1978 caddy seville engine mods - Cadillac Forum - Enthusiast forums for Cadillac Owners


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Old 01-13-2017, 11:50 PM
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Default 1978 caddy seville engine mods

i have a clean 1978 cadillac seville and i want to do get more horse power out of engine i am enterested in suggestions on engine modifacations or upgrades car has stock 350 fuel injection would like to create a sleeper open for suggestions
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Old 01-17-2017, 04:53 PM
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Unfortunately the EFI is not mod friendly. It is not reprogrammable and replacement parts are hard to find. It's an Oldsmobile 350 engine. Trying to keep the stock EFI will be tuff. It maybe possible to install a mild cam, aluminum heads, and headers. Headers for a 403 trans am should work. I believe they both used the same front sub frame.
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Old 02-15-2017, 05:56 PM
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hey thanks for the suggestion any suggestions on a mild cam i could use with the efi.
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Old 02-16-2017, 03:03 PM
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You will need to call around I think. You will need good vacuum at idle (above 16" I think). The ECM doesn't use feedback and is very limited. The biggest down side is the MAP sensor is contained within the ECM. It's possible to go to go to a modern stand alone EFI, which could be the best way to go. Of course if you loose the EFI. you could build a W31 350, a stroker, or a even a 403. 403's block is only for moderate hot rodding. GM lightened it which makes for hit and miss durability. A 455 should fit but it will be tight, and require hood scoop most likely.
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Old 08-06-2017, 01:58 PM
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IMHO, upgrading a 1970's engine with an ancient EFI system-well I would go with a slightly used Corvette drivetrain. The LSX series feature all aluminum block, the tranny is probably lighter as well. Good luck
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Old 09-08-2017, 08:05 AM
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My 77 Seville ECM has been changed but fuel injection does not allow engine to run unless fuel is added manuly? all sensors check out fine. I can't find the problem.
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