1975 Corvette
Moderators: MostMint, wxo, Fred32v, Basement Paul, ttamrettus
I have temporarily cured my self of my addiction to the Civilization game, and I have prepared my Lumina for sale, so I am starting back up on the Corvette.
I still do not have a resolution on my rear end issue, but I am not tackling that first.
Instead I have decided to work on the tach. I want to know the RPMs when the engine is going flat/cutting out.
So last night I went to work on taking out the tach. I had to take the dash pad out to get to the back of the tach, and to get that out I had to take the covers off the inside of the A-pillars. There was more underneath the dash that had to be removed. The dash is modular and all 3 parts had to be disconnected from the dash pad.
Eventually I got it apart and found a couple circuits on the tach circuit board were burnt out. This is what I was expecting. I think I can solder in a short piece of wire to fix each one.
As a bonus I found a build sheet for the car behind the dash! It shows all the original options for the car, and it shows the dealer that took delivery on the car. It was delivered to Charlotte NC. I think the dealer was LaPointe Chevrolet. I was quite pleased to find this, as it will help add value to the car.
Edit: I should also add that over the winter I have acquired the parts I need to make up a passenger side seat belt. The loop that connects the belt to the pillar I acquired for $25 with some other Corvette seat belt parts, and I got an entire set of belts from a 4th gen Camaro for $31. I will combine these parts with the Vette parts to make a seat belt for the passenger side.
I still do not have a resolution on my rear end issue, but I am not tackling that first.
Instead I have decided to work on the tach. I want to know the RPMs when the engine is going flat/cutting out.
So last night I went to work on taking out the tach. I had to take the dash pad out to get to the back of the tach, and to get that out I had to take the covers off the inside of the A-pillars. There was more underneath the dash that had to be removed. The dash is modular and all 3 parts had to be disconnected from the dash pad.
Eventually I got it apart and found a couple circuits on the tach circuit board were burnt out. This is what I was expecting. I think I can solder in a short piece of wire to fix each one.
As a bonus I found a build sheet for the car behind the dash! It shows all the original options for the car, and it shows the dealer that took delivery on the car. It was delivered to Charlotte NC. I think the dealer was LaPointe Chevrolet. I was quite pleased to find this, as it will help add value to the car.
Edit: I should also add that over the winter I have acquired the parts I need to make up a passenger side seat belt. The loop that connects the belt to the pillar I acquired for $25 with some other Corvette seat belt parts, and I got an entire set of belts from a 4th gen Camaro for $31. I will combine these parts with the Vette parts to make a seat belt for the passenger side.
[quote="Basement Paul"]Is that a mint rocketship on the hood?? :shock:
-BP[/quote]
-BP[/quote]
Update:
Before the swap meet this weekend I was able to make the repair to the tach. I soldered in two wires replacing the damage on the circuit board.
At Carlisle I spent a little over $100 at Corvette Central's booth on misc new parts. They were offering free shipping.
I also bought a used proportioning valve for $35. The guy had parted out a couple Corvettes so I took a chance the parts was working when it came off the car. Mine may be leaking.
I found another vendor who had new lower control arms for $150 each. I did not buy them but took a good look. I am more convinced than ever that my control arms are bent. I just need the gumption to drop $300 plus shipping to fix the problem.
Last night I tested out my tach repair. It did not work. Another circuit a little further up the chain burned out. There must be a bad resistor somewhere on the board. A replacement circuit board is $59.99 at Corvette Central. I'll be ordering one very soon.
Before the swap meet this weekend I was able to make the repair to the tach. I soldered in two wires replacing the damage on the circuit board.
At Carlisle I spent a little over $100 at Corvette Central's booth on misc new parts. They were offering free shipping.
I also bought a used proportioning valve for $35. The guy had parted out a couple Corvettes so I took a chance the parts was working when it came off the car. Mine may be leaking.
I found another vendor who had new lower control arms for $150 each. I did not buy them but took a good look. I am more convinced than ever that my control arms are bent. I just need the gumption to drop $300 plus shipping to fix the problem.
Last night I tested out my tach repair. It did not work. Another circuit a little further up the chain burned out. There must be a bad resistor somewhere on the board. A replacement circuit board is $59.99 at Corvette Central. I'll be ordering one very soon.
Wow another week has passed.
All my parts from I had ordered from Corvette Central are in.
Installed the new circuit board in the tach. Had to recalibrate the tach by removing the needle, and resetting it at zero, but it now works. I still need to finish dash reassembly.
