Olds powered 72 GMC

[Glennerd]

I was contemplating the 455 at some point in the future, if all goes well with this 350. I was told that both motors share the same mounts and exhaust and that the 455 would just hook right up (transmission would need to be changed out and driveshaft shortened). Are the two frames different up front or is the 455 just that much wider?

[truckster]

It's been a few years since I swapped a 455 in place of a 350 Olds, but if I remember right, I was able to use the same mounts, accessory brackets, and nearly everything. You'll need the flex plate from the 455, but you shouldn't have to shorten the driveshaft or move the motor mounts. The 350 mounts will make the engine sit about an inch higher than the 455 mounts, but in our trucks that shouldn't be a problem. You'll also need new accessory drive belts, since they'll have to reach farther.

That's all I can remember.

[Glennerd]

Reason for driveshaft was I figured the turbo 350 would have to go for the 400. Not sure about the length difference.

[truckster]

I think you could use the TH350 behind your 455, as long as the motor's not really built. The TH350 is really pretty solid. I've heard of them working with over 750 hp with some modifications.

I'm pretty sure you would have to shorten the driveshaft if you put in a TH400.

[Daves70]

I believe, if memory serves my right, that the 455 has a taller deck.The heads will "fit" each other.I wonder for mounts could you not use the early 80's olds diesel mounts to put these in our trucks? Had a few cutlass' in the past and I think these torque monters would be the ticket in a truck.They are very durable too,my first car was a 75 olds with a 350 all original it had 280000 miles on it when I stopped driving it.

[Glennerd]

Motor mount pics. I didn't mount the engine, I bought it this way. lol

[truckster]

Originally Posted by Daves70

I believe, if memory serves my right, that the 455 has a taller deck.The heads will "fit" each other.I wonder for mounts could you not use the early 80's olds diesel mounts to put these in our trucks? Had a few cutlass' in the past and I think these torque monters would be the ticket in a truck.They are very durable too,my first car was a 75 olds with a 350 all original it had 280000 miles on it when I stopped driving it.

The diesel mounts are a perfect fit for the 455, if they are from the 5.7 diesel. I don't know about other diesels.

[1972RedNeck]

My truck had (still has) the drivers side fender like yours. I assume that the holes in mine were for the Chevy trim. I just got the GMC edge moldings and it worked perfect. You can't even tell that it is a different fender.

[Glennerd]

I managed to wrangle up a new (used and better)fender that matches the pass. side. Pass. side just needs 3 holes drilled in it and it will take my new trim. Parts aren't as plentiful up here. WAY more expensive to find good quality and just plain rare. Reproduction parts are a hit and miss. Replace too many panels and you have $6000 into a truck worth $3000. The market up here is flooded with crap parts that aren't worth using.

[chevypoint]

Thanks for the pictures and the info on the motor mounts. I am suprised to see so many guys running a rocket. I am currently running the Olds 403 in my 47 Chevy Aerosedan but can't keep the temps down. Thought that it would be a better match in the GMC with a bigger radiator and more air flow.

[Glennerd]

A few pics of my Ford Thunderbolt inspired air intake in its early fab stages.

[Glennerd]

More pics.

[Pop's C-10]

This reminds me of tha 70 lwb my pop's drop a olds 350 in..that thing would scoot.

[Glennerd]

I'm feeling pretty lucky to own one of these trucks. Sure enjoying going through the old thing. VERY poorly put together, but I feel much more aware of what I will be driving now. Damn fun! Just a photo of my re-furbished heater box.

[Glennerd]

Even the patio is crowded with parts. No better time to clean up the inners than now. Gotta love our west coast weather.

[MARKDTN]

A 455 will bolt in where a 350 Olds was, but is wider at the top. You may have issues with headers.

[Glennerd]

Upon further discussion with Olds guys, I would be better served with a 350 over a 455. Huge build costs for the 455 and just a grenade waiting to happen. Some will argue otherwise, but if I want to go "really fast", it won't be in my fleet side 72 GMC. I have a little GMC S-15 that will be the speed project I think.

[dougminton]

man, Im likin that air cleaner setup.

[Glennerd]

Thanks Doug! Working on it a bit today, should have some more pics in the next couple days. I was checkn out your truck and I may have some gas tank questions for you in the near future. Obviously I will have to re-locate my battery to the bed and thought that the fuel tank in the rear would help the handling as well, so... you may be walking me through it a bit if you don't mind? lol

[Glennerd]

Here is the overall look that I think is going to work quite well. I will be putting the front end on the truck this weekend and should be able to actually test fit this stuff. Spun aluminum reducers from the local hardware store saved me a few bucks. I also will be making some plugs for the air inlets in case I end up in heavy rain. The clearance between the filter and reducer is enough to pull air in from within the engine compartment easily.

[406 Q-ship]

Originally Posted by Glennerd

Upon further discussion with Olds guys, I would be better served with a 350 over a 455. Huge build costs for the 455 and just a grenade waiting to happen. Some will argue otherwise, but if I want to go "really fast", it won't be in my fleet side 72 GMC. I have a little GMC S-15 that will be the speed project I think.

I don't know who you been talking too but the 455 is no more a grenade than the 350 olds. I agree if you want to make a go fast vehicle a full size pick up is not the best choice. The 350 olds will move a pickup very smartly without much sweat. Besides finding any of the buick/pontiac/olds 455 is a PITA nowadays, they will cost a lot to rebuild, and finding the tall upper accessory brackets for the 455 will be a huge PITA.

[kikkegek]

Subscribing...very cool build! love the golden engine!

[Glennerd]

Thanks Kekk. Yeah,406, a buddy of mine ran a 70 cutlass 455 quarter mile for years and built a few 455's and 350's. I think what I should have said was that the 350 was a "less expensive" grenade to build. Ha, ha, ha!

[Glennerd]

A little Olds hint outside of the hood.

[oldspowered67C10]

This thread caught my eye. I also have a Olds powered c-10(hence the screen name). I have a 67 C-10 w/ a 400 big block from a 67 442 backed by a th400 trans. I figured I share some pics and some Olds opinions.

First of all, all 350s are not equal. A 350 from a late 70s or early 80s car has about half the power as a 70 W-31 350. Its in the heads, compression and cam, theres alot of info on that kind of stuff at 442.com.

455s are good reliable engines but due to the long stroke dont like to stay together too long if spun much past 5500-6000 rpms but with as much low speed torque they make theres really no reason to spin one like that in a street car anyway. Early 400s and 425s had steel cranks, shorter stroke and longer rods and can survive the occasional spin up to 6500-7000 rpms. Late 400s share the long stroke of the 455 but with relatively small bore and are the least desirable power wise of the big blocks.

Small blocks are externally-wise dimensionally the same as big block except for a shorter deck height and range in size from 260-307-330-350-403 with the 330s and the early 350s being the most desirable power wise. The 260s and 307s are too small and the 403s have windowed main bearing webs giving them weak bottom ends. There is also a diesel 350 that was available in Chevy trucks making the install of a Olds engine in a Chevy truck fairly easy if you track down all the mounting parts. The 350 diesel block is the strongest off all the Olds blocks and can be bored heavily making them desirable for high power builds.

Weight wise the 350 is similar to a SBC and the big blocks fall in between a SBC and a BBC.

Anyways, I like the build, nice work and heres a couple pics of my engine.