Propane/Fuel Injection/Carb for a caddy 500?

Ricky B

Ricky B

Wiiide Open
Joined
Mar 20, 2005
Location
LKN - Tha Dirty Mo (Mooresville, NC)
As you guys probably saw from my other thread i'm getting ahold of a caddy 500, currently in my chevy i've got a 350 runnin on pane. Know I know just about nothing about pane setups as the truck already had it installed when I bought it. I'm wondering if it would be possible to swap the current pane setup from the 350 onto the caddy 500. From what I've heard the caddy 500 stock carb pushes bout 700 cfm, will my current pane setup push enough pane to quench that? If you need to know model/size or w/e from my current pane setup let me know where to look for it on the parts cause I don't know where it would say and what to look for, allthough I think John said it was a impco 425?

My next question is how does pane work in comparison to gas? Like when driving does the motor act any differently than if it was runnin on gas? With a close to 500 ft lb motor is pane gonna make it run just as good as gas would, not gonna rob any power properties is it?

If pane isnt the way to go then I also have a holley projection setup I could use, I think its only rated to handle small blocks though.

Is a holley 770 truck avenger gonna be my best bet?

Thanks
 
sticking with the running propane powered 350 and actually getting to drive a truck in the next ten years will be your best bet if you ask me

i have nothing else to add about the caddy
 
you would notice loss in the upper end of the power band. Low end grunt would work well. Driving out on the road, no you really wouldn't notice a big difference. Many propane trucks run 429's with pane on them.
Ricky, why make changes already. You have a truck near ready for the trail. Changing the engine, means changing the tranny, and so on, and so on.
 
CNG induction, More power, more heat than 'pane and you can fill your own from the house!!
 
sticking with the running propane powered 350 and actually getting to drive a truck in the next ten years will be your best bet if you ask me
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you would notice loss in the upper end of the power band. Low end grunt would work well. Driving out on the road, no you really wouldn't notice a big difference. Many propane trucks run 429's with pane on them.
Ricky, why make changes already. You have a truck near ready for the trail. Changing the engine, means changing the tranny, and so on, and so on.
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Yea yea, I know but im getting the engine in a trade deal so its no cash outta my pocket and I just can't say no to 500 cubic inches, I'm sorry but my Huge Truck, Huge Tires, Huge engine side of me is taking over I can't resist :shaking:

I should just get it over with and build a monster truck :driver:

In all seriousness thou i won't be driving the truck on the road at all, just wheelin so I'm thinkin propane aughta still be fine then cause all you use is low end pretty much right? Am I just gonna be able to directly swap what I have now onto the 500, or am I gonna need to mod some parts?

CNG induction, More power, more heat than 'pane and you can fill your own from the house!!
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Never heard of this before? Got any links or info?

I mean obviously I'd like to be able to swap the pane stuff strait over cause it'd be free that way but if what you were talkin bout is reasonable then . . . .
 
FORGET about the caddy, drive the truck, then you will realize that driving the truck is a milllion times more fun than building the truck and leave the 350, i garauntee
 
if you do run the propane let me know how it turns out. i'm thinking about running it on my 429
 
propane is approx equivalent to the octane level of 100 octane... but it doesnt have the thermal properties of gasoline, so its not as explosive.... therefore the propane will run more efficiently then gas when setup at the right compression ratios, but wont give you the same amount of power as the equivalent octane level gasoline....

As far as whether the current setup will swap, it should bolt up depending on the manifold, and like Chip said, power end youll be ok.... its when you turn more RPMs when the CFM of the carb is required.... so if you find out what setup you have then you can find the approx CFM rating on it, and maybe just get a bigger mixer

As far as the Pro-Injection, its a mess, but still might work... it still all depends on the CFM requirement of the engine, and what the system is rated for... personally i think the Howell setups are nicer though :p

Look at this it might help you out:
http://www.perfectracing.com/techtips/cfmcalculator.htm

And i know that we're prob not gonna be able to talk you outta puttin in that 500... so how much ya want for the 350 w/ the pane setup... PM me
 
Yo,

The Caddy motor is about 42% larger than the 350. My concern is idle. Assuming both idle the same speed and staying within 14:1 mixture, it appears the extra 42% will starve? But, I don't understand pane injection and its ability, or not, to adapt to different size motors. Maybe its got a fuel/air adjustment gizmo?

Best of luck with the 500. Just remember that when your rig breaks down near that Deliverance shack in Flat Rock, Tenn. its going to be much more difficult to find Caddy parts!

