the pig rig?

[The Dark Side of Will]

The throttle opening is obstructed by the throttle shaft, even at WOT... The same diameter bore is not an obstruction

dyno tests have shown that ports being stepped slightly smaller upstream make almost no difference in power, but stepped slightly smaller downstream can cause a not insignificant reduction in power.

Talking about intake ports?
A well-designed "port", which includes both the metal in the cylinder head and the metal/plastic of the intake manifold, tapers and thus accelerates the air it it travels toward the MCSA and valve seat. The edge discontinuities matter more at higher flow speeds.

it's also a TBI 350 for a Suburban. I'm definitely not setting it back up in the mill to redo it,

No, you have to CNC it

[ericjon262]

The throttle opening is obstructed by the throttle shaft, even at WOT... The same diameter bore is not an obstruction

dyno tests have shown that ports being stepped slightly smaller upstream make almost no difference in power, but stepped slightly smaller downstream can cause a not insignificant reduction in power.

Talking about intake ports?
A well-designed "port", which includes both the metal in the cylinder head and the metal/plastic of the intake manifold, tapers and thus accelerates the air it it travels toward the MCSA and valve seat. The edge discontinuities matter more at higher flow speeds.

I agree, but taper=/= step. A step down in cross section will cause a turbulent front ahead of the step, which will also partially obstruct flow in the port/runner/pipe, a step up in cross section causes a small turbulent area downstream, behind the step, and not into the bulk flow. in a perfect world, you don't have steps, or the steps are designed to create a thin boundary layer. What I'm referring to only occurs at joints, like the TB to manifold, or intake to head, and isn't necessarily a port design, but a function of available engineering tolerances

a simplified infographic.

it's also a TBI 350 for a Suburban. I'm definitely not setting it back up in the mill to redo it,

No, you have to CNC it

I mean, how do you think I did it this time? setting a intake up on a mill, manual or CNC, has it's complications though, especially when the bores being machined aren't perpendicular to the flat surfaces on the underside of the manifold. it wasn't impossibly hard, but it was a bit of work I don't care to repeat.

[ericjon262]

I need to clean The Pig up and get it ready for a road trip, I have a wedding to be at in about 2 weeks, and I plan to cruise the pig up there. Originally, I wanted to drive the Fiero, but with the metal in the oil, and some parts delays, it would be far too rushed and untested for me to make a trip that far from home...

as far as progress goes, I haven't made much on the new engine. I have most of the parts, now I just need to put them together. I installed screw in rocker studs on one head, and started pulling the press in studs on the other, but didn't finish. Hopefully this weekend I can manage to at least get the short block assembled, but if it has to wait until I get back, it's not a big deal.

[ericjon262]

I had hoped to squeeze more in, but I had to cut alot out of my trip up north for the wedding. I'll need to make another trip out there to get to the northeast corner. the good news, on the last leg of the trip, I was the heaviest on the gas, and still managed to pull off 13 MPG, I think that's respectable all things considered, Lifted Suburban on 33's with 4.10 gears... sure it could be way better, and hopefully it will get a little better with the L31, but it's hard to say for sure. I'll post a few pictures from the journey in the next few days.

[ericjon262]

I put some of the pistons for the L31 in an ultrasonic sink with this cleaning solution:

https://www.amazon.com/Ultrasonic-Solut ... 5406f&th=1

I didn't follow the instructions, so I only ended up diluting it about half as much as I should have, but it has worked pretty awesome, I'll post pictures when I get a chance. very much worth it if you plan on reusing pistons in an engine rebuild.

[ericjon262]

the ball joints in the front axle are all messed up, so I've been slowly moving forward with getting the Dana 60 ready to go in, on the list of important stuff, I needed single rear wheel hubs, I picked up a set a while back. Since a new axle will be going in, I'm going to go ahead and put new brakes on, but one thing I've never liked about squarebody front axles, is that the rotors are pressed onto the hubs, and kinda a PITA to R&R. Enter torq motorsports:

https://torqmotorsports.com/product/gm- ... nch-wheel/

it's a caliper bracket to install larger twin piston calipers and rotors like my 2500hd has, on a dana 60.

the SRW hubs have too large of an OD for the rotor to slip over, the instructions for kit say to turn the hubs down to 7.85" at first I wasn't cool with this, but then I thought about how the stock 2500 hubs are way thinner than the dana 60 hubs. so I went ahead and turned them down.




not sure when I'll actually get it installed, but hopefully soon.


saving for further use...

https://www.offroaddesign.com/catalog/p ... egory/490/

https://www.offroaddesign.com/dana-60-c ... taper.html

[ericjon262]

I cleaned the rest of the pistons for the L31, Hopefully over the next week, I can spend a little time in the garage, clean up the block, and then assemble the short block.

In other, less important news, I cut down a set of stock 8 lug hubs for a 8.5" ten bolt front axle, similar to how the dana 60 hubs were cut to allow installing a GMT800 brake rotor over the hub, I'm going to try and see if I can make a similar mod to a 10 bolt front axle when I swap in the dana 60, I may have further use for the pig's stock axle.