Flat carb responce

[angolmois52]

Sorry i'm new to computers and forum stuff but i will learn. Got 1984 2.8 v6 4x4 did the holley carb and dura spark change new fuel pump new plugs carbs got 42 mains w/31 squirter very good compresion timing dead on runs great however on past accelerator pump gos dead and backfires out the exhust. Anyone got any ideas as to what my oversight could be. new to this so I think I.m posting this to 2.8 forum. Did it before but I think I did it wrong.

 

[BichoBII]

Did you check your plugs?, 42 might be to small, im using 41 but im at 10,000ft., and what power valve are you using? Might be opening to late...

 

[alwaysFlOoReD]

however on past accelerator pump gos dead and backfires

I don't understand what you are saying. If you are getting backfires on acceleration then the A/F is lean. I would suspect your accelerator pump or pump linkage.

Richard

 

[RonD]

Make sure float levels are set high enough, and fuel pump with filter are making the required pressure at the carb.

And double check that you are using a ballast resistor(or wire) for the RUN wire on the Coil, otherwise coil will overheat and cause loss of power.

 

[angolmois52]

thank you for your input. I will check these things and let you know. In answer to some things. I got 7.5 power valve,and the plugs are new. Past 1/3 throttle no rpm gain and backfires out the exhust thought this ment rich but lower rpm is great, also useing stock coil wired to toggle switch as to control ign. have not felt coil heating up but will check it agin. thanks. going to fix this.

 

[BichoBII]

Im sorry i ment check your plugs to see if you are running lean or rich...

 

[BichoBII]

And you can check your timing advance too, maybe mechanical advance is not working properly...

 

[angolmois52]

Installed new plugs and wires just to make sure all was new. What's the timing advance suppose to be? Maybe I got the wrong one or a broken one. Also larger main jets still same problem, no change. Can I post a video of my engine running maybe that would help. Never had this problem before. I must have installed a bad part somewhere.

 

[BichoBII]

Timing advance is a system that advances ignition timing as rpm increases, if you have a timing lamp you can check if its working correctly, at idle should be at 10 degrees BTDC and should smoothly increase with rpms to around 36 degrees.

 

[angolmois52]

Thanks, got one will try that. And let you know. I'm going to fix it yet.

 

[angolmois52]

So I went to check my timing advance and my timing mark is moving in a cascading (never in the same place twice) from on time to 20 deg. about 5 or 6 flashes of timing light. Then repeats this over and over even when I try to rev it up. When I found this went and got new distributor same problem so I replaced dura spark same problem. I'm open to suggestions don't know whats wrong.

 

[Lil-Pony]

Replacements can be bad. But what else controls timing... Vacuum i would start there.

 

[enginepaul]

There are ways to test the DuraSpark unit - do a search and you should find something. They don't fail very often and when they do they usually fail totally.

Check all grounds, including inside the distributor; grounds are just as important as any other connection. They don't have to be "all your muscle tight" just snug and secure.

On any repairs, try and check the parts first because repair by replacement is expensive and only make you mad.

 

[angolmois52]

Hello, good news my truck problems so posted are fixed. Will now have new ones. However I have a 1984 4x4 2.8 with holley 350 cmf dura spark ign. Want to thank the people who answered very good advise. What I found was my problem was caused by the red and white wire plug in on the stock wiring was still linked to the computer I bypassed them now my truck runs great. Want to thank T.R.F. for being there. Gotta go play with my toy. Later.

 

[Lil-Pony]

Great to hear. Have fun and dont forget about us