Bluerocket76

Found a 1985 oldsmobile engine out of cutlass supreme.I have 1976 350 4bbl 8 # heads with egr.My question is will the parts interchange from 307 to 350. As far as what I need from it is timing chain cover ,valve cover ,fuel pump eccentric, oil slinger ,oil gallery plugs from front of block one with hole ,oil filter housing adapter .pulleys all the things I mention were stolen from me in a move by a scrap guy we weren't done moving I come back and all my parts were gone starter ignition coil starter plate alternator valve covers air filter housing I was po; ed all the stuff I mention up top so if reading this I thank you for any advice of were I can find those parts oh and the 166 plate all my hardware if that 85 engine parts interchange that would save me a grip of paper he asking 150 and he said it ran .

don71

YES. Be mindful of the water pump you use. Water pumps come in different lengths and the wrong one could lead to a mis match when trying to align the belts as straight. Consider the water pump and pulleys need to be used as a system and not mixed up between the two or else trial and error can occur.

69HO43

If it's out of a Supreme, it's a roller engine, VIN Y. It has the little intake and exhaust ports with the stainless steel exhaust manifolds. Rated at 140 HP.

95% of them had air conditioning, so they pretty much took an A/C SBO water pump. It's always good to keep the pulleys as a set, which is true. 99 percent of the external cover parts like valve covers, oil pan, oil pump, fuel pump, etc. will fit on the 350. The harmonic balancer will bolt up, but it's a skinny and smaller one than what came on the non-W31 350s. Well, the W31's as well, but normally those aren't plentiful.

Pump #556283 is the part number for the A/C 307, plus that fits a slew of 350/403 applications as well.

If you don't have A/C, the pump you can use would be #231886.

joe_padavano

The 307 and 350 are dimensionally identical. As noted, an 85-up 307 can either be a flat tappet motor (with 5A heads) or a roller cam motor (with 7A heads). All sheet metal (front cover, oil pan, valve covers) interchange, though the 307 has five bolt covers. All 307s used the 6.1" water pump. Flexplate interchanges. Crank and rods even interchange (same stroke, same rod length) but balance may be different due to the smaller pistons. 307s use the plastic timing tab. "Balancer" is just a solid lump. 307s use 1/2" head bolts, so the head bolts and studs do not interchange. If your 307 is a flat tappet motor with A4 intake, that interchanges. Distributor and carb on the 307 are CCC and don't work without the ECU.

69HO43

To expound on what Joe P said- note too that all 307s were hot air chokes intakes and all had EGR ports. But your 85 Y engine comes with an A5 intake, so you probably will need to use the 350 intake for any normal performance. Most 307 intakes are aluminum, but some early ones were cast iron. Not sure when the change occurred. I haven't researched it much at all, but it was early on. I mean, who wants a cast iron intake on a 307 anyway?

Not all 307s use a solid lump for a harmonic balancer. But that 85 VIN Y you have does. All the VIN 9 engines came with "normal" or typical 350-455 balancers, forget the part number, I think it was 417142 but I could be wrong on that. They did have the plastic timing tab. Only the 307 Y engines had a thin "meat slicer" balancer.

1985 was the only year that featured roller AND flat tappet engines for the 307. The VIN 9 engines (442 only) featured a flat tappet cam and the engine was virtually identical to the VIN 9 for 1984. The 1985 VIN Y engine and all subsequent 307s came with roller cams.

Cranks may interchange as was pointed out the same throw and journal size, but the roller engines and non-roller engines have different part numbers for cranks. I do not know the particular difference between the 2 cranks for that. Both have a different part number than a 350 crank as well. The 350 crank is heavier than a 307 crank. And it's a bit more meaty.

Your 85 Y engine and 86-up 307s have floating piston pins while the flat tappet engines have pressed piston pins. They use different part number rods for flat tappet vs roller cammed 307s. Basically, all flat tappet SBO will use the same rod. Again, not real sure of what is different between the pressed and floating pin rods.

The roller engines had what is commonly referred to as peanut ports. Easy to tell, there's an A4 cast on the flat tappet engine intake manifolds, and A5 cast into the roller engine manifolds. The A4's match up better with 350 or 403 heads if you have to use that intake.

Fun fact, ALL VIN 9 engines used the same valve spring, regardless of roller or flat tappet cam. Same valve spring was used in the Diesel 350N in the 80s as well.

At first glance, nobody would know it was a 350 instead of a 307.

69HO43

Note as well, the water pump #556283 for the A/C 307, is listed at 5.95" tall. Casting number 412265

Non-A/C, the pump p/n #231886 and is listed as 5.57" tall. Casting number 413307.

For all the metric stuff on the G-body cars, the 307 engines proper used predominately SAE hardware. So a lot of junk off the 307 bolts up/threads in just like the 350.