Trouble starting fresh build

[Readhead]

I wish missing push rods were the problem. That’s an easy fix!!


1977 Ford Bronco/Fiberglass Body/302 bored .030/balanced/Trick Flow aluminum heads/cam/5spd/Locked w/ 4.10’s/35” BFG/4” suspension/3” body

Just what I saw in the picture hoped that was it

 

[Readhead]

Knew a guy who struggled for 4 hours trying to start his car ... the rotor was missing

 

[centex77]

Ouch.


1977 Ford Bronco/Fiberglass Body/302 bored .030/balanced/Trick Flow aluminum heads/cam/5spd/Locked w/ 4.10’s/35” BFG/4” suspension/3” body

 

[centex77]

Tore the carb down tonight to make sure nothing was stuck or blocked and everything looked good. Put it back together and still the same problem. I can get it to back fire if I pump the carb a few times. I’m leaning towards timing being off but not sure how. I’ll play with it some more on Sunday.


1977 Ford Bronco/Fiberglass Body/302 bored .030/balanced/Trick Flow aluminum heads/cam/5spd/Locked w/ 4.10’s/35” BFG/4” suspension/3” body

 

[broncochevy]

Finish the thread, is it running now. What was the problem??

 

[centex77]

Hell if I know. Tried starting fluid and that didn’t work. Cleaned the brand new carb to make sure nothing was blocked. That didn’t work. Spun the distributor back and forth. That didn’t work. Swapped plug wires 180*. That didn’t work. Got a performance shop that works on older vehicles and specializes in Ford’s. I’m going to have it towed there. I’m traveling for the next 4 weeks straight and want this thing running by Christmas.


1977 Ford Bronco/Fiberglass Body/302 bored .030/balanced/Trick Flow aluminum heads/cam/5spd/Locked w/ 4.10’s/35” BFG/4” suspension/3” body

 

[pcf_mark]

I'm going to add my guess. You had everything right it just needs more fuel. If you work the throttle enough and the squirters are going you should have wet plugs after while. An MSD will fire those anyway. To check your spark end to end just put the timing light on it while you crank and dial it back to zero. It should align with zero on the pointer. If not you have the wrong cylnder, wire or some other odd combo. If it does then pump the carb about 10 times then start cranking.

Good luck!

 

[74 Bronco Billy]

You mean we gotta wait till Christmas to hear how this turns out?

I feel your frustration. Take a beer break, recheck your list, invite a buddy over and go through it together. My bet though is on timing, possibly distributor gear. I thought for sure it was 180*, but you tried that, so,

Good luck.
Forrest

 

[centex77]

I'm going to add my guess. You had everything right it just needs more fuel. If you work the throttle enough and the squirters are going you should have wet plugs after while. An MSD will fire those anyway. To check your spark end to end just put the timing light on it while you crank and dial it back to zero. It should align with zero on the pointer. If not you have the wrong cylnder, wire or some other odd combo. If it does then pump the carb about 10 times then start cranking.

Good luck!

Plugs aren’t wet at all which leads me to a fueling issue but the only time it fires is after I pump the throttle a bit and then it back fires out of the carb which tells me timing.


1977 Ford Bronco/Fiberglass Body/302 bored .030/balanced/Trick Flow aluminum heads/cam/5spd/Locked w/ 4.10’s/35” BFG/4” suspension/3” body

 

[pcf_mark]

Carb backfire can be 180 degrees out or 20 degrees out. Use the timing light while cranking to see if you are even in the ball park.

 

[Joe473]

Plugs aren’t wet at all which leads me to a fueling issue but the only time it fires is after I pump the throttle a bit and then it back fires out of the carb which tells me timing.


1977 Ford Bronco/Fiberglass Body/302 bored .030/balanced/Trick Flow aluminum heads/cam/5spd/Locked w/ 4.10’s/35” BFG/4” suspension/3” body

Even off one tooth when you drop in dizzy can make it backfire. Still sounds like timing. How long have you been cranking this thing. Bring the #1 piston up to TDC compression stroke check Mark's on balancer and check rotor under #1.

Where are you located?

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[centex77]

All said and done, probably 10mins of cranking.

