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Old 09-07-2005, 03:01 PM   #1 (permalink)
argo
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Gas to Diesel Conversion, 6.2L or 5.7L?

I just found a completely unmolested 1981 Delta 88 Diesel in the local pick a part. The car has severe rear end damage, but is perfect out front. The oil and coolant look good, and everything down to the air cleaner wing nuts is with it. Is it worth it to pull and refurb an 81? I want to get at least 150 hp out of it, so it runs similar to the 307 that is currently in the car I want to put this thing in. I was planning on a dual exhaust, EGR blockoff, 1 degree advance on the timing, ARP studs, a RAYCOR water separator, and 170 degree thermostat. I know alot about cars, but not 350 diesels. Is this engine worth it, should I hold out for a later model, or go with a 6.2? I am leaning toward the 5.7 because I know it fits, but would prefer the 6.2 if it can fit. I found two 6.2L engines in 1989 Suburbans at the yard as well, and I am kicking that idea around, since they were rated at 160-170 hp, (I think)? I want to use either engine with a THM 200-4R. I can make the converter lockup in any gear I want. I have done this for friends with older cars who wanted overdrive and no computer. I just thread a pressure switch into the tranny's test port for whatever gear we want lockup in and presto, full lockup. I can make it lockup in 2nd, 3rd, and 4th, just 3rd and 4th, or just 4th, depending on placement of the switch. This tranny has a dual pattern bellhousing and should work wherever a chevy or olds engine goes. The main reason I am interested in the NA 6.2/6.5 is that I want to have a reasonable amount of acceleration (maybe 0-60 in under 11 seconds). It doesn't need to be blazing fast, but I don't want it to be a sluggo either. If the 6.2/6.5 is the size of a BBC, then I could use it for sure. If the acceleration of a 5.7 diesel could match my goals, then I'd be inclined to use it. The problem is, I have driven a few of them, and while I do not believe that they are the clods that they have been made out to be, I also know that in a big car like mine (1984 Olds 98 Regency, last of the big, heavy,RWD jobs) they do 0-60 in about 20 seconds, which is just too slow for me. I figure that 11 seconds would require about 150 hp, and that's why I am leaning toward the 6.2. If anyone knows how to get that from a 350 diesel, I am all ears... BTW, thanks for your input, everyone.
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Old 09-07-2005, 04:11 PM   #2 (permalink)
chevydiesel
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Interesting...

I think the 5.7 would sure be easier to install.

Th 5.7 was 100ish on HP


The 6.2 varied for years and whether it was LD or HD (C or J)
C series (82-84) ~135HP
C series (85-92) ~145HP

J series (82-84) ~145HP
J series (85-92) ~155HP

They'll all (6.2's) make 160HP with a good pump/calibration and good exhaust and air intake.

As for size, the 6.2 is the same size as a BBC, but a little taller, valve cover wise, etc.

The transmission choice will be the weak link, being a 200R4, but only time will tell.

If you go 5.7, I'd stick to your suggestions made, but go one further, and drop the compression ratio at least a point. You can do this by having the pistons topped .010 to bring it down from 22:1 t 21:1 this should help in the blowing head gaskets problems.
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1982 C10 SCSWB 6.2NA, 2.73 700
1986 C10 SCLWB 6.2TD 3.73 700
1989 V20 SUB 6.2NA, 3.73 400
1994 G20 VAN 6.5NA, 3.42 60E
1994 K20LD ECSWB 6.5TD, 3.42 80E
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1995 C3500HD DRW 6.5TD, 12' Flatbed 5.13 80E
1995 C3500HD DRW 6.5TD, 18' Rollback Wrecker 4.63 80E
1995 C20LD ECSWB 6.5TD 3.73 80E
1995 K20LD SCLWB 6.5TD 3.73 80E
1996 K30 DRW 6.5TD 4.10 80E
2003 C10 SUB 5.3 Gas 3.73 60E, daily driver cause of high diesel prices.
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Old 09-07-2005, 05:59 PM   #3 (permalink)
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Or he could get the head gaskets for blocks that have been decked(.010 thicker) to lower the compression. But the 6.2 is probably going to be the one to get you the power your after.
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Old 09-07-2005, 11:48 PM   #4 (permalink)
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Just to add a little bit to driving experience, I had a '82 Toronado with a 5.7 Diesel, and it wasn't as bad as expected it to be in terms of acceleration. It was no speedster by any stretch, but it had enough power to pass and pulled hills pretty good. I had always heard they were complete dogs, but the FWD Toro wasn't near as big and heavy as a lot of Caddys, LeSabres and Electras they came in. I took it on trade just to sell, but I drove it a little more than I do most cars that I get like that just out of curiousity. I think the 6.2 would be a better choice though.
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Old 09-08-2005, 12:39 AM   #5 (permalink)
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I am NO expert by any means.
I think all the 5.7 diesel is, is a "350 gas block" with "diesel heads" bolted on. I think that the 6.2 is a ground up diesel. I heard that a long time ago.
My Dad had 2 of them, 1982 Chevy 1/2 ton P/U, 2wd, auto, and a 1982 GMC 1500 Custom Van. I was 18ys old, so I was into mussle cars. They were no rockets, but they weren't bad. They kept up with traffic at stoplights. We only had them for about 4 or 5 years.

