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Stock 360 output |
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Sonic Silver
Supporter of TheAMCForum Joined: Nov/23/2011 Location: East Tennessee Status: Offline Points: 7949 |
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WesternRed
AMC Addicted Joined: Aug/03/2010 Location: Australia Status: Offline Points: 5798 |
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I am getting all gears, but the factory shifter certainly makes things a little interesting.
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WesternRed
AMC Addicted Joined: Aug/03/2010 Location: Australia Status: Offline Points: 5798 |
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Spoke to the local performance converter shop today and they didn't think changing the converter at this point in time was a good idea. Considering they charge $1,300 (Aussie dollars)for a good converter, they suggested upgrading other areas for more power first, then build the converter for the final combination. That means at least more compression and a lot bigger cam to go with it.
I'll be able to do some more testing tomorrow and can go from there I guess. |
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tached_out
AMC Nut Joined: Feb/08/2008 Location: Vancouver, BC Status: Offline Points: 328 |
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Interested to hear how you did.
I don't think anyone asked you what your end goal is.
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WesternRed
AMC Addicted Joined: Aug/03/2010 Location: Australia Status: Offline Points: 5798 |
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I can run 11.00 before I have to install a cage, so that is the goal, but not on this motor I guess.
Unfortunately I didn't get to run today, was a car show at the strip with some racing on the side. They decided at the last minute that they didn't want any trailer queens running, only "street cars" that were driven there, which was a bit annoying after being advised otherwise previously. Anyway I did check a few things before heading down there. I made a better masking tape timing indicator and it looks like I have 15 degrees initial, plus 15 degrees mechanical, plus 8 degrees vacuum advance, so 38 degrees total. Would have been to test this and probably more initial without the vacuum advance to see what happens. I did verify TDC with a dial gauge rigged up down the spark plug hole and as far as I can tell, it's pretty much spot on. Also checked the plugs, which look pretty good to me: Did a compression test: 1: 130 2: 130 3: 130 4: 130 5: 125 6: 120 7: 125 8: 130 Ok I guess for a stock 360 with 8.5:1 compression. I have a leak down test kit but couldn't get that to work, I think it's broken and really a 2 man job as far as I can see, so gave up at that point. Not sure what next other than seeing if it runs any better with more timing. |
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70amcpwr
AMC Addicted Joined: Feb/16/2011 Location: Moultonboro NH Status: Offline Points: 1485 |
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Compression is down a bit for what you want to accomplish, good that all them besides #6 are very close though. Past history for me has shown 5+6 to be the lower compression cylinders on an older motor.
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70amcpwr You just can't fix stupid.
SOLD 1970 BBO Javelin, wifes 73 AMX 360 4spd. Next project 1969 AMX |
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WesternRed
AMC Addicted Joined: Aug/03/2010 Location: Australia Status: Offline Points: 5798 |
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Ha ha, yes 11's would be the pipe dream when I build a 401 for it.
I'm probably deluded, but I was hoping I could run low 13's with bolt on mods on this motor. I don't think there is enough compression there to run the 280H (needs 9:1), 270H perhaps? I did just lash out on a Holley Sniper setup since I can use the 600 Holley from the Gremlin on my Jeep, which doesn't have a carby at the moment. Not sure if there is much to be gained by running the Sniper and Torker on the current 360 though. |
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tached_out
AMC Nut Joined: Feb/08/2008 Location: Vancouver, BC Status: Offline Points: 328 |
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You still don't have enough spark advance.
The 8 degrees vacuum you speak of, isn't there at wide open throttle. So you only have 30 when you need 38. You can ad that 8 degrees and quite a bit more to your 38.
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tached_out
AMC Nut Joined: Feb/08/2008 Location: Vancouver, BC Status: Offline Points: 328 |
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Free advice time. I’m sorry if this isn’t welcomed. Let me know and I’ll shut up. You have a drag strip only car. Disconnect the vacuum advance. Take it completely out of the equation. Vacuum advance is only needed when there is little to no load on the engine. let me explain; A stock passenger car engine has to perform adequately and offer the greatest fuel economy under a wide variety of operating conditions. From idle to cruising down the highway, the throttle is barely open. That means very little air and fuel can enter the cylinder during an intake event. The result, when that mixture is compressed, is you have relatively few air and fuel molecules in the combustion chamber and they’re relatively far apart. Under these conditions, the mixture is very slow to burn. The chain reaction (combustion flame front) is hindered by how far apart those molecules are. This is when you will typically need about 50 degrees of total spark advance at cruising rpm and about 40 degrees at idle. A good analogy might be to consider yourself trying to cross a stream. If the stepping stones are far apart you will have to jump from one then to the other. Once you land on a stone, you will need to build up enough energy to jump to the next one. All the while time is passing. Since time is of the essence here, you need to get started much earlier. Under wide open throttle conditions. The intake isn’t restricted. Well yours is somewhat but I’ll save that for another rant. Much more air and fuel will enter the cylinder on the intake stroke. When it’s compressed, there will be many more molecules in there and they’ll be very close together. The flame front as a result, will travel very fast. Using the stream analogy, you’ll have a paved path to run flat out across. It’ll take less time to cross, so you can start later. Here you only need about 38 degrees. Any additional vacuum advance won’t be available because there won’t be enough vacuum to make it work. This is good because it would destroy your engine if it was. Your race car only needs to start, idle around the pits and go go down the track at wide open throttle. You don’t need vacuum advance period. Here’s a tuning tip. With your current setup, with the engine idling, advance your distributor to 38 degrees. Watch how much your rpm increases and the exhaust gets quieter. It’s doing that because it’s producing more power by burning the fuel in the cylinder where it belongs and not the exhaust pipe. You will now close your butterfly more to get down to your desired rpm. This will give you a stronger vacuum reading and make the carburetor much more sensitive to the idle mixture screw adjustments. |
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WesternRed
AMC Addicted Joined: Aug/03/2010 Location: Australia Status: Offline Points: 5798 |
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Your words are not lost on me tached-out, I just like to test things along the way to see what does and doesn't happen, it adds to the learning experience. The plan would have been to do a couple of runs with the current timing setup then drop the vacuum advance and add more initial to bring it back up to 38. After that I will need to find some advance springs to bring the advance on earlier. It would help if I had a dial-back timing light so that I can actually see what the advance curve looks like.
As for the 600 Holley/Performer combination, I can see that being a limitation at the top end, but at the moment it is all done by 5,000 RPM, probably earlier. I can't really see that a Torker and bigger cby will help me get off the line any quicker, since that is where the problem is at the moment, happy to be proven wrong on this though. I think the big question is how far I can go with the cam on a stock low compression engine? I know the real answer is to open the motor and pump some compression into it, but then the dollars start to add up big time. Could try to find some cast 343 flat tops and a set of ARP rod bolts I guess for a real budget build, but once the motor comes apart, it never ends up that way. Edited by WesternRed - Dec/17/2017 at 5:32am |
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