I'm pertty sure that you will have to change your manifold over for the rectangular port. There are folk on here that know far, far morethan I about this and I'm sure they'll pipe up.

Re: Head advice on BBC
 

Casting numbers ending in 781 or 049 from GM are oval port. they are the same head but one has a seat for leaded fuel and one does not. It won't matter because you will need to have them opened up to 2.25 or 2.30 intake and 1.88 or 1.90 exhaust. I think you know the rest of the story as far as materials of valves & seats.
Hope it helps.

Re: Head advice on BBC
 

yea, the large oval ports heads are fine for a 454 with that cam. what about edelbrock aluminum ovals? they have smaller chambers to pick up some compression and work well with some porting. They also come with the right valves. By the time you finish the gm oval ports, youll be close to the new edelbrocks money wise.

Re: Head advice on BBC
 

Thanks for the replys. The heads I have now are 118cc, with my setup I am only running about 8.5-8.6 to 1 compression. The L29 vortec heads have a heart shaped 100cc combusion chamber. This would give me about a 9.8 to 1 compression ratio. I also understand the timing will need retarded to about 30 deg and 92 octain fuel will always have to be used. If anyone has any experience with them I would love to hear about it.
Thanks,
Jeff

Re: Head advice on BBC
 

Airflow wise, the vortechs aren't any better than the old large oval ports. Before you spend a bunch of money, think how much faster your boat will be with 10-20 more hp. That's all you'll get from the higher compression. It sounds like you have a well balanced engine combination and you may have to spend a lot to pick up any more.

For instance, if you want more hp now, you'll have to rev higher. That means a hyd roller or solid roller cam. About 1000.00 for all the parts. Then you need a set of Canfield rect. port or equiv. heads. About 2500.00 set up for marine use. Them you'll have to do something with your induction system. At least 1000.00 for a carb system. All that and maybe you pick up 75 hp. 4-5 mph max.

If you want the best airflow out of a set of oval ports, talk to Jim Valako, aka Jim V on the board. Otherwise for a noticable perf. increase, look into supercharging. :D :D

Re: Head advice on BBC
 

The problem is I started with a 330HP Gen5 penut port ovals with a volume of about 200cc. Even though they have been ported and polished I still am not getting enough flow.

Re: Head advice on BBC
 

Jeff how's it going good to see you gettin your project going and letting us in . I've done a bunch of R and D with my marine poker run packages and I can tell you that if your comp is 8.9:1 or higher you can go with a set of Pro Topline cast iron heads they are about the same money as all the other heads listed and if there's one thing I can tell you is they make more power then all the others put together and I'm not trying to sell you a set they do work . The port shapes and cross sections are almost as good as same ported heads on the market even better the the grumpies that I've also used many of. Good luck Laz Mesa

Re: Head advice on BBC
 

Sorry, I thought they were large oval ports. Those small ones are junk. Hmmm, what to do now? :confused: The best value would be a set of Edelbrock oval ports with all the proper hardware and inconel exhaust valves already in place. By the time you get the work done on those vortechs, you'll have a thousand in them. Or you do what I posted above. I don't know what your budget is.

Re: Head advice on BBC
 

Hi Jeff and welcome to OSO.
I got your e-mail about the L-29 heads.
The L-29 heads will indeed up your compression and flow better than the peanut port heads. There are a few guys that have replaced the peanut port heads with L-29 heads on Gen V and early Gen VI low HP 454s with good results.
However, If your plan is to have lager valves install into the L-29s, It is not worth the $$.
A new set of after-market heads with larger valves would be a better place to spend your $$.
IMO of course...

Re: Head advice on BBC
 

summit racing has edelbrock alum performer heads for bbc for 979pr. get a set put in good valves and springs sell the valves and springs that come on them on ebay. bbc stuff brings all the money on ebay. the car guys jump all over it and pay stupid money for used parts.

Re: Head advice on BBC
 

I would replace the GM "peanut port" oval port heads with a better flowing set of aftermarket heads as most everyone else has suggested here.

