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| Engine & Carb Questions https://slantsix.org/forum/viewtopic.php?t=57674 |
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| Author: | kxracer728 [ Mon May 11, 2015 5:36 pm ] |
| Post subject: | Engine & Carb Questions |
Ok, my slant started giving me problems it went from running normally to running rough while getting on the highway one day. I was able to get it to start and idle again by rotating the distributor about an inch counter clockwise... I don't know if that advanced or retarded the timing or where the base timing is right now because I haven't put my timing light on it. I wonder what could have caused me having to readjust the distributor to that degree to get it Running again? The distributor was tight so it's not like it had moved to cause the problem Secondly, I put on a holley 1920 economaster carb that I've had for a while a rebuilt old stock. It has a 55 main jet the other 1920 I was using had a 55 main jet too. The carb seems to be working besides I don't have a choke. I've set the fast idle cam screw on the highest step the choke plate is closed (for a 1920) and opens completely after warmed up but there's no high idle speed no 1600 rpms...Why? So it's hard to start Are there other components within the carb that could be causing this problem? Is there more than the choke plate being closed increasing fuel verse air to create the higher idle speed? |
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| Author: | nm9stheham [ Tue May 12, 2015 10:05 am ] |
| Post subject: | |
Clockwise is retarded so CCW would be advancing the timing. An inch on the outer diameter of the distributor is a LOT.... like 60-80 crankshaft degrees! First thing that comes to mind is the the timing chain has worn and jumped a couple of teeth on the chain. That would retard the cam AND the distributor, so advancing the distributor compensated for that. Of course, the cam is still way out of time..... Did it run normally after moving the distributor or still crappy (idle only)? The cam being way of of time due to jumping teeth on the chain would do that. Chains are relatively easy to replace..... Are the carb issues separate from the timing issue? That is not clear.... |
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| Author: | kxracer728 [ Tue May 12, 2015 10:34 am ] |
| Post subject: | |
I was wondering if it jumped time and readjusting the distributor helped compensate for it. If it jumped time is it a given that it would bend valves? Or is that not always the case? It seems to run descent holds idle maybe some power loss...i think the carb choke problem is separate from timing issue. I'm going to keep learning and working with getting a working choke going One thing too is it's making a whistling sound...sounds like its coming from the intake side of the engine. I've checked for vacuum leaks but so far can't find any |
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| Author: | nm9stheham [ Tue May 12, 2015 6:23 pm ] |
| Post subject: | |
It'll bend valves on a so-called interference engine. Other will know better but I do not believe the /6 is an 'interference' engine in stock form. Whistles can come from the carb or air cleaner too... so could be a number of things. |
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| Author: | Charrlie_S [ Tue May 12, 2015 7:01 pm ] |
| Post subject: | |
170 is an interference engine, 225 is not, and I don't think a 198 is. |
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| Author: | nm9stheham [ Wed May 13, 2015 6:07 am ] |
| Post subject: | |
Quote: I was wondering if it jumped time and readjusting the distributor helped compensate for it. If it jumped time is it a given that it would bend valves? Or is that not always the case? Well, if it jumped time, then it is likely going to do it more.... and maybe soon. I'd have the timing cover coming off real soon and a new chain going in. You'll be pleased with the general driveability improvement anyway.It seems to run descent holds idle maybe some power loss...i think the carb choke problem is separate from timing issue. I'm going to keep learning and working with getting a working choke going One thing too is it's making a whistling sound...sounds like its coming from the intake side of the engine. I've checked for vacuum leaks but so far can't find any You can do a check on the timing chain; remove the valve cover, set the timing mark on the damper to TDC (0), and look at the valves for cylinders 1 and 6. The 2 valves on one or the other cylinder will be slightly open (overlap). They should be exactly equally open if the cam is in time; if it jumped the timing chain, then the exhaust will be more open than the intake. |
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| Author: | kxracer728 [ Thu May 14, 2015 5:02 pm ] |
| Post subject: | |
Thanks for the help! I've got a carb rebuild kit for the 1920...I don't think the accelerator pump is working right that should help make starting it easier... I bought another used motor about a month ago the previous owner said it was a good runner (hopefully that's true) my plan is to work with that one since it's out of the truck and make it the replacement. I'll definitely put a new timing chain and gear set most likely a double roller...I'll check the compression on it and see what that's like. What would be considered good compression range? |
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