Oldsmobile Engine Conversion

Disclaimer: Links on this page pointing to Amazon, eBay and other sites may include affiliate code. If you click them and make a purchase, we may earn a small commission.

HotRodPC

Administrator
Staff member
Admin
Joined
Aug 29, 2010
Posts
47,017
Reaction score
9,026
Location
OKC, OK
First Name
HotRod
Truck Year
85 K20 LWB
Truck Model
Silverado
Engine Size
454 - Turbo 400 - 3.73
Technically, since it is a build project, is a truck, and a GM truck, and kinda square, just with a couple waves in it, I actually don't see any reason it couldn't go in the Under Construction category if you're doing a full build on it. If it was way off target and something that might not have much interest, like a Yugo restoration, i'd say for sure just go in other vehicles. You're not the only one building different projects. 1low is also doing a 60's, One of the Johns is building an Fibreglass S-10 mud truggy. Once we get enough "Other Builds" We might just do a sub cat under the under construction.
 

AzGeo

Member
Joined
Aug 16, 2010
Posts
40
Reaction score
34
I've done a number of "403 into olds diesel 1/2 tons", but they were easy because the 260/350/403 gas are the same width as the Olds diesels. I think the 425/455's are the wider version of the motor. The larger motor may require the mounts be modified. The 'switch pitch' is nice, especially when you use a 'line lock button' on the shift lever to activate the converter. How about a NICE 500" CAD ?
 

HotRodPC

Administrator
Staff member
Admin
Joined
Aug 29, 2010
Posts
47,017
Reaction score
9,026
Location
OKC, OK
First Name
HotRod
Truck Year
85 K20 LWB
Truck Model
Silverado
Engine Size
454 - Turbo 400 - 3.73
I've done a number of "403 into olds diesel 1/2 tons", but they were easy because the 260/350/403 gas are the same width as the Olds diesels. I think the 425/455's are the wider version of the motor. The larger motor may require the mounts be modified. The 'switch pitch' is nice, especially when you use a 'line lock button' on the shift lever to activate the converter. How about a NICE 500" CAD ?

I've been told the mounts are the same on SBO and BBO. The oil pans interchage, the heads would even interchange on an any Olds. The deal is, the BBO is a taller block and the mounts being well below the heads, makes them equal at that point. But as the BBO goes taller that makes the distance between the head intake ports wider, so intakes don't interchange, otherwise alot does. Exhuast manifolds will bolt on both too.
I'm pretty sure I can have a CAD 500 if I wanted it. It's now been sitting out in the weather for almost 2 years to rot which is horrible. I didn't pursue cuz I had my Olds project I wanted to do, and not many aftermarket parts in a CAD. I had a buddy who built a Fordilac with a 472, passed it down to his son, then it was wrapped around a pole.
 

DoubleDingo

Full Access Member
Joined
Jul 3, 2012
Posts
10,315
Reaction score
14,793
Location
Right where I am
First Name
Bagoomba
Truck Year
1981
Truck Model
81-C20 Silverado Camper Special-TH400-4.10s
Engine Size
Carb'ed Vortec 350
If you're okay with it being in the Under Construction section, I will upload it there. You will learn some about little ol' me through the thread. I need to scrounge up some photos and such from before the rollover, and then how things progressed post rollover.
 

bucket

Super Moderator
Staff member
Super Moderator
Joined
Aug 3, 2010
Posts
29,190
Reaction score
24,270
Location
Usually not in Ohio
First Name
Andy
Truck Year
'77, '78, '79, '84, '88
Truck Model
K5 thru K30
Engine Size
350-454
Everyone here is perfectly OK with a '65 C20 project :)
 

towjoe

Full Access Member
Joined
Jul 22, 2012
Posts
695
Reaction score
136
Location
Lafayette,IN
First Name
joe
Truck Year
78,80,81,81,86,88,89
Truck Model
K30's or V3500's
Engine Size
6.2, 454
I've done a number of "403 into olds diesel 1/2 tons", but they were easy because the 260/350/403 gas are the same width as the Olds diesels. I think the 425/455's are the wider version of the motor. The larger motor may require the mounts be modified. The 'switch pitch' is nice, especially when you use a 'line lock button' on the shift lever to activate the converter. How about a NICE 500" CAD ?

Wow kinda amazed to hear people talk about a switch pitch tranny. My dad has done transmissions around 40 years now and have never heard talk of a switch pitch outside of our family. He cuts open the converters and modifies them to change stall speed. then sets the switch up on brake pedal for stall. He gets about 700-800 low stall and when hold brake anywhere up to 3,500 stall. combined with a reverse shift valve body, makes a wild transmission. sad part is Buick, Olds, and caddy in 65, 66,67 where only ones with a true 400 switch pitch.

