304 V8 Motorcraft 2100 carb... tuning question

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   Hello everyone,

I asked this on a Jeep forum - since the car is a jeep.  But it dawns on me that they're more likely to know about big tires and suspension... And this is where I can get some advice on the engine itself.

1976
304 with stock motorcraft 2100.  Rebuilt "approximately 5-6 years ago" according to previous owner
Running 5 degrees BTDC idle timing
pulling 15 lbs of vacuum pressure at idle
Completely loses power at about 2300 rpm.  pulls relatively strong until then.

Air fuel mixture set to 2.5 turns... 

So if it were you would you: 
A: advance timing
B: retard timing
C: give it more fuel
D: dial back on the fuel

I just want to be sure I'm fully understanding the cause of the problem before I go messing with it.

Any help is appreciated.

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jamesurq Members Profile Send Private Message Find Members Posts Add to Buddy List AMC Fan Joined: Oct/29/2012 Location: Greensboro, NC Status: Offline Points: 7	Post Options Post Reply Quote jamesurq Report Post Thanks(0) Quote Reply Topic: 304 V8 Motorcraft 2100 carb... tuning question Posted: Oct/29/2012 at 9:17am
	Hello everyone, I asked this on a Jeep forum - since the car is a jeep. But it dawns on me that they're more likely to know about big tires and suspension... And this is where I can get some advice on the engine itself. 1976 304 with stock motorcraft 2100. Rebuilt "approximately 5-6 years ago" according to previous owner Running 5 degrees BTDC idle timing pulling 15 lbs of vacuum pressure at idle Completely loses power at about 2300 rpm. pulls relatively strong until then. Air fuel mixture set to 2.5 turns... So if it were you would you: A: advance timing B: retard timing C: give it more fuel D: dial back on the fuel I just want to be sure I'm fully understanding the cause of the problem before I go messing with it. Any help is appreciated.

SCReplica Members Profile Send Private Message Find Members Posts Add to Buddy List AMC Apprentice Joined: Apr/18/2011 Location: Snellville GA Status: Offline Points: 47	Post Options Post Reply Quote SCReplica Report Post Thanks(0) Quote Reply Posted: Oct/29/2012 at 9:51am
	I'd check fuel filter and fuel pump first.

FSJunkie Members Profile Send Private Message Find Members Posts Add to Buddy List AMC Addicted Joined: Jan/09/2011 Location: Flagstaff, AZ Status: Offline Points: 4742	Post Options Post Reply Quote FSJunkie Report Post Thanks(0) Quote Reply Posted: Oct/29/2012 at 11:00am
	I'm not 100% sure for 1976, but initial timing with the distributor vacuum hose disconnected and the engine at 500 RPM was 5 degrees BTDC. They run fine with that timing, and those are the same timing speciofications used on the non smog equipped motors. Plugged fuel filter or pick up sock can cause them to lean out, so can a faulty fuel pump as already explained. If it's none of those, then something internal to the carb is more likely, like the power valve. In any cse, it's most likely a lean condition.
	1955 Packard 1966 Marlin 1972 Wagoneer 1973 Ambassador 1977 Hornet 1982 Concord D/L 1984 Eagle Limited

jamesurq Members Profile Send Private Message Find Members Posts Add to Buddy List AMC Fan Joined: Oct/29/2012 Location: Greensboro, NC Status: Offline Points: 7	Post Options Post Reply Quote jamesurq Report Post Thanks(0) Quote Reply Posted: Oct/29/2012 at 11:01am
	Good call - Interestingly enough, I just replaced the fuel filter a few months ago, and after a leak in the tank I put in a new tank and 15 gallons of super... I just figured that the pump was working and as long as that was the case I'd be ok... I'll hook up the pressure gauge and test it before and after the in-line filter. Anyone know what kind of pressure I should expect from a mechanical fuel pump?

jamesurq Members Profile Send Private Message Find Members Posts Add to Buddy List AMC Fan Joined: Oct/29/2012 Location: Greensboro, NC Status: Offline Points: 7	Post Options Post Reply Quote jamesurq Report Post Thanks(0) Quote Reply Posted: Oct/29/2012 at 2:19pm
	nevermind. It just dawned on me - how the heck can I check the pressure on a mechanical fuel pump? If I disconnect it to hook up the gauge, the engine stops and therefore the pump stops...

rockAMX Members Profile Send Private Message Find Members Posts Add to Buddy List AMC Addicted Joined: Sep/16/2011 Location: Lethbridge AB Status: Offline Points: 985	Post Options Post Reply Quote rockAMX Report Post Thanks(0) Quote Reply Posted: Oct/29/2012 at 2:28pm
	Ditto on the fuel pump. If it is old, just replace it, they are cheap from RockAuto. I always do this if the pump is old.
	DWR 1968 AMX

tsanchez Members Profile Send Private Message Find Members Posts Add to Buddy List AMC Addicted Joined: Jul/09/2007 Location: Arizona Status: Offline Points: 4303	Post Options Post Reply Quote tsanchez Report Post Thanks(0) Quote Reply Posted: Oct/29/2012 at 3:50pm
	IT wont die right away, you should have 4-7 psi. Check the basics before changing anything, like I said remove bowl and see what jets are in carb, usually you can reuse the gasket.


jamesurq Members Profile Send Private Message Find Members Posts Add to Buddy List AMC Fan Joined: Oct/29/2012 Location: Greensboro, NC Status: Offline Points: 7	Post Options Post Reply Quote jamesurq Report Post Thanks(0) Quote Reply Posted: Oct/29/2012 at 10:35pm
	like you said? I'm confused....

Pdok Members Profile Send Private Message Find Members Posts Add to Buddy List Supporter of TheAMCForum Joined: Apr/03/2011 Location: Alabama Status: Offline Points: 1025	Post Options Post Reply Quote Pdok Report Post Thanks(0) Quote Reply Posted: Oct/30/2012 at 6:28am
	You had a leaking tank = almost certainly was rust in there, right? Now that the tank is new, you should flush the entire fuel system and replace the pump. Filter too, but you already did that. The other thing would be to disassemble and clean the carb passages for stuff the filter didn't get. I went through this with mine, and just crappy gunk in the tank contaminated the entire system. I flushed the hard lines with solvent too, replaced all the rubber hoses, including the ones running to all the rollover valve fittings, etc. back there. My pump was completely shot, putting out barely a trickle after the rust issue. With debris, I'd expect the problem to be more intermittent or to occur at different speeds. Could be something in the bowl maybe. The fuel pressure thing isn't that hard to do, but you need a gauge hooked up while it's running! If you know any rodder friends, maybe borrow one? IF you replace the pump, then no need.
	76 Grem X 258/904,4.0 head/MPFI, Comp X250H cam, Hughes springs, Clifford header, serpentine swap.

ICEMAN6166 Members Profile Send Private Message Find Members Posts Add to Buddy List AMC Apprentice Joined: Oct/12/2012 Location: Utah Status: Offline Points: 102	Post Options Post Reply Quote ICEMAN6166 Report Post Thanks(0) Quote Reply Posted: Oct/30/2012 at 8:51am
	2.5 turns is too far out. something else is wrong either in the fuel tank,line pump or in the carb itself. never had any ford carb more than 2 turns most were 1.5-2.
	1964 Ambassador 990 1966 F250 4x4