Propane, anyone ever do dual carbs..?

[rob h]

A little story before, a few years ago we built a 358 at my part time side job. I took a 1974 350 chevy and had it bored, line honed, magged etc. I bought keith black .220 domed pistons, eagle crank,gm x rods , 515 lift comp cam and a pile of other misc parts including a set of bow tie heads 76cc chambers with 2.055 stainless valves. Ended up being 12.5:1 which I wasn't planning..lol. I added a air gap intake and a holley 750. Running race gas was way too expencsive and added up real fast. onto the next feat...

I purchased a propane conversion kit with one ohg x-450 carb and an x-1 vaporizer. I put it on and it runs real good and it real crisp but still not like the 750. Its worked flawless for the past few years. So on ebay about a year ago was the same carb with a newer style vaporizer but basicly a clone...I sangged it up real cheap. The new idea is to buy an impco dual carb adapter and put 2 carbs on with 2 vaporizers. I was told that its what I need to get back the hp im missing.

So after my boring story and the motor that was done, has anyone ever done the dual carb with propane deal..?

 

[80' 427]

I m planning to do it with a tunnel ram and 2 425s and 2 Es.

 

[rob h]

I was planning on using an adapter then the carbs don't have to be totally equal, not sure how it will work tho.. Since I already have the carbs and the vaporizers it might not be too expensive, just the adapter below which is 200.00.

 

[80' 427]

It will work great. One carb will be ahead of the other but it all has to go through the base plate. My 425s have a port to equalize the signal which I am going to use since mine will have dual 750 bases. A friend of mine ran the 2 into 1 for years and other than the hood clearance had no trouble.

 

[80' 427]

Remember LPG prefers lean so you may need to tune it some.

 

[rob h]

Hood clearance I took care of today, on local craigslist was a 4 year old goodmark 2.5 inch cowl hood painted gloss black. For 200.00 I took that puppy right home..lol. Ill bolt that on and hopefully it gets me enough for the air cleaner to fit.


I was told that two carbs would be like I put a whole new engine in the truck and with that adapter it ends up being fairly simple to set up. I picked up a rebuild kit for the x-1 I have and ill be doing it this week and bolting it on my truck instead of the other to make sure it works ok. Then ill know im good with that part. I also picked up a inline valve for my tank set up so I can run with both tanks open with out any problems. I did pick up to a rebuild kit for the x450 im currently using and all new fuel line.


Hopefully it all works out, will be a few weeks till I test everything out and purchase the adapter. I just want to make sure everything works ok before doing it. Tuning is no big deal unless it is a big prob...I bought a book on these kits/systems and also put in an aem wideband with a heated o2.

 

[rob h]

There is a custom made 14 inch air cleaner that fits the dual paopane carbs that fits and looks rather nice. Its a little expensive but it uses the normal 14 inch filter and lid, that way it sits down pretty low. I think it was like 150.00 but might be helpfull.

 

[80' 427]

I would like to try a pair of 450Xs someday.

 

[rob h]

Me too ...... Im going to do it asap, just want to go thru a few steps to make sure the parts I have are good to go.