Speaking of sb with Olds engines, I have a 80 C10 with one that was a Alabama truck I bought off the interstate with a bad transmission. I also had a Friend with a wrecker with a 455 in it and automatic 4wd. He used a 3/4 ton frame, a 455 from around 70, a 400 auto, a 205 transfer case to run PTO, and a dually rear end. Was a real sweet trck with a holmes 440 on it.
 

HotRodPC

Administrator
Staff member
Admin
Joined
Aug 29, 2010
Posts
47,017
Reaction score
9,026
Location
OKC, OK
First Name
HotRod
Truck Year
85 K20 LWB
Truck Model
Silverado
Engine Size
454 - Turbo 400 - 3.73
An Olds 455 would be great in a 4x4. Being the Torque monsters they are, but the only thing that concerns me, Olds don't like high RPM, and someone running in 4 Low hitting the high R's alot, it may not hold up. Olds motors require Oil restriction mods to run at 5500 rpm and to get over 5500 rpm the mains need to be strapped and/or girldled and really need the rotating assembly lightened. They are must to much bulk for high rpm.

I guess maybe it's better said, Olds 455 might not make a good mud truck motor due to high rpm, but man oh man, I'm not so sure you can get a better Rock Crawling motor with all the low end torque. I thiink you'd be finding all the weak links in your drivetrain.
 

towjoe

Full Access Member
Joined
Jul 22, 2012
Posts
695
Reaction score
136
Location
Lafayette,IN
First Name
joe
Truck Year
78,80,81,81,86,88,89
Truck Model
K30's or V3500's
Engine Size
6.2, 454
I had a 1970 delta 88 royale 2 dr I drove years ago with the 455 rocket in it. It was so much fun setting at the stoplight and a 5.0 mustang or camero pull up beside me. My car was beat up, rattle canned black, and rusted out so bad the fenders were loose at the bottoms. It made the kids sick when I'd just leave them at the light. Wish I still had it, I'd put the motor in a tow truck, but I sold the engine to a guy with a nice 71 cutlass.

My brother played with a 65 olds 425's years ago in a dynamic 88. It was a screamer for a old mans car. He's got the motor and trans in the back of his shop for a spare for a 65 delta 88 I picked up for junk the other day. Hard to belive there's some of them left that can be found in near mint condition. The 65 delta 88 I just got had been kept in a heated garage all it's life and was last drove in 1992.
 

HotRodPC

Administrator
Staff member
Admin
Joined
Aug 29, 2010
Posts
47,017
Reaction score
9,026
Location
OKC, OK
First Name
HotRod
Truck Year
85 K20 LWB
Truck Model
Silverado
Engine Size
454 - Turbo 400 - 3.73
I believe that story. I had a neighbor with a 69 Delta 88. She tells me, my car is making a a weird noise when I get on the freeway can you take it for a drive and tell my dad what it's doing. I got in the car thinking, getting on the freeway, I need to give it hell. Sumbish, that muthafugger was a Rocket. You nailed it right off the get go it was gone. I've been an Olds fan ever since. I've driven fast motor cars before, but from right off the light, not stalling the motor out, just nail the gas, that car would lay down rubber as far as you wanted to. If you wanted to power brake it, you could flat roast and I do mean literally roast the tires off the rims. I was infinate and wouldn't stop til you let off.

BTW, I never did hear a wierd noise, so I get back to the house and I said, hey come with me, and see if you can point the noise out to me when you hear it. Come to find out, the noise she was referring too was the deep groan in the carb when you got on it. I was laughing my ass off. She couldn't believe that was normal.
 

HotRodPC

Administrator
Staff member
Admin
Joined
Aug 29, 2010
Posts
47,017
Reaction score
9,026
Location
OKC, OK
First Name
HotRod
Truck Year
85 K20 LWB
Truck Model
Silverado
Engine Size
454 - Turbo 400 - 3.73
I did a compression test on the left bank of this motor last week and had that one cylinder with 60lbs. After charging the battery up real good, and pulling the plugs out of the right bank too, and also using a different new compression gauge that I had misplaced, I did a complete compression test starting all over and doing it right this time. I got 3 cylinders with 140, 4 with 125, and 1 with 80, and the one that I had previously gotten 60 out of, is one that I'm now getting 125 out of.

I think from the motor sitting it had some sticky valves. With the motor turning over fast by starter, I'm not hearing any rod knocks or valve train knocks. Granted, that's a no strain test. This is a 1970 455 with an OEM 2bbl carb which means it's a low compression motor by 1970 standards. It's ugly and dirty, but I hope to fire it up next week with an oil pressure gauge and see what that's like. If that Oil pressure is at least 30 cold and no knocks in it, I'm really thinking about installing it in the 84C20 as is.

