Cold Starting issues/Engine update

[77RHINO]

My bronco not starting this morning really sucked, so this is part ranting/part questioning about old school tech that I am still learning about. I don't have anyone to discuss these issues with, so ya'll gotta bear with me!

Backstory: I finished my first engine build back in March, and within the first few drives it destroyed the rear wheel bearings, and had to park it until I could save up enough for a rear end rebuild w/ new gears, upgrading from 3.50s to 4.56s. Now that I get to drive it more consistently, I am noticing some different handling issues and quirks with the rear-end being all nice and tight.

Starting: When the engine is cold, it is a pain to get going, usually 3-4 times trying before it hesitantly coughs to life, which is a complete 180 from how it'll start if I have cranked it that day. When hot, it'll fire up within 1-2 secs of the turn of the key, and it sounds good. I know I still have some choke adjustment, but with the weather changing like it is (30 something last weekend, 75 this coming weekend) I cant seem to find a happy spot.

Once I do get it to cold crank, I have to immediately get it out of the garage, because it blows black wet soot out of the exhaust pipes for the first few minutes, which my local mechanic said was probably just unburnt ethanol? When it is warmed up, it drives good half the time. I have times that it will absolutely scat down the road, and others that it will surge and sputter, not wanting to pick up and run like it should. I've never tried flooring it, and I haven't found a common hill/grade or a certain throttle position that causes this, which makes me wonder if it is just dumping too much fuel that its not getting it all burnt? I am going to buy a jet kit from Edelbrock, I have a 650 and wonder if maybe the primaries are too big? A couple weeks ago it did run-on just a couple weak times before turning off, which is the first time it has done that since I swapped to premium fuel. It had also surged that day as well, where I was getting up onto a highway and it just didn't want to accelerate. When I took it to the shop for the rear end, I asked about the timing and how it started for him and he said it started great all day, which means it never cooled off enough for him to witness my cold start issues.

New Leaks
Now that I have gone through a few heat cycles, I am noticing some leaks on the floor: Head gasket at rear driver side, master cylinder/booster started leaking (maybe caused by new vacuum levels of new engine?) the master is only 5 years old. Front main seal and power steering low pressure return line. I hope re-torquing the heads will help, as my oil looks great and my spark plug at #8 near that leak looked nice and tan. I can't tell if the spot on the floor is coolant or brake fluid anymore, as they both land in the same area and get blown around by the fan while running. I have added a whole bottle of brake fluid, and only about 1.5 inches coolant, which is only distilled water at the moment. I will be flushing the water and replacing with coolant once I believe everything is good and set, but I have probably only put 4-500 miles on this motor since the install.

Driving: Noticed at certain speeds (once around 50 and once around 70) that I will get a heavy vibration like its lost a wheel weight, and this has started with the new gearset/rear rebuild. I don't know if the rear end had so much slack in it before that it ate up the driveline vibration, or if something else is going on, like maybe flat spots in the tires from sitting, even though it usually doesn't sit more than 3 weeks without a drive. The vibration gets rhythmic, but if I give more or less throttle it will go away and I can cruise normally. I originally thought this was buffeting because I was running the bikini top with no windshield support, but it does it with my hard top on as well.

Engine Stats:
Block – 1996 Hyd. Roller bored .030”
Pistons – 6.50+ flat top w/ valve reliefs (hypereutectic)
Heads – FR GT40X Aluminum 64cc chamber, 178cc intake runners
Headers - WH long tubes
Valves – 1.94 Intake, 1.54 Exhaust
Carb – Edelbrock AVS 650 CFM Elec. Choke
Cam – Comp XE 266HR-12
Distributor – ’78 cap and rotor, ‘77 funnel, ’83 shaft/pickup, ’96 cam gear
Head Gaskets – Fel Pro 9333PT1 0.047” THK (mis-quoted this in another thread)
Wires – Ford Racing 9mm
Coil – Factory replacement
Ignition – Factory Duraspark module
Intake – Edelbrock Performer
Rockers – Scorpion Roller Rockers 1.6 ratio (pedestal mount)
Lifters – Factory FR hydraulic
Pushrods – factory length/hardened
Harmonic Balancer – Summit Racing 28 oz.
Flywheel – 351w 28oz.

Timing at idle is about 7-8*
I am nervous with setting my timing, I don't want to burn pistons or bend pushrods (is it an interference engine?) I'd like it to be in a good safe and reliable spot for all around driving.

Mated to nv3550, Suspension is WH 2.5 w/11-leafs and bilsteins, extended WH driveshaft, BFG MT 33s. No sway bars or axle-wrap bars

I need to buy a vac gauge, comp tester, what else for diagnostics?