Went to Canfield swap meent on Sunday - walked around for 5.5 hours - it was a large meet.
Only found a few vendors with Corvette parts. I had seen them before and there are no great deals with these regulars. Near the end of my day I found a 17 1/2" clutch fan that would work on my Corvette. It had a wire to make it direct drive still attached (indicating the clutch part was probably shot), and a couple fins were nicked, but it was on the $1 table!
The fan part alone is fetching 60-75$ on ebay plus shipping.
All my parts from I had ordered from Corvette Central are in.
Installed the new circuit board in the tach. Had to recalibrate the tach by removing the needle, and resetting it at zero, but it now works. I still need to finish dash reassembly.
Went to Canfield swap meent on Sunday - walked around for 5.5 hours - it was a large meet.
Only found a few vendors with Corvette parts. I had seen them before and there are no great deals with these regulars. Near the end of my day I found a 17 1/2" clutch fan that would work on my Corvette. It had a wire to make it direct drive still attached (indicating the clutch part was probably shot), and a couple fins were nicked, but it was on the $1 table!
The fan part alone is fetching 60-75$ on ebay plus shipping.
[quote="Basement Paul"]Is that a mint rocketship on the hood?? :shock:
-BP[/quote]
-BP[/quote]
-
TireSmoker
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Update:
The tach is in the driver side part of the dash, all the lights are connected. I completed fabricating the speaker mount, attached it to the dash top and reinstalled it. I put connectors on the speaker wires and connected them to the speakers. I thought about getting new speakers but then decided I wanted to finish the project and went ahead without any action.
Sold the Lumina and goofed off some this weekend so not much more to add. I plan to work on it again tonight.
The tach is in the driver side part of the dash, all the lights are connected. I completed fabricating the speaker mount, attached it to the dash top and reinstalled it. I put connectors on the speaker wires and connected them to the speakers. I thought about getting new speakers but then decided I wanted to finish the project and went ahead without any action.
Sold the Lumina and goofed off some this weekend so not much more to add. I plan to work on it again tonight.
[quote="Basement Paul"]Is that a mint rocketship on the hood?? :shock:
-BP[/quote]
-BP[/quote]
Yikes 11 days past and this is still not done. It looks like a dash, though the work at the bottom of the dash remains.
So I put almost two hours in last night trying to clean up some of those details under the dash. How could it take two hours and not be done you ask? Skip the next paragraph if you don't want the details.
Tightened the bolts holding the steering column to the firewall. Installed the cold air duct to the left side vent. Went to reinstall the bracket holding the courtesy light under the dash but it hits the hood latch handle. Remove the cold air duct. Dig through the factory build manual. There is no picture of the hood release anywhere so apparently they did not install that at the factory
. Found some pics of the ctsy light bracket. See my ctsy light bracket is bent, so I tighten down the hood release bracket, but first had to disconnect to left side of dash from a-pillar to reach the bolts. Tried correcting ctsy light bracket with pliers, but did not work well. Removed trip odometer reset button from the bracket and the ctsy light, used the vice and pliers to fix the bracket. Bracket is held on by two screws. I only have one that looks correct. Search through drawer of small screws to find a second. It is too long and bottoms out in the dash before pulling bracket tight. Find another and finally reinstall bracket. The ctsy light bulb is off, but if you push the orange wire further into the socket, the light comes on. Decide to investigate. Remove bulb and push orange wire, only it slides too far forward and now I can't get the contact on the end to go back into the bulb socket. There is a spring in there that is not working too well that needs to be stretched or replaced then put into base of the socket. I'll probably have to disconnect the fuse or the battery to fix this one.
Do you know how many times I had to crawl under the dash to get this far? I lost count.
I really can't complain though - I was working on my Corvette
So I put almost two hours in last night trying to clean up some of those details under the dash. How could it take two hours and not be done you ask? Skip the next paragraph if you don't want the details.
