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I have a 351 Windsor with the stock 600 cfm holley made by motorcraft. Just rebuilt the carb and having bad issues trying to get the thing running. The timing seems to be alright I checked it with a timing light and timed it after dropping in a new distributor and putting on new plug wires. It takes some effort to get it started but I can get it to idle. If i give it any gas the thing will just pop and backfire right out of the carb and has shot a few fire ***** at me. Accelerator pump is set right and so are the butterflies. The only thing I can think of is a vacuum leak. I reinstalled the intake manifold and might've not sealed it right. Until I can get a compression tester to check for burnt valves any advice?
I have a 351 Windsor with the stock 600 cfm holley made by motorcraft. Just rebuilt the carb and having bad issues trying to get the thing running. The timing seems to be alright I checked it with a timing light and timed it after dropping in a new distributor and putting on new plug wires. It takes some effort to get it started but I can get it to idle. If i give it any gas the thing will just pop and backfire right out of the carb and has shot a few fire ***** at me. Accelerator pump is set right and so are the butterflies. The only thing I can think of is a vacuum leak. I reinstalled the intake manifold and might've not sealed it right. Until I can get a compression tester to check for burnt valves any advice?
Double check you have all the plug wires going to the right place. 351W firing order below.
"It takes some effort to get started". That symptom sort of sticks out from your description.
Does the engine turn over unusually fast now, or maybe real slow? Normally with everything setup right the engine should light off quickly, hot or cold. Are you certain the distributor is stabbed correctly, the distributor gear roll pin isn't sheared, TDC mark is accurately located on balancer etc. Check everything.
Also, make sure you set the base timing with the vacuum advance disconnected.
A little update. Just got the thing started and had to keep it choked for a few minutes until it warmed up but after that it ran great. After messing with the carb I got the backfire to stop but it still is a bear to start sometimes and it shouldn't need choke that long so I'm still thinking there's a vacuum leak somewhere
When you say it "runs great" does that include driving it, under load?
I'm gonna drive it under load tomorrow and see how it does. It cranks fine but what stumps me is that after it's warmed up if you shut it off and try to start it back up it cranks super slow like the battery is dead which sounds like the timing is off to me but it runs great when parked. Revs up fine no issues and idles great. I just put a new distributor in so that's not the issue but I suppose the balancer could be off. I just feel like if the timing was off it would stick out more. The only thing I noticed was when it was still warming up I was standing by the exhaust and sounded like I heard a few misses but it happened about 3 times and never again in about 10 minutes of running. It has an electric fuel pump the previous owner put on which I think is over fueling it and until it warms up and smooths out it has too much fuel at first so that could play into it also
If you think the engine has a vacuum leak you need to fix that first. You could always use the old "starting fluid" trick. Spray starting fluid around the base of the carburetor and vacuum lines with the engine running to find the vacuum leak. Just make sure you have a fire extinguisher handy because it's definitely a fire hazard!
You might consider buying or renting a vacuum gauge. Here's a good schematic and a link on using a vacuum gauge.
It's a longshot, but you mention installing a new distributor. I guess just from the description one thing to rule out is some major defect in the centrifugal advance mechanism. Make sure ignition timing advances when revved all the way out to say 34° or so with the vac advance disconnected and plugged, and back down to base, smoothly without sticking.
after it's warmed up if you shut it off and try to start it back up it cranks super slow like the battery is dead
The slow cranking is probably not related to the present issue, but when you're ready to tackle that, this troubleshooting guide will hopefully save you some time and money:
Just for giggles, I'd suggest checking the battery voltage with the engine at idle. You should see around 13.75V or so. If seriously low, this could cause a weak spark and performance issues.
Originally Posted by Jerry_85ford
I just put a new distributor in so that's not the issue
Oy vey, you've made quite the dangerous statement! If this is a new problem, and only started after parts were changed, then that's your most likely cause. Don't limit your troubleshooting by saying a part can't be bad because it is new. I have experienced just the opposite on many occasions. Or if the new part itself isn't bad, there could still be an adjustment out of whack or something else (such as a connector) may have been disturbed during the replacement process.
If you think the engine has a vacuum leak you need to fix that first. You could always use the old "starting fluid" trick. Spray starting fluid around the base of the carburetor and vacuum lines with the engine running to find the vacuum leak. Just make sure you have a fire extinguisher handy because it's definitely a fire hazard!
You might consider buying or renting a vacuum gauge. Here's a good schematic and a link on using a vacuum gauge.
Lots of people are replying and I really appreciate it. I started the truck today and just drove it around the property not over 5 mph because its not legal for the street at the moment and I'm restoring the body so it's not in the right shape either. I found my vacuum leak it was a line for the ac control that was just hanging there. Someone took out the ac and didn't plug it. It made a big difference and starts right up and does everything it should. Still one problem and it's got a miss when I rev it up. No backfire or pop but you can hear it's missing and that could just be old plugs. I assume it's because of the miss but it has a little hesitation when I hit the gas too almost like its losing power. It didn't do the slow cranking today which is odd. I just put a new starter last week along with a new battery and cables and ground cable for the starter. Now my only problem is that miss and I'll see if new plugs fix that
When you do the plug being they are out then would be the time to do a compression test so you know the motor is in some what good shape.
When I road tested my truck, 300 six, the motor had a miss but it did hit on all six for a few seconds so was a some what good sign.
When I got it home I pulled the plugs and did a compression test and all holes where good. Installed a new set of plugs and no more miss.
Once the motor ran good I took the whole truck apart and over the next 4 years did a cab off frame rebuild.
It was not planed that way just kind of happened LOL
Dave ----
When you do the plug being they are out then would be the time to do a compression test so you know the motor is in some what good shape.
When I road tested my truck, 300 six, the motor had a miss but it did hit on all six for a few seconds so was a some what good sign.
When I got it home I pulled the plugs and did a compression test and all holes where good. Installed a new set of plugs and no more miss.
Once the motor ran good I took the whole truck apart and over the next 4 years did a cab off frame rebuild.
It was not planed that way just kind of happened LOL
Dave ----
Yeah I probably will do that. Besides the miss its acting very cold blooded and wants to warm up for probably 10 minutes even in 60 degree weather before I can put it in gear. If I don't let it warm up that much it has to idle in gear. Any throttle and it kills it
Make sure it has a factory temp 192° thermostat installed. Could be some el-cheapo junk installed. Also a good charging system & battery, + hot ignition, proper Tune-Up etc, the engine will warm up noticeably faster.
use TFI in 85? If so, your timing is computer controlled. Here's a good thread in which another member had a similar problem:
