Back to working on the twin 2bbl setup. Taking my plates out to a clean edge and waiting on my plaster molds to set so I can burn the positive out and cast.
Ontopic History of an Old Car
- Thread starter Mr. Argumentor
- Start date
Soliciting thoughts on adapting seat bolt patterns.
No, I have not yet checked to see if the rails can be removed and swapped.
Edit: @Mustard Dispenser, can you please change the tag of this thread to on topic?
No, I have not yet checked to see if the rails can be removed and swapped.
Edit: @Mustard Dispenser, can you please change the tag of this thread to on topic?
Jehannum
Puts the "pro" in procrastination
I'm not a fan of those seats in a classic, but I don't have a dog in that fight.
Whatever you do, make sure that you use appropriate grade hardware.
I made some adapter plates that shift the front seats in the GTO back about 4", they're just some thick steel that's had holes drilled and powder coat applied, though.
Whatever you do, make sure that you use appropriate grade hardware.
I made some adapter plates that shift the front seats in the GTO back about 4", they're just some thick steel that's had holes drilled and powder coat applied, though.
Jehannum
Puts the "pro" in procrastination
I went with 1/2" steel, but when you're dealing with a Pontiac 455 and an A-body, a couple extra pounds ain't gonna break the bank.
Also, 1/2" steel was what I had.
Casting day went well. Casts themselves... well...Back to working on the twin 2bbl setup. Taking my plates out to a clean edge and waiting on my plaster molds to set so I can burn the positive out and cast.
First mold went well. Poured well, but we poured very hot. I think closer to bronze temps than aluminum. Not sure if that did anything to this, but its the only thing I can think of.
Second pour I knew before we started that something was wrong. Looked inside the mold before putting it down and saw cracks in the plaster. Nothing to do about it at that time, just pour it. Temp was closer to what it should have been, but still over. Poured and barely used any aluminum. Poured the rest off to ingots and went to demold them.
A quick digression. The castable resin that Formlabs supplies is expensive as shit, to save money you commonly use hollow pieces for large forms. Did that with these, printed the positive used for the second pour first. Saw it was too thin, bumped the wall thickness up for the second print (which was the first pour)
The investment goes under a vacuum to ensure there are no bubbles, you can guess what the results are.
First pour on the right. Mold was tight enough in places to show the spline points of the model along a curve (third pic.). Last pic shows where I knew the wall was too thin for the first print. It actually cracked as it was curing, that crack came through in the molded part.
The cracked one will be desk art, but the ugly one will be an ingot.
Jehannum
Puts the "pro" in procrastination
Jehannum
Puts the "pro" in procrastination
Vacuuming a hollow piece and then pouring too hot are literally all I can think to cause these issues. Everything else is the same as I've done half a dozen times before.
Well, and using a known alloy. Previously I just used a hodgepodge of whatever I had available
I have access to a 3 axis CNC, and I believe we just got a 4th or 5th axis delivered today but I won't get to touch that one for a while. Too new.
Always bake it out. You can't not do it with wax or whatever the hell this is. With lost foam it is possible to not do so, but the plaster mold still needs to be cured which will bake it out anyways.
This resin is supposed to sublimate, I know the wax I used for the sprue and cup doesn't, but it would have melted out well before this stuff's sublimation temp.
I dunno. We'll try it again, maybe this time with a completely printed sprue and cup so I don't have to worry about different materials.
Upgrade for the upgrade.
Multiple reasons to start over, main one being that the preheat when I was brazing didn't help and when I got it magnafluxed it showed cracks around some of the brazed sections. I think I got it too thin when I was milling the flat spots and then the torch caused too much expansion.
This time I don't think I'll braze it, I'll just design the studs so they lock in place when they try to turn, then I'll epoxy em.
Frustrating, but I was able to find the optimum head for a "stock" build so it'll dovetail nicely into this build.
This is a 1980 head which was the last casting for the engine. It flows about 20-30CFM more than the head I was using in its stock condition. When I port it, it should be flowing 50-60CFM more
The capacity of the log itself is about 1.5x greater than the stock one.
Multiple reasons to start over, main one being that the preheat when I was brazing didn't help and when I got it magnafluxed it showed cracks around some of the brazed sections. I think I got it too thin when I was milling the flat spots and then the torch caused too much expansion.
This time I don't think I'll braze it, I'll just design the studs so they lock in place when they try to turn, then I'll epoxy em.
Frustrating, but I was able to find the optimum head for a "stock" build so it'll dovetail nicely into this build.
This is a 1980 head which was the last casting for the engine. It flows about 20-30CFM more than the head I was using in its stock condition. When I port it, it should be flowing 50-60CFM more
The capacity of the log itself is about 1.5x greater than the stock one.
Diagnostic time
Vibration while driving. Constantly, and a linear increase with speed. Feels like a flat spot or the brakes grabbing on a rusted spot or something similar.
Wheels are off the car and I dropped them off to get checked and balanced tomorrow. Did not see evidence of a flat spot or anything weird. Likewise, pulled the rear drums and inspected the front brakes and saw nothing out of the ordinary. Bearings also feel good (not that it sounds/feels like bearings)
Anyone have any thoughts on what it could be? Other than the engine, the drivetrain is fairly new throughout (or at least rebuilt a short amount of miles ago)
Vibration while driving. Constantly, and a linear increase with speed. Feels like a flat spot or the brakes grabbing on a rusted spot or something similar.
Wheels are off the car and I dropped them off to get checked and balanced tomorrow. Did not see evidence of a flat spot or anything weird. Likewise, pulled the rear drums and inspected the front brakes and saw nothing out of the ordinary. Bearings also feel good (not that it sounds/feels like bearings)
Anyone have any thoughts on what it could be? Other than the engine, the drivetrain is fairly new throughout (or at least rebuilt a short amount of miles ago)
Jehannum
Puts the "pro" in procrastination
Stock axle (from a V8 1968 Mustang) with leaf springs from a company I trust. Can't think why it wouldn't be. Didn't have this issue when I was in DC with the automatic at least.
Yup.
Yup.
Side note: you mentioned something that the spinning dorito guys use to redo port location. What was it?
Jehannum
Puts the "pro" in procrastination
So you swapped the auto for a stick, have you tried reclocking the driveshaft on the output spline?
Devcon is the stuff the dorito guys use to modify their ports.
Explain that more? Far as I know there isn't a reference point or anything on the tail spline.
Edit: devcon is a brand apparently, know which type exactly? One of the metal putties I assume?
If not I'll start digging on some dorito forums