1975 GMC Palm Beach Restomod

[gmc260]

the twin bed set up is best for us also but more than I want to take on with the '76, maybe when we get back on the '74. I considered it and the new wall ended up right in the middle of the utility door. I could split it up so when opening it from outside, the right side would just be a blank panel and the left half would have a 50w connector and a water inlet.

looks like your plans require moving everything from the existing utility door, correct? have also considered doing away with the rear window, whats your plan on that?

we've decided to keep the OE wet bath since it makes such good use of space. would like to move it to the left side but the PO had installed a new tank and macerator too and moving it would require custom tanks.

 

[Mike Perez]

the twin bed set up is best for us also but more than I want to take on with the '76, maybe when we get back on the '74. I considered it and the new wall ended up right in the middle of the utility door. I could split it up so when opening it from outside, the right side would just be a blank panel and the left half would have a 50w connector and a water inlet.

looks like your plans require moving everything from the existing utility door, correct? have also considered doing away with the rear window, whats your plan on that?

we've decided to keep the OE wet bath since it makes such good use of space. would like to move it to the left side but the PO had installed a new tank and macerator too and moving it would require custom tanks.

The entire floor plan will be different from the cockpit seats to the back. Twin beds will be underneath the window height in the back, so all windows will stay. Right now, I'm leaning toward twins, with a closet forward on the passenger side, then fridge, the door. Ahead of the door will be the dinette seating. Left side will be twin, storage cabinet/electrical/plumbing systems, and then toilet area, shower, and kitchen front back to front. Biggest thing that will be different is that I will have a step up in the back along the length of the twins about the same height as the front step. This will accommodate a larger single fuel tank and will allow for under bed storage on the propane side. I am most likely pulling out the LP system.

 

[1976GMC]

Impressive work. Can you list the parts (with part numbers) that you used to convert 455 to a serpentine belt drive. It is on my dream "to do" list to make that conversion plus an electric fan on the radiator.

 

[Mike Perez]

Needed a Break from the air conditioning fabrication, so I decided to de-scuzify the front end.

 

[Mike Perez]

If you were wondering how much insulation is behind the cockpit step.... the answer is zero

 

[pvfjr]

That's good to know; it'll go onto my list of improvements to make.

 

[Mike Perez]

So on the A/C, after I gutted the plenum, I glued two 2" ports onto a pice of ABS and glued that to where the defrost flapper used to be. Now I can use the original plenum for the defrost. Also, I'm going to be able to pull the hoses through the "heat duct" and route them to the original locations without having to actually make the air flow directly through the duct; just through the vintage air hoses.

 

[Mike Perez]

Close up of serpentine drive.

 

[Mike Perez]

Oldsmobile 6 cylinder Diesel Waterpump for an 1982 Cutlass Calais. Some bolt pattern as 455 but designed to run counter clockwise. Had Flowkooler change the impeller to something more sufficient for a high powered big block.

Olds Stock Pump on left and Diesel pump on right before new impeller.

 

[Mike Perez]

Good picture of roller rockers. Harland Sharp modified by Bernard Mondello for correct geometry.

 

[gmc260]

Now thats a 'Towing package'! Hahaha.. who's heads are those Mike? did you get or are doing a build sheet on that bad boy and will you be doing initial start up before putting the subframe back in?

 

[Mike Perez]

Now thats a 'Towing package'! Hahaha.. who's heads are those Mike? did you get or are doing a build sheet on that bad boy and will you be doing initial start up before putting the subframe back in?

The heads are Speedmaster/Pro Comp. They are basically a Chinese knockoff of the Edelbrocks. They are not bad at half the price of the Edelbrocks. Bernard Mondello uses them for his builds. I bought them bare and then had my engine shop build them up. There are a few features that are much improved over the stock heads, like for instance, the oil drain holes are lower, and at a different angle which allows the oil to drain back into the block faster/easier.

I used Icon 887 Forged Pistons. They have a 25cc dish to keep the compression reasonable. We ended up at 9.4:1, which should be OK with the aluminum heads, computer controlled ignition, and knock sensors. The rods are H-beam from Eagle with floating pins. The are each about 50 grams lighter than stock and much stronger. Rods in the Olds 455 are not great. Roller Cam from Crane. It has an Iron gear on it which allows it to be used with a stock distributor gear. Using any cam that requires a brass gear is asking for trouble.

The biggest takeaway I had having this engine built and reading Bill Travato's book is that one of the biggest improvements with modern engines (other than CNC tooling) is low friction piston rings. Ever wonder why modern engines go 200,000 miles and the older Muscle-car era engines were worn out at 80-100K? A big reason is the piston rings. The 455 originally had a 5/64-5/64-3/16 ring pack. The new pistons are setup for a 1/16-1/16-3/16 pack. I'll post the article below, the but the gist of it is that modern engine are going to thinner rings because 50% of the friction of an engine comes from the pistons and rings. 50% of that number is coming just from the rings. So thinner rings equals less wear on the cylinders, and free horsepower. They just didn't have the materials to make the rings strong enough to be that thin in the 70's. Now they do.

http://blog.jepistons.com/why-do-piston-rings-keep-getting-thinner-

 

[Mike Perez]

Now thats a 'Towing package'! Hahaha.. who's heads are those Mike? did you get or are doing a build sheet on that bad boy and will you be doing initial start up before putting the subframe back in?

