Thread: 305 build questions

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1. an oil plug (the kind with the square inset, on the rear of the block) would not come out and I tried various bolt extractors to get it out. It is almost drilled it out yet still enough remains to obscure all the threads of the hole, Should I a) finish drilling it out completely and then tap a larger diameter hole, e.g. to 1/2 inch, then use a 1/2 inch diameter, 1/2 inch long bolt to plug it? OR should I drill it out and use helicoil replacement threads, and then put a new oil plug in?

2. cylinder walls have a worn in ring around the top of the bore 1/4 inch from the deck. Is there an easy way to fix this at home or does this need professional machine shop to fix?

3. How do I remove wrist pins from pistons? (do not have retaining clips) tried heating rod and pin with a torch and then hammering with a rubber mallet.

4.what are the biggest bang for the buck things I should do to get to 250 HP? pistons, crank, cam, heads?

5. looking for a recommended setup for intake manifold and fuel delivery that will be legal in TX to replace a fuel injected engine from a 1991 vehicle.

Well it would appear that you’ve got yourself a project here. The 305 is a good little motor, but not typically associated with a lot of builders for horsepower. You can achieve 250 however, but first things first.

1. Your oil plug should be removed and replaced. At this point, you’d be best off to take the block to a reputable machine shop for several reasons, not least of which is to have them drill and re-tap this hole. You’ll also want the machine shop to hot tank the block, remove all the other plugs and replace the soft plugs. Have them check the alignment on the main bearings as well. This is critical, especially if you did not mark the original positions.

2. The ring you’re referring to is a “ridge” that is caused by the rings wearing into the cylinder. Again, this is a machine shop consideration and in all likelihood, your engine will require boring. A machine shop will bore (as required) and hone the cylinder walls to facilitate the seating of new rings.

3. The wrist pins are pressed in. Removal requires a press. I hope the heat has not harmed your rods. Take the assembled pistons and rods to the machine shop and have them check the rods. If they’re good, they can be reused. If not – well, a new set is in order. At the same time, have the machine shop install your new pistons. I also hope that you marked each rod as you disassembled them to allow for placement back in their original spot. This is important, especially in a “well used” engine as there is a wear pattern on the entire reciprocating assembly.

Now with all that said, you may want to just purchase a complete rotating assembly kit from Summit, Jegs, PAW, etc. like the one shown here. It will run you $600 or more, depending on options like forged crank and what compression ration you’re opting for. It would certainly be worth considering before spending a ton of money on your current crank and rods – especially if the rods need to be re-worked. This way you also get main and rod bearings matched to your crankshaft. I’m assuming that you’ll need new pistons in any case. You’ll want to have the machine work done first so you’ll know what size pistons (i.e., +.10, .20, .30) to buy.

4. As to cam – stay with a mild “aftermarket” from Summit like their K1102 which includes new hydraulic lifters with the cam for about $90. Have new cam bearings installed by your machine shop. Also buy a “true” double roller timing set from Summit (Comp Camp 2100 – about $30) and stick with basic (stock) timing settings. If you have questions, call the folks at Summit. Heads are a bit limited on the 305 but the GM Performance 12558060 is an exceptional cast iron head with 64cc combustion chambers, 170cc intake runners, and 1.94/1.50 valves. They’re about $600 a set and use the newer (Vortec-style) intake manifold and self-aligning rocker arms.

5. Intake manifold choice is a matter of preference. Many on this site like the Edelbrock Performer RPM with a 600-650 CFM carburetor. This is a winning combination and will run you about $600.

After reading all of this – I would recommend that you construct a spread sheet to list all of the components discussed, i.e., machine shop work, rotating assembly, heads, camshaft, intake and carburetor and then add in the following:
Distributer
Oil pump
Gasket set
New spark plugs and wires (don’t forget wire looms)
And don’t forget any “bling” (chrome stuff) that you may want to put on this engine.

Add it all up before you start and you may find an assembled engine will be more practical. I certainly do not want to discourage you from building a motor – but weigh the total cost (especially of a 305).

Remember too that you will need an engine stand and lots of time and patience as well as some specialized tools (piston ring compressor, torque wrench at a minimum). Above all, make sure if you do decide to do this yourself that when you get the block back from the machine shop you scrub it to death with hot soapy water (I like Dawn detergent) and dry it good with soft rags and compressed air. Paint the outside with a good grade engine enamel (rattle cans are fine) and lightly oil every nook and cranny that you don’t paint.

Buy a good Chevy engine book from Amazon or your local book store and study it like there’s no tomorrow. Keep it handy for all of the fine points during assembly, especially sequence of how things go back together and the appropriate torque values. Use the book to reference places for and types of assembly lube as you put things together. Go slow and above all, have fun.

