04SilveradoMykk

The tried and true, dime a dozen small block chevy.

So far I don't have a dime into this, so all is well.

::Monster Garage Voice:: FREEBIE!

87-95 LO5 350, one piece rear main, 4 bolt mains, roller cam block w/ TBI heads the first of the "swirl port" heads.



The motor has had a recent rebuild, .030" overbore and crank turned .010"/.010"

more freebies. L31 vortec heads with complete fuel injection. I already removed the poppet spider.



I already tore the block down and discovered why this motor was put on somebodies backburner. Cyl # 5 had an exploded piston, but did minmal damage to the cyl wall. The minor ring scuff will get taken out with another .010" overbore. BTW, I love the use of the flat tappet RV cam in a roller motor.







I originally intended to throw a stroker crank at this project, but after tearing it down and seeing that a machine shop balanced the rotating assembly I might just keep the crank and with the .040" bore run a 357ci small block. All in the name of empty pockets.

Aside from Cyl # 5 the entire block & heads are in excellent condition. The TBI heads still have the reman heat tabs on them, they are currently up on craigslist. I couldn't get a .002" feeler gauge under a straight edge anywhere on the deck surface. The cylinders have maintained a perfect 4.030" circle without any taper, egging or ring ridge and all of the bearings were un-scuffed. That was a recent rebuild before the mishap. Aparently the story is that the previous owner tossed the TBI for a carb, and had it jetted down so the motor was running consistantly lean & hot. Although I don't see any evidence of over heating.



was bored, so I figured a duplicolor rebuild was in order and dress up while it's on the stand untill I can really get ***** deep into it. Nevermind the perimeter bolt VC on centerbolt heads.



So stay tuned for the finished SBC. I'm am tapped out of expendable income for the month of July... so it will be a couple months before I put it back together.

I've given myself a budget of about $1500 total to have this puppy done, most of wich will be in the valve train.

And yes, before you ask. This motor is for my 2004 Silverado. Wait, so why not a LS/LQ based swap like what came in the truck from the factory?

I'll tell you why.

Because the L31 is the perfect candidate for a 4.3L to V8 swap. The fuel injection is practically identical and all of the 4.3L accessory brackets, serpentine belt system & pullies and engine control sensors can all be used on the L31 V8.

Performance parts for the old small block chevy are just a fraction of the cost of LS parts. I can retain a few currently used 4.3L performance parts. The K&N intake can be modified to work with the V8. The 75mm CFM-Tech throttlebody will transfer over. I already have HPTuners to write the v8 tune. The only custom work to be done will be modifying the trucks wiring harness for two more injectors. Exhaust work, I might as well do a set of long tube headers. And a motor mount adapter plate to adjust for the v8 re-located motor mount provisions.

I can play with gasket matching, port & polish and I plan to upgrade the vortec F.I. spider and clearance the valve guides for a high lift cam.

And finally, what custom street machine isn't complete without a small block chevy... I mean, come on

the Desktop Dyno estimated output for a .040" over vortec 350, stock crank, with head work and a 260HR cam.



That's pushing the horsepower envelope for that design of fuel injection anyways. I don't know about you but I can live with that kind of power from a daily driver and still maintain 17-24mpg


Cheers ~Mykk

LMSeven

iTrader: (3)

Never seen a swap like this, looking forward to the final product.

04SilveradoMykk

I just made another discovery that further facilitates the 4.3L to L31 as a v6 to v8 swap. Both engines use the same distributor base, just the cap changes. They even use the same rotor.

In fact I can retain most of my current ignition all together, the MSD 6a & accel coil. And if MSD sold individual leads I can use my current red 8.5mm wire set too.

(granted, a LSx doesn't use distributors.)

GMCtrk

iTrader: (27)

In some ways I think the old SBCs are better suited for trucks than the new LS engines. To tell you the truth I am kind of surprised at the lack of low end torque with the 6.0. Granted, it pulls hard up top, but I rarely go over 2500 rpm. Good luck with your swap.

04SilveradoMykk

Here is the plan. I have a template to make this plate out of 1/4" steel



The idea behind the plate is to mount a LSx engine using factory SBC locations & mounts. In theory, I should be able to use the same plate mounted to the SBC block provisions and use stock 4.8/5.3 motor mounts on the truck side.

I've already ditched the mechanical fan & clutch for stand alone flex-a-lite electric fans.



I intended to use the stock v6 radiator. The GMT800 does have two different radiators for v6 & v8. But they share the same core dimensions, both are 1 row and both have the same inlet & outlet sizes. The only difference is the v8 radiator has larger inlet & outlet headers (side tanks). If I have a cooling problem with the v6 rad I'll give the v8 rad a shot, if I still have issues I'll be looking for an aftermarket 3 or 4 row rad.

I am a gear head, And since I've got this engine torn down anyways. I want to build it my way, I want to use a gear drive timing set like what I had in the BBC of my 69 C-10.

Although hesitant to use a gear drive behind a plastic cover, I figured I could modify the cover with a metal lining to prevent the gear drive from rubbing through. I do intend to use a roller valve train including the rockers and I figured I could minimize the affects of the knock sensor or as a last resort write it out entirely thanks to HPTuners.

Which brings up another vital point, I have not yet begun investigating what I need to change in the trucks programming to accommodate the L31. After wiring the 2 injectors to the corresponding Pins on the computer. Surely it isn't as simple as just changing: Engine > General > Type> OHV 4.3L to OHV 5.7L or OHV 5.7L HO.

I am open to any and all input, so if you have an idea please post it!

Cheers ~Mykk

2005 Silverado

iTrader: (19)

Very interesting build! I will be watching this thread for updates.

Dustin

southern_chevy

iTrader: (9)

I know that one the trucks that cam with the L31 factory they were ditching the black box PCM for a 411 pcm and using a tune from a van with the L31 4l60e combo in it. I can say that I know that works cause I have done it. You might look up the 411 swap topics and find the tune there to upload then you would have a good base tune to start with. I think it was like a 02 express van that the tune is from.

04SilveradoMykk

Thanks, I'll look into it. I remember reading of the 411 swap, but was under the impression I don't need to do that with my flashable 2004 LS based computer.

04SilveradoMykk

A few snags. I decided against the pistons I originally settled on... availabilty was tough, and everytime I found a place with them the cost kept going up... So instead I decided on some Hypereutectic aluminum flat tops with 4 valve reliefs... the engine kit arrived today and they sent me 70cc dished pistons. Yikes, I am not building this motor for 8.5 compression ratio!

I also noticed that the rod with the exploded piston is slightly tweeked. I have extra 5.7" rods in the shop, but now I need to balance the entire rotating assembly... so if I can find a 383 kit priced right I might still go that way.

oldred95

For the power level you have in mind for this engine I'd go with a cast stroker kit if it were me. The extra torque it will make will allow you to bring your cruising rpms down and let the engines brute torque do the work for you while you run it in lean cruise mode going down the road. If its done right a stroker motor can actually get better gas mileage then a standarded bore engine just because of its workable power band. Looks like a really interesting and wise build IMO. There isn't anything wrong with the old SBC. Only being 4 bolt on the 3 middle mains is the only thing I don't like about them. They make good cheap reliable power.