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Old 02-24-2003, 09:40 AM
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Post 350/305HO combo?

I have this 89 van with a dead 86 305HO (part of piston gone, water in oil,head not cracked) and I have this 78 350 out of a pickup. 350 runs. I want to go 30 over with 9.0 to 1 pitons, an RV cam and run the 305 heads. Good idea? Some guys here say yep.A guy on a tech line at a parts store said the flex plate won't bolt on and some other stuff won't fit.Is he screwy or what? I have already modified the fuel injection intake to bolt to non injection heads.

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Old 02-24-2003, 10:02 AM
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The 305 heads on the 350 will run alot hotter than 350's. I have seen it done before and there is a big difference but if reliability is the question I would go with the 350 heads. See if you can get a hold of some vortec heads you may get as much power as the 305 heads.
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Old 02-24-2003, 10:34 AM
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Got a big *** rad in it and this 350 came with an oil cooler setup which I am going to run on the van. I was more concerned about spending some deniro on an engine that won't bolt in. Don't vortec heads have a different bolt pattern on the exhaust side?
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Old 02-24-2003, 11:49 AM
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305 heads have 58cc combustion chambers which will raise your compression over 10:1 with flat top pistons which is not a good idea using pump gas. the 305 heads are meant for the smaller 305 bore and don`t line up with a 350`s cylinders so well causeing the quench to be out of whack. use the 350 heads, flat top pistons, and GM head gaskets that are .028 compressed thickness and you should be right at 9:1. vortec heads use a different intake pattern and would require a vortec intake, the exhaust side is the same of a standard sbc.
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Old 02-24-2003, 01:59 PM
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By 10.0 to 1 do you mean with stock pistons? If the chambers don't line up well will you lose a lot of power enuf to make them a bad choice over the 350 heads which are not real performers. I'm just trying to get the most oomph with the parts I have. If I go with the 350 heads, should I get higher comp pistons?
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Old 02-24-2003, 04:13 PM
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The 305 head on a 350 deal was meant to be a cheap way to up the compression of a stock motor that has dished pistons, thick head gaskets, and maybe rebuilder pistons that are way down in cylinder dont try it with flat tops. It will work but like DV said theres better ways to get to 9:1.
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