Regards,
Glenn

thanks a ton for the good advice.

the reason i was asking about 250 HP considerations is that if I'm going to sink money into it, I'd like to be able to sell it in the end, and don't think people will want to buy a stock 305.

i actually bought this engine to learn on. paid 100 bucks for it complete, and have an engine stand so thats not a problem.

so the unasked question is should i really spend much more on this motor in terms of new parts vs go through rebuild w what i've gotten the "educational value" and exchange the core plus $ for a good 350 block.

thanks so much. great info.

apologies if this reply duplicates my previous reply - first one went to moderator for review for some reason.

bought this engine for 100 bucks complete, and my intention w it is just to learn. i want to build a 350, and thats one i'd sink more $ into.... so with this one, i was thinking i wanted to get it running and maximize reusing existing parts where feasible. but soudns like I'd probably have to spend quite a bit. so probably the best thing is to get my "100 buck's worth" reassembling and learning on it without trying to really get it running. And then take the thing to an engine shop and 'trade it in' for a few bucks (literally) toward the puchase of a 350 block that i really want to spend money building up.

Thanks for the great advice. I'm having trouble posting a response - keeps sending to the moderator. Hope this one makes it.

I've actually already got the rebuild book, the tools, and the engine stand. I paid 100 for the complete engine just to learn the fundamentals. what i want to do then is rebuild a 350 or 383. Sounds like it may be more $ than its worth to get this engine running again.

There's a lot of good points there. You can buy a complete new 350 straight from GM for about $1300; probably less than you'd put into the 305. If you're just looking to learn how to do a rebuild and want a smaller cube engine, I always recommend to people to look at either a 283, 307, or 327. The longer stroke, small bore combo on the 305 just wasn't their best design when it came to smaller cube small blocks.

I would concur with the above - the 327 is a wonderful motor. However, you can always find a complete 350 on Craigslist or Ebay in the Dallas Ft Worth area for couple hundred bucks as well and then you'll have a better base to build from.

Keep us informed as to how your project goes and don't hesitate to ask questions. The knowledge represented on this site can not be bought at any price and most are willing to share with those jumping in for the first time!

Regards,
Glenn

i've never had to spend more than $800 to build a 305, and that is counting new pistons, new cam & lifter, rebuild kit, ( reuse the old crank ), bored the cylinders, valve job, cam bearings installed, new pistons pressed on old rods ( rods checked )

Here is a trick I was taught by an old timer to remove plugs:

heat the plug with the braizing tip of a torch
throw water on it
immediately turn it out. Usually it will go the first time

For the cylinder ridges: you can buy a ridge cutting tool, I've used them and they do a good job if you follow the directions. It is very important to cut the ridge before you pull the piston, or you could damage the ring lands on the piston. However, if there are ridges, then you probably have to bore the cylinders anyway, so the old pistons are trash, so just drive them out using the wood handle of a hammer. ( good info for next time )

A 305 is a pretty good motor to learn on. Good luck

i have to say while not fast, the 305 is and was one of the most reliable sbc's i ever had.

You guys are giving me great stuff. Pearls of wisdom. Keep it coming! Thanks much.

So here's where things stand as of today. I've had the 305 about 3 months, and have torn it down completely. Disassembled the cylinder heads even. All the parts have been exactly tracked to which cylinder they came from etc ( I have a very good, detailed build manual I am learning from).

Block
Block is in good shape except for 1 oil galley plug hole which needs to be rethreaded and clyinder bores needing to have ridges bored/honed out. Need a cam bearing removal and install tool and new cam bearings. Machine shop will do all of these and i'll get the usual block services done. Eventually. After I do a full mock re-assembly or 2 just to go through the motions. Right now I've got the block completely cleaned with a home pressure washer, solvents, burshes, gun-bore brushes, etc. I've done the soapy water wash 3 times as well. All run-out water from the engine now comes out clear, and you can touch any place internally and not find residues/dirt. Tonight I masked off the block, painted it with a Duplicolor engine enamel (silver colored), and then lightly coated all the non-painted surfaces with WD40 to prevent rust. I'm giving the paint 4-5 days to really set then plastic bag the block and set it aside.

Block components and rotating assembly
Crank is clean and coated in WD40. Light discoloration down the center of each journal which will not come off. Crank key removed and the key-hole deburred. Camshaft cleaned and lightly coated in WD40. All pistons cleaned except: still need to clean tough deposits out of ring grooves, and cannot remove pins so cannot clean inside piston heads. Does cleaning with oven cleaner in the oven really work? I will clean grooves so I can put new rings on them, but not much i can do about the wrist pins. I marked the pistons w a punch. All main bearings and caps, all cap bolts, all connecting rod bearings and caps cleaned, tagged and bagged. Timing set cleaned. Oil pump is next to go into the solvent. Oil filter adapter cleaned. Timing cover trashed. Got a new one complete with all gaskets for 20.00. New Fuel pump also 20.00. New water pump 59.00. Accessory brackets are trash will have to replace. Alternator known bad when i bought the motor. Damper and pulleys still dirty but plan to clean and repaint them. No starter, have to get one of those.

Fuel-air delivery
Original Rochester carb was badly broken. I took it apart to see how it works, but ended up trashing it. So to get the engine to run I'd have to get another carb. Intake manifold is badly rusted and may have to be replaced-even for a 'learner' engine. All the various emissions control bits and sensors on the intake are in a bag, but they look like they are original from 1981, so those probably all have to be replaced.

