InfernalVortex
Well-Known Member
I see you're going to rebuidl the 305. Definitely not the route I would have taken.
Those L03's are practically worthless. I've got one in the backyard that I cant give away, and it runs! The cylinder heads are absolutely terrible. I'm going to assume you have a throttle body injected car and not a quadrajet carbureted car.
What you need are some corvette 113 heads if you want to go NA, which is still a waste IMO. If you're paying for all the machinework and new crank, new rods, new pistons, then you're not going to spend any more money than you would on a 350 (In fact, you can easily spend more). A 350 core costs $50, maybe.
If you just are that hung up on being "Different", understand that if you want to make power with less cubic inches you're going to need ab igger cam than an equivalent 350 and that means less streetability. You're going to need a nice stall converter, a rebuilt transmission to handle the power, and probably much steeper rear end gears to match.
I've probably mentioned my buddy with the 305 RS "Sport Coupe"? He just went 12.39 with 416 heads. A few years ago he went 12.31 with those corvette heads, but after he switched to the new heads, his times went from 12.3 to 13.3 - the corvette heads had a crack in them so they had to go, and it cost him dearly.
He's got a 4.56 rear end gear, mostly gutted car (it's got a full interior, but other than that...) with a hopped up Turbo 350 transmission (His 700r4 died). His car weighs a hair less than 3000 lbs (stock thirdgens weigh 3300-4,000). Also, to put it into perspective, the Turbo 350 transmission and 4.56 gears mean that with stock wheels/tires, you're going to turn around 4,000 RPMs at 65 mph. The Turbo 350s dont have a lockup either so they will constantly slip (creates tons of heat in the transmission too) as part of their normal operation, so knock that RPM number up a little higher. Th350's are much stronger and lighter than 700r4s, though.
So dont let me discourage you, you CAN go fast with a 305, but it's been done and it will cost you more than doing it with a 350 and it will cost you in terms of practicality to get there.
If you insist on reusing the 305, TRASH THE HEADS. Those swirlport garbage heads are absolutely useless for anything except towing or boat anchors. They do NOT make power.
With a rebuild you're going to be doing everything to that block that you'd have to do to a 350 block you find anyway. You dont want to reuse the heads because they're junk for power. So put yourself down for new heads (which for a 305 are much harder to find, you'll be stuck dealing with heads geared more towards 350s). Also since you're going to rebuild it, that means boring it out to clean up the cylinder walls. That means new pistons. You'll want to buy some decent forged connecting rods. They're barely more expensive than reconditioning the stock ones and they usually come with much nicer ARP bolts which make it easily worth it. You may want to go to a new crankshaft, depending on your feelings on reusing the old one. The cam is, again, useless. You'll want a new cam. The new cam will necessitate a better valvetrain. The stock rocker arms wont be happy with stiffer valve springs and so forth, so you might as well upgrade those too. That may mean you cant use the old valvecovers depending on what rockers you pick. You need a new distributor and intake manifold since you're going to a carburetor....
What does that leave that's original? Only the block, the oil pan, the flexplate, and maybe the timing chain cover.
As far as exhaust sound... ? That's got so much to do with what actual exhaust you're using and your cam and your heads than anything to do with the specific bore of your motor. The Ford 302's are a 4.000 inch bore just like 350s anyway.
One thing I would SERIOUSLY consider. Smaller bores are much less prone to detonation. The difference between 350s and 305s isn't huge, per se, but if you're going to go forced induction, like a turbo, a cheap 305 is a GREAT option. Consider stroking it out to a 334. You'll have to pay for all the irritating 383 parts that cost more, and you wont even have as much displacement as a standard 350, but you'll be able to handle more boost without detonation with a smaller bore, which could make it worth it. Seriously consider doing a turbo setup. It's going to require lower compression, so I'd go with 350 heads such as 083's, and then use dished pistons and you have a perfect motor for forced induction. Just finding a TPI setup and learning to tune it will be all you need to do to make it work. IT's not hard to get carbs to work with turbos, but you lose the small safety net that the knock sensor provides that way.
Do you want 300 hp at the crank or at the wheels? At the crank isnt too hard. A very mild cam plus some decent heads like the 081's, 416's, or 113s, shorties, 3 inch mandrel bent exhaust, and you might get there. 300hp at the wheels is going to require a cam closer to 230/230, some really good shortie headers or better yet, Long tube headers and a custom exhaust to go with it, and some really good heads. Corvette 113's at least.
For the carburetor swap, you're going to need a Fuel pressure regulator (The cheapest you'll want to go on this is a Mallory 4309 unit, $75), a carburetor (I suggest a Holley 650 DP, avoid Edelbroke), an intake manifold (the only thing edelbroke does right), a distributor, and fuel lines.