Not to hyjack the thread, but if the 5.7 diesel is a 350 gas block, does it have the same motor mount points as a 350 gas engine?

Thanks,
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Old 09-08-2005, 01:21 AM   #6 (permalink)
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Quote:
Originally Posted by jc64 View Post
I am NO expert by any means.
I think all the 5.7 diesel is, is a "350 gas block" with "diesel heads" bolted on. I think that the 6.2 is a ground up diesel. I heard that a long time ago.
My Dad had 2 of them, 1982 Chevy 1/2 ton P/U, 2wd, auto, and a 1982 GMC 1500 Custom Van. I was 18ys old, so I was into mussle cars. They were no rockets, but they weren't bad. They kept up with traffic at stoplights. We only had them for about 4 or 5 years.

Not to hyjack the thread, but if the 5.7 diesel is a 350 gas block, does it have the same motor mount points as a 350 gas engine?

Thanks,
jc

You are correct about the 5.7 being a conversion diesel, but it is a 350 Oldsmobile, and not a Chevy 350 block. All you have to do is use different motor mounts to put in something that had a SBC Chevy.
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Old 09-08-2005, 01:37 AM   #7 (permalink)
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Quote:
Originally Posted by 67_C-30 View Post
You are correct about the 5.7 being a conversion diesel, but it is a 350 Oldsmobile, and not a Chevy 350 block. All you have to do is use different motor mounts to put in something that had a SBC Chevy.
Now I remember.

Thanks
jc
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Old 09-08-2005, 02:04 PM   #8 (permalink)
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Thanks for the input. I will probably go for the 6.2, with a good pump overhaul, a quiet dual exhaust, and a dual snorkel air cleaner. I assume I'll need a diesel converter for my 200-4R. I intend to run in lockup except for 1st gear, so maybe I can keep the gas one. I also want to get softer governor springs and heavier flyweights to get it to upshift at about 3,500 rpm at WOT. Like I said, I am not trying to build a race car, but I don't want my Olds getting shown up by Geo Metros and Yugos at the on-ramp. I liked my first Olds, with the 5.7, especially being a poor high school and college kid, but I couldn't stand how sluggish it was. If I can get 30 MPG while cruising at 70 mph, and get 0-60 in under 11 seconds, I'll be thrilled. I know the 5.7 can bury the speedometer and keep climbing, but it takes forever. I am not looking for ultimate top speed, but rather I am looking for decent acceleration and fuel economy. The 6.2 sounds like it might just be the ticket.
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Old 09-08-2005, 03:12 PM   #9 (permalink)
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Oldsmobile Diesel

Based upon the 350 cubic-inch Olds gas engine, the diesel debuted for the 1978 model year to much fanfare. The promise of the future, it allowed big car comfort with small car fuel economy. Contrary to popular belief, the engine was completely different than its gasoline brethren, but it did look the same since it needed to go down the same assembly line and fit into vehicles that could be either gas or compression-ignition powered. The block was much sturdier and the crankshaft mains and crankpins were 0.500-inch bigger, measuring 3.00 inches instead of 2.5 inches. The crankcase was heavier and the pistons were fitted with full-floating pins. The block was so good that during that era many drag racers used it to make big power and it was known to stay together.

Then what happened to the Olds Diesel to give it such a poor reputation and the impetus for a class-action law suit? The engine suffered from poor familiarity by the consumer and Olds service personnel along with the lack of a water/fuel seperator and drain in the fuel system. This was compounded by a flood of very poor-quality diesel fuel into the market place shortly after the engine's introduction. Any moisture or dirt that would get into the high-pressure Roosa Master injection pump would cause some of the parts to hang up. This could have occurred for only a second, but that was enough time of an incorrect fuel inject cycle that would allow cylinder pressure to peak and overcome head bolt tension or break down the head gasket. The driver may have only sensed a slight shudder but the damage was already done. The injured head gasket would then let coolant seep into the cylinder and since there is little quench volume in a diesel, the uncompressability of a liquid was a theory very quickly reinforced. Something had to give and it often was a piston, connecting rod or crankshaft but it spelled disaster either way. In addition, both the dealer body and the consumer often used the incorrect oil for the engine, creating further service issues.

The Olds Diesel, when cared for properly, ran for hundreds of thousands of miles, but only in the hands of an experienced diesel operator. Other than that, it makes a great gasoline race engine block.
================================================== =======

It is a Olds 350 Beefed up with a bigblock bottom end, main size and stuff.
Cast crankshaft

Richard
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Old 09-08-2005, 10:44 PM   #10 (permalink)
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argo,
Good luck with your project.

PapaG,
Thank's for the info.

This thread has got me thinking about something. Hmmm....

jc
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