Sorry for the long winded rant and scattered questioning, I'm hoping a few of you know some simple and cheap tips to solve these issues!

Thank you,

Ryan

 

[Timmy390]

Well I'll chime in and say you have c carb/fuel deliver issue. Now to some specifics.

The cold startup that "black wet soot" is NOT unburnt ethanol. It's water or more specifically condensation from the heat of the exhaust and the cold wet air in the system. Even modern EFI cars/truck do this when cold i.e. that white fog you see from cars on cold days. It's black because the water picks up some soot from the pipes as it exits. JMO, you need a new mechanic. My 69 Mach 1 390 car only gets PURE gas and it's a water works till it warms up. Southern humidity adds to the issue.

Hard starting when cold? As in no matter the temps, it sits a few days and then will not start easy? This is a common issue with today's fuel and carbs. Once the engine is shut off, the fuel in the carburetor bowl begins to evaporate through the bowl vent. If there is no fuel in the carburetor, the engine will not start. Pumping the footfeed during this time simply prolongs the agony, as the accelerator pump will pump the fuel into the engine, but in amounts insufficient for starting. If you have this problem, try priming the carburetor by using an eyedropper and filling the carburetor bowl through the bowl vent prior to cranking the engine. If you do not wish to prime the engine, crank the engine for 15 to 20 seconds WITHOUT PUMPING. Then stop cranking, pump the foot feed 3 or 4 times, release it, and then reattempt to start the engine. Priming eliminates excessive wear on the starter. When mine has sat for a few days I always hit it with a shot of brake cleaner or starter fluid and it starts right up.

Drives good one day and spits and sutters the next sounds like fuel deliver. Bad pickup maybe, trash in the carb, water in the system etc.

Manual choke or electric? If electric, make sure you have the "hot" ran to a good 12v source.

Tim

 

[Seventee]

It really sounds like you have some work to do with the choke adjustment. Grab an Edelbrock manual and go through the adjustment procedures, including the pull-down setting. And as mentioned, make sure you have 12v power to the choke cap. Sometimes fuses get blown or wires accidentally get disconnected.

With a proper choke adjustment, you should be able to pump the gas pedal once and touch the key.

 

[77RHINO]

Thanks guys, I just ordered an edelbrock carb tuning kit, vacuum gauge, compression tester, piston stop tool (same cost as building one) and timing tape. I am going to verify TDC, timing, and markings since the pointer has swapped sides. I know I installed the new chain and cam at TDC, but didn't check that vs pointer while it was opened up. Ill check my compression since I don't know what my numbers are, and then dive into the carb tuning this weekend. My current factory sizes are .095 primary and .098 secondaries, with the metering rods at .068x.047. What is the best route to know which ones to swap and in which order, jets then rods or vice versa? What about knowing rich vs lean and which way I need to go safely without burning pistons or fouling up plugs? I know my tailpipe is nice and sooty but I don't usually see smoke just driving around. Is the surging at part throttle a too much fuel issue or not enough fuel issue?

 

[Seventee]

Here's a link to the Edelbrock carb manual: http://www.edelbrock.com/automotive/misc/tech-center/dl/carb-owners-manual.pdf

Looking at Page 12 (for a model 1406 assuming that's what you have) you can see with your rods/jets you have an odd ball combo that puts you 2.5 stages rich in the cruise mode and 1.5 stages lean in the power mode (location #16 on the chart).

Sometimes it's best to start over at the factory combination (#1 location), but if you don't want to change jets, you can use a couple of rod combinations to get you at #2 or #5 locations, which are much closer to factory calibration. Then see if things improve and go from there.

Edit: also another thing to check is which step-up springs you have.

 

[77RHINO]

Thanks Seventee and Timmy, I printed out that manual last night, I have the 1826 w/ elec choke hooked up on the alternator. I went last night and picked up a new air filter and a basic tach to help me better adjust it. I am waiting on fedex, I should be getting my package in sometime today. Until then, I am going to start piddling with what I already have, and see if I can get it to at least startup and get my fast idle settings adjusted.

 

[Rustytruck]

You didn't say what your running for an air cleaner but a stock type with heated heat stove and working dampers will make all the difference with a carburetor when its cold.

 

[Seventee]

I have the 1826 w/ elec choke hooked up on the alternator.

That changes things a bit. Page 19 has the calibration info for the 1826 and you can see that with those rods you are actually 2.5 stages LEAN in the cruise mode, which seems questionable at your elevation (for Alabama that is), and could certainly cause some surging or sputtering. Luckily a simple rod change to a 65x47 will get you back to stock calibration if you want to try that.