But just so that you know, the "peanut port" heads CAN be made to flow much better by installing larger intake/exhaust valves, and having the ports opened up for more volume. However, it takes a TON of porting to do this, and may not be worth the time/trouble/money to go this route vs going out and buy the better flowing aftermarket castings.

Several years ago the late John Lingenfelter did some "peanut port" mods with larger valves, porting, and they flowed real nice, and made decent power on a 496 or a 502 (I can't remember)---but that was back when there wasn't as many head options as there are today. I still would opt for a better flowing aftermarket casting, but for whatever reason you feel you must retain the "peanut port" heads you have now, then that is an option/route you have with them.

Re: Head advice on BBC
 

Thanks for all the input. I realize the best way to go would be the Edelbrock Marine 454-O at $739.50 each. I am just trying to keep the cost down. I have already spent a ton of money on this thing and the votec heads looked like a good deal if I could pick up a used set cheap and rebuild them. However it looks like it will cost about $300 to $400 just for the castings, then you have valves, seats, valve job, porting. I just want to make the right desision before I spend anymore money. My machine shop does have a set of mark IV large ovals I could rebuild, but I would only save a couple hundred going that way.
Thanks,
Jeff

Re: Head advice on BBC
 

Ratman
I looked in Summit Racing and I could not find any for that price. Is that some sort of special I am not seeing?
Thanks,
Jeff

Re: Head advice on BBC
 

Hey Jeff,
I think Rattman is talking about bare castings.

How much $$ do you have to spend?

You could bolt on a set of L-29s and gain some power; how much???
Maybe another 25-30HP for $800-900.

The Edelbrock Marine or World Products large oval heads will cost you $1600-1700. Plus you will need to replace the flat tops, more $$.
But then your engine would be capible of Big HP.

Re: Head advice on BBC
 

My small oval ports have allready been ported as far as they can go. I spent a lot of hours on them 2 years ago with a rorory tool. I took out all the defects in casting, polished the bowls, gasket matched with the intake. However not knowing any better at the time I went back with the stock valve size. How much more would bigger valves give me on the heads. For example 2.19 @ 1.88 vs 2.065 @ 1.725.
Thanks,
Jeff

Re: Head advice on BBC
 

Probably 20-30HP. Not really worth the time and $$.
If you cut the heads to install hardened seats for larger valves, the bowls will likely need to be ported again.

Hey Jeff,
How did you get to 8.5:1 with flat tops? Did you deck the block and mill the heads?

Also are you sure your intake won't seal against rectangular port heads? Some oval port intakes do...

Re: Head advice on BBC
 

Inconel exhaust costs 35-50.00 ea. Good intakes 15-20.00 ea. Right there you have 500.00 in valves. Seats have to be reworked for the larger valves. Hope you don't need to replace any guides. Then you need to machine for screw in studs. The Edelbrocks are a good deal when you look at it this way. Also they have a 110cc chamber option which will bring your compression up without buying new pistons.

Re: Head advice on BBC
 

Jegs has them for 709.99 ea with valves but without springs, retainers.

Re: Head advice on BBC
 

cp has them for 1500. just need springs 880 6155 rec Edelbrock i have flow chart on them. had my flow when i got them.i can email it to you.


http://www.cpperformance.com/detail.aspx?ID=4094

Re: Head advice on BBC
 

http://www.flatlanderracing.com/
$1349

Re: Head advice on BBC
 

JEFF, the heads are on the cover of the summit catalog i got in the mail about a week ago. give them a call, ratman

Re: Head advice on BBC
 

amer3 : can I get a copy of the flow chart? I'm thinking about buying a set for my 540.

Re: Head advice on BBC
 

I have used the edelbrocks on 454's and 509's with good results. On the 454 I had changed from rectangle port closed chambers 105cc to the edelbrocks at 110 cc's so I lowered the cr and still picked up about 200rpm's but I had to increase the timing to 40 with the flattops to get the power due to the change to aluminum heads and 8.9 cr.