This is how I have my lines routed:
I used Jegs Pushloc hose, which is cheap and works awesome and doesn't cut your hands to pieces like braided steel line. NHRA approved too. The fittings will cost you dearly. Expect to pay about $10-15 for each adapter and fitting you need. -6 AN should work fine for what you're doing (I'm using -6). Im using those screw-clamps for the time being, they work fine. I'll switch to proper fittings eventually. Your fuel lines will most likely be in the same place unless you've got a carbureted car, in which case they're on the other side of the engine bay which is better!
You can either use a regulator to dial the stock fuel pressure down to a useful level for a carburetor (should be going from around 15 to around 5-8psi). If you do it this way MAKE SURE YOU RUN A RETURN LINE. It allows the excess fuel to run back to the pump, keeps the pump from overworking, overheating, and failing. You do NOT want to drop the tank to swap out the pump. It's a job and a half. The feed and return lines are already there (You can see in the picture) so it's just a matter of connecting them to the regulator. THe 3rd hard line you see is for the evap canister which bleeds off built up gasses inside the fuel tank and the ECM pumps them into the throttle body whenever it feels like it. Just saves gas. You dont need it, so just leave the line open to the air or run it out the fender or something. The evap can is gone on my car entirely.
THe other option is to drop teh tank, install a carb pickup (I dont know how to do this, but apparently it's not difficult to make a carburetor pickup at all), and then just run your fuel lines to a mechanical pump and then to the carburetor. This is actually cheaper, but more work, and you've got to buy lots of fittings and fuel lines still. $$$$$
Then you have to deal with teh fuel pump wiring and the torque converter lockup.
The fuel pump is easy. I spent a LOT of time trying to figure out what the hell the actual circuit was. I got a LOT of contradicting information and this is what I managed to nail down. This is what the circuit looks like, stock:
Older cars have the oil pressure sending unit and the oil pressure switch at different places. Newer ones like mine have them in the same unit.
This is the newer style and where it's located:
What happens is that once oil pressure builds up to a certain amount, a switch in the sending unit allows +12v to hit the fuel pump relay, which triggers the fuel pump to turn on.
This is the Electronic Spark Control (ESC) module, and the Fuel Pump relay is behind it. The fan relay is next to it also.
The problem is that when you first hit the keys to start the car, you dont have enough oil pressure to trigger the switch. Therefore the car will take several seconds (at least) to fire. You'll wear out your battery and waste time, etc. It WILL start, but it will take forever. Not convenient. So what happens is when you first hit the switch, the ECM overrides the oil pressure switch and triggers the relay. The ECM only does this right at startup, though. Im not sure exactly, probably 5 or 10 seconds or something like that. It is no longer needed once you have sufficient oil pressure and it doesnt send signal after that.
This is actually a safety feature, it makes sure that once the engine is off, the fuel pump is off. As soon as you lose oil pressure, the fuel pump turns off. That means if you get into a horrendous accident and the motor is suddenly stopped/stalled, the fuel will stop also.
What you need to do to convert it to carb, is to wire up a manual priming switch. Not a big deal, just send +12v to a switch, and run that switch to the relay to where the ECM sent +12v to it. Essentially, you are taking over the role the ECM used to play. You turn on the fuel pump when the ECM used to, and as soon as you've got oil pressure, you can switch it off and not worry about horrendous fires just like you wouldn't if the car were stock.
If you drive your car often, you may not need to use it very much as fuel will probaly stay in the bowls. But if you park it overnight or something and it bleeds down, that's what the switch is for. You use it to prime the pump and get te car started, as soon as you're running, switch it back off and if you wired everything right you should still have fuel.
The Torque converter lockup is a relatively simple matter too, but Im not sure exactly what to do on that yet. My build ran into problems before I could get around to fixing it. You'll ahve 3 pins on the transmission that are used. 2 of them are relevant, 1 is not. One gets +12 to lockup the converter, one is a signal wire to the ECM (I think it tells the ECM it's in 4th gear), and one is a ground. I THINK that's right.
Run +12 to Pin A, and run Pin D to ground... that SHOULD be it. It's a little weird... just figure out which wires are coming from the ECM, and one of those should get +12v. Figure out which one, and wire up another manual switch for it.
The diagram above shows the lockup circuit running through the brake switch. The switch theyre referring to is a brake switch from a car that has cruise control. The switch is normally closed, except when you hit the brakes, that's when it disconnects the circuit. If you dont have cruise control, then that's great, get a switch for a car that does (It's like $10 or something, cheap) and run teh circuit through that. That means that the converter will unlock under braking (keeps you from stalling) like it's supposed to. It will lock again if you get off of it probably, so you need to remember to turn the switch off. Im not positive if it will only lock in 4th gear or whether it will lock in 2nd-4th. If it will only lock in 4th, then if it downshifts you wont have to worry about hitting the switch as much.
