swap 305 heads for 350 heads...????

[1983_JAL]

I've heard that the heads from a 350 will fit a 305 and give you more power. How true is this? I have a carbed 305 in mine and would like to get some heads from Summit to put on. Would everything hook up or would I need special parts? And wait for it..... anyone know roughly how much more power this would add? lol

[cejaay13]

I second this question. Does anyone know? Aside from the L31's

[GRIFF]

It would depend on the head you want to use first off some 350 heads have much larger chambers than the 305 head which would decrease you compression and lose power with the stock pistons. When it comes to street heads bigger isnt always better big valves may not flow more in a 305 as they would in a 350 due to valve shrouding of a smaller bore. I know a few people who have done the opposite of what you are thinking they use a 305 head on a 350 to increase compression 518?? casting 1.84 intake. If you are going aftermarket email the head companys and see what they suggest there are too many variables in this question and not enough enginebuild /use information to get alot of answers. I looked through alot of information on stock heads(alot of the stuffis bogus) and even built a manometer flow benchhttp://i99.photobucket.com/albums/l3...E/heads002.jpg to play around with the ones i have 993, 882, 493, 79 305 heads, and the vortecs overall the vortecs out flow all(the 993s are close) and have a far supperior combustion chamber may not be what you guys what to hear but the vortecs are superior to all factory production iron heads that fit the 1st gen block.

[machineman]

ORIGINAL: 1983_JAL

I've heard that the heads from a 350 will fit a 305 and give you more power. How true is this? I have a carbed 305 in mine and would like to get some heads from Summit to put on. Would everything hook up or would I need special parts? And wait for it..... anyone know roughly how much more power this would add? lol

They will bolt up but be cautious of losing too much compression. Another thing to remember is valve size. For a 3.766 bore, using the 52% intake valve rule on a race engine, the intake valve should be no bigger than 1.96 and I am assuming this is not going to be a maximum effort engine so you really need to watch putting too large of a valve in that bore. Also, the small bore will shroud a big valve and hurt the airflow. If you are trying to make this a fairly hot engine, stay with a 1.94 / 1.50 valve combination. The right cam and intake will really make it come alive. We have some cast iron heads we use in this application and they work quite well.

A side note, the 383 crank in this (with the matching pistons of course) makes 334 inches and it is a real shocker to most people. I have built a lot of them for trucks and street rod guys. The small bore is a little friendlier to pump gas too.