I apologize in advance for the length, but I am stumped and need some input from those more experienced than I am.
A little over a year ago, I was able to finally purchase my dream car project, specifically, a 1967 Camaro with a 468 big block.
When I bought it, it ran great. And clean. It had great throttle response and I was looking forward to getting it on the road.
I have not gotten it to the point of being able to actually drive it yet, so it has been sitting in my garage while I work on it.
One of the first things I did was rewire it from front to back with an American Autowire kit. The car has an electric fuel pump and while I was in the process of rewiring it, I inadvertently left the key on while doing some testing and did not disconnect the fuel pump. I realized it when I noticed that the fuel pressure gauge was reading somewhere around 12 - 13 lbs of fuel pressure. This is much higher than it should be for a carburetor, so I immediately switched the key off. I have since installed a switch on the fuel pump that only allows it to run for three seconds when the key is switched on unless it detects a signal from the tach wire.
Since that happened, the car has been running extremely rich. I'm talking burn your eyes and looks like the garage is on fire rich. I figured that having the pressure that high had overloaded the needle and seat or something like that to cause the problem. However, I have not been able to resolve the issue. I had basically rebuilt the carb and gotten no improvement, so I broke down and ordered a new carb and put it on. The car runs pretty much exactly like it did before, which has me wondering what the problem might be.
Let me tell you what I know about the engine, which is actually very little. The guy I got it from had gotten it in a trade and didn't have much information on the build, other than what he was told. The engine is a 3999289 casting, which tells me it started out as a 454 from the early to mid 70s. I am assuming it has been bored to get to the 468 cid. There is also a nitrous plate and the associated solenoids installed on the intake but I did not connect the wiring during the rewire. The transmission is a TH400 and the guy I bought it from said that it had been built for racing by a transmission shop at a cost of $3,800. I was told it had a 3,500 RPM stall converter in it.
The carb that was on it was a Holley double pumper, but I could not find any numbers on it to narrow it down beyond that. There is no choke on it. This was another thing that led me to replacing it in an attempt to resolve the rich running condition. I replaced it with a Holley Aluminum Street HP (0-82851SA) 850 cfm unit.
The intake is a Brodix single plane, but I do not know what model it is exactly, but it looks a lot like the BM2017. There is about a 1" spacer between the carb and the nitrous plate.
I have removed the valve cover on the driver's side to see what heads are on it and they are World Products Merlins with a casting number of 1-043. When I looked those up, everyone had a letter at the end of the casting number on theirs but I don't really see one on mine. There is something there and, if anything, it looks like a C, which would mean they have 320cc intake runners, a 119cc chamber and rectangle ports.
There are PRW 7/16" 1.7 roller rockers and Comp Cams 4806 rod guides installed on the heads. That is about all I can tell without further disassembly, which I am hoping I don't have to do.
I have no idea as to the internals on the short block. The idle is not overly "lopey" but it does sound healthy and still has great throttle response, even though it is running crazy rich.
The ignition consists of a MSD 6A box, Part No. 6200 and a MSD Pro-Billet Distributor, Part No. 85551.
Exhaust exits through Hooker headers.
When starting the car, I will usually pump the gas twice and then start it. When I first turn the key, it turns over like it has a low battery (newer Optima Red Top, purchased when I bought the car, and a MSD starter). It will do this for a couple of turns and then it will backfire, usually through the carb (with varying degrees of severity) but sometimes through the exhaust. After it does this, it will turn faster and usually fire up within a couple of rotations.
Since it has been running so rich, I pulled the plugs and found very different results on each of them, ranging from being completely black and fouled to a couple of them looking practically brand new, so something is definitely up. I replaced the plugs with the same brand that were in it, NGK V-Power UR4. Since then, I have only ran it for short periods and I pulled the plugs the other day to do a compression test and found basically the same thing I found when I pulled the original ones, they ranged from being heavily fouled to a couple still looking brand new.
The results of the compression test were:
1 = 180
3 = 180
5 = 170
7 = 190
2 = 135
4 = 180
6 = 180
8 = 180
I am a bit concerned with the #2 cylinder reading but the others are pretty consistent, even though they seem a bit high from what I have read about the results others have had.
Anyway, to wrap it up, does anyone have any ideas as to what might be causing the extremely rich condition, keeping in mind that it runs almost exactly same with the brand new carb installed.
I am thinking it may be timing related, but I guess it could be something internal with a valve or something. I purchased a timing light in order to attempt to check the timing but I must be doing something wrong. When I connect the light and shoot it on the balancer, I can barely see the timing mark coming around when the engine is idling, even with the advance knob turned all the way up. To me, that would make the timing way advanced and I am thinking the distributor would have to be locked out for it to be that far advanced at idle. I honestly don't even know how it would run, but it does. I loosened the hold down and rotated the distributor counterclockwise a small bit and it definitely ran worse until I put it back where it was.
I doubt anyone will read this, given the length but, if you do, I would be most appreciative of any clues as to what to do next.