I have a feeling with some clean oil, warming it up and driving it, it just might free the valves up and improve the compression to more equal #'s and bring that one with 80 on up to at least 125 too. If not, one weak cylinder is no biggie, and the compression test doesn't show anything to be wrong as far as a blown head gasket or cracked head. Also getting it running, A vac test will tell alot too.
 

X-cabsquarebody

Full Access Member
Joined
Aug 19, 2012
Posts
213
Reaction score
73
Location
Western NC
First Name
Billy
Truck Year
80, 80, 87, 91
Truck Model
C10, C10 ,K30 , 3500
Engine Size
305 TPI, 454, 8.1
I had an Olds 455 in my 80 C10. When the 350 diesel cracked a head with only 18000 miles on it, it got swapped out. That was around 1982. The truck was a monster!!! With 200,000 miles on the motor it would flat out pull my 2000 1 ton ! 3.73 gear worked good in the too.

Sold the olds motor a few months ago. Having a little regret.
You must be registered for see images attach

You must be registered for see images attach
 

HotRodPC

Administrator
Staff member
Admin
Joined
Aug 29, 2010
Posts
47,017
Reaction score
9,026
Location
OKC, OK
First Name
HotRod
Truck Year
85 K20 LWB
Truck Model
Silverado
Engine Size
454 - Turbo 400 - 3.73
Nice to see another ChevrOldslet. I don't think many realize how good of a truck motor Olds motors make. Chevy had to peanut port head the 454 for low end torque. Olds has massive torque right off of idle but yet still have the big ports for mid range and top end. Of course top end quits fairly early, around 5500 since the rotating assembly is so heavy. But it'll damn sure hold up to anything low end.

About my only shortage as of now is 455 bracketry. I have 77 small block brackets off of a 350 Olds, and I know the late 60's small block Olds brackets work on the big blocks, but not sure of the later mid 70's small block brackets fitting the Big Block.
 

GreaseDog

Full Access Member
Joined
Aug 8, 2010
Posts
1,189
Reaction score
33
Location
Elkhart, IN
First Name
Jeremy
Truck Year
1977 K20
Truck Model
1980 K2500
Engine Size
350
Hot Rod, sounds you and I are in a similar situation. Trucks to build but not building them for this reason or that. Granted mine is not a square, but it is a Chevy.

I want to ask you, an Administrator, and the others that are moderator's, if you object to me sharing my 1965 C20 project with you all on this site? If you all are okay with it, let me know. If you're all okay with it, I challenge you to a truck-off so to speak. You have some Old's to build and stab; I have a truck to build and then a frame to setup and do a body swap.

I'm in the same boat, all of the drivetrain to put my 80/93 project together, just no motivation or cash flow to get it rolling. Maybe this weekend I'll finish stripping the cab and drivetrain off of it.
 

HotRodPC

Administrator
Staff member
Admin
Joined
Aug 29, 2010
Posts
47,017
Reaction score
9,026
Location
OKC, OK
First Name
HotRod
Truck Year
85 K20 LWB
Truck Model
Silverado
Engine Size
454 - Turbo 400 - 3.73
Not sure if I'll shoot for it tonight, but I'm about 15 minutes away from firing up the Olds 455 motor in the garage to see if it runs without any knocks, check oil pressure and if and how much smoke it puts out. Of course I expect some smoke. The thing has not ran for years. All I have left is plug the vac ports on the intake, add the oil pressure guage, put the plug wires on, I have an electric inline fuel pump and a gas can, battery is hooked up and hit the remote starter button after I hook power to the dizzy.

Only thing keeping me from doing it tonight, is no muffler and it'll be open exhaust manifold. Sure don't want to wake that fuggin baby next door.
 

J Knight

Full Access Member
Joined
Sep 8, 2011
Posts
4,298
Reaction score
141
Location
Baytown TX
First Name
John
Truck Year
82 Chevy
Truck Model
C10
Engine Size
350ci
Not sure if I'll shoot for it tonight, but I'm about 15 minutes away from firing up the Olds 455 motor in the garage to see if it runs without any knocks, check oil pressure and if and how much smoke it puts out. Of course I expect some smoke. The thing has not ran for years. All I have left is plug the vac ports on the intake, add the oil pressure guage, put the plug wires on, I have an electric inline fuel pump and a gas can, battery is hooked up and hit the remote starter button after I hook power to the dizzy.

Only thing keeping me from doing it tonight, is no muffler and it'll be open exhaust manifold. Sure don't want to wake that fuggin baby next door.
Huh! I remember a while back the war was on with the neighbor lady.:shitsweak:
 

Latest posts

Forum statistics

Threads
42,293
Posts
913,183
Members
33,794
Latest member
Twistedwhisky
Top