I'll start by saying this-
I'm a teen hot rodder, so I don't know everything!
Alright, I own a 1978 Camaro, and I'm putting an Edelbrock Supercharged 383 motor in it this summer, and I need some advice on how to do my setup. (Where better to go than the Internet...)
Alright, so I have these parts on my shopping list-
Supercharger
Carb (x2)
Heads
And then MSD 6 BTM and other timing parts...
What I need is to know this-
Will my engine blowout?
I'll be generating about 5-6.5psi of boost, and will have H345NCP .030 over pistons. (Sealed Power pistons, coated)
I have 1:6 ratio roller rockers with a .594 roller camshaft
If you need anything else just ask and I'll have the answer for you.
I need advice for fuel (going for both mechanical and electric fuel pumps)
I need advice for CR (10:1)
I need advice for what drivetrain to use (I have a TCI TH400 atm...)
I need a lot of advice. Anything helps!
~JThanks in advance!!
Well Dude, at least you didn't come here with an attitude. I'll stay up past my bedtime to help someone who comes across as genuine like you do. Let the education begin.
First, carburetors are very fuel-pressure sensitive. Flow is controlled by a tiny little needle and seat arrangement, whereby as the flow of fuel into the bowl increases, it raises the bowl float. A tang on the backside of the float pushes up against a needle that has a pointed tip made from a composite material so that it will seal well in the seat. As the needle approaches the needle seat, the flow of fuel begins to slow down until the needle is fully seated in the seat and flow comes to a halt. That is, flow comes to a halt if the fuel pressure is within range of the ability of the needle and seat to control fuel flow. If pressure exceeds the ability of the needle and seat to control the flow, then the bowl overfills and fuel runs out into the intake manifold, where it becomes a fire hazard as well as flooding the motor with fuel and creating a tuning nightmare for you if you're unaware it's happening.
http://4.bp.blogspot.com/-OwZJ_wpag.../s640/0802phr_05_z+how_carburetors_work+.jpge
Most any modern 4-bbl carburetor will operate well up to 5 to 6 psi of fuel pressure. Over that and you're risking the scenario I explained above. I have had several fellows tell me that their Edelbrocks work best with 4 3/4 to 5 psi. So, understand that high pressure is not what you want here. High volume will serve you well however and if I were doing it for you, I'd run 1/2" fuel lines from the tank to the carburetor. I like to run a supply line and a return line to prevent the fuel pump from dead-heading and burning itself out, because you know where it will burn out, on the bypass construction road just outside Burnt Stump (population 23, including 7 burros, and no cell phone reception) at 3:00 in the morning. I'd install a premium fuel filter before and after the pump and inspect them weekly. I'd also forget the mechanical pump idea. One electric pump will provide all the volume and pressure you will need. Mount your fuel pressure regulator and pressure gauge up close to the carburetors.
Now, as far as static compression ratio, if you're going to use pump gas, then you will have to pay attention to this chart from Blower Drive Service. The static compression ratio is shown down the left column and the blower pressure is shown across the top of the chart. The shaded area shows the maximum pressure to be used with what static compression ratio. In other words, you can see on the chart that an 8.00:1 SCR motor is limited to 8 lbs of boost on pump gas and an 8.5:1 SCR motor is limited to 6 lbs of boost. If you were to use the 10.0:1 SCR that you referenced above, the boost would have to be limited to 4 lbs to prevent detonation and complete destruction of the motor.
Technical Charts
If you insist on using 64cc heads, then you will need a piston with a 31cc dish to arrive at the 8.5:1 that will allow you to puff 6 1/2 psi into the motor without detonation. SRP 148750 forged pistons is what I would use. You can see in the photo that the piston has a fair-sized flat area on the crown to generate a good squish, although some fellows will not care too much about squish on a blower motor.
SRP 148750 350 SBC Dish
I would not begin a blower build using cast or cast hypereutectic pistons.
70cc heads and a 24cc dished piston would yield 8.6:1 SCR.
No need to add more strain to the motor with 1.6 rockers. This is a blower motor. If you want more poop, change pulleys. Use 1.5 rockers.
Aluminum heads are going to want a ~0.040" thickness gasket, so in order to engineer the squish at 0.035" to 0.045", you will need to cut the block decks to zero deck, after having your machine shop tech check the main bearing bores for being round and parallel with each other. Measure the dimension of your stack of parts, (1/2 the stroke, piston compression height and rod length) to determine your stack height. Half the stroke is 1.875", the rod length to use with the 148750 piston is 5.7" and the piston is 1.425", for a stack of 9.000". Since the production blueprint block height is 9.025", you would want to remove 0.025" from the decks to bring them to 9.000" for a zero deck. With the piston at flush with the block deck with the piston at top dead center, the squish would be described by the head gasket compressed thickness. I would use a Fel-Pro 1003 (0.041" compressed). I don't foresee any problems with this gasket and 6 1/2 lbs of boost, if you have detonation under control.
OK, get wrapped around that and we'll talk more later......
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