Another 454 ID thread..
 

I'm trying to make some long-term engine plans, and need to start with figuring out exactly what's in my engines, because they aren't original. I do know from researching here that the blocks are #10237297, L-29 Gen VI, 1996 and up, 7.4 4-bolt. I have only looked in the heads enough to know that they are standard rockers, not gold or rollers. Intake # is 33384L.

Basically looking to figure out, based on what I have, whether to (someday):
-build these (N/A)
-refresh, leave mostly stock and add blowers
-scrap these and go with completely different motors.

So, I guess I need to know if the internals are forged or cast, and if the heads are decent.

I know everyone has their opinion about supercharging vs NA, but for now i'm just trying to figure out if these are worth putting any effort into. Thanks in advance for any info.

454's are probably one the best bang for your buck engines. They arent going to be the fastest but as far reliability they are one of the best and repair cost and finding parts is easier and cheaper.

Somebody must know what's in these...

L29 are the vortec heads. Chances are that is a low hp 454 with cast internals, two bolt mains, etc. The L29 head is better than a peanut port, but still has its limitations.

Weird thing is I thought the L29 heads only came on Gen VI engines. If they are gen VI I think they should have roller lifters on that setup.

I got that info from this thread,
http://www.offshoreonly.com/forums/g...engine-id.html

Just looked back at it, and it says Gen VI, I posted it incorrectly in the 1st post. I'll fix.

10M: Your asking a lot of questions that depend on budget $, drives currently in your boat, and how wild do you want to go. The std Mark 4,5,6 will go to 450-500 hp with a good cam, intake, carb, head work, including new valves w/o going to 4 bolt mains if you have 2 bolt. Beyond that you really need to consider either blower, bigger cubes (new motor), or spending alot on your current motors.

I put new Dart heads on my merc 400's (old Bowties were shot), new roller cams, timing covers etc. and dynod at 475 hp (I do have HP 500 intakes and Holley 700's).

Wannabe

Thanks. I understand there are a lot of variables, I've read the 454 build threads, I know what they're capable of. At this point I'm simply trying to find out if these blocks have forged internals or cast, and if the heads are worth using.

wannabe- what rpm you reaching with your 454's? I did alot of work to mine im pretty sure im in low 400's hp, it seems like the heads are key, i went with 781 but dont think they gave me the power i wanted, im turning it around 5000 rpm, that is with domed forged pistons as well bored .030 over

You can make a 454 make some decent power with whats available today.

Cylinder heads. You just can't compare a good set of aftermarket Dart, Brodix, AFR, etc, to stock GM stuff. Going aluminum will allow for more compression to be used also, so you gain from that plus the airflow too.

Cam profiles, today's hyd roller cams properly spec'd will do wonders for you. Also, the lifters on the market today, hyd roller wise, are absolutely capable of 6000RPM without issues. In order to make good numbers with a 454, compared to say a 502, you'll need to turn the 454 a bit faster to move the same amount of air. A engine is a air pump, plain and simple.

Carbs. I see lots of guys talk about how a 454 is a small engine, and a 750 is just fine. If you are talking a tow rig 454, or a mild 454, then yes, a 750 is ok. But, if we are talking about a build with good heads, big cam, 6000RPM, single plane intake, I'd personally run a 850 or even 950 on it.

Same goes for intakes. Most dual planes will outperform a single plane on the street. however, not many dual planes will outperform a single plane at 5500+rpm. Personally, in a offshore boat, i can care less if im making a extra 25hp in the midrange. I'd rather have the extra power at WOT.

Engine Masters hopped up a GM crate 454HO not too long ago. They installed Dart pro 1 310 aluminum heads, off the shelf somewhat mild hyd roller cam, single plane dart, and a 1000CFM holley 4150. 525hp at 5600RPM. That was also with like 8.25 compression I believe. So 87 octane can be run. Up that to about 9.5-10:1, and i dont see why that build wouldnt have done 550-575hp on 93 octane.

Many are quick to write off a 454 based engine. Mainly because 500+ cubic inches just sounds way cooler. Absolutely nothing wrong building a 454 as long as your goals are within reason. The stroke, rod angle, and overall design has been a proven reliable marine engine since the early 70's.

Big CI stuff was the hype 20 years ago when 400-450hp just wasnt enough. Flat tappet lifters were incapable of controlling the valvetrain in a marine engine at much more than 5300-5400rpm, and solids were high maintainance. The answer was big CI. While most big CI pleasure boat engines were able to make an extra 100-150hp over their little 454 based brothers, they werent exactly the fire breathers they are today. Back in those days, if you had a 540/550HP 5200RPM engine, you were doing well. Nowadays, pump gas marine 540's are doing 700HP all day without breaking a sweat at 6000RPM.

Just my thoughts!

Great info, thanks. The heads were a big question mark for me, but you suggest going aftermarket regardless, so that's helpful. I'm still curious what crank & pistons I have, but realistically it doesn't matter much. I'd be looking at replacing (2 sets of) heads, exhaust, intake, carb, pistons, cams....everything. Might be better off looking for a set of used/rebuilt/takeoffs at that point. I have also considered doing a basic refresh to these and adding some small blowers (177 or 250s). From what I understand 454s can run small amounts of boost pretty reliably in stock form, with forged internals.