I have a source for gen 6 454 motors that are all low mile takeouts.......I have a couple sets of std TRW pistons and was thinking of taking a shortblock throwing some 10-1's in it, running a 502/502 cam, a set of #781 heads ( 65-90 heads will bolt right on with stock gaskts), edelbrock RPM intake with an 800Dp carb........I have all the parts and figure this should be a 2500-6000RPM with 400-425HP motor and should be able to asssemble it for around $1000-1200 including cost of shortblock. The part that scares me is the cast cranks in these motors, the counter wieghts are real small and crank doesnt look to strong...........was considering buying a real seal adapter and throwing and old 454 crank in it. Any ideas?????????

I had a cast crank GenVI here, the counterweights were the same diameter. Both the MrkIV & GenVI use the same balancer, flywheel is different due to shape of rear main seal, but rods and pistons are interchangeable. If you can get the shorblock cheap enough, no reason not to go with it.

I'm running one. I had no problems making the power you want with a ZZ502 cam and stock L29 oval ports w/ 9:1 CR. I hope to test the crank this summer with a cam/heads swap.

Can anyone confirm if the L29 have a cast or forged crank, and are they forged or cast rods?

I am finding a guy who is digging on the L21 454 (RV's and Medium Duty Trucks) have a Forged crank. So was wondering what the L29 might have. Mine is in a 99 K2500 Suburban.

Thanks!

I have been messing around with a Gen VI for the last year. . . .. and have had several complications when trying to use old (earlier) heads (oval port) on the Gen VI block. . . . the valve geometry was goofy !!! I had to put a set of .125 "shorter" push rods in it, to make it work. . . . also, you can't just grab an old head gasket and throw it on. . . . the water passages are "quite" different. . . . I would highly recommend that if you use a Gen VI block. . .to use the Vortex Heads that was originally made for them. . You can get a gasket from Felpro that will adapt an earlier head to the GEN VI block.

I will admit that I was using a Comp Retro-fit Hyd Roller/Lifters. . . . but I checked them against the old rollers I took out, and the deminisions were the same. . . so there definately is something to watch there. . . .

You can use aftermarket heads... But need a adapter gasket for old style heads.

I thought the Gen 6 could use any of the head designs; it was the Gen 5 that needed special gaskets (and a prayer) to use the Mk IV heads. I would expect--but have not verified--that any Gen 6 gasket could be used to install Mk IV heads.

I heard there are piston differences from Mk IV to Gen 5/6, too. There was a thread about that a month or two ago.

My motor is a Gen VI. ANY head can be used with this block. Not sure why one of the posters had to use shorter pushrods as the dimensions of this block have not changed from the Mark IV.

Nice thing about the Gen 6 block is the one-piece seal, and the fact that its roller-cam ready. The factory "spider" is nice b/c you can use lifters that dont have the tie-bar (little less weight). I have Eddy heads on mine, and used the Fel Pro 1027 gasket - perfect fit.

Right about the pushrods though - needed a set that was really short for some reason. The block has tall lifter bores - might have something to do with it.

I've been racing and street driving mine with the cam/head swap for 2 years now. Shifting at 6000-6200 with no problems. I too had to go with a very short set of pushrods

knud,

What et's are you pulling with the voodoo 60622?

I heard there are piston differences from Mk IV to Gen 5/6, too. There was a thread about that a month or two ago.
I missed that, could someone point me toward it?

http://www.chevelles.com/forums/showthread.php?t=171652&highlight=Gen+Piston

knud,

What et's are you pulling with the voodoo 60622?

New bests last friday. The jet extensions were just what the doctor ordered.

60' - 1.520
1/8 - 7.193 @ 93.320
1/4 - 11.430 @ 114.286

I need to adjust my shifter cable. It must have some slack so it shifted into 2nd gear at 4000RPM on this pass. I had a small amount of wheel hop also. 18 psi in the drag radials. timing locked out at 36 degrees. Not too bad for used junk.

yes i have gen 6 in me car good engines to rebuild had no probs

New bests last friday. The jet extensions were just what the doctor ordered.

60' - 1.520
1/8 - 7.193 @ 93.320
1/4 - 11.430 @ 114.286

I need to adjust my shifter cable. It must have some slack so it shifted into 2nd gear at 4000RPM on this pass. I had a small amount of wheel hop also. 18 psi in the drag radials. timing locked out at 36 degrees. Not too bad for used junk.


Got her running good! Looks like those heads worked out OK afterall. Nice ET/'60. What's the weight of that truck? Did you end up getting a converter/gears to get that cam to work?

