arborvitian
Junior Member
- Joined
- Nov 29, 2024
- Posts
- 19
- Reaction score
- 87
- Location
- Virginia
- First Name
- Michael
- Truck Year
- 1974
- Truck Model
- C30
- Engine Size
- 350
I've gotten as far as I can reading old threads and poking around with my truck. It's time to lay everything out, and get some input from people who are smarter than I am.
Background:
I have a '74 C30 with a 350 and a 4-speed that is approaching 118,000 miles. When I drove the truck home, it was running very poorly under load, and would barely climb a hill. The divorced choke had been replaced with a manual, and the linkage popped off instantly when I tried to use it. The carburetor was bristling with little stubs of hoses with screws jammed into them. The original carburetor is a 7045222. The plugs were fouled, but I think it was fuel and not oil. It smoked a lot at first. Even in that state, it did idle just fine, and it seemed to idle itself down from the fastest idle to a street idle all by itself.
The truck would have had an A.I.R. pump, and that is long gone. If it had EGR, that is long gone too. It had an air cleaner with some kind of valve in it (vacuum?) that wasn't hooked to anything, and somebody had put a plug in the valve cover where the PCV system used to run. I replaced the plug with a breather, but not before I turned a custom, weirdly skinny breather nipple to fit neatly into what I didn't realize was a plug until I tried and failed to install the thing. D'OH! (I'm out of pictures, but I ended up with a proper grommet and some sensible auto parts store breather filter to replace that idiotic billet nonsense that didn't even work.)
The guy who sold me the truck had just given it enough of a tune to get it running after sitting for 10 years in a corn field. He replaced the flywheel and starter, the vacuum advance on the distributor, the cap and rotor, and changed the points. It didn't start well, but it started. I drove it home, and the power steering pressure line exploded as I was backing it in. Hey, it got me home, so I knew I had bought a good truck!
I changed the plugs and wires, set the dwell to 28° (it was at like 36°), and changed the coil. After weighing my options on the fuel delivery system, I stayed with a q-jet, and I attempted to buy a really good rebuild. I installed a JET Performance Stage 1. I also put on one of those muscle car style air cleaners, because, you know, a cool air cleaner makes a truck go faster, right?
After putting on the Stage 1, I attempted to follow the setup instruction sheet. Step 1, set the idle. I couldn't get the idle below about 1200. The screw ceased to contact anything, and that was just the lower limit. Research pointed me at timing. Initial timing with vacuum disconnected was something on the order of 36°, which (my research seems to indicate) explains the high idle and hard starting.
I set the timing to 8°, which let me adjust the idle down to something around 500 on the screw. I cranked it up to about 850, and the idle was better.
I had performance issues that seemed to point to timing. I'm sorry I have to be vague about that, but it was a busy period in my life. I no longer remember specifically why I decided to put more timing in it. I cranked initial timing up to 12°, and that seemed magical. My son drove the truck too, and agreed that it ran better overall. Less hesitation, better transition to the secondaries.
Problems:
At this point right here and now, I've got 12° initial timing, and the idle is set at about 950. 950 is the bottom out point on the screw. It will go no lower.
I checked the total timing at 3500 RPM (vacuum disconnected), and it was 26°. 12 + 14 = 26, so I suspect my centrifugal advance isn't putting out. I should be getting about 24°out of the weights, right?
In 200 miles, my points have opened up from 28° to 36°, which seems weird. The oldest vehicle I ever owned before this had HEI, so I'm a points newbie.
I haven't pulled a spark plug to see how they're doing. The engine no longer smokes enough to make me think the rings are shot. It probably bears mentioning that I installed a new gas tank and dual fuel filters. The fuel pump was working well enough to push gas through a filter that was 99% obstructed with rust, so I figured the fuel pressure must be fine. I didn't check it. I did pour a quart of Marvel Mystery Oil into the crankcase, and I've run two cans of Sea Foam through the gas.
I get to buy gas frequently, since I'm getting about 6.5 mpg.
The biggest problem I'm having is idle speed after a cold start, and what behaves like a stuck throttle, even though it can't be a stuck throttle. I can jiggle the clip on the end and make my gas pedal flop like a fish, just flicking two fingers. I don't see any conceivable way that cable could be binding.
Note to self:
It's conceivable that my throttle cable actually could be binding. The Stage 1 had the stud in the wrong hole, so I fabricated a new stud, which I installed alongside the original. I fiddled with it and determined that I didn't think there would be any interference issues. I think I zip tied something to be extra sure. How sure am I? This is worth another look.
