The Stovebolt Site Forums The Shop Area The HiPo Shop 305 vs 350 Help?!?!

Hey guys and gals,
I pulled my 250 out of my project truck to put in my dads fishing boat. I got a 77 Chev 4x4 for the axles and the 350, that wasn't running. I pulled the 350 today, and found 2 broken rods, a trashed crank and pan. But the cylinders look ok, the heads look good. It has never been rebuilt, and other than some chips out of the lower skirts of the two cylinders, everything looks ok.
My dad has a 305 long-block that is supposed to be ok. Can I use the 305 Crank inthe 350 block? Or would it be easier to rebuild the lower end on the 305 and put the 350 heads and accessories on the 305?
I am new to the Chev small block. My wrech turning has mostly been on SBF, Chev inline 6's, and Datsun OHV 4 cylinders...
Thanks in advance, Garry K in Port Orchard, WA

Yes, as far as I know, you can put the 305 crank in the 350. They've got the same stroke. And I believe the journal size in both is the same. But no, you can't put the 350 heads on the 305, without drastically reducing the already low compression of the 305.

If your cylinders are okay, you got lucky. Check the bottom of the skirts carefully to make sure nothing broke through to the water jacket. Even if some compromise there is found, you can have it welded. Yes, iron blocks can be welded.

I'd upgrade the rods though. 305 rods aren't known for their strength. You can get Eagle forged 5140 rods for just a few hundred bucks, and they're far superior to stock cast rods. Then use that crank in the 350 after your machinist checks both out.
Also, plan on overbored pistons. Just to clean up the bores it might be necessary.

Stock 350 heads are fine, but 305 heads would raise the 350's compression too high. So either have a valve job done on the 350 factory heads, or put your money into a vastly superior set of $499 Vortec heads...which will also mean a different intake, but they're worth every penny.

P.S. You'd be disappointed with the 305. Not very strong. You could build a stovebolt straight six more powerful than a 305. But a 350 is a different story. VERY powerful. That's a good compromise between power and streetability.

Thanks, I'll be pulling the 305 apart in the next few days, and checking it out. Then start looking for a reasonable machine shop to take care of the block, crank and heads. Unfortunately this is a project truck, so cost is everything, and the cheaper the better, but I want to only do it once. So I'll look into some rods, but may have to live with the 350 rods. This will be a basic stock 350 rebuild, with maybe a RV cam, and a 4bbl intake. With the SM-435, and rockwell from the 68 K20 and the Dana 44 and 12bolt from the 77 K-10, all under the body of a 1964 Datsun pick-up, I should be able to go just about any where and still get reasonable mileage with my 35x12.50x15's.
Thanks again, Garry K

Say, come to think of it, my machinist showed me a very nice mid-90's LT1 350 engine that he totally rebuilt for a guy and got stood up. It's the completely assembled short block, and it's up for sale for only $1000. E-mail me if you want the details. You can't build a 350 that cheap.

Garry before you go and spend money on a 350 rebuild check on a new 350 crate from GM. If you give them the Vin # off the 77 the will give you a warranty for 24,000 2 years. You cant rebuild some of these 350s for what you can buy brandnew. Last i bought was 1275. out the door and in the truck the next day. Its a long block with heads. They get 15-20 mpg depending on gears and weight.
305 heads are a little trick we do around hear to boost comp and they dont work out all that bad if your not turning over 4500 rpms as they fall on there face after that with out mods.

Thanks for all the input. I may have to look into the Crate motors, as I do not know yet the cost of machine work. I have a friend that does machine work, so may be able to do some swaps to get it done low-budget, but right now I dont have a grand to drop on this project...... Wish I did. I am still building the chassis and getting ready to prep the body for install on the chassis, so maybe by the time I get all that done I may have the $1000 or so for the Crate saved up.
DJ, I don't plan on going over 4500rpm. This will be a daily driver, capable of going off-road when-ever I like, but primarily for 4x4 in snow in the winter.
I was actually hoping that either the 305 or the 350 was in good enough shape that I could just go for a hone job, rings bearings, cam and maybe a valve job, and not have to do all the really expensive machine work. If the 305 is not too bad, I may do that to the 305, and save the 350 for making it a 383 later, as I will be needing a crank anyway...
All your inputs are greatly appreciated. I have read a fair bit over the 22+ years I have been restoring and working on old cars, so 350's are not foregn to me, just the fact I have never re-done one, I could usee all theinput I can get!
THANKS Again to all!
Garry K, Port Orchard, WA