Thanks,
Tim
A little over a year ago, I was able to finally purchase my dream car project, specifically, a 1967 Camaro with a 468 big block.
When I bought it, it ran great. And clean. It had great throttle response and I was looking forward to getting it on the road.
I have not gotten it to the point of being able to actually drive it yet, so it has been sitting in my garage while I work on it.
One of the first things I did was rewire it from front to back with an American Autowire kit. The car has an electric fuel pump and while I was in the process of rewiring it, I inadvertently left the key on while doing some testing and did not disconnect the fuel pump. I realized it when I noticed that the fuel pressure gauge was reading somewhere around 12 - 13 lbs of fuel pressure. This is much higher than it should be for a carburetor, so I immediately switched the key off. I have since installed a switch on the fuel pump that only allows it to run for three seconds when the key is switched on unless it detects a signal from the tach wire.
Since that happened, the car has been running extremely rich. I'm talking burn your eyes and looks like the garage is on fire rich. I figured that having the pressure that high had overloaded the needle and seat or something like that to cause the problem. However, I have not been able to resolve the issue. I had basically rebuilt the carb and gotten no improvement, so I broke down and ordered a new carb and put it on. The car runs pretty much exactly like it did before, which has me wondering what the problem might be.
Let me tell you what I know about the engine, which is actually very little. The guy I got it from had gotten it in a trade and didn't have much information on the build, other than what he was told. The engine is a 3999289 casting, which tells me it started out as a 454 from the early to mid 70s. I am assuming it has been bored to get to the 468 cid. There is also a nitrous plate and the associated solenoids installed on the intake but I did not connect the wiring during the rewire. The transmission is a TH400 and the guy I bought it from said that it had been built for racing by a transmission shop at a cost of $3,800. I was told it had a 3,500 RPM stall converter in it.
The carb that was on it was a Holley double pumper, but I could not find any numbers on it to narrow it down beyond that. There is no choke on it. This was another thing that led me to replacing it in an attempt to resolve the rich running condition. I replaced it with a Holley Aluminum Street HP (0-82851SA) 850 cfm unit.
The intake is a Brodix single plane, but I do not know what model it is exactly, but it looks a lot like the BM2017. There is about a 1" spacer between the carb and the nitrous plate.
I have removed the valve cover on the driver's side to see what heads are on it and they are World Products Merlins with a casting number of 1-043. When I looked those up, everyone had a letter at the end of the casting number on theirs but I don't really see one on mine. There is something there and, if anything, it looks like a C, which would mean they have 320cc intake runners, a 119cc chamber and rectangle ports.
There are PRW 7/16" 1.7 roller rockers and Comp Cams 4806 rod guides installed on the heads. That is about all I can tell without further disassembly, which I am hoping I don't have to do.
I have no idea as to the internals on the short block. The idle is not overly "lopey" but it does sound healthy and still has great throttle response, even though it is running crazy rich.
The ignition consists of a MSD 6A box, Part No. 6200 and a MSD Pro-Billet Distributor, Part No. 85551.
Exhaust exits through Hooker headers.
When starting the car, I will usually pump the gas twice and then start it. When I first turn the key, it turns over like it has a low battery (newer Optima Red Top, purchased when I bought the car, and a MSD starter). It will do this for a couple of turns and then it will backfire, usually through the carb (with varying degrees of severity) but sometimes through the exhaust. After it does this, it will turn faster and usually fire up within a couple of rotations.
Since it has been running so rich, I pulled the plugs and found very different results on each of them, ranging from being completely black and fouled to a couple of them looking practically brand new, so something is definitely up. I replaced the plugs with the same brand that were in it, NGK V-Power UR4. Since then, I have only ran it for short periods and I pulled the plugs the other day to do a compression test and found basically the same thing I found when I pulled the original ones, they ranged from being heavily fouled to a couple still looking brand new.
The results of the compression test were:
1 = 180
3 = 180
5 = 170
7 = 190
2 = 135
4 = 180
6 = 180
8 = 180
I am a bit concerned with the #2 cylinder reading but the others are pretty consistent, even though they seem a bit high from what I have read about the results others have had.
Anyway, to wrap it up, does anyone have any ideas as to what might be causing the extremely rich condition, keeping in mind that it runs almost exactly same with the brand new carb installed.
I am thinking it may be timing related, but I guess it could be something internal with a valve or something. I purchased a timing light in order to attempt to check the timing but I must be doing something wrong. When I connect the light and shoot it on the balancer, I can barely see the timing mark coming around when the engine is idling, even with the advance knob turned all the way up. To me, that would make the timing way advanced and I am thinking the distributor would have to be locked out for it to be that far advanced at idle. I honestly don't even know how it would run, but it does. I loosened the hold down and rotated the distributor counterclockwise a small bit and it definitely ran worse until I put it back where it was.
I doubt anyone will read this, given the length but, if you do, I would be most appreciative of any clues as to what to do next.
Thanks,
Tim