As far the subframe, my original intent was to run it in the garage before putting it back in. I have since changed my mind. The reason is because there are too many electrical connections for the ECM, fusebox, etc... to just mock it up in the garage. I need a permanent location to run wires to so the ECM and fuse box needs to be mounted permanently. Also, I need to install an air filter along with a Mass Air Flow sensor somewhere upstream of the throttle body, and I can't really figure out the best way to mount the tube/sensor until it is back in.

I'm working on cleaning up the cockpit area now so I'll be able to have a clean place to install the new floors, and step. I'm shooting to put the subframe back in next month while I have some vacation time.

 

[pvfjr]

The heads are Speedmaster/Pro Comp. They are basically a Chinese knockoff of the Edelbrocks. They are not bad at half the price of the Edelbrocks. Bernard Mondello uses them for his builds. I bought them bare and then had my engine shop build them up. There are a few features that are much improved over the stock heads, like for instance, the oil drain holes are lower, and at a different angle which allows the oil to drain back into the block faster/easier.

I used Icon 887 Forged Pistons. They have a 25cc dish to keep the compression reasonable. We ended up at 9.4:1, which should be OK with the aluminum heads, computer controlled ignition, and knock sensors. The rods are H-beam from Eagle with floating pins. The are each about 50 grams lighter than stock and much stronger. Rods in the Olds 455 are not great. Roller Cam from Crane. It has an Iron gear on it which allows it to be used with a stock distributor gear. Using any cam that requires a brass gear is asking for trouble.

The biggest takeaway I had having this engine built and reading Bill Travato's book is that one of the biggest improvements with modern engines (other than CNC tooling) is low friction piston rings. Ever wonder why modern engines go 200,000 miles and the older Muscle-car era engines were worn out at 80-100K? A big reason is the piston rings. The 455 originally had a 5/64-5/64-3/16 ring pack. The new pistons are setup for a 1/16-1/16-3/16 pack. I'll post the article below, the but the gist of it is that modern engine are going to thinner rings because 50% of the friction of an engine comes from the pistons and rings. 50% of that number is coming just from the rings. So thinner rings equals less wear on the cylinders, and free horsepower. They just didn't have the materials to make the rings strong enough to be that thin in the 70's. Now they do.

http://blog.jepistons.com/why-do-piston-rings-keep-getting-thinner-

I'm really geeking out with all this tech you've been presenting. You're making me want to rebuild my engine for no good reason. I'm now sitting here resisting the urge to shop for pistons and rings! Maybe I'll just take a peek over on Summit real quick...

Thanks for everything you've been sharing. I'll be using this thread as a reference for years, I'm sure.

 

[traveler1980]

Have to say, reading these build threads is just amazing. I wish I had 1/10th of the knowledge and skills demonstrated in these posts. Keep the information coming as this is a great opportunity for those of us that are less mechanically knowledgeable to learn.

 

[gmc260]

not familiar with Travato but while digging for BB Olds info, came across Dick Miller https://store.dickmillerracing.com/enginepartsoldsmobile.aspx

Ever wonder why modern engines go 200,000 miles and the older Muscle-car era engines were worn out at 80-100K? A big reason is the piston rings.

synthetic oils and FI are the biggest factor, I have +350,000 on an original 50's era design SB '88 GMC with TBI and its still in service. but certainly the ring tech and also piston designs and coatings have come a long way. and new tech such as http://www.meta-lax.com/ has also been a game changer.

Im looking forward to going through our '74 455 when we get back to it and starting from scratch using the modern tech available.

 

[Mike Perez]

not familiar with Travato but while digging for BB Olds info, came across Dick Miller https://store.dickmillerracing.com/enginepartsoldsmobile.aspx



synthetic oils and FI are the biggest factor, I have +350,000 on an original 50's era design SB '88 GMC with TBI and its still in service. but certainly the ring tech and also piston designs and coatings have come a long way. and new tech such as http://www.meta-lax.com/ has also been a game changer.

Im looking forward to going through our '74 455 when we get back to it and starting from scratch using the modern tech available.

By 1988, I would bet that the rings in your truck are thinner than they were in that same small block from 1975.

This is Bill's book. He builds most of these Olds engines for drag racing, so a lot of it doesn't apply, but much of the information is good and can cross over to the GMC.

 

[6cuda6]

Oh i shouldn't be looking at this....my wife would be pissed if starting building an engine in the basement over the winter. Being a muscle car guy and a mechanic by trade seeing these engine pics are not a good thing.....lol. Hmmmmm maybe i need a stroked 403 to go with my stroked 340........

 

[6cuda6]

Curious Mike.....is that serpentine setup scavenged from a GM vehicle? Looks to be pretty oem to me if i remember the stock GM layout and components

 

[Mike Perez]

Impressive work. Can you list the parts (with part numbers) that you used to convert 455 to a serpentine belt drive. It is on my dream "to do" list to make that conversion plus an electric fan on the radiator.
[/QUOTE

Sorry, I just saw this. Let me see what I can put together.