jeffswav

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

Lofty

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.

JasonSmith

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.

formula31

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.

jeffswav

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

PatriYacht

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.

jeffswav

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.

MESABALANCING

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

PatriYacht

Sorry, I thought they were large oval ports. Those small ones are junk. Hmmm, what to do now? 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.

Pat McPherson

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...