OK, made up my mind. Going to try and rebuild the stock 305 in my 79MC. Plans are Federal Mogul rebuild kit w/ flat top pistons, Edlebrock 2101 intake with stock rebuilt 4 barell, stock 350 cam (or similar), and Hedman street header. stock rebuild on heads with mild port matching. Want to keep good torque for low rpm cruising. First order will be taking it to a machine shop for cleaning/checking to see how much bore it will need, etc. Anyone else rebuilt or upgraded the 305 in their MC? Again, made up my mind on the 305, so please no "just drop a 350 in it". Dont have the money to drop on another motor right now, but i can buy parts and get work done piece by piece on the motor i have. Plus, it will never see the drag strip, just want a clean cruiser. Thanks.
Keeping it stock...305 options
- Thread starter jmangham
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sorry just the machine shop bill will cover replacing the 305 with a larger SBC. If you can't find a rebuildible 350 core for under $100. something's wrong. Money spent trying to better a 305 is money better spent on more cubes. Atleast you aren't spending Olds money lol.
IIRC the only difference in the parts will be the pistons and rings due to the different bore, i think the stroke is the same. and the heads are different of course. so not to ignore you or beat it to death, a 350 is usually about $50-75. why not? actually, you might save some money since the few 350 specific parts are more common than for a 305--stock and performance.
305's have been built to 350-400hp, but it took ALOT of work. a stock and junkyard parts 350 will get that same power and be completely driveable, streetable, possibly fuel efficient, and reliable--all more so than the 305.
again, sorry to beat you with the 350 stick but...
305's have been built to 350-400hp, but it took ALOT of work. a stock and junkyard parts 350 will get that same power and be completely driveable, streetable, possibly fuel efficient, and reliable--all more so than the 305.
again, sorry to beat you with the 350 stick but...
Yanno, it does say something when an Olds guy suggests swapping a Chevy 350. lol ... but seriously I think an Olds 307 is a better performance choice than a 305 and I wouldn't blow the cash on it either. Think of it this way ... your goal is something in the 350 horse range .... dollar for dollar it costs less to build a 1hp/1CID engine than to try and get 1.1 hp/1 CID out of anything ... remember all things equal it takes a more radical small engine to make the same power as a mild larger engine
I hate to agree with the 350 stick. I was in your same exact position with my my 80 malibu since the bu and MC are almost the same. It was completely stock when I got her (not anymore) and had the origional 305. I spent so much time doing stupid stuff like chucking the emissions (which is a pain in the arse) and trying multiple things to get decent power. The only good thing I can say about the 305 is that with the right heads they can make some good compression numbers.
I sat down for countless nights comparing the numbers on the builds for a 305 and a 350 and the 350 is cheaper and easier to find parts. So I went and traded a junkyard guy my 305 for a 350 out of an 82' silverado, only reason I did was because the motor was so sludged up and the valves had sludge built up to the middle of the rockers. All in all, building a nice hot rodded and streetable 350 with mainly summit cam, parts, and freebies cost me under 1000$. If your not the origional owner of your MC, then machine work may be a bit since most people beat the living hell out of the 305's.
Just my two cents. Now since you sound pretty dead set on building this 305 (please ignore the Olds guy lol) I'll talk about that. As far as the cam, get a summit cam which costs around 50$ for just the cam or 90$ with lifters. They're great cruising torque cams and are very reliable. DO NOT use a stock cam out of a 350 junker, your asking for trouble. Next to tackle is the compression since the 305 is the smog motor. Shave the stock heads to raise your compression numbers because your not gonna have a nice cruiser with really low compression (unless you got a blower or supercharger). A good number to aim for is 9 to 9.5 to 1. Of course put in flat top pistons which will definately help with compression. Hedman's are good headers and the intake is good as well, I use the same one.
Here's a motor for under a 1000$ that's 4 years old now:
I sat down for countless nights comparing the numbers on the builds for a 305 and a 350 and the 350 is cheaper and easier to find parts. So I went and traded a junkyard guy my 305 for a 350 out of an 82' silverado, only reason I did was because the motor was so sludged up and the valves had sludge built up to the middle of the rockers. All in all, building a nice hot rodded and streetable 350 with mainly summit cam, parts, and freebies cost me under 1000$. If your not the origional owner of your MC, then machine work may be a bit since most people beat the living hell out of the 305's.
