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Can you use Oldsmobile 307 5A heads on a Oldsmobile 403?
YES, the 5A heads FROM A 307 can be installed on a 403. The307 heads are a BETERR choice than the 67 to 72 Olds 350 heads. The 307 heads have similar sized intake & exhaust ports to the stock 403 heads. The 307 heads have a much smaller combustions chamber at arounf 67cc. This alone will raise compression to around 9.5:1. The only down side is the 307 heads have much smaller valves. You really must get larger valves installed into the 307 heads. The stock 403 valves will fit with some machining (of course) and you'll have a high compression 403. Get some port work done while you are at it & a little polishing too. Buy a new intake & have it machine & port matched to the intake & a middle of the road Lunati cam. This will result in a 403 producing around 330 HP. I know it works because this is exactly what I did. Enjoy your Olds, Mark
Will headers for a 403 Olds fit on a 455 Olds?
No, the blocks are different.
What cylinder heads will fit a 2003 olds silhouette?
what heads will fit on my 2000 olds silhouette v6 3.4
Could a 350 Olds exhsaust manifold fit on an Olds 403 motor?
yes i think so
Will double hump heads fit on a 307?
YES NO problems
Will 403 olds engine mounts fit a 350 olds?
The blocks were physically the same size so I don't see why not.
Will Chevy 307 heads fit on a Chevy 305?
Yes, they will fit on the block. The larger combustion chambers of the 307 heads will probably reduce the compression ratio by a fair amount, reducing power output.
Will a Chevy 350 turbo transmission fit a Pontiac 307 engine?
Pontiac didn't make a 307. If it's an Olds 307, you need an adapter or a BOP transmission.
Will 350 exhaust headers fit on a 403 olds?
There were both small blocks and I'm going to say, yes.
Will 350 vortec heads fit on a 307 block?
Yes they will. The bore is 3.785 so they wont hit
Will Chevy 305 heads fit on a Chevy 307?
Yes they will, but 305 heads have a smaller combustion chamber so it may raise your compression ratio.
Will parts from a 305 motor fit on a 307 motor?
no I respectfully disagree. I am running 305 Chevy TBI heads on my 1971 Chevy 307 and all is very well.