I agree with DJ on the crate engine. Great package. If you could of just done a simple ring-valve job it would have been different. I,ve used many of them & have had good results. I,m going to put one in my 70 stepside as soon as I finish my 55. They have a new one out that has a little more horsepower for alittle more money. I think the difference is in the cam. If I was using a manual trans. I would go for it.

Garry K have you identified a machine shop? I'm not far away, and would appreciate knowing what you find.

There is one in Kingston I've heard is good, but I'd like to find one in Bremerton, Silverdale, Poulsbo area (I work in Poulsbo).

You'll spend $1200 in parts alone, if you do it right.

I'd go crate.

I would just put the 305 in it until you have the cash for a crate engine or a rebuild. You said the 305 long-block is okay. Just put a carb and accessories on it and go.

Phil

I need to open up the 305 and check it out, as the info that it is good is third hand info. If it works out ok, I will do the 305 to get the truck under it's own power, then save up for a crate I think. But may have to still do the heads on the 305.
By the way, I ended up with a Carter AFB but it is a Spread-bore, so it will not fit the stock chevy 4bbl intake. Anyone know of a good intake that will fit the spread bore, or an adapter to fit the spreadbore to the chevy intake?
Thanks again for all the help.
Old Sub,
You don't happen to have a spare left front fender in great shape do you? Mine got a bit of a dent in it. Nothing I cant straighten, but would be nice to just swap and paint, vice all the body work on mine... And I'll let you know about a machine shop. A friend has a lot of equipment to do some stuff, but My friend that works at the Poulsbo Ford dealer in Parts and Repair, says that it is better to send your stuff to Tacoma, as it is much cheaper and alot faster.
Thanks again,
Garry K in Port Orchard, WA

Might have a spreadbore intake. A dual plane of course. Let me check and get back to you.

Yes, the 305 will work out fine for the time being. When you pull it apart, look the bores over carefully for scoring or a ridge at the top of the ring travel, about a quarter of an inch below the deck. If the bores are clean, and if they still show the original hone pattern, you may luck out and just be able to buy rings, bearings and seals, and have a machinist hone it up for you.

If you do that, have the machinist check the crank to see how it's wearing! If need be, he can take a little off the crank too, and then you get thicker bearings to compensate. You don't want to skip that step and then end up with low oil pressure from excessive clearance.

I don't have what you really need. PM or email me if you want to have a Stovebolt rules compliant dialog about my collection of fenders.

There's something wrong here. A Carter AFB is a squarebore and the stock chevy manifold is a spreadbore. You're right that they won't fit, but you can buy an adapter for about $20 at your local parts store...or you should be able to find an Edelbrock 2101 manifold around somewhere (like xXxxx) for cheap. They're basically stock replacement manifolds, but the 305 can't handle a lot more than that anyway.

Thanks for all the input about the 305. the cylinders look real nice, no ridge that i can even catch a finger nail on. I have yet to pull the bearing caps, but the bottom end looks pretty clean. I plan to use the 350 exhaust mainfolds, and other exterior parts to get a complete engine. these are the parts i plan on new, please give me your opinions on my choices:
Rings, bearings, oil pump, water pump, gaskets, valve springs, push rods, cam and lifters. The machine work I plan is to have the crank checked, the cam bearings replaced, and I plan to lap the existing valves as they look pretty good. The carb happened to be off a 383 Charger, and the bolt pattern is much "wider" than the stock manifold. Is there a Chevy manifold or adapter that will work to put this carb on my 305? Thanks again for all the input on this "Low Buck" project.
I am a Navy man with 4 kids and all the usual bills, so I don't have much money for my "toys" but this project has been so far self paying, as I have been selling parts to make money for the project to pay for itself as much as possible.
I know once I get into the engine and rears it may get more expensive.
Thanks again all,
Garry K

Like I said, if the carb truly IS a Carter AFB, then it's a squarebore carb.