Just my two cents. Now since you sound pretty dead set on building this 305 (please ignore the Olds guy lol) I'll talk about that. As far as the cam, get a summit cam which costs around 50$ for just the cam or 90$ with lifters. They're great cruising torque cams and are very reliable. DO NOT use a stock cam out of a 350 junker, your asking for trouble. Next to tackle is the compression since the 305 is the smog motor. Shave the stock heads to raise your compression numbers because your not gonna have a nice cruiser with really low compression (unless you got a blower or supercharger). A good number to aim for is 9 to 9.5 to 1. Of course put in flat top pistons which will definately help with compression. Hedman's are good headers and the intake is good as well, I use the same one.
Here's a motor for under a 1000$ that's 4 years old now:
While I 100% totally agree with the "start with a 350" guys, here's my 2 cents if you absolutely, positively have to have a 305. Unless you need to overbore, stay with the stock pistons. Spend your money on a decent set of 96-up 305 vortec heads. Same gains as the popular 350 vortecs, but made for the smaller bore, and they're worth a lot less on the used parts market. A budget RV cam with advertised duration of about 250 degrees and lift in the .430-.450 area will do a lot better than the stock #929 350 cam with .390 and .414 lift, without sacrificing low end torque.
I did this deal about 20 years ago on a '78 305 in my Century Sport Coupe. I can tell you from firsthand experience that the 350 cam definitely extends the power range of a 350, but one look at the ugly ports of the stock 305 heads and I knew I was going down the wrong road. Eventually, I was able to sell my 305, and I used the funds to buy a low mileage, rusted out Impala with a 400. After swapping the dead-stock 400 in my Buick, one trip around the block was enough to remind me that there's no cheap substitute for cubic inches.
Bill
I did this deal about 20 years ago on a '78 305 in my Century Sport Coupe. I can tell you from firsthand experience that the 350 cam definitely extends the power range of a 350, but one look at the ugly ports of the stock 305 heads and I knew I was going down the wrong road. Eventually, I was able to sell my 305, and I used the funds to buy a low mileage, rusted out Impala with a 400. After swapping the dead-stock 400 in my Buick, one trip around the block was enough to remind me that there's no cheap substitute for cubic inches.
Bill
The key is in your statement right there; if you don't intend to race it, then why go through the trouble of a 350? If performance is the goal, then yes, a 350 is a better choice. A daily driver/weekend cruiser? eh, maybe, but why buy a junkyard engine that will probably need to be gone through anyway, and when it's all said and done, have worse fuel mileage?
I love the 350, but for what you're building, I have to vote 305. But yeah, anyway...
What are the casting #'s on your heads? 416's and I think 801's are the best to start out with; do a little cleaning up (casting flash and all that mess, easy to do on your own), some quality valve springs, and go with the type of cam billyjack recommended. This should put you in the ballpark for a decent performing 305.
Assuming condition of the blocks is the same .... the machine work on a 305 and the machine work on a 350 would be the exact same .... is why! Heck I'd be willing to bet, you can take the average seasonned 350 ... not have it tanked, bored or reemed ... just re-ring it, stick in a cam and make more power than you would with 5 grand worth of machine receipts on a 305! If a mesely $100. can net you an extra 45 cubic inches .... that maybe the single best return for dollar in a build! Many magazines with seemingly unlimited budgets and people just willing to throw freebies at them, have done a performance 305 build and I suggest you look for these back issues .... I've noticed one thing they have ALL had in common - the writer tells you, you are better off applying everything they did to a larger engine. Best results I have seen from 305s are the same results I've seen from "mild" or "budget" 350 builds. If you are doing it to just be different - convert your Monte to an Oldsmobile!
and i've never met a person who did minor mods to an engine, than didn't want more power. it also depends on your definition of cruiser.
very true, if some performance wasn't expected. This would be a discussion of where to buy gaskets, rings and bearings! Forget about machining and cams. Way I see it, engine has to come out to have machine work done. So it's no more work to switch from a 305 to a 350. We've already talked about costs vs gains. If it's still running fine ... DRIVE IT!!!!
Buy a 350 and get everything ready to swap in. You mentioned good low-end torque and frankly that just won't happen with a 305 (this is why I said I'd prefer a 307 over a 305). 305 is frankly a performance turd ... best flushed.
Buy a 350 and get everything ready to swap in. You mentioned good low-end torque and frankly that just won't happen with a 305 (this is why I said I'd prefer a 307 over a 305). 305 is frankly a performance turd ... best flushed.
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