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Did GM make a 307? and will 305 parts fit?

  • I'm trying to get new headers and exhaust for my 77 Silverado. My first problem is the engine, it works fine but it is a 307, I know my truck came with a factory 305 but it got thrown in there sometime. Problem is that I can't find parts for a 307 that leads me to wonder, did GM make a 307? and also if I were to buy headers for a 305, would they work just as fine on the 307? thanks

  • Answer:

    GM did make a 307ci engine they were in late 60's and early 70's trucks and mucle cars. almost all small block chevy motors will have interchangable parts. Exhaust manifolds/headers off a 305 will fit on a 307.

Michael Ritchie at Yahoo! Answers Visit the source

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Like the other post said - the 307 was the pedestrian level small block in the late 60's/early 70's - the heads are small valve heads, and the head bolt patterns and all are essentially the same - the headers will fit - with one caveat. If the headers require adapter plates to properly bolt the alternator/A/C on, be sure that the heads you have actually have the bolt holes - the older heads sometimes are missing them. If you needed to, you could swap on 305 heads from the late 70's early 80's onto that 307 to get those bolts holes, and you'll likely find the heads dirt cheap. Don't do this if you're looking to build for performance, though, and don't expect a whole lot out of the 307 with the existing heads - its not the most awesome build candidate.

apoorapothecary

what makes you think this engine is a 307?

jesse

they may have or people modified them either way most parts should be interchangeble since they would have most likely would have taken a 305 and bored the cylinders to make a 307

John Wasson

gm did make a 307 for olmobile i believe. the two are not very similar.

mdk68gto, ase certified m tech

Yes chevy made a 307! It was make from 1968 through 1973. It has a 3.875" bore and a 3.250" stroke (bore size of a 283 and stroke lenght of a 327) 1968-71 had 200 HP but was gross rated power. In 72 the std went to NET rated power and figures fell but real HP didnt change, just the way it was measured, so 72/73 307's had 115 HP All std small block chevy parts will interchange with each other. You can use 350, 307, 305, etc intakes, exhaust, carbs, water pumps, etc on each other. So yes just buy a set of headers to fit your 1977 truck with a SBC (small block chevy) engine and it will fit. Oh BTW by the time the 307 came around, all engines had front end drilled acc. holes in heads Hooker and hedman is the two best off the shelf header brands. Use long tube headers to gain more torque. That small engine will like smaller pri. tubes better, like 1.5" tubes and 2.5" colletors. Then run dual 1.75" or dual 2.0" pipes with 2 good flowing mufflers like dynomax super turbos or ultra flows

chevyraceman_383

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