Problem, continued:
So anyway, here's a typical day. It's around freezing outside, give the gas pedal two pumps, start the truck.
Truck catches and runs sluggishly. Idle is around 1200. As it warms up, idle climbs all the way to 2000.
Rev the gas. Idle stays stuck high. (One time when I was trying to get the idle to kick down by blipping the gas, I got a couple of backfires out of the carburetor, so I stopped doing that. Throttle response newly started at idle is not really smooth. It's kind of stumbly and unhappy. Not vrooooOOOOM, but more like vr oo o ooO O OOOOOM, possibly punctuated with backfires.)
Give up and put the truck in gear. Truck idles high down the road. Change gears, still high.
At some point in the cycle, I can get the idle down by blipping the gas hard a few times. It seems like it's getting stuck on the fast idle cam. The original dirt black q-jet idled itself down just sitting in the driveway, so this shiny JET Performance should be able to do that. It doesn't seem to be that anything is binding or sticking. I shot some WD-40 gel lube on the moving bits just for added insurance. (New product. I like it. I'm using it instead of white lithium in many applications.)
While driving the truck, I'm getting some stumble on acceleration.
There is this one hill that killed many classic cars back in my youth. I saw a flywheel explode out of a '67 Plymouth on that hill, when my buddy floored it, and KA-WHANNNGG!!!! So my truck isn't doing anything serious that I can tell, and actually seems to be handling this pretty well. I think I have 4.10 gears. I'm at 70 mph at the bottom of the hill. I get into the gas. Halfway up the hill, it's wanting to slow down, so I throw more gas to it, and I hear it make noises that make me think the engine just got a big shot of go fast juice, and the truck maintains speed. My new Jeep can't do that. I have to drop two gears to maintain speed up that hill. Which actually puts me in the same gear as the Chevy, come to think of it, but anyway.
So I'm not hearing any knocking, or noticing any signs of a stumble or other ignition problem, but my tach starts jumping up. Say my road speed and gears put me at about 3000 in this situation, the tach will blip up to 3500 or 4000 or 6000. It's fed off the negative side of the coil via a very direct and brand new wire I just ran myself, and I can't figure out why on earth it would jump up like that. I have Dakota Digital RTX gauges that seem to be working perfectly, and I've purchased running vehicles that cost less than those ridiculous luxury gauges, so I'm inclined to think it's something other than the RTX brain box. Something wacky is going on there. Maybe I'm getting misfires that I just don't notice, because the speed of the engine balances everything out. Why would misfires make the tach jump UP though? I don't know. This seems like a clue, but damfino what the clue is trying to tell me.
Vacuum setup:
When I installed the Stage 1, I copied the original vacuum setup as best I could. There was a big fitting in the back that was plugged off on my original. The new carb had empty threads there, so I transferred the nipple, and plugged it off with a proper cap. I have the vacuum advance running from the small bore port in the same general area where it was originally. I have the brake booster going wherever it did on the original. (Seems like that would go into the big empty fitting at the base, but that's not how it was rigged originally, so that's not how I have it rigged now.) I bought a new PCV valve, and have that running to the same port it did originally. All my vacuum hoses are brand new, and I went around and around with map gas and carb cleaner, and I can detect zero vacuum leaks.
I was going to post pictures, but discovered I didn't take any with the air cleaner off and all the vacuum hooked up. It's dark and freezing, so that can wait until tomorrow.
Plan of attack:
My ignition seems to be wonky, and I feel like I need to sort that out first.
I decided to stay with points, and got a meter with dwell capability, but my points are already out of whack after just 200 miles. I bought into the idea of replacing my points with a Pertronix Igniter II. Then I read the instructions, which required me to remove the distributor. The instructions for the recurve kit also required me to remove the distributor.
If I have to remove the distributor, I should just change the distributor. At least one of the wires coming off that thing is ancient, and every time I try to strip it, the insulation doesn't want to come off, and the conductors want to break. I can't figure out how to get that wire replaced without removing the distributor. Plus, it's 50 years old, and replacing a 50 year old critical engine component doesn't seem like a silly waste of money. Plus if I do this without my engine blowing a fireball through the carburetor, maybe I will be able to look women in the eye again, and get my first date in seven years. (Yeah, not likely. I'm a divorced male spinster at this point. But hey, I have a wicked awesome truck, a cool Jeep, and two Great Danes, so life is good!)