I’m pretty deep into building my ’99 Vortec 454. For what I have into it, I think it’s an awesome deal! However throwing the parts you have at it, ain’t a $1000 build. The only thing you’re saving out of the L29 engine, is the block … and an earlier block would definitely be a better performance choice.



Do a search, you’ll find a lot of info. I believe 400hp is capable with a stock build, and ZZ cam (~$150 new).



Gen6 blocks are different! Unless you’re getting a crate motor block, there is no fuel pump or 4spd threads. The 4spd can be drilled and tapped easy enough. The fuel pump MUST be an electric pump.



The crank, rods, and pistons are all cast. Though I think just about any BBC is pretty stout … it sure feels that way to pick it up:-)



The crank I have to differ with others. I didn’t balance mine, but was told that Gen6 454ci are a different balance. It doesn’t matter because you have to use a 1pc rear seal flywheel or flexplate anyhow. I can say, that my stock harmonic dampener is MOST definitely different! A standard crank pulley will not bolt onto it. Looks like the same crank snout and keyway though.



The pistons were a pain, if you’re using the original one’s. GM’s used a special “shallow” oil ring since ’91. Performance rings are available, but limited. They’re also a flat-top, 2 valve relief piston … which means that virtually no other head combination will work. Even the old, old closed chambers aren’t small enough to keep compression.



I also suspect that most Gen6 blocks are going to be thin castings. Meaning I wouldn't try any .120" overbores!



Overall, I think it's a good motor for mild BBC. Anything more serious should probably be looking at an aftermarket block anyhow.



Thanks, Neal

Thanks for the link Schurkey.
I see that the pistons mentioned were TRW L2399F and that there is indeed a note that they can't be used on the Gen V or VI. I double checked what I have and they are SRP 212156's. Fortunately I don't see any such restrictions on those. Wolfy picked them out for me a while back so I was pretty confident I was getting the right ones.
The damper is another story however. I just checked and mine doesn't differentiate between block styles, just internal and external balance. I'll have to look into that a bit more.

Pistons will interchange all years : MKIV, GENV & GENVI, just match to the correct rod. Factory GenVI use a low tension oil ring, pistons are machined differentyly. Just use the appropriate ring package for the piston.

Neal, I'm betting those rods are forged - all I've taken apart are either truck or passenger car forged pieces with 3/8" rod bolts.
I agree, they're thinner and won't go as far but are a great choice for a daily driver if you want to run cheap (read: OEM) hydraulic rollers.

Got her running good! Looks like those heads worked out OK afterall. Nice ET/'60. What's the weight of that truck? Did you end up getting a converter/gears to get that cam to work?

The Blazer weighs around 3400-3500#. The new converter made all of the difference. The one I had was for nitrous, the new one is a Redneck 3000 stall off of ebay. I leave at idle and just whack the gas. It picks the front end up, and move out pretty well for amount of HP I have. The combo is still mismatched, but it's what I have to work with.

I belive the deal with some pistons not be compatable with MARK 6 motors is because the head design of the MARK 6 vortec cylinder head. U cant use a dome piston with it. But If earlier MARK 4 heads are used I dont see why any big block piston wouldnt work.

Skirts on the Gen 6 block are different due to size of the counterweights. I've been told by more than one machinist that Mark IV's won't work on a Gen 6, the skirts will hit the counterweights. I've never mocked one up, so I can't say for sure. All the rods are the same, though - 6.135".

I have not heard this about the piston skirts hitting the counterweights on a Gen VI. I am putting together a Gen VI block using FM H581CP pistons and the stock Gen VI cast crank. Anyone know for sure if it will be ok? I am not at the point of mock set up yet but would like to know before I buy all my parts.

Slip a piston on a rod and you can measure it against the counterweight, you'll have your answer. The Gen 6 I'm rebuilding used a rebuilder hyper Speed Pro piston, old style rings and the skirts didn't hit the counterweights. I helped a buddy rebuild one several months ago and he found out about the shallow ring grooves and crank counterweight interference.

For the guys who have L29 454's, what intake do you run if you run a carb? Is there any that port match to the L29 heads?

I have a L29 in my 2500 Suburban and have been thinking of a normal intake and put on injector rails and a throttle body.

Thanks!

the standard edelbrock large oval port intake matched up perfectly. I was running the RPM AirGap

Cool, thanks!

Any tips that the L29 454's like? Most of the people I know with them have them in trucks, but still, it seems quite anemic for a 454. Stock cam seems very small (206/210 duration).