Exhaust manifolds
Cleaned up pretty nicely. Painted with high heat 2000 degree enamel for exhaust.

Valve train
Mess. Cam is the only thing that looks good. Cam bearings still need to be removed from block and replaced. Valves look, to my untrained eye, like a total lost cause. They are so badly charred. Every one of them. I wonder WTF happened in this car. Anyway will try to clean them for the initial mock re-assembly. Will clean with solvent and see if i cant polish them up. Will need new rubber seals for the valve guides. Heads themselves are a mess. Repeated cleaning making some progress. Rocker arms cleaned up fine and are organized. Tappets still need cleaning. Going to buy a new set of pushrods. Lost track of cylinder assignment on 3-4 of them. They are cheap anyway, and really even after repeated solvent cleaning have proven in bad shape. Metal is badly pitted.

Electrical
Besides sensors, will need all wiring, plugs & wires, distributor, coil, alternator.

Miscellaeous
will need thermostat, and many other small odds and ends.

So the question i'll have to make a judgement call on is when have i learned enough and therefore its time to swap the 305 for a 350 or other SB. right now not counting tools and expendables like solvents and paint i have 100 spent on the initial purchase and about 100 spent on replacement parts.

can someone tell me why everytime i try to post my posting goes to the moderator? i have particpated on several forums using same forum software and never had this.

:-) You guys are giving me great stuff. Pearls of wisdom. Keep it coming! Thanks much.

So here's where things stand as of today. I've had the 305 about 3 months, and have torn it down completely. Disassembled the cylinder heads even. All the parts have been exactly tracked to which cylinder they came from etc ( I have a very good, detailed build manual I am learning from).

Block
Block is in good shape except for 1 oil galley plug hole which needs to be rethreaded and clyinder bores needing to have ridges bored/honed out. Need a cam bearing removal and install tool and new cam bearings. Machine shop will do all of these and i'll get the usual block services done. Eventually. After I do a full mock re-assembly or 2 just to go through the motions. Right now I've got the block completely cleaned with a home pressure washer, solvents, burshes, gun-bore brushes, etc. I've done the soapy water wash 3 times as well. All run-out water from the engine now comes out clear, and you can touch any place internally and not find residues/dirt. Tonight I masked off the block, painted it with a Duplicolor engine enamel (silver colored), and then lightly coated all the non-painted surfaces with WD40 to prevent rust. I'm giving the paint 4-5 days to really set then plastic bag the block and set it aside.

Block components and rotating assembly
Crank is clean and coated in WD40. Light discoloration down the center of each journal which will not come off. Crank key removed and the key-hole deburred. Camshaft cleaned and lightly coated in WD40. All pistons cleaned except: still need to clean tough deposits out of ring grooves, and cannot remove pins so cannot clean inside piston heads. Does cleaning with oven cleaner in the oven really work? I will clean grooves so I can put new rings on them, but not much i can do about the wrist pins. I marked the pistons w a punch. All main bearings and caps, all cap bolts, all connecting rod bearings and caps cleaned, tagged and bagged. Timing set cleaned. Oil pump is next to go into the solvent. Oil filter adapter cleaned. Timing cover trashed. Got a new one complete with all gaskets for 20.00. New Fuel pump also 20.00. New water pump 59.00. Accessory brackets are trash will have to replace. Alternator known bad when i bought the motor. Damper and pulleys still dirty but plan to clean and repaint them. No starter, have to get one of those.

Fuel-air delivery
Original Rochester carb was badly broken. I took it apart to see how it works, but ended up trashing it. So to get the engine to run I'd have to get another carb. Intake manifold is badly rusted and may have to be replaced-even for a 'learner' engine. All the various emissions control bits and sensors on the intake are in a bag, but they look like they are original from 1981, so those probably all have to be replaced.

Exhaust manifolds
Cleaned up pretty nicely. Painted with high heat 2000 degree enamel for exhaust.

Valve train
Mess. Cam is the only thing that looks good. Cam bearings still need to be removed from block and replaced. Valves look, to my untrained eye, like a total lost cause. They are so badly charred. Every one of them. I wonder WTF happened in this car. Anyway will try to clean them for the initial mock re-assembly. Will clean with solvent and see if i cant polish them up. Will need new rubber seals for the valve guides. Heads themselves are a mess. Repeated cleaning making some progress. Rocker arms cleaned up fine and are organized. Tappets still need cleaning. Going to buy a new set of pushrods. Lost track of cylinder assignment on 3-4 of them. They are cheap anyway, and really even after repeated solvent cleaning have proven in bad shape. Metal is badly pitted.

Electrical
Besides sensors, will need all wiring, plugs & wires, distributor, coil, alternator.

Miscellaeous
will need thermostat, and many other small odds and ends.

So the question i'll have to make a judgement call on is when have i learned enough and therefore its time to swap the 305 for a 350 or other SB. right now not counting tools and expendables like solvents and paint i have 100 spent on the initial purchase and about 100 spent on replacement parts.