pro-jection or q-jet?

1106 Views 18 Replies 10 Participants Last post by nmscout, Jan 4, 2004

nmscout

Discussion Starter · Dec 29, 2003

I just recently bought a 78 scout with an AMC 401. The guy that owned it before me put a projection on it in the late eighties. I have been told by a few people that I should dump the projection and put a quadra jet on it. It seems like a good idea to me becasue it doesnt feel like a 401 and runs horrible when it is cold. The projection is a silver analog box with two injectors. Should I go with a q-jet or try and tune the projection? Thanks

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Hammerlock

· #6 · Dec 30, 2003 (Edited)

Ditto everything above. Q-jet is the best 4 barrel but still doesn't run well upside down.

Here are the problems I've seen:

Bad/dirty injectors - yours are way old.
incorrect fuel pressure.
bad fuel pressure regulator diaphragm or spring
restrictive fuel return line
Bad TPS or incorrectly adjusted TPS.

Probably the best thing for you to do is download the manual from the holley website and take it and your truck to a good shop. Any mechanic worth his paycheck should be able to find all your problems in under a hour.

If you want to do it yourself buy a multimeter and have at it.

BTW: Summit sells projection parts.

Also since it's running bad when cold ohm out the temp sender.

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Hammerlock

· #13 · Jan 1, 2004

nmscout said:
So how much is a closed loop projection worth?

Yours is worth $300 tops.

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Hammerlock

· #15 · Jan 2, 2004

green73 said:
From my reading/research on the Holley Pro-Jection, there were 2 different computers. One analog and one digital. The analog one takes some adjusting/tuning, even with the closed loop kit. The digital is supposed to be much more user friendly, and makes full use of the closed loop design for automatic adjustments. If you do have the analog computer Holley has a conversion to the digital one. A good suggestion here id to contact Holley and get the owners manual sent to you. I recently bought a used Pro-Jection kit without instructions, they sent me them in like a week. Just don't tell them what kind of vehicle you are using it on. They seem to only comprehend Chevy/Ford applications, and maybe &eep. The "tech" guy was really confused when I told him I was putting it on a Land Cruiser.

We're talking about the analog computer (see first post). There are really 2 different digital kits. The DI kit allows for use of a laptop for tuning. Holley.com has some of their manuals available for download, but it looks like they removed the analog manual.

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