With the choke connected to the back of the alternator, it's likely you are only getting +/- 7volts which will cause the choke to operate incorrectly. I would for sure get it connected to a 12v source.

 

[77RHINO]

I just came in from the garage, installed a tach, put on a new air filter (I run a basic 10"x2" edelbrock cleaner assembly) and a new see-through plastic fuel filter, primed the carb and then it fired up! I haven't ever driven this with a tach so it was nice to see what I was actually turning vs what I was hearing. I lowered the fast idle down to about 1100, the reg idle looks to be between 725-750, so I waited for it to warm up and took it around the block. I still noticed the surging (about 2700-3000 RPMS) after a heavy accel, so I am going to read the manual and tackle that tomorrow. I also noticed after I parked it that within about 20 mins the fuel filter was basically empty. I didn't notice how much was in it right after I turned it off, but it seems my fuel system seems to be losing its prime pretty quick. Can I install some type of check valve between the tank and filter to keep it from losing prime so quickly?

 

[blubuckaroo]

I just came in from the garage, installed a tach, put on a new air filter (I run a basic 10"x2" edelbrock cleaner assembly) and a new see-through plastic fuel filter, primed the carb and then it fired up! I haven't ever driven this with a tach so it was nice to see what I was actually turning vs what I was hearing. I lowered the fast idle down to about 1100, the reg idle looks to be between 725-750, so I waited for it to warm up and took it around the block. I still noticed the surging (about 2700-3000 RPMS) after a heavy accel, so I am going to read the manual and tackle that tomorrow. I also noticed after I parked it that within about 20 mins the fuel filter was basically empty. I didn't notice how much was in it right after I turned it off, but it seems my fuel system seems to be losing its prime pretty quick. Can I install some type of check valve between the tank and filter to keep it from losing prime so quickly?

I don't think your fuel is running back to the tank. More likely, it's evaporating from the carb bowl. That's a problem with the boiling point of modern fuel. It will usually take a bit of cranking after sitting a few days.

One way to deal with this is to use an electric fuel pump, and let it prime the bowl for a moment before you turn the key.

Now for your surging problem...
One thing to consider is your carburetor heat riser port. Most aftermarket heads leave the decision to the owner weather they want to drill out and activate the exhaust rail or not. I'm like most and leave them disabled to help eliminate carb percolation. The downside to this is it takes the carb a little longer to warm-up. Until the carb warms up on mine, I experience a bit of hesitation too. I've just adjusted the electric choke to help deal with it.

 

[Timmy390]

I parked it that within about 20 mins the fuel filter was basically empty. I didn't notice how much was in it right after I turned it off, but it seems my fuel system seems to be losing its prime pretty quick. Can I install some type of check valve between the tank and filter to keep it from losing prime so quickly?

OK, been there done that on the Mach 1.

First like blubuckaroo said, it's more than likely evaporation. I added a Plastic Insulating Carb Spacer which really helped. Engines heat soak when turned off and the temps can get much higher than N.O.T. Spacers come in different heights so get the tallest that will not cause clearance issues.

Second, I found the system on the Mach 1 was not venting properly. I was removing fuel from the tank while driving but not enough air was venting in via the cap thus it would be sucked back into the tank emptying the filter and lines making it hard to start.

Fixing these two issues solved all the fuel issues on the Mach 1. I can sit for weeks and will fire right up. It is kept in a heated/cooled garage which also helps.

The Bronco on the other hand sits outside in the 100 degree AR heat so the bowls evaporating dry is a fact of life for me.

Tim

 

[77RHINO]

I think I have fixed my tough starting issue, started it up this morning and drove into work, no major problems..carb stuttered a little when braking before I was fully up to operating temp, but aside from that no problems! I replaced the rubber aux tank bypass line that the PO had installed, and put on a new fuel cap. I checked filter level when I turned it off Saturday afternoon, and it had a little less than half. Checked it before I started it this morning, and it was completely full! I'm not sure how it is able to slowly re-fill with the engine off, but it sure cranked easy this morning. My garage stays close to the same temp as my house, which I'm sure helps.

As far as tuning, I have adjusted the pump stroke to the middle hole, lowered fast idle to 1100, new air filter, new fuel filter, and went one stage richer with the rods. I will see at lunch if that makes it better, I didn't have a decent place to open it up with the morning traffic.

I did notice my vibration issue today, but it really didn't seem that bad. I have torqued my u-bolts to 85 ft-lbs, and did a small check around on nuts and bolts underneath.