If the intake manifold is the stock intake for a 305 with 4-barrel carb, then it's a spreadbore.

There are no easily available Chevy squarebore intake manifolds that I'm aware of. Yeah, some were made, but for special applications.

And as I said, you can probably find an Edelbrock 2101 intake manifold pretty cheap. I found 6 of them in a quick search on eBay, with prices varying from $13 to $115 (stay away from that one. They sell brand new for $115.95 at Summit.)

If you don't want to do that, you can go to a local parts house that carries a few speed parts and buy spreadbore to squarebore adapter for about $20. I don't like them because they're aluminum and conduct heat to the carb real easily. But they will make the carb and manifold bolt up.

Thanks ChevyAsylum,
I am already watching a few of the manifolds on e-bay. I noticed you have made many comments to rebuilding many small blocks. For you or any other Bolters out there, For a primarily daily driver (gas-milage inportant) but would like decent low end torque for when I use it to tow occasionally, and for pushing 35" tires with 3.73 gears and a sm-465 4spd. I did the number crunching on the tire calculator sites and at 55 I should be turning 2300ish, and at 65 about 2500ish. This sounds pretty good for a 305, I think. Any comments? I am on a serious bucget, and was going to stick with the 250 I-6 until it got used for the boat, so now I have the 305 to use... Thanks all for putting up with my questions, I am just trying to do this the best, yet least expensive way I can. No Hot-Rod, just a nice daily driver...
Garry K

the 305 with a small cam and good heads and intake will suprise you get one of the low end torque designed cams it should have good power and fuel milage.

As much as I hate to admit it here, I've built a lot more smallblocks than Bolts. Maybe if I just refer to them as "twin-fours" it won't sound so bad.

I'm not sure what you're asking about the 305. It wouldn't be my choice of motors, but I understand where you're coming from.

If you haven't bought a cam and lifters yet, I don't think you can go wrong with a Summit house brand set. You can get the cam AND the lifters for $80. I'd recommend the 1102. It should be small enough for the 305, yet increase the amount of torque over the stock cams. (Any of the stockers.) ( www.summitracing.com part number sum-k1102)

If you can find a set of heads from an 83-85 Monte Carlo SS (I don't know the number) they should improve the air/fuel flow and raise the compression to 9.5:1 (They're actually Camaro Cross-Fire heads, but I don't know the years on those.)

Another alternative would be to look for a set of 882 heads with 1.94" intake valves (I believe they'll fit the 305 bore, but measuring would be a good idea.) 882s are the "best of the worst" or said another way, smogger heads that flow pretty well. I'm using them on my 63 Nova (with bigger valves) and they perform adequately.)

Good luck.

the L69 305 (used in monte carlo SS and camaros) used the same heads as the plain jane LG4. the difference was in the pistons and cam

Complex: you could be right. I've never compared them side-by side. I've always given 305s away. But according to numberous Monte Carlos SS boards and sites, the heads were different on the SS.

I still have an 85 Monte SS, but the 305 and heads are long gone, otherwise I'd check. Here's one page written by a guy I've known for years and trust ( Paul Carreiro):
http://www.montecarloss.com/SS_FAQ_1.html#2

It includes the "Cross Fire Heads" info.

Again, If I could compare them side by side, I'd do it...but right now my Monte Carlo has a roller-cam AFR head 406 in it and is being prepared to run on the Salt Flats.

Well my 305 is either a 78-84 or 80-84 block. Most sites say that it is an 80-84, but it had a 4bbl intake, which makes me believe it is a 78-79 block...
Any good trick for getting the harmonic balancer off with out destroying the thing? The one from the dead 350 took a large sledge hammer, but I need to save the one from the 305...
Thanks in advance, Garry K

my 84 z28 was a 305 four barrel.

Use a balancer puller. That's what I do. One big threaded shaft with 3 arms and bolts that screw into the balancer. Same as a gear puller, basically.

You can,t use the larger valve heads on a 305 without grinding a relief in the cylinder walls. I had a Monte with a 305. It lasted 250,000 miles but was sluggish.

