SB,
Your numbers are the same as mine out of some GM High Performance literature I have. This L29 head is described as a large oval port design that flows better then any other oval. We must note though these numbers I am sure are with a stock valve job and a 2.065" intake valve.

bcarpman,
I was recently involved in a project with a base engine consisting of a Mercruiser 330/454. The owner wanted a cam/head (the peanuts had to go) swap that would net a 100 HP gain. One of the options consisted of a swap to the L-29 Vortec heads.

As SB pointed out the raw (box) flow numbers for this head are not particularly strong, however the overall design is superior to the early ovals. The opportunity was available to have the bare heads sent to a member of this board (HayJay) that works in the cylinder head department at Katech. The heads were not fully ported, however the flow improvement from the modifications was impressive. The Merlin was slightly stronger mid-lift but the L-29 carries nearly 30 CC less intake with a smaller CSA and easily stays with the Merlin on top.. Attached is the flow graph, both intake and exhaust, comparing the:
Stock Vortec L-29
GM 049 Oval
Merlin Oval
Katech/HayJay Modified L-29

The flow values were measured at Katech @ 28” and I am confident they are valid. Buying the heads bare, performing the above modifications, SS Intakes and Inconel exhaust, and a spring/retainer package that matches the cam profile, could be a very cost effective option, easily capable of exceeding your target power goal. I wasn’t a believer in these heads initially, but with some modifications they respond well and definitely have a place in moderate performance applications.

Bob

Yes, I've worked with Katech before, and I'm sure their data is trustworthy. I haven't talked to anyone there in a long time, and I'm not sure who "HayJay" is. Hopefully he'll chime in. This would be an option I'd like to persue.

Seeing you are from MI, give Tyler Crockett a call. He is the guru !!! Dave

http://www.crockettmarineengines.com/

Send me over an email and I will pass along the contact information with the data.
Bob

Can I swing a vote to some Brodix Race Rite Oval's or if you can wait some AFR ovals ? They should help your cause other than some outdrive torque breakage. LOL.

Just playin. Kind of. Not really. Sort of.

Thanks for the reference Bob.

bcarpman.....It sounds like you know what you're getting into and with your history at GM, it sounds like you know what you're looking for.

The build that Bob is talking about was successful in a few different ways. First, the owner's set of "peanut port" heads originally on the engine, had been grossly mishandled and poorly prepared. The valvejobs leaked terribly and they were built with mis-matched components. A real mess. So to start, just bolting on a set of well prepared heads made a big difference. Second, I think Bob recommended a very good cam for the application and created a strong running package. Third, the 18cc difference in chamber volume increased the compression ratio by about 1 point, from about 8:1 to 9:1. I am a firm believer in compression making power (when it's applicable), not just good airflow.

I didn't have a chance to measure the port volume on these heads after I ported them, but the work was just in the bowl area and would not have increased the volume by much. It worked well with this 454 and I think it would work well for good low to mid range power on a 496.

You can contact me through Bob or you can send me a PM and we can discuss this option if you're interested. I'd be happy to work with you on your project.

Jason

Question? In ref to the GM 049 head castings as referenced in the graph....are those 049's modified with any bowl/pocket porting or short side radius work or larger valves----OR are those just BONE STOCK untouched 049's with stock 2.06" intake valves/1.72" exhausts??? Just curious thanks.

Well, although I started out looking for cam suggestions, I ended up with a lot of good cyl head advice.

However, in that time, I've also gotten some good cam advice, and have decided I'm looking for an HP500 cam. It's 230/236 @.050 and .570 lift on 114LSA. It should obviously be good for 500 HP and should also idle decent.

I found one for sale that is a "regrind". I'm a little hesitant about that, and would rather find a "takeout". Anyone know anything about reground roller cams? Or does anyone have a takeout for sale?

thanks

Merc 500EFI
Crane Grind#HR-292-2S-14 IG
292,298 at .004” Lift with 1.7 rocker .598” , .610”
230, 236 at .050”
ICL 109 , ECL 119
LSA 114


======================

Merc HP500 Carb
Crane Grind#HR-284-2S-10IG
Adv 284, 292 at .004” Lift with 1.7 .576 / .598
At .050” 222, 230
ICL 105, ECL 115
LSA 110