496 vs 502
 

Is the 496 or 502 based motors better to build off of. I have a pair of 496 motors with carb intakes and msd distributors. Are the 496 exhaust the same as a 454/502 or different? Also these motors are 30 over and need rebuilt again. My question is do I find 502 blocks to build off or build the 496's. Seems like the 496 is its own motor and nothing in common with the 454/502 motors?

what 496's are they? I always thought a 496 was a stroked sixty over 454 which in my mind would be a throw away motor at that bore. Do you have the 8.1 Vortech based blocks?

GD he listed the 496 with MSD ignition set up and Carb / intake so no way its the 8.1 MPI distributorless 496 CID from 2001 thru 2010 from Mercruiser,

The 496 carb with a distributor ignition is bored and stroked based from a 454 / 7.4 L.

I think gm performance offered the 8.1 Voetech as a carb motor

Looking at the years of his boats in his profile, I would guess he has stroked 454's.

They are the 8.1 based motor with carb intake

If a bored and stroked 496 it's a good engine. If factory 496 don't bother with them. Go with a 502.

what exactly is the 8.1 Vortech and what was its purpose as opposed to the 502, how does it differ from the rest of GM's big block? Just curious really

2500+3500HD trucks with more modern FI and cats. That's what it's purpose was.

Luckily GM kept the 502 for over the counter sales. Boats / old cars/tucks / etc.

The 8.1L isn't 'bad' but.........

OK I am lost now you have a 496 - 8.1 L base like what was used in the marine apps from 2001 thru 2013 (Volvo bought a bunch of stock to keep them going)

You are saying Carb app and intake so what ignition set up did you use. I might be wrong but if I remember correctly the cam for a 8.1 L - 496 does not even have a gear to match up with a distributor hence a true 496 stock base used coil over plug. Do you have a MSD set up with a crank trigger and coils over plugs along with the rest of the MSD ignition components ? Just asking.

I do not recall GM offering a crate engine OEM 496 CID 8.1 matched up with a carb intake or even having a carb intake for the 496 - 8.1 L. .

Also Dart has a lot to offer to change over the 496 MPI to carb app. Maybe this is what you have.

They were marine 8.1 motors set up by a company to run with a carb and distributor and ran on natural gas. Have a 4 barrel aluminum intake and use the same distributor as a 350/454. I'm not sure what all has been changed to make this work. From the research I've done they are there own engine based off the 6.0 and nothing off the 454/502 motors. Seems they have cast internals and no longer made after 2010. I have 4 of them and trying to decide if I should try a build a high HP motor out of them or not. Seems most people throw them away and go to 502s

I can't add much to this, but I do believe the 8.1 has a gear on the cam. I seem to remember having one out when working at a GM dealership and wondering why they bothered, but that was many moons ago.

Dart makes a carb intake, also has provisions for distibutor. http://www.dartheads.com/products/in...-manifold.html

The 8.1 uses same cam type as earlier engines but has a firing order swap.

That's when the aftermarket got more into firing order swaps as the cam cores where more available and cheaper since, again, the 8.1 used it in production.

DArt intake:
http://www.dartheads.com/products/me...manifold_1.jpg

I know you are a mechanic so think about what you are saying and picture the 496/8.1 - at first, I agreed with you in my head than thought, WAIT thats what the little ball bearing reinforced carrier that bolts in for the oil pump is for...

How would you drive the oil pump?

Its all there you just need to take out the oil pump drive gear assembly and swap for a distributor and you are back to a distributor type ignition.

I did a lot of research and talked to a lot of people before repowering the Donzi. Everyone except Ray at Raylar (he was a little biased) said to lose the 496 and go with a 502 based engine. I'm sure glad I took their advice. Those are some unique engines you have there. I'm not sure why someone would think that a carburetor and distributor would be an upgrade though.

It is possible that a carb/intake combo will make more power than a FI setup. On LS motors with the same internals a carb setup will make more power. It is your call, if already have everything 8.1 you need to do the math on parts, combos and costs.

I believe the 8100's were tall decks and had 4.375 stroke cranks GM introduced into the truck line. Which Merc marinized.

Yep Keith Atlanta I remember now since you brought it up. Its been about 3 or 4 years ago to have completely torn down a 496 to the last rod bolt.. I do remember the OIL PUMP DRIVE and one screw / bolt holding it down. Yes it does have to be removed for the distributor placement. You are 100 % correct and I was 100 % wrong about possible no gear on the cam for a distributor app.

One of these days I will tell a story about the biggest lunch eater Mercruiser 496 / 8.1 that showed up back about 6 or 8 years ago. Cam sensor code and ran like a distributor motor 180 out. What a F' in lunch eater.

Next I took the 2 hour seminar from Dart University in person about the all new Gen VII stuff back in Dec 2010 before it hit the market in April 2011. I know Dart has the carb intake manifold with distributor hole mount if needed. That same class should be on youtube as well. They tape the whole seminar and said it was going on Power TV and youtube just incase any wants to look for it.

I personally think it would be cool if someone build up a 8100 Vortec engine, with the intake SB posted, and an overall custom combination.

I say lets start a thread on building up what you have. Maybe Raylar can chime in. Lets keep it old school carbed....throw some cam at it, and have some fun. Please, lets not do another "stroker 454" build....theres already about 100 threads on that topic.

I'm not super familiar with the 8100 engines, but , I think they had many technology advancements over the old big block engines. Like the intake runner design for starters. Isnt it sort of like a giant LS engine??????

Where's the dislike button ?

Lol.

It's not dominant over the old BBC by any stretch.......add to that the cost is relatively high.

The LS small blocks vs Gen 1 small blocks....Yeh, now we are talking. $$$/HP/Modern FI, if prefered, aftermarket support.....yes, sir.

The Gen VII 8.1L vs older BBC's ? Not a freakin chance.

Now, if we can get GM to make 500+ cid 12°-15° spread port splayed valve 11:1 compression pump gas motors in such #'s that they cost less than 4k pulled out of a low mileage wrecked truck...then we are talking !

LOL.

Don`t do the 8.1, its a gas hog!!!!


:cool-smiley-027: