Breathing new life into the 318 in the Scamp!
Hi everyone,
I wanted to share my latest project on this forum, as it may interest others who are looking to get some more power out of a 318 on a budget, with a combination of bolt on parts (some very new and some old) that are set up for an increase in fuel economy and performance, for good throttle response and torque from idle. This is for a driver vehicle in mind that will see the road, with torque increase over a factory engine.
The engine that I'm working on is a '72 cast '73 vintage, EGR 318. Nothing spectacular, but I wanted to see what it could do with a lung transplant. :)
So, after doing a lot of research, I wanted something that would deliver some low end power, keep the throttle response and vacuum index up for torque off of idle, I decided to go with a small primary circuit carburetor, with a high velocity intake and utilize the high velocity with a swirl port cylinder head. I wanted something that will help the engine use the fuel more efficiently, make power more effectively and give me the option to motivate the wheels if I want to, without terrorizing my gas milage if I want to keep out of it!
I thought about using a Carter ThermoQuad carburetor for this build, and while I have a lot of respect for them and have a couple that I can use, I wanted to try something a little more advanced and accessible, so I went with the new Street Demon.
This carburetor has three primary boosters like a quadrajet for high atomization off of three booster rings, instead of one per primary, and utilizes a lot of the design charactaristics of the ThermoQuad, like it's temperature insulating fuel bowl and tiny 1 3/8" primary bores, while simplifying the entire design and crushing it all down to a square bore pattern, instead of retaining the spread bore designs that this was reverse engineered from, for more centralized fuel delivery across the manifold planes. It also does the same thing at high RPM as a notched plane divider manifold (LD340), because it has a bridged secondary goggle valve and allows equalization at secondary open, when you need it. Technically, I guess this is a 3bbl carburetor.
Barry Grant no longer owns the Demon company. When I called about factory jet sizes to order them, I was put on a five minute call back list and was contacted by a Holley rep. I imagine that the guys at BG carburetors having access to Holley's design equipment is what spawned the creation of this carburetor.
The Street Demon 625 comes factory with .080" / .080" Primary/ Seconday jets, for sea level jetting, just like the Edelbrock 1405/ 1406. That information was nowhere to be found, anywhere else online for some reason, even at their website when I searched. You find out soon enough when you get the carburetor delivered, but it was difficult for me to gather that info to also order the jets and metering rods for the one I'm using for 6000ft elevation above sea level, here in Denver, Colorado.
The intake manifold that I decided on was a bit of a challenge to get in it's stock form, but I managed to find a stock 318 intake port spec Edelbrock LD4B (Chrysler PN# 2836139 offered in Direct Connection catalogs) to manage the fuel induction.
The reason I wanted this manifold in particular was because of it's increased velocity and true 273/ 318 port size. After doing a lot of measuring, I found a couple of very close candidates, but none of them were as true as the LD4B to factory spec size. I wanted to keep the port volume down and get a close match between the intake and head port, for smooth flow operation and this was the best option, even though it took me two months and several offers on other intakes that had been ported for 340/ 360 sizes.
One thing I did discover, though, is that the Weiand Stealth manifold that Holley still makes is nearly a carbon copy of this intake manifold. They also sell it in a spread bore carb layout with the same runner and port design, as the Weiand Action Plus.
I set the two manifolds side by side that I had and while there were subtle differences in the outer casting, the insides of the runners were nearly identical in shape and volume. The rise of the Weiand manifold was a touch taller at the carb base, putting it at about the same height as a Mopar Performance M1, with the 180 runner design of the Edelbrock LD4B. So if you want to try this combo without hunting for fossils, use a Stealth.
The cylinder heads that I am using are dead stock, pre-magnum, 1980's vingage "...302" cast heads. The swirl porting in these heads is very distinct and under high velocity, do just that extremely well.
I picked up this air cleaner in haggard shape at a swap meet a long time ago. After some hammer and dolly work, some filing, primer, 800 grit wet sanding, cleaning and a tac cloth and a can of high gloss black rustoleum, I came up with something that isn't overpowering for the top of the engine.
The sticker is from the truck engine air cleaner. I don't think Chrysler ever offered a high performance 318 of any kind in '73, but I don't think the numbers are too far off. I thought I'd go with a modest look, rather than a bright orange eye grabbing deal.
I will be back soon with some pictures of the cylinder heads as I clean them up at the shop, as well as the engine bay before and after the swap. I'm going to be making a galvanized fuel line for this that looks right, as I'm not a fan of all rubber fuel delivery.
I'm also on the fence with valve covers. I'm thinking about getting stamped steel Direct Connection ones and building some girdles to spot weld on to the bolt/ gasket flange to keep them from leaking and painting them to match the engine. I'd also like better wire dividers that will better orient the spark plug wires to fit the truck 360 manifolds that doesn't rise on the driver's side. I don't want this engine to call too much attention to itself at first glance, but I want to have some fun with it.
I'll get a gallery link of the car soon, but these are the fenders where all of this gear will be living between. -
Dave
Hi everyone,
I wanted to share my latest project on this forum, as it may interest others who are looking to get some more power out of a 318 on a budget, with a combination of bolt on parts (some very new and some old) that are set up for an increase in fuel economy and performance, for good throttle response and torque from idle. This is for a driver vehicle in mind that will see the road, with torque increase over a factory engine.
The engine that I'm working on is a '72 cast '73 vintage, EGR 318. Nothing spectacular, but I wanted to see what it could do with a lung transplant. :)
So, after doing a lot of research, I wanted something that would deliver some low end power, keep the throttle response and vacuum index up for torque off of idle, I decided to go with a small primary circuit carburetor, with a high velocity intake and utilize the high velocity with a swirl port cylinder head. I wanted something that will help the engine use the fuel more efficiently, make power more effectively and give me the option to motivate the wheels if I want to, without terrorizing my gas milage if I want to keep out of it!
I thought about using a Carter ThermoQuad carburetor for this build, and while I have a lot of respect for them and have a couple that I can use, I wanted to try something a little more advanced and accessible, so I went with the new Street Demon.
This carburetor has three primary boosters like a quadrajet for high atomization off of three booster rings, instead of one per primary, and utilizes a lot of the design charactaristics of the ThermoQuad, like it's temperature insulating fuel bowl and tiny 1 3/8" primary bores, while simplifying the entire design and crushing it all down to a square bore pattern, instead of retaining the spread bore designs that this was reverse engineered from, for more centralized fuel delivery across the manifold planes. It also does the same thing at high RPM as a notched plane divider manifold (LD340), because it has a bridged secondary goggle valve and allows equalization at secondary open, when you need it. Technically, I guess this is a 3bbl carburetor.
Barry Grant no longer owns the Demon company. When I called about factory jet sizes to order them, I was put on a five minute call back list and was contacted by a Holley rep. I imagine that the guys at BG carburetors having access to Holley's design equipment is what spawned the creation of this carburetor.
The Street Demon 625 comes factory with .080" / .080" Primary/ Seconday jets, for sea level jetting, just like the Edelbrock 1405/ 1406. That information was nowhere to be found, anywhere else online for some reason, even at their website when I searched. You find out soon enough when you get the carburetor delivered, but it was difficult for me to gather that info to also order the jets and metering rods for the one I'm using for 6000ft elevation above sea level, here in Denver, Colorado.
The intake manifold that I decided on was a bit of a challenge to get in it's stock form, but I managed to find a stock 318 intake port spec Edelbrock LD4B (Chrysler PN# 2836139 offered in Direct Connection catalogs) to manage the fuel induction.
The reason I wanted this manifold in particular was because of it's increased velocity and true 273/ 318 port size. After doing a lot of measuring, I found a couple of very close candidates, but none of them were as true as the LD4B to factory spec size. I wanted to keep the port volume down and get a close match between the intake and head port, for smooth flow operation and this was the best option, even though it took me two months and several offers on other intakes that had been ported for 340/ 360 sizes.
One thing I did discover, though, is that the Weiand Stealth manifold that Holley still makes is nearly a carbon copy of this intake manifold. They also sell it in a spread bore carb layout with the same runner and port design, as the Weiand Action Plus.
I set the two manifolds side by side that I had and while there were subtle differences in the outer casting, the insides of the runners were nearly identical in shape and volume. The rise of the Weiand manifold was a touch taller at the carb base, putting it at about the same height as a Mopar Performance M1, with the 180 runner design of the Edelbrock LD4B. So if you want to try this combo without hunting for fossils, use a Stealth.
The cylinder heads that I am using are dead stock, pre-magnum, 1980's vingage "...302" cast heads. The swirl porting in these heads is very distinct and under high velocity, do just that extremely well.
I picked up this air cleaner in haggard shape at a swap meet a long time ago. After some hammer and dolly work, some filing, primer, 800 grit wet sanding, cleaning and a tac cloth and a can of high gloss black rustoleum, I came up with something that isn't overpowering for the top of the engine.
The sticker is from the truck engine air cleaner. I don't think Chrysler ever offered a high performance 318 of any kind in '73, but I don't think the numbers are too far off. I thought I'd go with a modest look, rather than a bright orange eye grabbing deal.
I will be back soon with some pictures of the cylinder heads as I clean them up at the shop, as well as the engine bay before and after the swap. I'm going to be making a galvanized fuel line for this that looks right, as I'm not a fan of all rubber fuel delivery.
I'm also on the fence with valve covers. I'm thinking about getting stamped steel Direct Connection ones and building some girdles to spot weld on to the bolt/ gasket flange to keep them from leaking and painting them to match the engine. I'd also like better wire dividers that will better orient the spark plug wires to fit the truck 360 manifolds that doesn't rise on the driver's side. I don't want this engine to call too much attention to itself at first glance, but I want to have some fun with it.
I'll get a gallery link of the car soon, but these are the fenders where all of this gear will be living between. -
Dave
