What's the weakest point, in an 87 305? The manual says it has PM rods, so I'm assuming they're fairly decent.. the pistons are lighter due to the small bore, so is it the crank? I'm assuming so since it's cast iron..

 

your almost right its the pistons the crank is good to 500hp if done right the rods are the same its the cast pistons that are the problem

 

Thanks for the response, at what RPM, assuming NA? I'm thinking of rebuilding, porting, and putting larger 1.94 valves on my 081s or getting 305 vortecs with 1.94s. Would 325 horses be unreasonable by 5500 RPM? I'm thinking that should be about right and allow me to keep my 2.73s without being too much of a dog, though I may need a wider LSA and just touch 300 hp?

 

yes you can do that with out the need for expensive parts with 1.94/ 1.50 valves even in the smaller bore 305's and below the 5500 rpm you want it takes some creative thinking and cam spec's that I cant get into tonight but let me run some ideas and get back to you in the morning

 

Awesome, thanks man. I'm running 081s, unworked. I saw that they flow 195 @ .5, should be able to get close to unworked 350 vortecs out of them with porting and valves I believe.

 

you arent going to get that close to vortecs by any means the 350's had 165cc intakes its too much money to open those up but whats your budget on heads?

 

I'm pretty limited, no set $ but I can't go out and buy top notch heads or I'd go buy a crate 355. I'd like to keep my 081s but don't know if they'll flow well enough. I know vortecs are the best buy, but that's a minimum of $600 plus whatever to get them cleaned up, new springs, etc.. puts me at $1000 or so. I'd really like to stay under $1000.

 

you can get a set of bare vortec heads new off ebay for about $200, thats what I did. You would need center bolt valve covers and have them angle milled to get back to a 58cc chamber, but they come with a 3 angle valve job and are set up for 1.94/1.50 and a 6 bolt intake pattern so no need to buy a expensive vortec intake.
as far as the cam goes looks like the best choice for your power goal is a comp cams part number 12-209-2 275DEH it has a duration of 219/229 at .050 and .462/.482 with 1.5 rockers and should work with the stock converter. the power peak would be at about 5500 and torque would max at about 4000 hope this helps

 

Back to your rotating assembly question. Stock, the biggest limitation is the bolts that hold everything together. Rod bolts go before anything else and allow the bearings to spin. On a stock bottom end, anything more than 5500 rpms is pushing your luck.

Also, I'm not sure you have powder metal rods. I didn't think they came out until the time of the LT1.

Your crank should be fine for 500 hp and about 5500 rpms.

Discussion about the LO3 shortblock.