305 heads on a 350?

[81ratrodc10]

i read some were that you can put 305 heads on a 350 for better compresion is this true or posable

[3r!c84]

high compression/bad flow,small valves

[81ratrodc10]

i didnt know the reson for this but thought i would ask why would you want to do this

[3r!c84]

high compression means more hp. it can bring more fuel and air in and push more out. but with the smaller valves and bad flow it kinda defeats the purpose

[81ratrodc10]

i thought it would doesnt make sense to me thanx again for your help

[3r!c84]

lol yourwelcome.but im probly not 100% right.some one else will chime in

[81ratrodc10]

doesnt matter not doing it just wondering on something i read some were

[bitchin85]

i got 305 heads on my truck and they suck.. i pretty much have to run at least mid grade cuz it runs like crap on 87 and it doesnt go anywhere fast.. good thing i have a set of fresh vortec heads and a new cam and intake waiting in line to go in

[81ratrodc10]

i didnt think it would be a good idea but im no motor builder

[USSkoval]

I have a Camaro that had a 350 with 305 heads when I bought it. It did pretty well and got fantastic mileage, but it had the larger 1.84 valves and they were also ported. It felt like a VERY strong stock motor, which is what I was told it was when I bought it. I was surprised when I tore down that "rebuilt 305", lol.

With that said, that motor now has edelbrock heads and a few other things, and it has MUCH more power.

[qu1cks1lver56]

305 heads have small combustion chambers and do build some more compression, but they flow terribly, they have to have some major work done to get them to flow good. just stick with some 350 heads and have them cut a little to build compression.

[68longhorn]

not worth it, like said above, they flow horribly. If you want a cheap head that actually makes power look into vortec heads.

[slugish]

The person that built my 400 ( BUILDER FOR 40 YRS PLUS ) tOLD ME & I SAW SOME VIDEOS of some of his old school drag cars . One Corvette ( record holder at that time in his class ) had a 350 with 305 heads . But like the other posts have said ,it takes a lot of head work to get the flow you need to utilize the increased compression . If you know what you are doing it can be very effective , but just slapping some 305 heads on a 350 or 400 without doing much else wont do you any good .

[qu1cks1lver56]

Thats about the only people that use them is the dragster people. But for a daily driver/street machine the work that it takes to make them worth while isn't worth it.

[Jim85IROC]

This wasn't a bad idea back in the 70s when ALL The heads were garbage, including the 350 heads. They all flowed bad, so you might as well get the compression bump.

But in any other case, the added compression is more than offset by the choked airflow, and with the vast amount of dirt cheap modern 350 heads out there for virtually nothing, I can't see any situation where 305 heads would be a smart choice.

[knightowl73]

yes and to my understanding the vortecs are the much better choice for an upgrade.....but if you paln on runniing a high-lift cam then they can get pretty expensive too. if you are trying to stay with a somewhat small lift cam your in the good, but anything big and its back to spending some major cash again. i considered them a few times, but the price of the head work involved to run the cam i was going for just didnt make sense in my "budget" build.

[Mattsch18]

so i just found out i have 305's but im hoping my motor is auctually a 350 not a 305 so i guess ill jsut have to wait and see but in my openion there worthless

[USSkoval]

Originally Posted by Mattsch18

so i just found out i have 305's but im hoping my motor is auctually a 350 not a 305 so i guess ill jsut have to wait and see but in my openion there worthless

Depending on the casting #, they really aren't worthless. If they've been worked on, they are nice on a mild little street motor.

[Mattsch18]

well lol here you go i just got casting numbers for ya! lol 376450

[USSkoval]

I have a set of those, IIRC, they are the ported ones. Apparently there are some roundy round guys that like to run them because they are legal to use in their class. I will be using mine again, but only because I have them, and I'm building a Camaro on the cheap, with parts I have laying around.

[bitchin85]

Originally Posted by Mattsch18

well lol here you go i just got casting numbers for ya! lol 376450

did a little research on these.. 60cc chambers.. flow very badly and have tiny valves.. recomended running them on like 93 octane fuel.. with a super high compression ratio engine (depending what pistons you have), its not gonna have much power or rev real high when they flow that bad.. i have the same problem as you.. which is why im gathering parts for a vortec swap

[Mattsch18]

well thanks for doing some research on my behalf! why the hell would someone sawp those heads for stock 350 heads?

[bitchin85]

Originally Posted by Mattsch18

well thanks for doing some research on my behalf! why the hell would someone sawp those heads for stock 350 heads?

probly did the same think my PO did.. rebuilt the motor and had them laying around and they were nicer then the ones that came off it so they tossed em on and sold it.. again,why i got vortecs lol i figure its time i do it right.. i beat the hell outa my truck, i think its time i give back to her a little and let her breathe a little better

[USSkoval]

Originally Posted by Mattsch18

well thanks for doing some research on my behalf! why the hell would someone sawp those heads for stock 350 heads?

Climb in your engine compartment with a rag and a flashlight, then look for the block casting number on the rear bellhousing area. You may have a 305 block to go right along with those heads. Hopefully not, but you will want to check.

[Mattsch18]

kk so not to thread jack the casting numbers are 10066036 which i guess is some kinda crate motor that is a 350?!