Checked the 305 this weekend, and it is standard bearings in great shape. Walls of cylinders are great, and sides of pistons barely show any "polishing" wear. I have been looking at the Summit Cam sets. I would like a "RV" torque cam/mileage cam... Any recommendations...
I have a new set of valves springs coming, and a new set of valves on hand, and have 2 sets of pushrods to choose from to get one good set. Will be ordering a HV oil-pump, and a new water pump along with standard bearings and rings.
So hopefully I can get the 305 rebuilt soon and in the 4x4...
Thanks again for all the help!
Garry K

The rv/torque cam with a good set of heads (1.94 intake valves 1.60 exhaust valves with small chambers dual plane Hi rise intake and 650 cfm carb with good free flowing exhaust will really wake the 305 up( i think it will suprise you ) built this combo for a buddies work truck with a 350 turbo it will spin the tires with all his tools and equipment in the back of his 81 C-10.and it gets around 20 mpg.

Thanks V-6 jimmy,
That is what I was thinkning of, but when you speak of free flowing exhaust, will a dual 2" be enough? Or do I need to go with a dual 2 1/4" or 2 1/2"?? I know you can go TOO big on exhaust, and I had an old 289 F... that went really good with just dual 2" and glass-packs... For now stock truck 350 exhaust manifolds will be used, and I'm still looking for an intake.
Thanks Again, Garry K

This is just my experience, but a with a high volume oil pump there is a chance of pumping the sump dry unless you have either (or both) a deep sump oil pan or enlarged oil return galleys.

I had a HV pump in the last incarnation of the 406 in my 85 Monte and the motor ate the cam in a couple of months. I went back to a standard volume, high-pressure pump (Melling 45a, I think) but I haven't fired up the new incarnation of the motor to see how it's gonna work.

But this version has a roller cam instead of the flat-tappet that was in the previous version, so there shouldn't be any cam flattening issues.

2to 21/4 pipe should do it with good mufflers.as for the high volume pump i would buy a melling replacement pump it will pump more oil than the stocker but wont suck the pan dry or flood the valve covers with oil(small blocks are famous for that)we used to stuff pipe cleaners in the push rods to stop over oiling in the valve covers.or you could install restrictors while you have it apart they go into the oil holes under the main bearings.

So let me get this right, a high pressure or stock pump is better for a stock engine than a high volume, due to supply and drainage issues? Interesting, I always thought that more oil was better, but I guess there is a limit...
Would a 450-500 CFM 4bbl be enough carb for the 305 with a RV cam, and still be good for mileage?
I plan to go with the dual 2" most likely, with possibly Flowmasters, but haven't decided yet, if $$ is still an issue, I may order up the Summit "CA Turbo" mufflers, as I ran them on a 289 Ford in a 84 Bronco II, and they did just fine behind that truck.
Thanks again for all the information. Need to pull the harmonic balancer yet, and pull the timing cover, set and cam and crank, then I will be ready for the cleaning, and preping for reassembly.
Any preferences as to brass or steel freeze plugs??
Thanks again, Garry K

OH BOY guys!!! Just got the offer of a life-time, or at least the offer of the month...
A co-worker just bought a 1970 Chevy Nova bone stock with only 44,000 on the odometer, with the factory 307. He is buying a crate 350 to "HOP-it up" and go hot-rodding. He said I could HAVE the 307, if I pulled it for him, and cleaned and painted the engine bay (my hobby has always been paint and body before wrenching...) SOOOO, I have been doing a little reading, and many say to use my 305 heads on the 307. For now, I plan to simply place the 307 as is into my project truck, but if the 305 heads are better for the 307, I will save them for when I put a cam and intake on the 307. For now I plan to drop it in so I can be closer to driving my truck. Thanks for all the help, and I'll keep you all posted as to when I can get this 307.
Garry K

Bore the 307 to 4 inch and install 327 pistons and ya got yerself a 327

better off if you'd use the 307 crank in a 350 block if you want a 327. you might bore through the cylinder walls

I am in a similar situation and am looking to buy a crate motor. I went to GM's website and found the crate motor section but can't seem to find prices or how to order one. Can you guys send me a link?

Thanks,
Rog

Thanks for the link but I was looking for the one that was $1275. The cheapest 350 on that link was $1675.

Thanks,
Rog