I ordered a plug-and-play Pertronix distributor that will have fresh everything, and a tunable mechanical advance. I can keep the original points distributor in case there is an EMP. I have a Painless wiring harness that required me to install a ballast resistor. I am going to bypass my brand new ballast resistor, and I have a Flame Thrower II coil, and a chrome coil bracket. Putting shiny billet aluminum and chrome stuff on a grungy old engine block is actually a tradition of mine. My first car had a 305 SBC whose sloppy timing chain ate a hole through the cover, and the only cover I could get was chrome, so I had a chrome timing chain cover on that leaky, worn out, barely running bucket of junk. (My 50 year old 350 is actually in far better shape than my 13 year old 305 was.)
I don't really expect throwing a hotter spark to fix anything, and I find myself questioning the wisdom of going this route. If I'm changing distributors and bypassing my ballast resistor anyway, I should just switch to HEI, and get a real HEI distributor. My choice to go with Pertronix is based almost purely on the fact that it will look more stock, and with a red cap, it will just look really, really cool, and I know the red cap will get me an extra 20 mpg, 200 hp, and 300 ft. lbs. of torque. I could get an HEI distributor with a red cap too, but HEI caps don't look as cool. Plus my chrome coil has a sticker with flames on it, and I know the flames will make my engine develop still another extra 20 mpg, for a total of 46 mpg! I will be getting the same mileage out of my 50 year old Chevy as I did out of my Ford Focus with the Special Fuel Economy package.
In all seriousness, I'm quesitoning the Pertronix distributor. I plan to use the silver springs, which would put me at 24° at 3500 RPM, but the advance limiter feature allows me to choose from 12°, 16°, or 20° total advance, so I'm not sure what's up with that. Don't install the limiters and I get 24°? Anybody know. The instruction sheet says these limiters can be mixed "in unique ways," resulting in 78 different possible curves, but there is no chart. I smell male bovine manure marketing nonsense there.
Okay, I think I'm done rambling. Sorry this was so long and disorganized. I tried to make it succinct and easy to follow, and I failed. Bourbon may or may not have been involved in the creation of this message. (Hint, it was.)
What I'm hoping to get out of this is for somebody to follow along, point out the holes in my thinking, and steer me toward how I can tune this bad old girl up so she runs like a scalded dog. Since, you know, I spent such an insane amount on parts for this old truck that I am broke for the next six years. Necessary, necessary parts.
Background:
I have a '74 C30 with a 350 and a 4-speed that is approaching 118,000 miles. When I drove the truck home, it was running very poorly under load, and would barely climb a hill. The divorced choke had been replaced with a manual, and the linkage popped off instantly when I tried to use it. The carburetor was bristling with little stubs of hoses with screws jammed into them. The original carburetor is a 7045222. The plugs were fouled, but I think it was fuel and not oil. It smoked a lot at first. Even in that state, it did idle just fine, and it seemed to idle itself down from the fastest idle to a street idle all by itself.
The truck would have had an A.I.R. pump, and that is long gone. If it had EGR, that is long gone too. It had an air cleaner with some kind of valve in it (vacuum?) that wasn't hooked to anything, and somebody had put a plug in the valve cover where the PCV system used to run. I replaced the plug with a breather, but not before I turned a custom, weirdly skinny breather nipple to fit neatly into what I didn't realize was a plug until I tried and failed to install the thing. D'OH! (I'm out of pictures, but I ended up with a proper grommet and some sensible auto parts store breather filter to replace that idiotic billet nonsense that didn't even work.)
You must be registered for see images attach
The guy who sold me the truck had just given it enough of a tune to get it running after sitting for 10 years in a corn field. He replaced the flywheel and starter, the vacuum advance on the distributor, the cap and rotor, and changed the points. It didn't start well, but it started. I drove it home, and the power steering pressure line exploded as I was backing it in. Hey, it got me home, so I knew I had bought a good truck!
I changed the plugs and wires, set the dwell to 28° (it was at like 36°), and changed the coil. After weighing my options on the fuel delivery system, I stayed with a q-jet, and I attempted to buy a really good rebuild. I installed a JET Performance Stage 1. I also put on one of those muscle car style air cleaners, because, you know, a cool air cleaner makes a truck go faster, right?
You must be registered for see images attach
You must be registered for see images attach
After putting on the Stage 1, I attempted to follow the setup instruction sheet. Step 1, set the idle. I couldn't get the idle below about 1200. The screw ceased to contact anything, and that was just the lower limit. Research pointed me at timing. Initial timing with vacuum disconnected was something on the order of 36°, which (my research seems to indicate) explains the high idle and hard starting.
