Thread: 305 parts on a 350

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I have an early 80's 305 with a cracked block and am wanting to build up my 350. Will the whole rotating assembly work on a 350? What parts are interchangeable? Heads? Thanks

It all interchanges ,except the pistons.305 has a smaller bore.....

heads will change your compression ratio, but they will bolt right on.

Originally Posted by firebird77clone

heads will change your compression ratio, but they will bolt right on.

more power is always better

Hey Face, sounds like Tim Allen......."More Power" arrgghhh arrghhhh! LOL

What will it do to the compression ratio? Would it increase it? The 350 has been bored .30" over. I am hoping to achieve close to 300 hp with the 305 crank, decent pistons and cam, and a Torker intake that I already have and a little work on the 305 heads, do you think this could be attained?

Comp ratio will definitely increase. Careful with going too big on valves. Combustion chambers will shroud the intake and flow will be affected. Which cam have you chosen?

Haven't chosen a cam yet. Something that will fit my budget, you know cheap! But not too cheap

Daily driver I assume. Keep the advertised duration under 280 (even a bit lower). Don't short cut valve springs and machine work. You'll produce a good street thumper to give you a good ride. Most cam combos are affordable for this set up.

I was told by a builder that 305's are balanced differently, the crank will need rebalancing to work in a 350. ??

305 crankshafts share the same casting number as 350 but are balanced differently. Yes, get the assembly balanced for your set up. You'll get a much better system and it's free horsepower as the assembly runs.

Sounds great. Does anyone recommend a certain type of piston? And what size valves do you think I should use in the stock heads? How do I know if I use 1.5 or 1.6:1 rockers?

I love the best piston you can afford, I love aluminum rods......etc, etc. For the street you can use what ever you can get the best deal on. Until you get some longtime experience built up, I always recommend 1.5 rockers. It's not prone to give you geometry problems and really helps you just keep the thing running smoothly while you get a feel for your application. As for now stick with your idea and tune and adjust for your best running combo. As you get more and more into what you want to change, do it one step at a time and slowly.

P.S. the HO 305 of the early 80's had an option of 1.91 intake valves. Very hard to get OEM but aftermarket can supply them. I don't think you need to go there yet. Factory 4bbl intakes were 1.88. Sufficient for street use on the combustion chambers you have. I would however recommend stepping up to a larger exh valve. Probably a 1.6. It will help enough to give you a good feel for what you want.

have you tried any engle cams?