Well, I agonized over whether to share this here or not. It is a crappy old chevy and not a Cobra, but the info can easily transfer to a Cobra.
So, the wife wanted a fun car. Her dream car was always the older C3 vette, with the chrome bumpers.
We got one, but the old 350 was tired and carbrated with no choke, so she hated driving it and didn't trust it to not stall pulling out of the neighborhood onto the busty 2 lane road.
SO, I thought lets make it flashy but well mannered. How about a nice little 450 HP 383 with a megasquirted chinese 8 stack.
Oct 16, 2016#2
The chinese manifold had a bit of work that needed to be done to make it work well with megasquirt and have all of the features I wanted. Mainly, a idle air motor and good solid MAP sensor.
It was a bit of fabricating, but I have 2 separate vacuum chambers. A larger one with 8- 3/8" tubes, one to each port, then a smaller one with 4- 1/4" tubes, but Siamesed into each port. The larger port is for idle air motor and PCV valve. Another thing it provides is a little balance to make the carb syncing a little less critical. One thing about an EFI 8 stack, is the injector will pour the same fuel into each cylinder. If the air isn't perfectly balanced, it can make the mixture go out really quickly. Another thing I reasoned, is you can't sense manifold vacuum off of the IAC/PVC chamber with any reliability if the IAC is changing.
Another issue I didn't like about the hardware as it came, it had the rails on the outside of the throttle bodies, squirting at the hump in the manifold rather than on the hot intake valve. Swapping the throttle bodies around fixed this, but required the samllest Dodge Neon turbo injectors, and even then, the rails are slightly binding into each other. This also makes the plumbing difficult because there's no room for fittings.
Oct 16, 2016#3
Regulator and air cleaner base I made. I trimmed the stacks down on the lathe so they would fit under the hood.
I used the idle air motor for a 5.4L ford
Oct 16, 2016#4
Trying to keep as much as I could of the original car, I'm using the mechanical pump to fill a swirl pot under the hood. The excess fuel is returned to the tank via the vent line.
I used my CNC plasma table with a router mounted on it to carve a mold for the carbon fiber air cleaner base.
Oct 16, 2016#5
I drilled and threaded a block of aluminum to make a clean U turn for the fuel rails. Th only other option was a big hoop of fuel line.
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I REALLY liked Rick's wasted spark setup, so I did the same. But I had to make an oil pump drive.
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I also made all of the brackets. Since I don't have a good vacuum port, but a C3 has a ton of vacuum bullshit, I added a vacuum pump from a late 90's powerstroke van.
I've only began to tune on it, but so far, it runs great. No problems with idling with the AC on at 800 RPM. Stick it, and it jumps to attention... more so than you feel safe with a washy old vette.
To be continued.
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One more pic....
So, the wife wanted a fun car. Her dream car was always the older C3 vette, with the chrome bumpers.
We got one, but the old 350 was tired and carbrated with no choke, so she hated driving it and didn't trust it to not stall pulling out of the neighborhood onto the busty 2 lane road.
SO, I thought lets make it flashy but well mannered. How about a nice little 450 HP 383 with a megasquirted chinese 8 stack.
Oct 16, 2016#2
The chinese manifold had a bit of work that needed to be done to make it work well with megasquirt and have all of the features I wanted. Mainly, a idle air motor and good solid MAP sensor.
It was a bit of fabricating, but I have 2 separate vacuum chambers. A larger one with 8- 3/8" tubes, one to each port, then a smaller one with 4- 1/4" tubes, but Siamesed into each port. The larger port is for idle air motor and PCV valve. Another thing it provides is a little balance to make the carb syncing a little less critical. One thing about an EFI 8 stack, is the injector will pour the same fuel into each cylinder. If the air isn't perfectly balanced, it can make the mixture go out really quickly. Another thing I reasoned, is you can't sense manifold vacuum off of the IAC/PVC chamber with any reliability if the IAC is changing.
Another issue I didn't like about the hardware as it came, it had the rails on the outside of the throttle bodies, squirting at the hump in the manifold rather than on the hot intake valve. Swapping the throttle bodies around fixed this, but required the samllest Dodge Neon turbo injectors, and even then, the rails are slightly binding into each other. This also makes the plumbing difficult because there's no room for fittings.
Oct 16, 2016#3
Regulator and air cleaner base I made. I trimmed the stacks down on the lathe so they would fit under the hood.
I used the idle air motor for a 5.4L ford
Oct 16, 2016#4
Trying to keep as much as I could of the original car, I'm using the mechanical pump to fill a swirl pot under the hood. The excess fuel is returned to the tank via the vent line.
I used my CNC plasma table with a router mounted on it to carve a mold for the carbon fiber air cleaner base.
Oct 16, 2016#5
I drilled and threaded a block of aluminum to make a clean U turn for the fuel rails. Th only other option was a big hoop of fuel line.
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I REALLY liked Rick's wasted spark setup, so I did the same. But I had to make an oil pump drive.
Quote
Edit
Like
Dislike
Share
I also made all of the brackets. Since I don't have a good vacuum port, but a C3 has a ton of vacuum bullshit, I added a vacuum pump from a late 90's powerstroke van.
I've only began to tune on it, but so far, it runs great. No problems with idling with the AC on at 800 RPM. Stick it, and it jumps to attention... more so than you feel safe with a washy old vette.
To be continued.
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One more pic....