Re: Head advice on BBC
 

I have a stroker kit, the extra displacement give a higher compression ratio.
I called Holley and the ports could not be ported on my oval port EFI intake to match the Rec ports.
Thanks,
Jeff

Re: Head advice on BBC
 

if you weld them up you can probably port them to match. back in the day when the were racing 900cc z1 kawasakis they welded up the intake port to go from a stock 28mm carb to 44mm carbs, there was no material left from the original port after all was said and done cuz the new ports were huge. id lay a gasket from a rect port on the intake and see how much you would have to build it up with alum welding before port matching it! if there a will there's a way. merc doesn't look at it that way, nescessity is the mother of invention

Re: Head advice on BBC
 

Thanks for all the great input.
It sounds as though the edelbrock marine ovals are the best bet. If I add them to my setup how much HP, RPMs, and Speed do you guys think this would add to boat?
I have a Bravo 1, 1.5 drive, 25 pitch Lab finished Mirage running 4600 RPM 66 MPH GPS.
Thanks,
Jeff

Re: Head advice on BBC
 

I would think that changing to the Edelbrock heads would gain you 50+HP. Would be a great choice if you have the $$...
I would guess 3 to 5mph increase... :drink:

Re: Head advice on BBC
 

Does anyone have the flow numbers for the Edelbrock Marine heads?
Where is the substantiating information that warrants this recommendation?
Anodizing, Inconel and price sure makes them sound attractive but what are you getting beyond that?

Re: Head advice on BBC
 

Edelbrock does have flow numbers on their web-page. How accurate there are ???
I would say that they have to be a hell of a lot better than peanut port heads... :rolleyes:

Re: Head advice on BBC
 

True True.

Re: Head advice on BBC
 

My wife shot down the new heads. I need to keep my cost down. I have been looking at different casting numbers for large ovals and have found a lot of conflicting information on chamber volumes. I am looking for a head with 105 to 110 cc chamber with good flow. Anyone have any suggesions, my machinist has a set of 3993820's and 353049's. His book shows smaller chambers than mortec.
Thanks,
Jeff

Re: Head advice on BBC
 

049's are 119-121. Ive measured plenty myself. I would stay away from the small chamber (closed) heads. They dont make good marine power.

Re: Head advice on BBC
 

These inconel exhaust valves...how important are they? I recently had a local engine builder do me a 502, 8.5:1 with a hydraulic roller 535/554 lift but I don't think I have those valves. Was this a terrible mistake?

Re: Head advice on BBC
 

Inconel you ask?
Let's put it this way. I have seen enough failures on marine engines that didn't use Inconel exhaust that I wouldn't build a marine engine without them.
Manley recommends them for Top Fuel, Funny Car and Marine applications.
Pretty much sums it up right there.

Re: Head advice on BBC
 

Tell The Wife Who The Boss Is And Buy The New Heads!Better Yet,Buy Them,Put Them On And Then Tell Her You Got Them!This Is What I Would Do Since Boating And More Hp Is The Most Important Thing In Life!All In All With All Im Considering Changing Out My Heads And Cams On MY 525sc's Am Just Staring My Research And Am Curious How Well This Comes Out!

Re: Head advice on BBC
 

I know this may be redundant now, but "JimV" has the flow numbers on the Edelbrock heads as they come from the factory out of the box. Apparently, a guy sent Jim two sets last winter to have them flow tested. He also had Jim port them for better flow.

Re: Head advice on BBC
 

Jeff, be careful if you decide to buy old Gen IV heads.
They will not seal well on Gen V blocks. I know that there may be some special head gaskets out there, but I would recommend against it.
If you can not spend the $$ for after-market heads, then I would go back to your original thinking.
A set of L-29 Heads or Bigger valves in your existing heads...

Re: Head advice on BBC
 

Merc put Manley inconel valves in 400 Cyclones, 420 HP's, 450HP's, 465HP's, 500HP's. I would say if you're building more than 400hp, you need inconel.

Re: Head advice on BBC
 

After doing more reserch I am probably going to find a set of L29 vortec castings, I already have rockers, studs, valve guides and springs. All I need are the castings. If anyone has a good deal on a set let me know. I am located in the St Louis MO area.
Thanks,
Jeff