Tightened the bolts holding the steering column to the firewall. Installed the cold air duct to the left side vent. Went to reinstall the bracket holding the courtesy light under the dash but it hits the hood latch handle. Remove the cold air duct. Dig through the factory build manual. There is no picture of the hood release anywhere so apparently they did not install that at the factory
. Found some pics of the ctsy light bracket. See my ctsy light bracket is bent, so I tighten down the hood release bracket, but first had to disconnect to left side of dash from a-pillar to reach the bolts. Tried correcting ctsy light bracket with pliers, but did not work well. Removed trip odometer reset button from the bracket and the ctsy light, used the vice and pliers to fix the bracket. Bracket is held on by two screws. I only have one that looks correct. Search through drawer of small screws to find a second. It is too long and bottoms out in the dash before pulling bracket tight. Find another and finally reinstall bracket. The ctsy light bulb is off, but if you push the orange wire further into the socket, the light comes on. Decide to investigate. Remove bulb and push orange wire, only it slides too far forward and now I can't get the contact on the end to go back into the bulb socket. There is a spring in there that is not working too well that needs to be stretched or replaced then put into base of the socket. I'll probably have to disconnect the fuse or the battery to fix this one.Do you know how many times I had to crawl under the dash to get this far? I lost count.
I really can't complain though - I was working on my Corvette
[quote="Basement Paul"]Is that a mint rocketship on the hood?? :shock:
-BP[/quote]
-BP[/quote]
Good news - the dash is back together. The ctsy light on driver side under dash is back together though still not working right. I can address that on another day.
Took the car out on a test drive. Put that tach to work to help me diagnose the problem with the engine. The engine RPMs go up just fine at part throttle, well past 4000. But when I hit the gas it hesitates no matter what speed - even easing into it. This pretty much rules out the fuel pump but I still have blocked catalytic converter and now carb problems on the list.
Bad news - the temperature gauge is now not working. I know it worked last year but it is not working now.
Other -
Installed the new radio antenna mast so I could catch the race Sat. night.
I took a look at the $1 fan. One of the blades was bent slightly, so I straightened it. I thought about painting it - but I think it is going to get a basic cleaning and then installing. I hate to think how many of these I might have thrown out over the years.
I also did some research on the original dealer that sold the car: LaPointe Chevrolet at 531 East Trade St, Charlotte, NC. I knew they were the selling dealer from the build sheet. Prior internet searches did not uncover any businesses at that address. Now I know why - according to the satellite image that location is now a parking lot.
Took the car out on a test drive. Put that tach to work to help me diagnose the problem with the engine. The engine RPMs go up just fine at part throttle, well past 4000. But when I hit the gas it hesitates no matter what speed - even easing into it. This pretty much rules out the fuel pump but I still have blocked catalytic converter and now carb problems on the list.
Bad news - the temperature gauge is now not working. I know it worked last year but it is not working now.
Other -
Installed the new radio antenna mast so I could catch the race Sat. night.
I took a look at the $1 fan. One of the blades was bent slightly, so I straightened it. I thought about painting it - but I think it is going to get a basic cleaning and then installing. I hate to think how many of these I might have thrown out over the years.
I also did some research on the original dealer that sold the car: LaPointe Chevrolet at 531 East Trade St, Charlotte, NC. I knew they were the selling dealer from the build sheet. Prior internet searches did not uncover any businesses at that address. Now I know why - according to the satellite image that location is now a parking lot.
Update:
I think the temp gauge is working, at this point I am not sure the car has a thermostat. Eventually it will warm up.
I was also able to get the blower fan working – a wire had come off a relay under the hood.
Tried changing the carb to clear up the hesitation. Remove carb A and install the carb that came on it (carb B) back on the car but the accelerator pump did not work. The next night I took carb B off and planned to try to fix it. Just for fun I worked the throttle and the pump started working again. Put carb B back on the car and took it around the block. The exact same problem continues. Since two carbs have the same problem I doubt that the carb is the problem. Carb A said “told you it wasn’t me”.
After that I was convinced the catalytic converter (aftermarket) was blocked so I removed it. First I took off the back half of the exhaust – separating it from the front at the sleeve under the axle. The rest of the exhaust was welded so to get the convert off I tried grinding off the weld. After a while it became obvious I could not tell where the pipe ended and the weld began, so I decided to cut the converter pipe near the weld, trying not to cut the pipe underneath so I could put it back together. As it turns out the converter and the header pipe only overlapped each other by ½” so I did not cut the inside pipe. Putting it back together is probably going to require welding.
There was no obvious blockage in the converter, though some fine particles fell out of it when I tapped it on the ground. It looked like sand.
Took it out around the block, but the problem was exactly the same!
