4.3L and an Impco 425...

[sled_dog]

Think a 425 is too much for a stock(to be modded) 4.3L? Seriouslly considering grabbing a junkyard 4.3L for my S10 and already have a brand new 425 for my propane setup. future plans would be bored out and cammed or maybe turbo(in which case a 425 would make plenty of sense).

 

[HarryH3]

Sled, search around over at www.austink5.com There are a few guys on there that drive bunsen burners.

 

[Citizen Rider]

haha, yea, quite a few guys know alot about propane over there.

 

[neverendingproject]

I dont know about propane setups, but I know a properly modded 4.3 can put out some insane numbers for a 6 cylinder.

 

[mrk5]

I've been checking out propane kits on gotpropane.com and I saw this:

Standard output V8 and V6 kits


This kit is exactly the same kit as our high output kit except the mixer and regulator we use on these is the IMPCO 425 mixer. It will still run a big block well but we offer both options now. These kits include everything necessary to do a conversion in a day. We include all fittings, hoses, adapters, etc. The equipment has been upgraded from rubber internals to silicone. This greatly increases the service life of the equipment to about 10 to 15 years before a rebuild. Some last many more years than that.
The price of this kit is $995

Looks to me like you'd be okay.

 

[85mudblazin]

If the 425 is to much then I have a 225 that would work for ya. A 225 is to big for a 22re so I am assuming it would be good on jeep type motors. So the 4.3l might fall into that slot.

 

[Blazr77400]

This will tell what you want to know.
CID * RPM / 3456 * 0.85 = CFM required

425 flows 460 cfm max

262.5 * 7000 / 3456* 0.85 = 452 cfm required
carb size formula LINK
So you will be good to over 7000 rpm
Over carbing it should just make it burn rich. Shouldnt hurt power output. It just wont burn all of the propane.

On my truck it was either be under carbed or over carbed with the 425's. I went with 2 just to make sure there was enough power.

Here are some other good propane links.
http://franzh.home.texas.net/engine.html
http://www.dualcurve.com/home.htm
http://www.patooyee.com/ (Go to the technical section and click on Propane)
http://www.wps.com/LPG/index.html#INDEX
www.propaneguy.com (where I got all my stuff)

 

[sled_dog]

This will tell what you want to know.
CID * RPM / 3456 * 0.85 = CFM required

425 flows 460 cfm max

262.5 * 7000 / 3456* 0.85 = 452 cfm required
carb size formula LINK
So you will be good to over 7000 rpm
Over carbing it should just make it burn rich. Shouldnt hurt power output. It just wont burn all of the propane.

On my truck it was either be under carbed or over carbed with the 425's. I went with 2 just to make sure there was enough power.

Here are some other good propane links.
http://franzh.home.texas.net/engine.html
http://www.dualcurve.com/home.htm
http://www.patooyee.com/ (Go to the technical section and click on Propane)
http://www.wps.com/LPG/index.html#INDEX
www.propaneguy.com (where I got all my stuff)

Yeah thats part of what the problem is. I'm going to finish my 383. Big issue for me is my 383 is the same boat as your 400. Its either going to be under or overcarbed. Oh well. I am just not looking forward to the cost of another 425, 2 Model E regulators, 2 carbs for their bases, dual carb intake, and the linkage/lines to make everything work. Oh well, it ought to run like a raped ape when all is said and done.

 

[mrk5]

gotpropane.com sells a kit for "big blocks and hot small blocks" that flows better than the Impco 425.

 

[sled_dog]

gotpropane.com sells a kit for "big blocks and hot small blocks" that flows better than the Impco 425.

The X450 mixer. Try finding a new one. I'm buying all new components for my system(no messing with rebuilding or hoping things arne't worn out). THey however do not flow THAT much more air than the 425 does. Forget what the comparison specs are. Besides which, $1100??? I'll have less than that into my dual carb setup with tanks! And all BRAND NEW Impco stuff.

 

[73k10sub]

Where to buy parts?

Besides which, $1100??? I'll have less than that into my dual carb setup with tanks! And all BRAND NEW Impco stuff.

Can you let us in on where you are buying your new parts? It looks like I fall in with some of you on whether the 425 would be enough - 350 bored .030 over running a mild cam and currently topped with a Q-jet.

Thnaks, Ronnie

 

[sled_dog]

Ebay man. Bought from a couple places so far. All I have at the moment is one 8 gallon fuel tank, my 425, and a VFF30 Lockoff. Lockoff and Mixer are brand new.