I might have found a real steal on a rebuilt 350 short block, and I was wondering if I could use the heads off my current 305 on a 350. I know they will bolt right on, but will I need to make and mods internally, valvetrain, etc. Will this cause running issues? I want a simple 'plug and play' operation with minimum complications.

 

well they will bolt on with no problem but it will cut down the hp the valves an intake ports are smaller than the 350's

 

So to keep it simple I should just find a set of rebuilt 350 heads. Next question. Can I use oversize rockers on a stock setup w/o probs?

 

if you are comparing stock 305 heads and stock 350 heads you will turn more horsepower with the 305 heads due to the smaller combustion chamber and higher compression. alot of restricted racers run 305 heads on a 350 because of that fact. 305 heads can also be pocket ported and oversized to 1.94. this combination will definately out perform stock 350 heads. only thing you need to be aware of is the heads that were used for TBI engines do not flow as well as 305HO heads or 305 TPI heads. Sick

 

Yo Sick, is there ANYTHING you dont know about these cars? Damn man, you are good...

Seriously, you spoke about the TBI heads. My car was originally Crossfire. Will this be an issue? And, you mentioned pocket porting. I dont want to do any machine work other than bringing them in for a 'freshing up'. Will these things just bolt on to a stock 350 and not cause any probs? An engine swap will be a MAJOR undertaking for me and I HAVE to get it right the first time. I mean, why isnt everyone running 305 heads if they produce such better numbers?

 

they will fit like a glove. the TBI heads if i'm not mistaken where designed for swirled intake runners and they don't flow as well as the 305HO heads which were used with 4 barrel carbs and TPI engines but, they will work fine in a street ride. the only possible problem you may run into is having to run premium fuel. with the higher compression you may have some pinging issues running regular gas. the reason alot people don't use 305 heads is the combustion chamber is so small the biggest valves you can run in them is 1.94 compared to 2.02 in 350 heads. Sick

 

Premium fuel is no big deal. This car wil be driven 2, 3 days a weeks, 30 miles round trip maybe a few trips around town here and there. I FINALLY have a job where I can afford a little more gas...

Again, I dont get why more people dont run 305 heads. Do I understand correctly that a 305 head will...

Produce more power in its 'stock' state than a 350 head, BUT,

Cannot, for all real purposes, be modified to the extent that a 350 head can?

 

exactly. 350 heads can be greater modified than 305. unless your brother or dad is a machinist and has the tools to do it. 305 heads could be made to modify the same as a 350 head but, it would cost a fortune. there is a misconception about 305 heads that because of the slightly smaller intake runners and valves that they can't produce as much horsepower as 350 heads. that just plainly isn't true. what actually happens is you wind up with more horsepower because of the higher compression and and the slightly smaller runners and valves translates into a higher air/fuel velocity which will make a torque monster out of a stock 350. there is no theory behind any of this check the numbers and you will see that it is true. this subject has been argued for as long as they have been making 305's. personally i'm a 305 man so my opinon may be slightly bias. Sick

 

Sick, I have a 305 HO z28 and I'm looking to put more horse power to her. Am I better off getting a 350 block and performing a swap like you guys are talking about here. It seems that would be cheaper way to go then buying a high performance engine. (sorry to steal the forum guys)

 

depends on how much your wanting to spend and how much HP your looking for. for about a thousand bucks you could put a 100 or so extra HP in your 305. but thats about as far as you can go without MAJOR money. that $1000 would include, 4/7 swap "golly whopper" cam, headers, intake, carb, and distributor. you would wind up with something just a tad better than a stock 350. the only problem i see about the block building thingy is theres alot of hidden cost that your not accounting for. so much so that you would wind up spending as much as you could get a decent crate engine for. i was looking on ebay and i seen some crate 375 HP 350's selling for $1300 or so. if it was me and i had the $1300 to spend. i would most definately invest my money in a crate than shoving it down the throat of a 305. they are money pits. i'm getting ready to tear mine apart again. going to put in a forged 400 crank, forged pistons, forged rods and maybe a 4/7 swap cam. another $1000 or so bucks plus machining but, i've done come too far to turn back now. Sick