I set the timing to 8°, which let me adjust the idle down to something around 500 on the screw. I cranked it up to about 850, and the idle was better.
I had performance issues that seemed to point to timing. I'm sorry I have to be vague about that, but it was a busy period in my life. I no longer remember specifically why I decided to put more timing in it. I cranked initial timing up to 12°, and that seemed magical. My son drove the truck too, and agreed that it ran better overall. Less hesitation, better transition to the secondaries.
Problems:
At this point right here and now, I've got 12° initial timing, and the idle is set at about 950. 950 is the bottom out point on the screw. It will go no lower.
I checked the total timing at 3500 RPM (vacuum disconnected), and it was 26°. 12 + 14 = 26, so I suspect my centrifugal advance isn't putting out. I should be getting about 24°out of the weights, right?
In 200 miles, my points have opened up from 28° to 36°, which seems weird. The oldest vehicle I ever owned before this had HEI, so I'm a points newbie.
I haven't pulled a spark plug to see how they're doing. The engine no longer smokes enough to make me think the rings are shot. It probably bears mentioning that I installed a new gas tank and dual fuel filters. The fuel pump was working well enough to push gas through a filter that was 99% obstructed with rust, so I figured the fuel pressure must be fine. I didn't check it. I did pour a quart of Marvel Mystery Oil into the crankcase, and I've run two cans of Sea Foam through the gas.
I get to buy gas frequently, since I'm getting about 6.5 mpg.
The biggest problem I'm having is idle speed after a cold start, and what behaves like a stuck throttle, even though it can't be a stuck throttle. I can jiggle the clip on the end and make my gas pedal flop like a fish, just flicking two fingers. I don't see any conceivable way that cable could be binding.
Note to self:
It's conceivable that my throttle cable actually could be binding. The Stage 1 had the stud in the wrong hole, so I fabricated a new stud, which I installed alongside the original. I fiddled with it and determined that I didn't think there would be any interference issues. I think I zip tied something to be extra sure. How sure am I? This is worth another look.
You must be registered for see images attach
Problem, continued:
So anyway, here's a typical day. It's around freezing outside, give the gas pedal two pumps, start the truck.
Truck catches and runs sluggishly. Idle is around 1200. As it warms up, idle climbs all the way to 2000.
Rev the gas. Idle stays stuck high. (One time when I was trying to get the idle to kick down by blipping the gas, I got a couple of backfires out of the carburetor, so I stopped doing that. Throttle response newly started at idle is not really smooth. It's kind of stumbly and unhappy. Not vrooooOOOOM, but more like vr oo o ooO O OOOOOM, possibly punctuated with backfires.)
Give up and put the truck in gear. Truck idles high down the road. Change gears, still high.
At some point in the cycle, I can get the idle down by blipping the gas hard a few times. It seems like it's getting stuck on the fast idle cam. The original dirt black q-jet idled itself down just sitting in the driveway, so this shiny JET Performance should be able to do that. It doesn't seem to be that anything is binding or sticking. I shot some WD-40 gel lube on the moving bits just for added insurance. (New product. I like it. I'm using it instead of white lithium in many applications.)
While driving the truck, I'm getting some stumble on acceleration.
There is this one hill that killed many classic cars back in my youth. I saw a flywheel explode out of a '67 Plymouth on that hill, when my buddy floored it, and KA-WHANNNGG!!!! So my truck isn't doing anything serious that I can tell, and actually seems to be handling this pretty well. I think I have 4.10 gears. I'm at 70 mph at the bottom of the hill. I get into the gas. Halfway up the hill, it's wanting to slow down, so I throw more gas to it, and I hear it make noises that make me think the engine just got a big shot of go fast juice, and the truck maintains speed. My new Jeep can't do that. I have to drop two gears to maintain speed up that hill. Which actually puts me in the same gear as the Chevy, come to think of it, but anyway.
So I'm not hearing any knocking, or noticing any signs of a stumble or other ignition problem, but my tach starts jumping up. Say my road speed and gears put me at about 3000 in this situation, the tach will blip up to 3500 or 4000 or 6000. It's fed off the negative side of the coil via a very direct and brand new wire I just ran myself, and I can't figure out why on earth it would jump up like that. I have Dakota Digital RTX gauges that seem to be working perfectly, and I've purchased running vehicles that cost less than those ridiculous luxury gauges, so I'm inclined to think it's something other than the RTX brain box. Something wacky is going on there. Maybe I'm getting misfires that I just don't notice, because the speed of the engine balances everything out. Why would misfires make the tach jump UP though? I don't know. This seems like a clue, but damfino what the clue is trying to tell me.