Those L03's are practically worthless. I've got one in the backyard that I cant give away, and it runs! The cylinder heads are absolutely terrible. I'm going to assume you have a throttle body injected car and not a quadrajet carbureted car.
What you need are some corvette 113 heads if you want to go NA, which is still a waste IMO. If you're paying for all the machinework and new crank, new rods, new pistons, then you're not going to spend any more money than you would on a 350 (In fact, you can easily spend more). A 350 core costs $50, maybe.
If you just are that hung up on being "Different", understand that if you want to make power with less cubic inches you're going to need ab igger cam than an equivalent 350 and that means less streetability. You're going to need a nice stall converter, a rebuilt transmission to handle the power, and probably much steeper rear end gears to match.
I've probably mentioned my buddy with the 305 RS "Sport Coupe"? He just went 12.39 with 416 heads. A few years ago he went 12.31 with those corvette heads, but after he switched to the new heads, his times went from 12.3 to 13.3 - the corvette heads had a crack in them so they had to go, and it cost him dearly.
He's got a 4.56 rear end gear, mostly gutted car (it's got a full interior, but other than that...) with a hopped up Turbo 350 transmission (His 700r4 died). His car weighs a hair less than 3000 lbs (stock thirdgens weigh 3300-4,000). Also, to put it into perspective, the Turbo 350 transmission and 4.56 gears mean that with stock wheels/tires, you're going to turn around 4,000 RPMs at 65 mph. The Turbo 350s dont have a lockup either so they will constantly slip (creates tons of heat in the transmission too) as part of their normal operation, so knock that RPM number up a little higher. Th350's are much stronger and lighter than 700r4s, though.
So dont let me discourage you, you CAN go fast with a 305, but it's been done and it will cost you more than doing it with a 350 and it will cost you in terms of practicality to get there.
If you insist on reusing the 305, TRASH THE HEADS. Those swirlport garbage heads are absolutely useless for anything except towing or boat anchors. They do NOT make power.
With a rebuild you're going to be doing everything to that block that you'd have to do to a 350 block you find anyway. You dont want to reuse the heads because they're junk for power. So put yourself down for new heads (which for a 305 are much harder to find, you'll be stuck dealing with heads geared more towards 350s). Also since you're going to rebuild it, that means boring it out to clean up the cylinder walls. That means new pistons. You'll want to buy some decent forged connecting rods. They're barely more expensive than reconditioning the stock ones and they usually come with much nicer ARP bolts which make it easily worth it. You may want to go to a new crankshaft, depending on your feelings on reusing the old one. The cam is, again, useless. You'll want a new cam. The new cam will necessitate a better valvetrain. The stock rocker arms wont be happy with stiffer valve springs and so forth, so you might as well upgrade those too. That may mean you cant use the old valvecovers depending on what rockers you pick. You need a new distributor and intake manifold since you're going to a carburetor....
What does that leave that's original? Only the block, the oil pan, the flexplate, and maybe the timing chain cover.
As far as exhaust sound... ? That's got so much to do with what actual exhaust you're using and your cam and your heads than anything to do with the specific bore of your motor. The Ford 302's are a 4.000 inch bore just like 350s anyway.
One thing I would SERIOUSLY consider. Smaller bores are much less prone to detonation. The difference between 350s and 305s isn't huge, per se, but if you're going to go forced induction, like a turbo, a cheap 305 is a GREAT option. Consider stroking it out to a 334. You'll have to pay for all the irritating 383 parts that cost more, and you wont even have as much displacement as a standard 350, but you'll be able to handle more boost without detonation with a smaller bore, which could make it worth it. Seriously consider doing a turbo setup. It's going to require lower compression, so I'd go with 350 heads such as 083's, and then use dished pistons and you have a perfect motor for forced induction. Just finding a TPI setup and learning to tune it will be all you need to do to make it work. IT's not hard to get carbs to work with turbos, but you lose the small safety net that the knock sensor provides that way.
Do you want 300 hp at the crank or at the wheels? At the crank isnt too hard. A very mild cam plus some decent heads like the 081's, 416's, or 113s, shorties, 3 inch mandrel bent exhaust, and you might get there. 300hp at the wheels is going to require a cam closer to 230/230, some really good shortie headers or better yet, Long tube headers and a custom exhaust to go with it, and some really good heads. Corvette 113's at least.
For the carburetor swap, you're going to need a Fuel pressure regulator (The cheapest you'll want to go on this is a Mallory 4309 unit, $75), a carburetor (I suggest a Holley 650 DP, avoid Edelbroke), an intake manifold (the only thing edelbroke does right), a distributor, and fuel lines.
