Gary Lewis Posted January 16, 2019 Share Posted January 16, 2019 Rembrant, I think you might be on to something there... I am pulling a compression check tomorrow night. As much as I would hate for that to have happened, it sure would explain a lot! Did plenty of testing tonight and shot some video, but I will have to upload tomorrow. Getting too late and my laptop is at 4% and I left my charger at my office 🙃 I don't think a compression test is going to tell you much about the cam. Not that you shouldn't do it, but unless the intake valve isn't opening at all, the cylinder will probably get enough air to compress and look like it is working. I think the only way to find out about the cam, short of pulling it, is to pull the valve covers and measure the travel. And, wiped lobes would do what you've been seeing. Especially having half the cylinders not running, or not running much, given the exhaust temps. Link to comment Share on other sites More sharing options...
Ferdinand Posted January 16, 2019 Author Share Posted January 16, 2019 I don't think a compression test is going to tell you much about the cam. Not that you shouldn't do it, but unless the intake valve isn't opening at all, the cylinder will probably get enough air to compress and look like it is working. I think the only way to find out about the cam, short of pulling it, is to pull the valve covers and measure the travel. And, wiped lobes would do what you've been seeing. Especially having half the cylinders not running, or not running much, given the exhaust temps. Good point Gary. I will still try to do the compression test just to see what is happening. Although, I am at a bit of a loss as to what else could be causing my issues but all things considered, I'd really rather not have to pull the cam but I would like to find SOMETHING that could explain this funky lobing once I'm in gear... 🙃 Link to comment Share on other sites More sharing options...
Gary Lewis Posted January 16, 2019 Share Posted January 16, 2019 Good point Gary. I will still try to do the compression test just to see what is happening. Although, I am at a bit of a loss as to what else could be causing my issues but all things considered, I'd really rather not have to pull the cam but I would like to find SOMETHING that could explain this funky lobing once I'm in gear... 🙃 I had a 351W that had bad valves on three cylinders, two of which were adjacent in the firing order. It idled horribly. You wanted to shift to Neutral at a shop or you were sure the mirrors were going to come off. A bad cam can do the same thing. And you have four cylinders which aren't truly running. But, for grins you might check out the intake manifold and see which runners go to which cylinders. In other words, does one side of the carb feed those four cylinders? And, can you borrow that 500 CFM carb again and put it in gear using it? Lots easier than pulling valve covers and checking rocker movement. Link to comment Share on other sites More sharing options...
FuzzFace2 Posted January 17, 2019 Share Posted January 17, 2019 I had a 351W that had bad valves on three cylinders, two of which were adjacent in the firing order. It idled horribly. You wanted to shift to Neutral at a shop or you were sure the mirrors were going to come off. A bad cam can do the same thing. And you have four cylinders which aren't truly running. But, for grins you might check out the intake manifold and see which runners go to which cylinders. In other words, does one side of the carb feed those four cylinders? And, can you borrow that 500 CFM carb again and put it in gear using it? Lots easier than pulling valve covers and checking rocker movement. I knew that motor was not hitting on all 8 and why I kept saying firing order. After the fire you went with a new intake? What kind of gasket does it use between heads & manifold? If it is a metal type what type of sealer is used at the water & intake ports? See where I am going with this? If the heads & manifold angles are not the same and don't use enough sealer you could have a vacuum leak to the inside / valley. If you did get it on the road you might find it going thru oil and not know where it is going. If you think the can went flat I would pull the covers and crank it over / run it just to check movement. Dave ---- Link to comment Share on other sites More sharing options...
Ferdinand Posted January 17, 2019 Author Share Posted January 17, 2019 Some of last nights work: Working on getting a few more loaded. More narrative later. (Got home from Bible study too late to crank any tonight but I did snag a compression test gauge to try tomorrow night. Also snagging that friends 500cfm Edelbrock) Link to comment Share on other sites More sharing options...