Anything you have seen wake these up?

the standard edelbrock large oval port intake matched up perfectly. I was running the RPM AirGap

NODIH, I flipped the top half of the L29 clamshell intake over and had about 3" of the dividers milled out. The intake divides airflow into 4 big runners, then splits into 8. Where it splits, the ports are about the size and shape of the intake port of a small block. Milling this divider out opens the ports at the split to nearly the same size as the head port, removing what I found to be the biggest restriction, by far. I'm hoping to get 5000 - 5500 out of mine with the worked intake, a 214/222 .575/.575 hydraulic roller and a pair of lightly ported big valve 702 heads on a 489. The heads have had the chambers opened up on a Serdi to near the gasket line, makes 'em a whole lot more heart-shaped, compression should be around 9.5:1. If this stroker can pull to 5 grand plus, it should be able to get a 454 close to 6000 if the ignition system can handle it. I have some bigger injectors and expect some trial and error on the tune, but this port injection system should have the capacity to deliver the air and fuel I need now that it's been butchered...er...refined. I'll try to round up some pics to show you what was done. The truck is in the shop now getting the frame cleaned and coated while the bed is off for body work. I don't expect to have it on the road for 6 months or so.

Is there any chance you have picts of the inside? Would love to see it. I am swapping injectors on mine soon to LS6 and have pondered modding the intake.....

NODIH, I flipped the top half of the L29 clamshell intake over and had about 3" of the dividers milled out. The intake divides airflow into 4 big runners, then splits into 8. Where it splits, the ports are about the size and shape of the intake port of a small block. Milling this divider out opens the ports at the split to nearly the same size as the head port, removing what I found to be the biggest restriction, by far. I'm hoping to get 5000 - 5500 out of mine with the worked intake, a 214/222 .575/.575 hydraulic roller and a pair of lightly ported big valve 702 heads on a 489. The heads have had the chambers opened up on a Serdi to near the gasket line, makes 'em a whole lot more heart-shaped, compression should be around 9.5:1. If this stroker can pull to 5 grand plus, it should be able to get a 454 close to 6000 if the ignition system can handle it. I have some bigger injectors and expect some trial and error on the tune, but this port injection system should have the capacity to deliver the air and fuel I need now that it's been butchered...er...refined. I'll try to round up some pics to show you what was done. The truck is in the shop now getting the frame cleaned and coated while the bed is off for body work. I don't expect to have it on the road for 6 months or so.

I'll get those pics, hopefully this weekend, and get 'em posted here.

Sweet, I will be pulling my intake soon for injector swapping anyway. Would love to take a look at it.

Do you know much about the cam in the stock L29? Do they make good power at all? In stock they are 290hp/410 lb-ft torque with the computer and all. I can tune them, just wondering what is realistic on them with a carb or how they are typically installed in cars.

Cam is pretty weak. I bought a take-out core from a guy in Washington and had him send it to Delta. They ground me a Crane grind, 214/222, about .565 lift if I remember right, all on a 114LSA. Every GM roller cam I've pulled has been on a steel core, so I don't mind regrinding 'em. I did pull a cast core piece out of a Jasper rebuilt, but don't know how it got in there. This is going to need some tuning, I'm trying to get as much info as possible about some of the mail-order tuners out there, I'm confident I'm not the first who's tried to get more out of one of these engines.

one big problem, is the lack of fuel pump mounting. you must run a electric fuel pump.
maybe this is not a big problem just more food for thought.

I had one of the rare over the counter blocks that had a fuel pump boss but sold it, sure wish I had it back!

You can see where my machinist milled the divider completely out, top to bottom, for about 3" or so:


http://i936.photobucket.com/albums/ad205/81vette4speed/Intake1.jpg

So once the divider was ground out, what did he use to seal up the intake again?

Weld it up?



You can see where my machinist milled the divider completely out, top to bottom, for about 3" or so:


http://i936.photobucket.com/albums/ad205/81vette4speed/Intake1.jpg

No, what you're seeing is the cut across the bottom. I've tried welding Chevy's aluminum intakes with no success - it's some sort of weird alloy.
Since it's a dry manifold at this point (injection doesn't come until downstream of this point), I think I'll use tape as a backing and fill the grooves with JB Chemweld. I have used it with no problems in the past, so I'm sure it'll work fine here. Since what you're looking at is the top half of the clamshell flipped upside down, the place where it was cut is actually on the floor of the ports. I'm sending the intake out to be cleaned so the epoxy will stick better. BTW, the groove is wide enough to get a cutter thru to smooth the transitions, etc.