This is how I have my lines routed:
I used Jegs Pushloc hose, which is cheap and works awesome and doesn't cut your hands to pieces like braided steel line. NHRA approved too. The fittings will cost you dearly. Expect to pay about $10-15 for each adapter and fitting you need. -6 AN should work fine for what you're doing (I'm using -6). Im using those screw-clamps for the time being, they work fine. I'll switch to proper fittings eventually. Your fuel lines will most likely be in the same place unless you've got a carbureted car, in which case they're on the other side of the engine bay which is better!
You can either use a regulator to dial the stock fuel pressure down to a useful level for a carburetor (should be going from around 15 to around 5-8psi). If you do it this way MAKE SURE YOU RUN A RETURN LINE. It allows the excess fuel to run back to the pump, keeps the pump from overworking, overheating, and failing. You do NOT want to drop the tank to swap out the pump. It's a job and a half. The feed and return lines are already there (You can see in the picture) so it's just a matter of connecting them to the regulator. THe 3rd hard line you see is for the evap canister which bleeds off built up gasses inside the fuel tank and the ECM pumps them into the throttle body whenever it feels like it. Just saves gas. You dont need it, so just leave the line open to the air or run it out the fender or something. The evap can is gone on my car entirely.
THe other option is to drop teh tank, install a carb pickup (I dont know how to do this, but apparently it's not difficult to make a carburetor pickup at all), and then just run your fuel lines to a mechanical pump and then to the carburetor. This is actually cheaper, but more work, and you've got to buy lots of fittings and fuel lines still. $$$$$
Then you have to deal with teh fuel pump wiring and the torque converter lockup.
The fuel pump is easy. I spent a LOT of time trying to figure out what the hell the actual circuit was. I got a LOT of contradicting information and this is what I managed to nail down. This is what the circuit looks like, stock:
Older cars have the oil pressure sending unit and the oil pressure switch at different places. Newer ones like mine have them in the same unit.
This is the newer style and where it's located:
What happens is that once oil pressure builds up to a certain amount, a switch in the sending unit allows +12v to hit the fuel pump relay, which triggers the fuel pump to turn on.
This is the Electronic Spark Control (ESC) module, and the Fuel Pump relay is behind it. The fan relay is next to it also.
The problem is that when you first hit the keys to start the car, you dont have enough oil pressure to trigger the switch. Therefore the car will take several seconds (at least) to fire. You'll wear out your battery and waste time, etc. It WILL start, but it will take forever. Not convenient. So what happens is when you first hit the switch, the ECM overrides the oil pressure switch and triggers the relay. The ECM only does this right at startup, though. Im not sure exactly, probably 5 or 10 seconds or something like that. It is no longer needed once you have sufficient oil pressure and it doesnt send signal after that.
This is actually a safety feature, it makes sure that once the engine is off, the fuel pump is off. As soon as you lose oil pressure, the fuel pump turns off. That means if you get into a horrendous accident and the motor is suddenly stopped/stalled, the fuel will stop also.
What you need to do to convert it to carb, is to wire up a manual priming switch. Not a big deal, just send +12v to a switch, and run that switch to the relay to where the ECM sent +12v to it. Essentially, you are taking over the role the ECM used to play. You turn on the fuel pump when the ECM used to, and as soon as you've got oil pressure, you can switch it off and not worry about horrendous fires just like you wouldn't if the car were stock.
If you drive your car often, you may not need to use it very much as fuel will probaly stay in the bowls. But if you park it overnight or something and it bleeds down, that's what the switch is for. You use it to prime the pump and get te car started, as soon as you're running, switch it back off and if you wired everything right you should still have fuel.
The Torque converter lockup is a relatively simple matter too, but Im not sure exactly what to do on that yet. My build ran into problems before I could get around to fixing it. You'll ahve 3 pins on the transmission that are used. 2 of them are relevant, 1 is not. One gets +12 to lockup the converter, one is a signal wire to the ECM (I think it tells the ECM it's in 4th gear), and one is a ground. I THINK that's right.
Run +12 to Pin A, and run Pin D to ground... that SHOULD be it. It's a little weird... just figure out which wires are coming from the ECM, and one of those should get +12v. Figure out which one, and wire up another manual switch for it.
The diagram above shows the lockup circuit running through the brake switch. The switch theyre referring to is a brake switch from a car that has cruise control. The switch is normally closed, except when you hit the brakes, that's when it disconnects the circuit. If you dont have cruise control, then that's great, get a switch for a car that does (It's like $10 or something, cheap) and run teh circuit through that. That means that the converter will unlock under braking (keeps you from stalling) like it's supposed to. It will lock again if you get off of it probably, so you need to remember to turn the switch off. Im not positive if it will only lock in 4th gear or whether it will lock in 2nd-4th. If it will only lock in 4th, then if it downshifts you wont have to worry about hitting the switch as much.
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