Vacuum setup:
When I installed the Stage 1, I copied the original vacuum setup as best I could. There was a big fitting in the back that was plugged off on my original. The new carb had empty threads there, so I transferred the nipple, and plugged it off with a proper cap. I have the vacuum advance running from the small bore port in the same general area where it was originally. I have the brake booster going wherever it did on the original. (Seems like that would go into the big empty fitting at the base, but that's not how it was rigged originally, so that's not how I have it rigged now.) I bought a new PCV valve, and have that running to the same port it did originally. All my vacuum hoses are brand new, and I went around and around with map gas and carb cleaner, and I can detect zero vacuum leaks.
I was going to post pictures, but discovered I didn't take any with the air cleaner off and all the vacuum hooked up. It's dark and freezing, so that can wait until tomorrow.
Plan of attack:
My ignition seems to be wonky, and I feel like I need to sort that out first.
I decided to stay with points, and got a meter with dwell capability, but my points are already out of whack after just 200 miles. I bought into the idea of replacing my points with a Pertronix Igniter II. Then I read the instructions, which required me to remove the distributor. The instructions for the recurve kit also required me to remove the distributor.
If I have to remove the distributor, I should just change the distributor. At least one of the wires coming off that thing is ancient, and every time I try to strip it, the insulation doesn't want to come off, and the conductors want to break. I can't figure out how to get that wire replaced without removing the distributor. Plus, it's 50 years old, and replacing a 50 year old critical engine component doesn't seem like a silly waste of money. Plus if I do this without my engine blowing a fireball through the carburetor, maybe I will be able to look women in the eye again, and get my first date in seven years. (Yeah, not likely. I'm a divorced male spinster at this point. But hey, I have a wicked awesome truck, a cool Jeep, and two Great Danes, so life is good!)
I ordered a plug-and-play Pertronix distributor that will have fresh everything, and a tunable mechanical advance. I can keep the original points distributor in case there is an EMP. I have a Painless wiring harness that required me to install a ballast resistor. I am going to bypass my brand new ballast resistor, and I have a Flame Thrower II coil, and a chrome coil bracket. Putting shiny billet aluminum and chrome stuff on a grungy old engine block is actually a tradition of mine. My first car had a 305 SBC whose sloppy timing chain ate a hole through the cover, and the only cover I could get was chrome, so I had a chrome timing chain cover on that leaky, worn out, barely running bucket of junk. (My 50 year old 350 is actually in far better shape than my 13 year old 305 was.)
I don't really expect throwing a hotter spark to fix anything, and I find myself questioning the wisdom of going this route. If I'm changing distributors and bypassing my ballast resistor anyway, I should just switch to HEI, and get a real HEI distributor. My choice to go with Pertronix is based almost purely on the fact that it will look more stock, and with a red cap, it will just look really, really cool, and I know the red cap will get me an extra 20 mpg, 200 hp, and 300 ft. lbs. of torque. I could get an HEI distributor with a red cap too, but HEI caps don't look as cool. Plus my chrome coil has a sticker with flames on it, and I know the flames will make my engine develop still another extra 20 mpg, for a total of 46 mpg! I will be getting the same mileage out of my 50 year old Chevy as I did out of my Ford Focus with the Special Fuel Economy package.
In all seriousness, I'm quesitoning the Pertronix distributor. I plan to use the silver springs, which would put me at 24° at 3500 RPM, but the advance limiter feature allows me to choose from 12°, 16°, or 20° total advance, so I'm not sure what's up with that. Don't install the limiters and I get 24°? Anybody know. The instruction sheet says these limiters can be mixed "in unique ways," resulting in 78 different possible curves, but there is no chart. I smell male bovine manure marketing nonsense there.
Okay, I think I'm done rambling. Sorry this was so long and disorganized. I tried to make it succinct and easy to follow, and I failed. Bourbon may or may not have been involved in the creation of this message. (Hint, it was.)
What I'm hoping to get out of this is for somebody to follow along, point out the holes in my thinking, and steer me toward how I can tune this bad old girl up so she runs like a scalded dog. Since, you know, I spent such an insane amount on parts for this old truck that I am broke for the next six years. Necessary, necessary parts.
You must be registered for see images attach
Last edited:
