Hard starting 302 “all of the sudden”

[DeepC73]

Thanks in advance everyone! I drive my Bronco probably 6 days a week. It normally starts right up. Last week I drove it around probably 2-3 hours. Toward the end I of the drive it sputtered as I stopped at a couple of stoplights. It never stalled. I switched tanks because it was acting like it was running out of gas. It didn’t really affect it. When I pulled into the store parking lot and put it in park it idled up really high, about 1200-1500 rpm’s. It was like it had a vacuum leak. I searched everywhere, no leak. I couldn’t find why it was idling high. I ended up backing off the idle screw about 3/4 turn and brought the idle back to normal. I drove it home about 25 minutes away and it ran fine. When I slowed down to pull into my driveway it was idling very low and almost stalled. When I got out and popped the hood, I turned the idle back up to where it was originally.

The next day when I got home from work I went to take the. Dog for his daily ride. When I cranked it up, it was again idling high. I couldn’t find any leaks, nothing stuck on the carb, nothing anywhere. I tightened all clamps on the vacuum lines, fuel lines, cleaned out the carb (Holley 600), replaced the fuel filter etc. After all of that it ran normal for a few days. Tuesday afternoon it started getting “hard to start”. It turns over STRONG. When I first crank it up I have to pump it or put it on the floor and hold it there, it will start. After that it starts right up, unless it has been off for more than about ten minutes. If does the same thing as when it’s cold. It hasn’t done this since rebuilding the motor two years go. It normally starts up as soon as I turn the key. Any ideas? I checked the plugs and they are a little white, like it is running lean.

 

[DirtDonk]

Sounds like this one’s gonna be all on you.
From out here we’ll throw suggestions out, but you’ve already tried some of them. Something changed, and most likely with the carburetor. But also possibly with the distributor.
You need to check your ignition timing first, just to see if it’s cooperating. Then look all over the place for any other hoses that might pop off, and anything out of the ordinary. Which you’ve already done, but probably need to do it again.
Did you pull the air cleaner off to check all the carburetor mechanism? Sounds like you did, but I wanted to make sure.

 

[m_m70]

i think most of the early responses are going to be "do you have this"? Saying that, it would be helpful if you added your trucks details in your signature. The basics. We know you have a carb, but what type of ignition, fuel pump and any mods should be listed. Just helps us help you.

 

[B RON CO]

Hi, I would remove the air cleaner and verify the choke operation. When the engine is cold, the choke should close when you touch the throttle. When the engine is warmed up, the choke should be fully open and be held open by spring pressure. Good luck

 

[DeepC73]

Thanks for the responses, sorry for the delay. I had duty and then came home to dig into the engine. I have a blown head gasket on the passenger side. It’s the cylinder closest to the firewall. I did a cold compression check and got 35 psi on that cylinder, around 100 psi on the other 7 cylinders.

Engine details:
302, .030 over
Mild cam, stage 3
Electronic ignition
Aluminum Ford racing intake manifold
Holley 600 carb

I plan to remove the intake this weekend and replace the head gasket.

I’m thinking of replacing the heads. Any suggestions if I decide to do so?
GT40, E7 or maybe aluminum heads. Which will be best for a daily driver. I drive it every afternoon. I never go off-road.

Thanks!

 

[DeepC73]

Well, I’m a little perplexed. I tore apart the intake and the right head. I will post a video link below. I’m a little out of my depth, but I didn’t find anything that jumps out at me like I was expecting. I might have just tore apart a perfectly good head and intake. Please take a look at the three short videos and give me your thoughts. Much appreciated.

https://share.icloud.com/photos/0bdPD-ZfTtytZ8RZ9k8M128JQ

https://share.icloud.com/photos/0ccao31Zyp7HB7VX981du1V6w

https://share.icloud.com/photos/0e4l8D0YdbyYCT1WS97Klh_cw

 

[nvrstuk]

Low compression, hard starting, idle doing weird things...

Did you check your valve train before ripping it apart by chance? Lifter noise (cam or lifter issue) or valvetrain noise (need adj or got out of adj) b4 tearing it down? So hard to diagnose by typing but pour some paint thinner or laquer thinner into the chamber of your head so you can see if the valves are seating properly. Maybe some crud got under a valve causing the low compr, hard start, etc. Lot's of possibilities.

 

[DeepC73]

Low compression, hard starting, idle doing weird things...

Did you check your valve train before ripping it apart by chance? Lifter noise (cam or lifter issue) or valvetrain noise (need adj or got out of adj) b4 tearing it down? So hard to diagnose by typing but pour some paint thinner or laquer thinner into the chamber of your head so you can see if the valves are seating properly. Maybe some crud got under a valve causing the low compr, hard start, etc. Lot's of possibilities.

Thanks for the response. I will pour some thinner in it tomorrow afternoon and see. It was knocking every now and again, but I’m pretty sure it was lifter tick. The rockers were tight and torqued to spec. It sounded like it had a slight exhaust leak which was slowly getting worse over the last month or so. How does the pistons and cylinders look to you? Maybe I will just slap another gasket on it and put it back together. Maybe I will put a new set of heads on it while it’s apart. MTF.

