Can someone identify this engine?

[paulcola]

Just bought a 1980 GMC Sierra. Owner claimed the engine to be a 350 (chevy?) but my mechanic thinks it might be an olds 307. I posted the pics here:

http://www.integratedrecreation.com/sierra.html

If you know, please let me know. I have a feeling it's an olds due to the location of the oil filler tube and distributor, but not completely sure and definitely don't know what size this thing is either.

Thanks!

[BIGCHEVYMAN]

yes you have a olds motor, its been a wils since i have been around a olds motor but i think the engine size is cast into the side of the block just above the starter.

[f.monroe]

Its an olds engine . Looks like your truck was a diesel originally and the olds gas engine is the common conversion . Nice truck . Frank

[paulcola]

Excellent info, thanks to both of you for those replies. I measured the distance between valve covers and got about 14" which, I believe, tells me it's a big block. I'm going to degrease the engine in a little bit looking for any other numbers or identifying marks I can find (and yes, I realize I need new head gaskets for those who've noticed).

Thanks again, I'm so glad there's a forum for this stuff.

Hey Frank, that truck looks familiar! Ditto, nice truck.
Paul

[Ziptar]

Yeah, that's an Olds Motor. I can tell you for sure that your truck was a originally powered by an olds Diesel and then swapped to a 307.

The hydro boost brakes are the tip off, Diesels came with Hydro boost and not vacuum boosted brakes. an LF9 on your RPO Code sticker or if the 3rd digit of the VIN is an "N" will telkl you it was an olds 5.7L Diesel originally.

Enjoy the hydroboost brakes, they are awesome. Much better than the Vacuum brakes in my 85. Wish my 79 looked as nice as your 80.

[paulcola]

Thanks a bunch Ziptar. It's funny you say that about the brakes, I was driving about an hour ago and commented to myself how awesome they worked, now I know why (I've only had the truck for a few days and I'm learning something new about it every day). Didn't even realize that about the brakes, I was wondering why it looked different behind the master cylinder than other trucks I've seen.

So, you think it's a 307? I did find out that the number on manifold (411961 - drivers side) says that it was built specifically for a small block engine, so you could be on to something. Then I consider the 14" of space between valve covers and get confused (12" = SB 14" = BB, maybe I'm measuring wrong or using the wrong logic). Also, I took a snapshot of the passenger side manifold and got a different number (563619) which, according to classicoldsmobile.com says it could be a 350 diesel! Huh? Below that number is D1Y.

Sorry to keep this topic alive, I just want to be exactly sure what size engine this is. Now that I know it's an Olds, I can at least get the right parts for it.

Thanks again guys.
Paul

[Ziptar]

The exhaust manifolds are most likely the original Olds Diesel manifolds, they bolt right up to the Olds gas blocks and were probably reused in the conversion. I am willing to bet you have an Olds 307 or 350, those were most often used when converting the diesels, they are a straight drop in replacement for the Olds 5.7L Diesel. I have seen a few 455's but, not too many. Why anyone would give up an Olds 5.7L Diesel is beyond me, I love mine.

I think what's throwing you on the measurements is that the Olds small blocks are wider than the chevy small blocks.

A few more differences the diesel trucks had than the gas, these were all standard on the diesel package. There might still be a small square above and between the Speedo and gas gauge on the instrument cluster, if it still has the original bezel. Thats the "Don't Start" / Glow Plug / "Water in Fuel" Lightt. If it still has the diesel bezel and you ever change it out, let me know, I am looking for one. The diesel came equipped with two batteries so you might have two battery trays under the hood. They also came with a "Special Insulation Package" extra sound deadener / insulation in the cab and under the hood. Engine oil cooler built into the radiator (which is a 4-core). TH400 with low slip clutches, Thermostatic fan clutch, "Low Drag Front Disc Brakes" (whatever that means), block heater, 63 amp Alternator, Dual exhaust. Power Steering (had to have the pump for the brakes).

BTW: Where in Florida are you?? I am on teh west coast 40 miles south of Sarasota.

[oscareltemblo]

My dad used to have a 1980 Chevy shortbed like that and had the deisel in it I was a strong engin .I dont know why they would change it .

[dwcsr]

your dad got the only one that worked.

[piecesparts]

The Olds diesel/Chevy engine was piece of junk. The head gaskets kept blowing out and they spent more time in the shop that giving true service. I got the opportunity to do a head job on one of these fine relics of the past and it was a pain in the booty to get down to the actual heads. The fuel pump mounted in between the heads, being driven off of the timing chain and it had eight different fuel lines to the culinders. This is the same pump setup that International used on their tractor and heavy equipment motors. Once this was removed then the artful job of timing it was needed. The shop rate manual gave 12 hours for a head gasket replacement job and that is for an experieinced GM mechanic.

Most owners traded that out for a 350 Chevy motor or the Olds direct 350 replacement motor, just to get away from the pain.

