87suberb
Registered Member
hi i was wondering if i could put a 350 cam in a 305 motor
CK5
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engine question
- Thread starter 87suberb
- Start date
All SBC cams from 1955-1995 are all interchangeable as long as they are both flat tappet cams and not a factory hydraulic roller cam. The specs are the only thing that change between different years and models of vehicles.
WannabeRacing
Registered Member
Yup, swap it in.
87suberb
Registered Member
so if i do this i can use 305 heads or do i have to put 350 heads on it
305 heads on a 350 chokes the power and raises compression considerably to the point of needing premium or better fuel. 350 heads on a 305 can't be done if the heads have the 1.94" intake valves as they will hit the cylinder walls of the small 305 bore.
Going with 305 heads would rais your compresion ratio some but where you cut your ownt throat is on the intake and exhaust ports they are smaller and any advantage you gained with the cam you will mostly loose bu choaking and starving the engine.find you a good set of used 350 heads and put half gaskets on them. this will allow the engine to breath and give you a lil bit of higher compression ratio. remember restricting the exhaust too much will cause fouled plugs and a higher posability od detonation. 
WannabeRacing
Registered Member
There is NO difference between a 305 and an early 350. NONE. The heads interchange, the intakes, the cams, blocks, and the list goes on. Same idea as a the 427 and the 454. The size of the stroke of the crank does not change any of the other components. But don't think that a cam swap is going to make a huge difference.
You better go do a lot of research my friend. 305 heads are 58cc heads with 1.72" intake valves and 350 heads are 76cc heads and came with either 1.72", 1.84", or 1.94" intake valves.
Oh, if there wasn't a difference how do you think there were different size engines?
In order to run the 350 heads on the 305 you have to relieve the top of the cylinders to keep the valves from hitting. The bore on the 305 is too small for 350 headsFind a set of 305 or 307 heads they are plentiful and not too expensive. Although There were some 350 heads with small valves, but at 76cc, your compression would be very low. It's best to stick with the smaller chamber 305 heads. hope this better answers your questions
4xcrazy
3/4 ton status
i'm running 305 heads on the 355 in my dually, it runs and drives fine on regular (87 octane) fuel, i'm not into it for high performance though, it doesn't ping, has RV cam in it, Weiend intake, Edelbrock carb and headers.
again it's not a racing engine, basically stuff i had to get the motor running and it's doing just that purpose and really isn't all that bad of getting out of it's own way.
if it's what ya have, and you need it running, use it until you get everything else lined up to redo it again later the wya you really want it.
hell mine is someday getting fuel injection on it, i hate doing things multiple times, but again, it NEEDED to be running, and it is, providing me with transportation while the Burb keeps eating up shotty rebuilt transmissions
again it's not a racing engine, basically stuff i had to get the motor running and it's doing just that purpose and really isn't all that bad of getting out of it's own way.
if it's what ya have, and you need it running, use it until you get everything else lined up to redo it again later the wya you really want it.
hell mine is someday getting fuel injection on it, i hate doing things multiple times, but again, it NEEDED to be running, and it is, providing me with transportation while the Burb keeps eating up shotty rebuilt transmissions
WannabeRacing
Registered Member
I should have preferenced my post a little better. I was leaning it tward his question regarding head changes because of a cam change. I guess I will be a little more careful next time.
No. You do not need to change heads because of a cam change. Just because it is a cam profile that came in a 350 does not require a casting that came on a 350 engine. A cam is a cam and only tells the valve when and how much to open. If your engine is working fine, just swap the cam and lifters.
I have about a dozen sets of heads around here from GM that came or were designed for 350s. The combustion chambers range from 48cc to 76cc. The intake runners currently sit anywhere from 170cc to 284cc, and intake valves from 2.02 to 2.17. There are so many castings that I can't keep track without books to tell me. As long as you don't have so small of a bore that the intake valve crashes the block, the heads don't know or don't care what cubic inch is underneath them. 3" stroke or a 4" stroke. It does not know. 4.00 bore or a 4.185 bore. Just as long as you have pisont to valve clearance.
Let me see. What heads came equipped from the factory on 305's off of the top of my head? There was the tripple nickel (14020555), the 81's the 87's, the 801's were equipped there for a short time. The 415's, the 416's, the 440's, the 520's were very common for a while, the 59's were probably the best of the heads GM put on the 305's, and as a side note, really work well with 390+ cubic inches. Then the 201's snuck on for a very little while, although I have never personally seen one. I can't really remember some of the early ones. Like I said, I need books for this. And they are all at the shop.
So I guess what I am trying to say is that there is not a 350 head. Just casting numbers GM put on the 350. There is not a 305 head, just what GM commonly put on them. Many of these casting numbers were actually installed on both engines.
But back to the question, a cam that came out of a 350, or designed for a 350 does not require heads that came on a 350 from the factory. Just swap the cam and go.
No. You do not need to change heads because of a cam change. Just because it is a cam profile that came in a 350 does not require a casting that came on a 350 engine. A cam is a cam and only tells the valve when and how much to open. If your engine is working fine, just swap the cam and lifters.
I have about a dozen sets of heads around here from GM that came or were designed for 350s. The combustion chambers range from 48cc to 76cc. The intake runners currently sit anywhere from 170cc to 284cc, and intake valves from 2.02 to 2.17. There are so many castings that I can't keep track without books to tell me. As long as you don't have so small of a bore that the intake valve crashes the block, the heads don't know or don't care what cubic inch is underneath them. 3" stroke or a 4" stroke. It does not know. 4.00 bore or a 4.185 bore. Just as long as you have pisont to valve clearance.
Let me see. What heads came equipped from the factory on 305's off of the top of my head? There was the tripple nickel (14020555), the 81's the 87's, the 801's were equipped there for a short time. The 415's, the 416's, the 440's, the 520's were very common for a while, the 59's were probably the best of the heads GM put on the 305's, and as a side note, really work well with 390+ cubic inches. Then the 201's snuck on for a very little while, although I have never personally seen one. I can't really remember some of the early ones. Like I said, I need books for this. And they are all at the shop.
So I guess what I am trying to say is that there is not a 350 head. Just casting numbers GM put on the 350. There is not a 305 head, just what GM commonly put on them. Many of these casting numbers were actually installed on both engines.
But back to the question, a cam that came out of a 350, or designed for a 350 does not require heads that came on a 350 from the factory. Just swap the cam and go.
87suberb
Registered Member
ok thanks i was just wondering cuase i have a 305 motor but no cam and my 350 motor had a cam in it and its just going in the 305 till i can get the 400 sbc built
pauly383
Daddy383
Probably the best factory cam for a 305 is the grind they stuck in the 9.2 to 1 compression truck motors , those rigs moved ok for a 5000 pound brick
A 350 cam would work fine too , may change the motors characteristics though . If I had to use a 350 cam , I would rather run the TBI cam , its actually a pretty good cam when running a carb .
A 350 cam would work fine too , may change the motors characteristics though . If I had to use a 350 cam , I would rather run the TBI cam , its actually a pretty good cam when running a carb .
WannabeRacing
Registered Member
Just use what you've got. It will work fine. (And it will same money over buying new.) It won't be optimum. But that is what planning and building the 400 is for.
