[Marc]

Dears,

I open a new topic, as I am not anymore talking about the short block
I am thinking to go for this engine instead BluePrint Engines 383 CI Stroker Crate Engine | Small Block GM Style |
but I did not yet go my option for the 355 vortec.
If finally decide on the 383, I think I will not regret it but my wallet will be empty

And I need a twin carb/mixer set up to feed correctly the engine, using propane mixers on a holley 4 barrel base plate.
My intention with this topic is to help me understand if my ideas are realistic, if there is a simple option for my application.

Looking at the different options, I can :
- run with my edelbrock performer modified intake, single quad base, on top of it a 90°elbow with Y or Y elbow and 2 mixers, Y is like the black piece of metal on this picture
Resized_100_0748-1.jpg (1040×772) (gmh-torana.com.au)
problem comes with the linkage, make this Y piece special, what about the limit of my intake for a 430 HP engine?
- run a new low profile dual quad intake manifold
Edelbrock 5425 Small Block Chevy Dual Quad Intake Manifold (speedwaymotors.com)
this one is really low rise so I can mount 2 mixers like carbs without issues
I could not install the edelbrock edelborck 7520 dual quad air gap the same way.
- run any other type ram intake with a modified 90° angle flange connection, seems complicate custom built.

Easy way is just to go with the 5425, there are available used on ebay.
BUT :

• they come with a large hole left of the water neck connection, what is that?
• it is advertise good for 1500 - 5000 rpm and the engine considered pulls hard until 5700...

Any comments are welcome.

I try to evaluate the different options and cost for the complete built. I already am considering the fuel delivery to the engine this is also something.

Thanks!

Marc

 

[Marc]

www.superchevy.com/how-to/engines-drivetrain/sucp-0708-carburetor-dyno-test

It seems the single quad air gap is the best.
What is not clear than is what happens when I bolt an elbow on it and this system
TWIN CT425M-2 MIXER 4 BARREL KIT | Mercer (mercer-gfpd.com)

 

[DOUG G]

We have a member in NZ whos name I can't remember... ran Propane.... someone ?

 

[Larger Dave]

I ran a dual fuel system on my 454 '73 Chevy pick up back in the early eighties. The propane carburetor was entirely inside the air cleaner that sat on top of my Holley carb on an Edelbrock single four intake. When I ran out of Propane (which was often the case when traveling this country) I just switched over to run gas by starting up my electric fuel pump. The propane heater (plumbed into the car's heater) and pressure regulator bolted to the front of the engine.

The system didn't take up any extra room under the hood than the stock intake carb and air cleaner system (other than the propane tank in the bed of the pick-up).

Big Dave

 

[Marc]

Thanks guys for trying to help.
I have the chance to have here close to me a very good shop on propane building projects for customers with V8 engines... as long as it still exist...
Anyway, I made my reasonable choice, I will keep my actual set up with one straight propane mixer, as I am used to have.
Twin mixers set up can seem nice to have on large size engines but it represents many custom built and tuning,+I am not sure of drivability. Also it is very seldom these days so not much data available...
With all these unknown data, which at the end brings headache and hole in the wallet, I prefer to keep to things I can handle and install a 350 engine that we will tune the best with a perfectly updated ignition.
Also this BPE engine is less expensive to buy from the start.
It will help me keep some budget...

Regards.

 

[SoCal805]

Dears,

I open a new topic, as I am not anymore talking about the short block
I am thinking to go for this engine instead BluePrint Engines 383 CI Stroker Crate Engine | Small Block GM Style |


Looking at the different options, I can :
- run with my edelbrock performer modified intake, single quad base, on top of it a 90°elbow with Y or Y elbow and 2 mixers, Y is like the black piece of metal on this picture
Resized_100_0748-1.jpg (1040×772) (gmh-torana.com.au)
problem comes with the linkage, make this Y piece special, what about the limit of my intake for a 430 HP engine?
- run a new low profile dual quad intake manifold
Edelbrock 5425 Small Block Chevy Dual Quad Intake Manifold (speedwaymotors.com)
this one is really low rise so I can mount 2 mixers like carbs without issues
I could not install the edelbrock edelborck 7520 dual quad air gap the same way.
- run any other type ram intake with a modified 90° angle flange connection, seems complicate custom built.

Easy way is just to go with the 5425, there are available used on ebay.
BUT :

• they come with a large hole left of the water neck connection, what is that?
• it is advertise good for 1500 - 5000 rpm and the engine considered pulls hard until 5700...

Marc

Marc

That large hole on the 5425 is for oil fill tube. Typically those motors had the PCV port on the back of the block with a breather cap on top of the oil fill tube

Your new BP 383 (good choice) would have a newer valve cover type PCV set up. You could just block that hole with an appropriate size freeze plug on the 5425. The 2 NPT holes on front of intake are for temp sender and heater hose (or bypass to water pump)

To bad the Air Gap won't fit under your hood with the propane set up. Do you have a stock flat hood? A cowl hood would allow for more clearance with the Propane set up. Otherise the Air Gap would work as they are good to 6000 RPM (and your new BP motor will be pulling at that RPM)

If your throttle linkage is set up to work with a single quad carb...you would need to modify it to work with dual carbs

 

[Bruce1968]

As for the 383, I went with the 355 by the time I got to ordering I was tired of writing checks and I wanted to save some money. I really wish I had just gone ahead and gotten the 383 My 355 runs just fine but I really want the extra power.

 

[Marc]

I long hesitated between the 383 and the 355 as well, the 355 was lastly only availble with the vortec heads... lately I found I don't want to mess again with heads porting, I did one head but I will need to do it all again on the new heads.

I have works planned on the camaro : wiring harness, new interior, sfc, engine bay / chassis degreasing painting,.. and I though I will only want to install the engine when I get it.

Concerning intakes, I made my mind : I will keep my current single carb/mixer set up which is not a perfect match I know.
I am willing to keep the propane as fuel, and the mixer is very tall. Only possibility to fit under hood is a low rise intake like the one I have : the Edelbrock Performer. I modified it for propane with a plenum (divider plate milled) and I will polish it too.
From what I read porting intake is useless? what do you think? Shall i work on a heads port's matching?

Then my propane mixer will be tuned for the best available power together with ignition and fuel delivery set up. This should provide very good drivebility but sure, I will lose top end power compared to a gasoline carburation. I think I will reach 400 hp @ 5000 when the engine could provide advertised ~ 430 hp @ 5500
Honestly I think it is all ok, we do not run our cars in high revs all day long. Propane allows me to drive it with the 383 torque capacity without thinking I burn my money, gasoline allows me to talk about my powerfull car staying in my garage. For me decision is made

Thanks,

Marc

 

[Bruce1968]

I didn't realize that you'd only lose about 30 hp going with propane. That is not bad at all. I assume it has to be very significantly cheaper than gasoline.

 

[Marc]

Here in Belgium propane is 3 x cheaper than gasoline.
This target of ~ 400 hp with single mixer should be reached yes (I hope so ) together with tuned ignition, fuel delivery and mixer adaptation.

More is difficult, then we need to step over to double mixers I believe.

I hope my intake would not limit too much flow, I think it will be ok because advertised for 0-5500 rpm.