400 stalling when in gear
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400 stalling when in gear
Just rebuilt the 400 in my 78 f150. Put a comp cams 255deh, matching valve springs, and timing set. Edelbrock performer 400, used Holley 650 double pumper. Everything else is stock.
It idles great in park. Don't have a tach but I'm guessing it drops 400-600 rpm when put in gear and almost stalls. Used a timing light and set the distributor at 12 degrees BTDC. While in park I'm reading about 13psi of vaccum but the needle flutters a few psi.
When coasting or coming to a stop I have to put the truck in neutral otherwise it will die. But it runs like a raped ape when accelerating.
I've tried every idle mixture screw setting and curb idle speed setting it doesn't help. Checked the fuel level with the sight plugs taken out and it seems good. Tried a new base gasket and vaccum hoses and it didnt help. Where should I go from here?
It idles great in park. Don't have a tach but I'm guessing it drops 400-600 rpm when put in gear and almost stalls. Used a timing light and set the distributor at 12 degrees BTDC. While in park I'm reading about 13psi of vaccum but the needle flutters a few psi.
When coasting or coming to a stop I have to put the truck in neutral otherwise it will die. But it runs like a raped ape when accelerating.
I've tried every idle mixture screw setting and curb idle speed setting it doesn't help. Checked the fuel level with the sight plugs taken out and it seems good. Tried a new base gasket and vaccum hoses and it didnt help. Where should I go from here?
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From: US/Baja border
Yes! Your vacum reading should be up around 21 inches
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im starting to think i did a poor job sealing the intake. i might spray something around the gasket surface and see if that does anything. i did not use a valley pan as edelbrock calls for.
here is the motor as i was putting it together. no longer have the headers due to clearance issues.
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decided to just pull the intake this morning since i convinced myself i did a poor job with the sealant. let it dry all day then finally fired it up. idled OK, still fluctuating between 10-15psi of vaccum. dropped it in gear and it immediately died. i almost lost my sanity. then i decided to unplug the hose from the oil filler cap and stick a bolt in it. idle was a little better, and now read 17psi steadily. put it in gear and it dropped RPM normally and stayed strong!
my timing is still probably at around 20 degrees advanced @ idle from when i was messing with it and the idle is also set fairly high so i need to make some adjustments tomorrow and it should be back to normal.
well pulled that intake for nothing but at least i figured it out and know not to rule out something stupid like an oil cap...thanks again for all your help and i never would have suspected the pcv!
my timing is still probably at around 20 degrees advanced @ idle from when i was messing with it and the idle is also set fairly high so i need to make some adjustments tomorrow and it should be back to normal.
well pulled that intake for nothing but at least i figured it out and know not to rule out something stupid like an oil cap...thanks again for all your help and i never would have suspected the pcv!
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Joined: Dec 2009
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From: NorCal
A PCV is basically a check valve. Manifold vacuum pulls the valve off its seat. Pull it out of its grommet and shake it.. it should rattle. If not, hit it with some brake cleaner until is drains clean. Reinstall.
'Chalk it up as a learning experience... we've all been there at one time or another!
'Chalk it up as a learning experience... we've all been there at one time or another!
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i did take a look at it during the rebuild and the thing was packed full of sledghma i got as much of it out as i could and if i recall it sounded like there was a ball bearing of some sort inside it. ill probably just buy a new one and not have to worry.
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Hi BlueThunder - my 73 ford f100 302 with a brand new holley 2300 is also dying in gear, and I've been looking around to figure out why. Just wanted to ask a quick question as I'm looking to test my PCV. You said you stuck a bolt in the oil filler cap? Would this be the side without the PCV Valve, which is usually vented to the air cleaner?
if so, then would that increase the vacuum inside the engine as its exhausting through the PCV valve but has no intake? How did you diagnose the PCV valve?
Also, when i removed my PCV valve to put on a new hose and clamps while installing my Holley 2300, the PCV just pulled right out of the cap on the valve cover (actually really easy) -- I'm suspicious as this is not a great seal and isnt holding pressure. Is this bad? Would it just be venting the crank case to the engine bay? I was thinking about some teflon around the base of the PCV to seal up the PCV valve into the screw on cap to the valve cover.
Sorry for being stupid here.. just wanted to make sure I understood what you wrote/trying to get my truck running in gear!
Thanks!
if so, then would that increase the vacuum inside the engine as its exhausting through the PCV valve but has no intake? How did you diagnose the PCV valve?
Also, when i removed my PCV valve to put on a new hose and clamps while installing my Holley 2300, the PCV just pulled right out of the cap on the valve cover (actually really easy) -- I'm suspicious as this is not a great seal and isnt holding pressure. Is this bad? Would it just be venting the crank case to the engine bay? I was thinking about some teflon around the base of the PCV to seal up the PCV valve into the screw on cap to the valve cover.
Sorry for being stupid here.. just wanted to make sure I understood what you wrote/trying to get my truck running in gear!
Thanks!
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Hi BlueThunder - my 73 ford f100 302 with a brand new holley 2300 is also dying in gear, and I've been looking around to figure out why. Just wanted to ask a quick question as I'm looking to test my PCV. You said you stuck a bolt in the oil filler cap? Would this be the side without the PCV Valve, which is usually vented to the air cleaner?
if so, then would that increase the vacuum inside the engine as its exhausting through the PCV valve but has no intake? How did you diagnose the PCV valve?
Also, when i removed my PCV valve to put on a new hose and clamps while installing my Holley 2300, the PCV just pulled right out of the cap on the valve cover (actually really easy) -- I'm suspicious as this is not a great seal and isnt holding pressure. Is this bad? Would it just be venting the crank case to the engine bay? I was thinking about some teflon around the base of the PCV to seal up the PCV valve into the screw on cap to the valve cover.
Sorry for being stupid here.. just wanted to make sure I understood what you wrote/trying to get my truck running in gear!
Thanks!
if so, then would that increase the vacuum inside the engine as its exhausting through the PCV valve but has no intake? How did you diagnose the PCV valve?
Also, when i removed my PCV valve to put on a new hose and clamps while installing my Holley 2300, the PCV just pulled right out of the cap on the valve cover (actually really easy) -- I'm suspicious as this is not a great seal and isnt holding pressure. Is this bad? Would it just be venting the crank case to the engine bay? I was thinking about some teflon around the base of the PCV to seal up the PCV valve into the screw on cap to the valve cover.
Sorry for being stupid here.. just wanted to make sure I understood what you wrote/trying to get my truck running in gear!
Thanks!
power steering and brakes got stiff at low rpm. even after fixing the pcv, it wasnt running that great, even though it wasnt stalling anymore. idle was very choppy but i just thought it was the cam i put in it. bought a brand new holley 670 truck avenger and its running very smooth right out of the box.
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