Ferdinand Posted January 17, 2019 Author Share Posted January 17, 2019 I knew that motor was not hitting on all 8 and why I kept saying firing order. After the fire you went with a new intake? What kind of gasket does it use between heads & manifold? If it is a metal type what type of sealer is used at the water & intake ports? See where I am going with this? If the heads & manifold angles are not the same and don't use enough sealer you could have a vacuum leak to the inside / valley. If you did get it on the road you might find it going thru oil and not know where it is going. If you think the can went flat I would pull the covers and crank it over / run it just to check movement. Dave ---- Dave, Thanks for all the advice. After the fire I had the motor completely rebuilt. I had a slightly larger cam (280/289) put in but I had a really reputable shop do all the work. That's way above my pay grade! Anyhow, I went with an Edelbrock Airgap intake. I had to pull it once already because of an internal coolant leak caused by burs on the lower mating surfaces of the heads on both sides. The aftermarket intake sets in a little deeper than factory and kept me from getting a good seal. I filed all that down, and used Felpro Performance Gaskets with Printoseal for my rail gaskets and straight Permatex for front and rear. I did also put a thin coating of Permatex at the water jackets. I believe it is sealed rather well at this point. (I have been using Ultra Black Permatex and have had great results) Also, I do hope to do the compression checks tonight to see where I am there, but as you and a few others have suggested it does seem smarter to pull the valve covers again and measure from there. Plenty of work left to do, that's for sure! Thanks for following along. Link to comment Share on other sites More sharing options...
Ferdinand Posted January 18, 2019 Author Share Posted January 18, 2019 A few clips from the other night. These are all mid changes so I just wanted to show the vacuum and see if anyone thinks the air in the fuel line would be an issue? I have heard a lot of opinion but am a little short on proof or documentation as to it being a real issue: I am going to try and pull valve covers here one of the next few nights and see if I can measure valve movement, but I need to research and figure out which valves are which and how much movement there should be. I'd rather do that, the compression check and maybe a compressed air check for each cylinder before I pull the cam. Link to comment Share on other sites More sharing options...
Ferdinand Posted January 18, 2019 Author Share Posted January 18, 2019 I don't think a compression test is going to tell you much about the cam. Not that you shouldn't do it, but unless the intake valve isn't opening at all, the cylinder will probably get enough air to compress and look like it is working. I think the only way to find out about the cam, short of pulling it, is to pull the valve covers and measure the travel. And, wiped lobes would do what you've been seeing. Especially having half the cylinders not running, or not running much, given the exhaust temps. Gary, Your comment from a while back on what I did in the longer video, I must apologize. I have tried so many things at this point I lost track. And I edited that video 🙃 However, I don't believe it was anything significant. A simple throttle stab would dramatically change the way things sounded when I had the vac advance hooked up. Since being unhooked, the idle (and timing) has been a great deal smoother. I have also listened to a lot of videos of guys running a motor 180 degrees out (which is one of the problems I thought could be possible in my situation) but they barely could keep them running... Mine fires at the bump of the key when I am at 15-18 degrees BTDC timing and it takes gradual throttle all the way to nearly full throttle and it doesn't die. So, at this point I am thinking that I couldn't run as "well" as I have been so far if I was that far out timing-wise... Thoughts on that? I am going to try the smaller carb tomorrow evening as well. If it runs smoothly again, and we check it under load as well, I would say that it would have to be fuel at that point but I'm not ruling anything out at this point... Link to comment Share on other sites More sharing options...
Ferdinand Posted January 18, 2019 Author Share Posted January 18, 2019 EVTM in action‼️ Link to comment Share on other sites More sharing options...
Gary Lewis Posted January 18, 2019 Share Posted January 18, 2019 Gary, Your comment from a while back on what I did in the longer video, I must apologize. I have tried so many things at this point I lost track. And I edited that video 🙃 However, I don't believe it was anything significant. A simple throttle stab would dramatically change the way things sounded when I had the vac advance hooked up. Since being unhooked, the idle (and timing) has been a great deal smoother. I have also listened to a lot of videos of guys running a motor 180 degrees out (which is one of the problems I thought could be possible in my situation) but they barely could keep them running... Mine fires at the bump of the key when I am at 15-18 degrees BTDC timing and it takes gradual throttle all the way to nearly full throttle and it doesn't die. So, at this point I am thinking that I couldn't run as "well" as I have been so far if I was that far out timing-wise... Thoughts on that? I am going to try the smaller carb tomorrow evening as well. If it runs smoothly again, and we check it under load as well, I would say that it would have to be fuel at that point but I'm not ruling anything out at this point... I don't think it could possibly run "that" well if it was 180 degrees out. But, the fact that it runs much better (less poorly) with the vacuum disconnected is interesting. That suggests that timing is an issue. Have you checked to make sure the damper is correct? Bring #1 up on TDC and see that the mark aligns. Maybe you have the order correct but are way off on timing? But, that doesn't really work when we think about 1/2 of the cylinders running and 1/2 not. Anyway, something more to check. As for the EVTM, that's a laptop in a holder in your shop? That's cool! Link to comment Share on other sites More sharing options...
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