When the guy said he had a '63 pickup with a 307ci V6 i didn't believe him and was uninclined to work on it - can't be original, no such thing i said. When he told me it had the original V6 emblems on the hood i reconsidered, i've made an *** out of myself before thinking i knew it all and maybe, just maybe i'd better have a looksee. It showed up this morning and sure enough it is a big block V6, look at those rocker covers. I grabbed my calculator, divided 409 by 8 cyls & then multiplied by 6 and guess what - 306.75 cubic inches. I am sure there are a few members on here taht have experience with this engine, if they would chime in i'd appreciate it. The carb was all messed up and i have it in the cooker. This has to be one of the neater engines i have seen.
I don't want to be the search nazi, but there are several good threads and lots of info already on the board. " The search ****on is your friend."
If the Search Function Lets you down, Google is also your friend. Here is a very good site on GMC's Big 6. http://www.6066gmcguy.org/
Not worth the time to spray paint it. Low rpm motor without any guts or after market hop up equipment. r
man I haven't seen one of those in many many years...seems like I remember they were in the gmc trucks but that was long ago...forgot all about that, cool
A rare post for me here. I had to bone up on this V6 305. These were ORIGINALLY designed to be diesel engines with the glow plugs where you see the spark plugs are. Has huge beefy bearings etc. For whatever reason, GM ****canned it and then later GMC turned it into a gas motor and it was pretty much worthless. What I find really ironic is that during the gas shortage in the 70's, GM started putting diesels into the Olds cars (the 307) and they were originally designed to be gas engines. Needless to say a lot of these 70's diesel engines didn't hold up and were junk. Pretty stupid in my book since GM already had the 305 V6 diesel engine design and they could have stuck that into the Olds during the 70's. Whatever. All junk. Travis
They weren't worthless. They would usually last 200,000 miles and put out more torque than the V-8's. Even the diesel version, the Toro-flow, was not a bad engine when used in the medium duty service that it was designed for. It kinda pisses me off when people say "it's a boat anchor" or "they were worthless" when they know absolutely nothing about the engine. In the mid 60's a GMC pickup would almost always have higher resale value than a Chevy, and the V6 was a good part of the reason why.
Travis, I wont say your wrong, just that history wasn't very kind to the domestic p***enger car diesel. Yes, GM did a lot of things wrong back in the 70's, and the technology wasn't really there for Detroit, but the overall design was actually quite good. The #1 problem with the Olds 350 diesel was it's fuel filter. The diesel fuel of the time was notorious for containing a lot of water. Large commercial diesel trucks had water traps in the fuel system that could catch and hold up to a gallon of water, and commercial truck drivers were trained to drain the water out of it at regular intervals. Regular Ma and Pa car folks, however, were clueless. The filter on the Olds didn't have a separate water trap, and when it did require draining, most drivers didn't have a clue as to how to service it... So they kept driving with the "water in fuel" light on, resulting in a dead motor that required a $500 repair. Mercedes, on the other hand, had a fuel filter with an integral water trap that was simple and straight-forward. It actually worked, was user friendly, and could hold almost a quart of water before it became critical. As a result, Mercedes diesel cars of the 70's can still be found running across the highways of every nation on earth, sometimes with close to a million miles on them, but the Olds diesel is practically extinct. Think about this. Back in '79, you could buy a brand new Cadillac SDV with a 350 Olds diesel that weighed close to 6000 lbs, and got 30 mpg. While it wasn't the fastest car on the road, it was at least as quick down the 1/4 mile as the low end Kia's and Hyundai's sold today. If GM were to release the 350 Olds diesel today with nothing more than a modern diesel fuel system, a turbo, and a splash of modern electronics in a swoopy aerodynamic full sized sedan @ ~3200 lbs, it would get 40 mpg, have more power than any V6, and be hailed as the greatest domestic engine ever made, bar none!
The GMC truck engine was exactly that - a high torque, low-RPM, TRUCK engine designed for pulling heavy **** without breaking down. And that they did, very well, for a long time, in both small and very large trucks. The odd design is because as mentioned it began life as a diesel engine.
I take exception to your comments as you did mine......I WAS around these clunkers, in light duty pickups, when they were new.......and maybe in YOUR world, they brought as much or more used than a Chev V8....but that is totally contrary to my experience and observations......used ones were nearly "saleproof".........They may have been somewhat durable, but they were neither fuel efficient nor peppy performers, even with 300+ cubic inches........you must be thinking of the old inline 6 cyl GMC's having a good following as used trucks........now those were engines in their day....still are. Ray
The old saying "that was then, this is now" Worthless? I don't know. I would guess that if a person was trying to sell a good running 305 engine, it may only get $100??? There is no resale market in my area, for many years now. The slightly later 351 engine "might" find a buyer..maybe.. to a restorer?.. They have durability and torque as positives, but the negatives really hurt trying to use one today; bad gas mileage, extreme weight, low revving/slow revving, low horsepower, no aftermarket goodies. I really did not care for the extra weight affecting the good handling, braking, and ride of those 60s pickups when compared to a SBC. These motors feel very unresponsive IMO. I was going to say they would be still be good for snowplowing and hauling heavy dirt or stone, but these days there are much more economical alternatives to using that motor. Now, you could say the 348 chev falls into the same catagory. However, the 348 was originally known as both a truck motor and a hi-perf car motor. They REALLY fell out of fashion by the mid-late 60's, but have regained their status. I just don't see the GMC V6 re-finding it's niche these days.
the injectors whent where the spark plugs are. The first 305 where gas only diesel was the 478 toro flow and it didnt need glow plugs. they would pull about the only good thing about them.
142 horsepower, 260 lbs-ft of torque. About like a 70s Chevrolet 350 V-8 (We had a '73 Impala 350 rated at 145 horse and 250 lbs-ft of torque)
As stated, they worked for the purpose they were intended, but they were rather thirsty---I knew two people with them in GMC pickups, and at the rate they ****ed gas, they might as well have had medium to large V8s in them. The only piece of speed equipment I've ever seen for them is a Mallory dual point distributor.
"Boat anchor!!".. I guess a Ford H-D BIG truck MEL 534" gas engine is a boat anchor too! And fwiw, my old RR Buddy really likes the old Gimmie bent-6 bangers in WORK-TRUCKS to this day! He say's that the old ****ers had more guts than the Chevy 6-banger's ever had back then! pdq67
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