Chevy LT1 Head Questions - Performance Q&A

Kevin McClelland Jun 1, 2009 0 Comment(s)

What a Gas! Natural, That Is
Q: I'm building a '58 Chevy Apache frame-off resto. I want to step up to the plate by going green. Do you guys have any idea where I can get the kit/equipment for CNG conversion for a Chevy short-block? I figure I might as well step into tomorrow and get cheaper fuel at the same time. Also, I'd be able to fill 'er up at home. Is it possible you guys could do an article on a small-block CNG conversion? What do you say? By the way, keep up the good work!
James Walter
Via email

A: CGN is sure a hot topic these days. T. Boon Pickens is going on TV and telling everyone that we could be running on CNG today. That's the truth, but the likelihood of everyone doing it is another story. Also, outfitting older vehicles is a challenge compared with the late-model EFI vehicles. We dug around for a while and will list several websites where you can do some research. After you've looked into natural gas, you can decide if it's for you.

One of your comments is that you could fuel your truck at home. While this is technically true, the compressor to do this today is around $4,500. This price is just for the compressor, not any of the conversion components and the fuel storage tanks that are DOT-legal. These fuel tanks are made from composite material and hold the natural gas under a working pressure of 3,600 psi. A tank that would hold the equivalent of 10 gallons of gas is priced around $2,800. The conversion kits we found online were from all around the world. The prices varied, but they come in around $1,800 for EFI systems, higher for carbureted systems. There have been tremendous advancements in the EFI side of the conversion market. There are systems available that are OBD II compliant and can be installed on current-model-year vehicles and retain the factory warranty!

Check out the sites below for more information. If you would like to speak with someone in person, give Impco Technologies a call (714.656.1200). Impco has been the premier mixer and regulator manufacturer for propane conversions ever since propane came into favor. I worked with the company years ago on a CNG project in the Texas Panhandle, where Don Hardy Race Cars was outfitting irrigation pump engines to run on natural gas. CNG is being used all around the globe to fuel cars and industry. As for CHP doing a conversion story, it may be a little early in the learning curve. We'll have to wait and see.


Early Iron Flow
Q: I have been clawing my way through the Internet, looking for small-block Chevy head flow data. Specifically the mid-'60s double-hump heads with the casting numbers of either 3782461 or 3782461X. If you could point me to a website that has this info, I would be very thankful.
Red Slover
Norco, CA

A: The early iron double-hump, or camelback, cylinder heads flow very similarly. The 461, 462, 486, and 492 heads all had very similar port volumes and valve sizes. Most of these came equipped with either 1.94/1.50- or 2.02/1.60-inch valves. Here is the typical double-hump or fuelie casting stock head flow.


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