My $0.02 :beer: Happy New Year
 
SEAIRESCUE said:
Yo,
The Caddy motor is about 42% larger than the 350. My concern is idle. Assuming both idle the same speed and staying within 14:1 mixture, it appears the extra 42% will starve? But, I don't understand pane injection and its ability, or not, to adapt to different size motors. Maybe its got a fuel/air adjustment gizmo?
Best of luck with the 500. Just remember that when your rig breaks down near that Deliverance shack in Flat Rock, Tenn. its going to be much more difficult to find Caddy parts!
My $0.02 :beer: Happy New Year
Click to expand...

See that's my concern too. I know hardly anything about pane and I'm wondering how it will adapt to the larger motor if it is adjustable or if you have to upgrade certain parts to get it to power larger engines (larger mixer was mentioned above)? I'll see tommorow if I can find model #'s and what not on my current propane setup so ya'll can tell me what I have to work with. And I have the stock carb from the 500 so I'm gonna try and look up its part # to see what kinda feul delivery it had.
 
OK I will try and help here a little. No You will not realize full potential of your 500ci Caddy with a Impco 425 mixer. If you want all you can get, go to www.propaneguy.com they have bigger mixers, and even a double 425 set up to get all the top end power.
The Impco 425 mixer has to have a baseplate to connect to the intake. A Holley 600 base plate will bolt directly to the Impco 425, so it will bolt directly to a square bore intake. The Caddy uses a Quadrajet, so you will have to use a squarebore to spread bore adapter, or order an adapter to go from the Impco 425 to a spreadbore baseplate(Quadrajet). Either or will work.
I helped John(over the phone) with this set up. If I remember correctly, it has a Holley baseplate.
So to answer the question above, the base plate will have adjustment just like a carb.
I have heard too many horror stories about the Holley projection, I would never want one. I have have heard good stuff about the Howell system. Another option is the GM throttle body, and having it reworked for simplicity(Andy at CRS can get this done for you at a decent price).
The pane system you have now will work just fine. I have seen many BB on the trail and they worked great. On the road? will it do 100mph? Yes, it'll just take a little longer to get there.
Will the Quadrajet work off road? Yes, but not as well as the Pane or Fuel injection. Mods can be made though. Turning it around backwards, lowering float level help a lot. A accelerator cable from an early 90's model Lumina is long enough for the the turn around and has the shift cable for the auto attached to it.
Buick, Oldsmobile, , and Caddy all have the same bolt pattern on the bellhousing(older model stuff) and Chevy stood alone as far a bellhousing patterns. But many different chevys had the same pattern. 283, 327, 305, 307, 350, 400sb 396 400bb, 454, and so on, I am sure I left out some, but these were the most popular. They did have a metric transmissio that had the pattern for all the GM's, made in Canada, but not sure it it ever come In a 4WD version.
And of course there is the J truck 400turbo that mated to the Buick engines that had Dana 20 transfer cases, that would work. This would be the easiest cheapest way to get power to all four wheels without expensive adapters. There may be others, but that's the one that comes to mind. Dana 20 is strong, but pitiful low range, something like 2.02: 1

So there are some facts, hope it helps

Ricky if you really want to be happy, not spend a bundle on the caddy swap, and have more low end torque, and get that thing on the trail instead of putting yet another rig on jack stands. Keep the 350, add a torqer cam, build the cage and go wheel. Just my .02
 
i completely agree with Chip... id leave in the SBC until you have everything all together to just bolt the caddy in, if you put it in at all... personally if i had a runnin rig, i would wanna wheel it some to see how the SBC will treat you, bfor i get rid of it...

but i know you and you have some wheel turnin in your head, so were not gonna be able to talk you outta the caddy motor if thats what you want....

basically with the pane the mixer is just like a carb is to gasoline.... and each one has a CFM rating.... so find your model, and its rating, and then find the size mixer that has the CFM that you need.... prob around 800+ or so.... and i agree with Chip bout the proinjection.... plus i think theyre only like 500 CFM 2bbls so deff not enough
 
yea the projection wont work cause its like 500 something cfm, it is 4 barrel thou.

I think what I'm gonna do is just swap my current pane setup onto my 500 and see what its like, then if I feel like I need it I can get the bigger mixer, or just get a holley truck avenger 770 cfm carb. I'm almost leanin toward the holley but I'd really like to just reuse the current setup if possible, from what Chip says he seems to think it will be fine, and I don't care about top end power, I mean when would you need that offroad anyway (unless you were mud dragging I guess)? But yea I'll just try my current pane setup and see how it does probably.

As far as the drivetrain all I have to do is order a $80 adapter plate and bolt a chevy th400 right up and then I'm stil in the air about the doubler, I mean I can try it and run the 241/205 or I can just run a 205, not sure.
 
you should run a 203/205 doubler, so that way you can let me trade you that 203 towards your propane... right, yeaah :huggy:
 
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