'72 K5 - BYT - 1 ton swap

[ashman]

Wouldn't it be a lot easier to chop the firewall.

You may be right, but I have a 3" body lift on it now and if I can't clear with that I think I'm too close.

I'm going to play with it over the next few days and see what makes sense. Maybe give some time for a few other guys to chime in too.

 

[Greg72]

I will study these pics more closely from a real computer later, but it seems like the engine needs to be raised by maybe 1/2" or more.

With a 3" body lift you have miles of clearance under the hood.


-G

 

[Greg72]

I will study these pics more closely from a real computer later, but it seems like the engine needs to be raised by maybe 1/2" or more.

With a 3" body lift you have miles of clearance under the hood.


-G

Now that I see that it's a PacFab (Tilden Motorsports) crossmember specifically designed for the early Chevy Trucks (4x4) my first call would be to them to explain why the exhaust doesn't fit.

Send them a pic on FaceBook or whatever and let them see the interferences.... and let THEM come up with an answer.

Maybe there's a simple explanation or correction that can be made. I certainly wouldn't do anything crazy until you spoken with them. They do this kind of conversion a LOT so I find it hard to believe that they'd miss something so obvious as manifold / frame interference.


-G

 

[ashman]

Now that I see that it's a PacFab (Tilden Motorsports) crossmember specifically designed for the early Chevy Trucks (4x4) my first call would be to them to explain why the exhaust doesn't fit.

Send them a pic on FaceBook or whatever and let them see the interferences.... and let THEM come up with an answer.

Maybe there's a simple explanation or correction that can be made. I certainly wouldn't do anything crazy until you spoken with them. They do this kind of conversion a LOT so I find it hard to believe that they'd miss something so obvious as manifold / frame interference.


-G

That was my thought too Greg. I'll be calling them this morning.
It's hard to tell for sure, but I think the LS is sitting higher than the stock engine sat already. From the looks of things I need to raise the transmission for it to match up in its current location.

 

[warrpath4x4]

it looks like you have the truck exhaust manifolds, from what I have found in my planning for my 5.3L swap is that the truck ones always contact the frame. I read that trailblazer SS manifolds will fit better than car manifolds, car manifolds point the exhaust pipes towards the oil pan while the trailblazer SS ones point straighter down.

but I havnt done the swap yet so......

 

[ashman]

it looks like you have the truck exhaust manifolds, from what I have found in my planning for my 5.3L swap is that the truck ones always contact the frame. I read that trailblazer SS manifolds will fit better than car manifolds, car manifolds point the exhaust pipes towards the oil pan while the trailblazer SS ones point straighter down.

but I havnt done the swap yet so......

The one in the pic is a car manifold. Both the car and the truck manifolds (I have those too) stick out in the same spot for EGR stuff and that is what is hitting at the moment.

 

[folkenheath]

headers all the way!

 

[bigblock72]

Will the truck manifold clear if the three bolt flange is cut off of it? The truck manifolds are cast steel and can be welded.

Just move the transmission forward, cutting the firewall is a whole lot more work. I looked at the same problem with my swap and moving the trans forward had a lot fewer down sides than cutting the firewall. The biggest benefit is having the engine out where it can be reached without having to crawl in the engine compartment. The stock engine location is quite ridiculous and really needs to be fixed IMO.

 

[skunked]

the firewall clearance issue doesn't seem right to me, I would be calling Pacific Fab as already mentioned.

 

[ashman]

Will the truck manifold clear if the three bolt flange is cut off of it? The truck manifolds are cast steel and can be welded.

The 3 bolt flange is clearing as-is. The only thing causing interference is the EGR port sticking out to the side. I talked to pacific fab about it and they recommended thorley 372y-c headers http://www.amazon.com/Doug-Thorley-Headers-THY-372Y-C-Exhaust/dp/B009OZA8ZY

For $600+ for headers, I'm willing to try making these manifolds work. They said that when they use stock manifolds they use 2010+ f-body manifolds and evidently they do not have the ERG ports.