Now I am starting to suspect fuel pressure. I found a way to hook the pump up to the pressure gauge. The gauge showed a max 5 lbs pressure at idle, but the needle shot back and forth between 5 and almost zero each time the pump would make a cycle. Another interesting thing I noted is that there is never any pressure in the fuel line when I remove it from the carb. The pump has a low pressure return line, and I suspect there is a check ball in there that is not doing its job.
For fun I pulled the right side valve cover to see if the valves were opening and closing (easy way to see if a cam lobe was worn off). I ran it for a minute and they all looked good.
Autozone has a replacement pump in stock for about $28.
I think the temp gauge is working, at this point I am not sure the car has a thermostat. Eventually it will warm up.
I was also able to get the blower fan working – a wire had come off a relay under the hood.
Tried changing the carb to clear up the hesitation. Remove carb A and install the carb that came on it (carb B) back on the car but the accelerator pump did not work. The next night I took carb B off and planned to try to fix it. Just for fun I worked the throttle and the pump started working again. Put carb B back on the car and took it around the block. The exact same problem continues. Since two carbs have the same problem I doubt that the carb is the problem. Carb A said “told you it wasn’t me”.
After that I was convinced the catalytic converter (aftermarket) was blocked so I removed it. First I took off the back half of the exhaust – separating it from the front at the sleeve under the axle. The rest of the exhaust was welded so to get the convert off I tried grinding off the weld. After a while it became obvious I could not tell where the pipe ended and the weld began, so I decided to cut the converter pipe near the weld, trying not to cut the pipe underneath so I could put it back together. As it turns out the converter and the header pipe only overlapped each other by ½” so I did not cut the inside pipe. Putting it back together is probably going to require welding.
There was no obvious blockage in the converter, though some fine particles fell out of it when I tapped it on the ground. It looked like sand.
Took it out around the block, but the problem was exactly the same!
Now I am starting to suspect fuel pressure. I found a way to hook the pump up to the pressure gauge. The gauge showed a max 5 lbs pressure at idle, but the needle shot back and forth between 5 and almost zero each time the pump would make a cycle. Another interesting thing I noted is that there is never any pressure in the fuel line when I remove it from the carb. The pump has a low pressure return line, and I suspect there is a check ball in there that is not doing its job.
For fun I pulled the right side valve cover to see if the valves were opening and closing (easy way to see if a cam lobe was worn off). I ran it for a minute and they all looked good.
Autozone has a replacement pump in stock for about $28.
[quote="Basement Paul"]Is that a mint rocketship on the hood?? :shock:
-BP[/quote]
-BP[/quote]
Argh. The fuel pump was replaced but that did not fix the problem. Had an adventure the first test drive as the fuel filter was not in and the new pump was overpowering the needle and flooding the carb.
Decided to fix the exhaust as I was tired of all these test drives through the y-pipe only. So I cut the excess metal and ground off the old welds on the pipe before the catalytic converter ( alot of grinding under the car). I removed all the loose debris from inside the converer (I "accidently" put a 3/8 drive extension through it) then trimmed a little off the input end of the converter to true up the end of the pipe. I still need a clamp or weld where the converter connects to the pipe but the fit is snug.
It also dawned on me that maybe the vacuum advance was not working properly (hooked up to the wrong type of vacuum on the carb) so I disconnected it - to no avail.
I am starting to think there may be a problem with the main bearings. I had a problem with a 305 that had three spun mains and it would not make RPMs under power - a lot like this. Yikes I hope thats not it. This car shows 20 psi on the gauge at idle but who knows how good the gauge is. The needle is not smooth - it twitches.
Decided to fix the exhaust as I was tired of all these test drives through the y-pipe only. So I cut the excess metal and ground off the old welds on the pipe before the catalytic converter ( alot of grinding under the car). I removed all the loose debris from inside the converer (I "accidently" put a 3/8 drive extension through it) then trimmed a little off the input end of the converter to true up the end of the pipe. I still need a clamp or weld where the converter connects to the pipe but the fit is snug.
It also dawned on me that maybe the vacuum advance was not working properly (hooked up to the wrong type of vacuum on the carb) so I disconnected it - to no avail.
I am starting to think there may be a problem with the main bearings. I had a problem with a 305 that had three spun mains and it would not make RPMs under power - a lot like this. Yikes I hope thats not it. This car shows 20 psi on the gauge at idle but who knows how good the gauge is. The needle is not smooth - it twitches.
[quote="Basement Paul"]Is that a mint rocketship on the hood?? :shock:
-BP[/quote]
-BP[/quote]
-
booker
A main or rod bearing that actually turns inside the saddle, will (I gota assume) prohibit rotation.