[bodydropped]

my diesel teacher at school use to own a olds with the 5.7 diesel and he said at 50k miles he had to pull the heads due to head gaskets blowin the reason behind them blowin were the fact that there was so much comp. that the head bolts couldnt stand them and they would break but at 90k the engine decided to rip all of the mains out of the block so basically gm had a learnin experince but i rather a 5.7 gas than a 5.7 diesel

[Ziptar]

That's pretty much the issue with them, The later DX blocks (have one in my truck) solved the problem with the mains. but, GM never quite got it into it's head that they should stop using stretch bolts for the head, and certainly not instruct the techs to reuse them.

ARP bolts makes hardened main and head studs for the Olds 5.7L Diesel that solve the head problem once and for all. Guys on the 350 diesel forum using ARP main and head bolts / studs have 200K and more racked up with no issues. That's whats going in mine when rebuild time comes.

[paulcola]

Ziptar:

"The exhaust manifolds are most likely the original Olds Diesel manifolds"
That could explain the numbers!
I think I'm leaning towards a 350, it's very possible, it's a fairly large engine.

I think the instrument cluster is not original and it does not have that square. Here are the other things you asked about:

Two battery trays: Nope, just one. Doesn't mean there wasn't one a long time ago though.
Special Insulation Package: Definitely not. I think it got equipped with the opposite of that: No insulation.
Engine oil cooler built into the radiator: Uh, I don't know.
TH400 with low slip clutches: Don't know.
Thermostatic fan clutch: Don't know
Low Drag Front Disc Brakes: Don't know
Block heater: Haven't looked into that yet
63 amp Alternator: Need to find this out too.
Dual exhaust: Yes
Power Steering: Yes, works excellent by the way.

Where in Florida are you? I live in Naples, you're about 2 hours away! Let me know when the next GMC/Chevy truck show is!

Everyone else: Wow, you guys know a lot. Think I'll slowly back out of this conversation now, hoping no one asks me anything technical. Seriously though, thanks again.

Paul

[the baron]

Hi all ,

I also owned a 1979 C-10 with that stupid Diesel engine , which was remotorized with an Olds gas engine ( 260ci , it sucks , I know ) before I bought it ...

to identify your engine , check the casting number on the block just behind the water pump , it is casted in 6 numbers + a code with one number & one letter in bigger font ...

another option for later blocks ( from the eighties on ): the cubic inches displacement is casted on the side of the engine , in HUGE numbers ( 307 , 350 , 403 )

hereby a list of the usual casting numbers you should find :

http://www.442.com/oldsfaq/ofblk.htm...dentification/

the link doesn't work for now , you'd better hit it later , and if it doesn't work at all , send me a PM , I have a hard copy of this file ...

regards ,

the Baron

[Slonaker]

Originally Posted by paulcola

Ziptar:

I think I'm leaning towards a 350, it's very possible, it's a fairly large engine.

Paul

On Olds engines, they are the same size externally whether they are a 260, a 455, or something in between. The info The Baron gave you is your best bet for figuring it out.

I used to have a Cutlass with a 260. We called it the "Oldsmobile Gutless Supreme" because it had no power at all. A 350 Olds fixed that problem, and was a direct bolt-in using all of the original brackets and manifolds. I have also seen the same swap using a 455 if that tells you how similar the different Olds blocks are.

Slonaker

[paulcola]

Thanks Baron, I will definitely look behind the water pump (and take a picture when I do).

That's really good to know Slonaker, now it's starting to make sense. No wonder the local mechanic couldn't even tell.

[boatpuller]

yup,it was a diesel.the hydroboost gives it away.mines a converted diesel.alot of guys i've talked to like the hydroboost.it allows a little more cam, doesn't steal your vacum.mine's cammed up a bit.and stops great.it'll make a good one,hang in there.

[the baron]

Hi all ,

the link didn't work yesterday , it does today ...

hereby the casting ####'s :

ID/ Casting

Code Year(s) CID Number Notes

1 '64-'66 330 381917 45° cam bank angle.

1A 330 381917 45° cam bank angle.

2 '68-'76 350 381917

2 '68-'70 350 395558

3 '66-'67 330 394417 39° cam bank angle.
4

5 '73,'74 350 395558

2A '75-'81 260 Solid main webs for 2A's only? At least for '76.

2B ??-'81 260 557751 Windowed main webs. Windowed
main webs for 2B's only?

3A '79 350

3B '77-'80 350 557752

4A '77 403 557265 Solid main webs possibly
553990 for these three
554990 casting numbers.

4B '77-'79 403 557265 Windowed main webs always.

?? '85 307 556607

5A '81- 307 3161

D3 350 7582 Diesel


Cheerzzz ,

the Baron

[jimfulco]

Look on the front outer corner of the driver's side head. What number or letter is cast there?