 

[nvrstuk]

Well, I’m a little perplexed. I tore apart the intake and the right head. I will post a video link below. I’m a little out of my depth, but I didn’t find anything that jumps out at me like I was expecting. I might have just tore apart a perfectly good head and intake. Please take a look at the three short videos and give me your thoughts. Much appreciated.

https://share.icloud.com/photos/0bdPD-ZfTtytZ8RZ9k8M128JQ

https://share.icloud.com/photos/0ccao31Zyp7HB7VX981du1V6w

https://share.icloud.com/photos/0e4l8D0YdbyYCT1WS97Klh_cw

I don't use the cloud so I can't download.

Send them to me individually.

PM for my email addy.

 

[gr8scott]

The very top valve in the video looks a little strange.

 

[gnpenning]

The very top valve in the video looks a little strange.

View attachment 927226

On my .75 cent phone that looks like a burnt exhaust valve.

 

[DirtDonk]

Same here. Seriously compromised.

 

[DeepC73]

Yep, you guys are definitely spot on. I was so focused on the head gasket that I wasn’t seeing the snake right in front of me. That’s definitely the “smoking gun “. So what would cause it to run so lean and burn a valve? Timing advanced too far? Leaking Exhaust gasket?

 

[DirtDonk]

I’m not sure how you determined that it could only be a head gasket, by a compression check. But the good news is, you would’ve had to remove the head anyway to fix the valve!
So you’re not out any extra labor or extra frustration yet.
And you were already thinking about changing the heads too, to something better. Seems like that’s definitely in the cards at this point.
The E7’s were considered to go to until the GT40s came out. With the GT40P being the ultimate factory 302 head.
But with its own set of difficulties, of course, making sure that your exhaust manifolds or headers fit with the modified spark plug angle.
Seems like the other head should come off too, just to make sure.

As far as what did it? Hard to say.
Running things too lean and that cylinder got the brunt of it due to fuel and air distribution in the intake?
Spark too advanced, and that cylinder the only one having a pre-ignition issue? What does the piston look like?
Defective valve maybe? Or just plain old age.
How old are the cylinder heads and valves? Sounds like the engine has been worked on, but were they replaced at the same time?

 

[gr8scott]

When you do get it sorted with a rebuilt head(s) or new heads go with these gaskets.
I put them on several thousand miles ago and never had to to touch them since.

Remflex Graphite Header Gaskets, Ford 289/302/351W V8

Check out the deal on Remflex Graphite Header Gaskets, Ford 289/302/351W V8 at WILD HORSES 4X4

www.wildhorses4x4.com

 

[DeepC73]

I’m not sure how you determined that it could only be a head gasket, by a compression check. But the good news is, you would’ve had to remove the head anyway to fix the valve!
So you’re not out any extra labor or extra frustration yet.
And you were already thinking about changing the heads too, to something better. Seems like that’s definitely in the cards at this point.
The E7’s were considered to go to until the GT40s came out. With the GT40P being the ultimate factory 302 head.
But with its own set of difficulties, of course, making sure that your exhaust manifolds or headers fit with the modified spark plug angle.
Seems like the other head should come off too, just to make sure.

As far as what did it? Hard to say.
Running things too lean and that cylinder got the brunt of it due to fuel and air distribution in the intake?
Spark too advanced, and that cylinder the only one having a pre-ignition issue? What does the piston look like?
Defective valve maybe? Or just plain old age.
How old are the cylinder heads and valves? Sounds like the engine has been worked on, but were they replaced at the same time?

I was just focused on the head gasket, rookie mistake. I inspected that the valve wasn’t bent and was operating correctly and moved on to the head. Lesson learned.

I have the factory exhaust manifolds still on there. I’m a little concerned about what I’ve read and heard about the GT40 and 40p heads and clearance for the plugs etc. it turns out an old team mate buddy of mine’s brother runs a machine/head shop. I dropped it off to him this morning for inspection and rebuild. He said the other valves and the head looked fine. He will let me know what he finds in a few days. It could have been the valve or the guide.

I have the original motor on a stand in the garage to build this summer. I’m going to start on it and drop off the block in late July. My current motor I installed two years ago. I bought it from a buddy then. It had around 10k miles on it when I put it in. We went through it really good before installing it and I have put almost exactly 10k on it over the last two years. When they looked at the head briefly this morning they guessed it had around 20 k on it so it all adds up.

I’m just going to rebuild the valves in the affected cylinder and have rhe head resurfaced and inspected, then re-install it and drive it while I build the original one the way I want it nice and slow. I am going to buy a nice set of heads for the rebuild. I would like to stick with the factory exhaust manifold. Any ideas or suggestions on that? I would prefer aluminum since I’m doing it right. However, this is a daily therapy cruiser for me and the dog, not a street rod.

 

[DeepC73]

Sorry for the continued harassment. I’m leaning toward removing the other head, since it’s already apart. Should I do that or leave well enough alone?

 

[m_m70]

I would. Head gaskets and exhaust manifold/header gaskets come in pairs so the only thing you will be out on is the time it takes to remove and clean up. I would want to have the top end gaskets to have the same mileage/time on them. Some will say leave it but not me........Might as well see what those valves look like.