The notch in the bearing itself, that locates the bearing in the saddle, will, if rotated, create an 'interference fit'.
As far as the hesitation, I'm thinking ignition, or carberation. Obviously, the accelerator pump, and all associated internal circuitry, should get inspected. Next I'd look at the distributor. Look for functioning centrifugal advance. I believe even with no advance, she'll rev nicely with no load. Put her in gear, (under load) and it's a different story.
Just my $.02.
And this advice comes from a guy who stripped down a functioning motor to a short block, chasing a miss.
The notch in the bearing itself, that locates the bearing in the saddle, will, if rotated, create an 'interference fit'.
As far as the hesitation, I'm thinking ignition, or carberation. Obviously, the accelerator pump, and all associated internal circuitry, should get inspected. Next I'd look at the distributor. Look for functioning centrifugal advance. I believe even with no advance, she'll rev nicely with no load. Put her in gear, (under load) and it's a different story.
Just my $.02.
And this advice comes from a guy who stripped down a functioning motor to a short block, chasing a miss.
-Mark
2012 Impala LT 3.6 VVTDI
300hp - a bit much for FWD!
2012 Impala LT 3.6 VVTDI
300hp - a bit much for FWD!
booker – had not thought of that yet. I don’t believe it is starving for fuel – though I will keep this in mind if I run out of other options.
Markss327 – I can hammer the thing from idle and it runs clean up to about 2800 RPM. That would eliminate the carb basics you mentioned IMO, besides I had two carbs on there and it acted the same, and finally I took one of the Q-jets apart looking for the loose secondary tubes but found none of that.
So I made up my mind I wanted to look at the main bearings. Before I did that I cut open the oil filter. This engine has less than 500 miles on the oli, yet there appeared to be very fine particles of metal in the bottom of the oil filter (like dust). It reminded me of the stuff you find in the bottom of your transmission pan when you change the fluid.
This finding was not conclusive, but coupling the oil filter, the gas that was in the oil when I bought the car, and the way the engine was behaving, I resigned myself to taking down the pan.
It was not that hard once I decided to do it. I loosened the exhaust from the manifolds and loosened the exh bracket bolted to the back of the tranny, removed the engine mount bolts, the oil pan bolts, and the cooling fan, then hooked the engine hoist to the front of the engine and lifted it up. I had to disconnect the power steering piston from the frame side to get the pan down, but out it came.
I have since looked at all the mains and they look good, barely any signs of wear at all.
So now I am cleaning parts. The pan is basically rust free but almost all the paint is gone. I plan to clean and repaint. I will also take this opportunity to replace the engine mounts, and put on a clutch fan. After that I need to figure out what’s next. BP insists I should change the distributor – I want to check under the driver side valve cover to look for a worn out cam lobe on that side. So I guess those are next.
Markss327 – I can hammer the thing from idle and it runs clean up to about 2800 RPM. That would eliminate the carb basics you mentioned IMO, besides I had two carbs on there and it acted the same, and finally I took one of the Q-jets apart looking for the loose secondary tubes but found none of that.
So I made up my mind I wanted to look at the main bearings. Before I did that I cut open the oil filter. This engine has less than 500 miles on the oli, yet there appeared to be very fine particles of metal in the bottom of the oil filter (like dust). It reminded me of the stuff you find in the bottom of your transmission pan when you change the fluid.
This finding was not conclusive, but coupling the oil filter, the gas that was in the oil when I bought the car, and the way the engine was behaving, I resigned myself to taking down the pan.
It was not that hard once I decided to do it. I loosened the exhaust from the manifolds and loosened the exh bracket bolted to the back of the tranny, removed the engine mount bolts, the oil pan bolts, and the cooling fan, then hooked the engine hoist to the front of the engine and lifted it up. I had to disconnect the power steering piston from the frame side to get the pan down, but out it came.
I have since looked at all the mains and they look good, barely any signs of wear at all.
So now I am cleaning parts. The pan is basically rust free but almost all the paint is gone. I plan to clean and repaint. I will also take this opportunity to replace the engine mounts, and put on a clutch fan. After that I need to figure out what’s next. BP insists I should change the distributor – I want to check under the driver side valve cover to look for a worn out cam lobe on that side. So I guess those are next.
[quote="Basement Paul"]Is that a mint rocketship on the hood?? :shock:
-BP[/quote]
-BP[/quote]