Just move the transmission forward, cutting the firewall is a whole lot more work. I looked at the same problem with my swap and moving the trans forward had a lot fewer down sides than cutting the firewall. The biggest benefit is having the engine out where it can be reached without having to crawl in the engine compartment. The stock engine location is quite ridiculous and really needs to be fixed IMO.

agreed.

the firewall clearance issue doesn't seem right to me, I would be calling Pacific Fab as already mentioned.

when I talked to them I forgot to mention the firewall clearance issue, but the crossmember is designed to be put where you want it and then have holes drilled. I suspect that they will just tell me to set it where there is no clearance issue.

 

[bigblock72]

I have a truck manifold that doesn't have the EGR boss if you want to try it.

 

[ashman]

I have a truck manifold that doesn't have the EGR boss if you want to try it.

It's worth looking at for sure. I'll give you a buzz.

 

[ashman]

I got the trans unbolted and moved it forward 1-1/2". I picked that magic number because the back crossmember bolts lined up with the front crossmember holes that way.

Also, my trans crossmember was spaced down 1-1/2" so I removed the spacer bringing the back end up some. That helped create some room by the top of the valve covers as well.

The drivers side is still a touch close so I may give that some BFH love but otherwise I think this is going to work.

I was able to bolt the engine to the trans for the first time but it lead me to a question for you later gen guys. With my stock motor mounts I was always able to slide the engine onto the trans and then run one bolt up through the crossmember into the mounts. How do you do that with this style of motor mounts?

With the bolt running horizontal you have to drop the engine directly down onto the mounts. Do you always have to pull the tranny back first? I guess maybe I can jack the tranny up enough that I can slide the engine onto the input shaft and then lower it down onto the mounts. How do you guys normally do it?

 

[ashman]

I have a truck manifold that doesn't have the EGR boss if you want to try it.

Thanks man, that cleared no problem. On to the next problem.

As mentioned earlier in the thread, the exhaust manifolds were going to make my current external clutch slave unusable. (discussion starts at post #395)

Unfortunately, my NV4500 is the 89-96 variety and it uses a different input bearing cover than the later models so the bearing cover I bought that will accept the internal slave does not fit... nothing is ever easy.

Looking for a solution now.

 

[ashman]

I'm wondering how hard it would be to just modify the retainer I have.

The only real difference between the 2 is that my original has the tube coming up for the clutch fork bearing to ride on. The other just has a flat surface for the slave to sit on and a couple of threaded holes so that it can be held in place. It seems like just cutting the tube off would give me the flat surface I need...

 

[K85 Octane]

ohhh decisions decisions What a PITA some stuff can be!!

 

[bigblock72]

I'm wondering how hard it would be to just modify the retainer I have.

The only real difference between the 2 is that my original has the tube coming up for the clutch fork bearing to ride on. The other just has a flat surface for the slave to sit on and a couple of threaded holes so that it can be held in place. It seems like just cutting the tube off would give me the flat surface I need...

Do the retainers have the same bolt pattern? I know the diameters are different but I've never compared the bolt pattern.

If the bolt patterns are the same then I think I can machine the O.D. down to 5.125 and have it work with your bellhousing.

 

[ashman]

Do the retainers have the same bolt pattern? I know the diameters are different but I've never compared the bolt pattern.

If the bolt patterns are the same then I think I can machine the O.D. down to 5.125 and have it work with your bellhousing.

Unfortunately the bolt pattern is wider as well. I appreciate the offer though.

That said, I decided that since I had access to the bellhousing now maybe I should do a better job than just "eyeballing it" to see how bad the interference between the exhaust and the external slave was going to be.

hmmm, it seems that with the f-body manifold and some careful bending I actually should be able to clear the slave cylinder after all.

Score one for actual measuring vs eyeballing.

 

[y5mgisi]

With the motor mount bolt question, I always bolt the engine to the Trans with the engine sitting just above the mounts. Then, once I get a bolt or two in the bellhousing, drop the engine into the motor mounts and slide the bolt through.

 

[ashman]

With the motor mount bolt question, I always bolt the engine to the Trans with the engine sitting just above the mounts. Then, once I get a bolt or two in the bellhousing, drop the engine into the motor mounts and slide the bolt through.

Thanks man. I assumed that was how it had to be done, I guess I'm just used to the old style mounts so keeping the engine that high sounds like a pain to get hooked up.