I’ll try the timing light. Can’t hurt. Neither could a match.


1977 Ford Bronco/Fiberglass Body/302 bored .030/balanced/Trick Flow aluminum heads/cam/5spd/Locked w/ 4.10’s/35” BFG/4” suspension/3” body

 

[74 Bronco Billy]

Any update? Is it running?

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[centex77]

Haven’t had a chance to work on it much. Work and holidays and life get in the way of projects. Decided to work on something else the other day and it took me 4hrs to put a single caliper on. Damn truck has fought me every step of the way.


1977 Ford Bronco/Fiberglass Body/302 bored .030/balanced/Trick Flow aluminum heads/cam/5spd/Locked w/ 4.10’s/35” BFG/4” suspension/3” body

 

[centex77]

I'm bringing this thread back from the dead. I got tired of arguing with the engine and brought it to a shop. Took them a while but they traced it down to a pinched wire inside the fuse box and the valves being to tight. They just sent me a quick video of the engine firing for the first time. I'm heading to the shop now to take a look and will post a video of it later. First time in 3 years the engine has run. I can't wait. Just need body work and paint and it'll be on the road!!

 

[DirtDonk]

Well congrats!
Uh, and well it's about time too! Hah! Sorry you had to wait so long to hear it running, but at least it's going now. You'll be drivin' it soon hopefully.

Did they say which wire was pinched?

Paul

 

[centex77]

Holy shit. This thing is AWESOME sounding. The video quality doesn't do it justice. Was speaking to the shop and the 750 carb that's on there is to small for the engine and you can actually run it out of fuel going over half throttle. So they are going to install a much larger carb to deal with that and are upgrading the msd ignition system to a more robust one as well.

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[DirtDonk]

Wait... A 750 is too small(!) for a 302-based engine build in a Bronco? What the heck kind of cam do you have in there?
Never heard of such a thing in the normal engine world. Too large, yes, all the time. But too small? Not very often.
With super-hipo builds maybe, but anything shy of 600hp should be able to breathe through a 750 carb. Just might need larger jets.
What power level do you estimate you're running up to? And at what rpm?

Ok, so that's not using any hard and fast rules based on CFM, efficiency, blah blah blah, or any calculations. Just on fairly common knowledge stuff. There are probably a lot of variables, and your guys are likely a lot more experienced and maybe are using a dyno? If so they could tell if the carb is causing a restriction especially at higher rpm. And carbs don't always flow their rating in every condition anyway. Maybe they found through testing that you were losing some fuel on the top end.
Must be pretty severe if they think re-jetting is not going to work, but a larger carb will.

Pretty normal to utilize sub-1000cfm carbs on engines of less than 800bhp I think.
Probably a crossover gray area in there somewhere above 600 of course, so maybe I'm over analyzing it with bad, or limited info on my part. But what size are they talking? An 800cfm carb? Maybe an 850, or even a 1000cfm carb? Or something in-between?
Using the same intake, or going with a larger footprint? If the same, then I'm guessing they're keeping it below 900cfm.

I was curious before, but now I'm REALLY interested!
Can't wait to see the video either, and see the News at 11 too!

Paul

 

[DirtDonk]

Holy shit. This thing is AWESOME sounding.

Besides, everything else aside, that pretty much says it all!;D

Paul

 

[centex77]

Wait... A 750 is too small(!) for a 302-based engine build in a Bronco? What the heck kind of cam do you have in there?
Never heard of such a thing in the normal engine world. Too large, yes, all the time. But too small? Not very often.
With super-hipo builds maybe, but anything shy of 600hp should be able to breathe through a 750 carb. Just might need larger jets.
What power level do you estimate you're running up to? And at what rpm?

Ok, so that's not using any hard and fast rules based on CFM, efficiency, blah blah blah, or any calculations. Just on fairly common knowledge stuff. There are probably a lot of variables, and your guys are likely a lot more experienced and maybe are using a dyno? If so they could tell if the carb is causing a restriction especially at higher rpm. And carbs don't always flow their rating in every condition anyway. Maybe they found through testing that you were losing some fuel on the top end.
Must be pretty severe if they think re-jetting is not going to work, but a larger carb will.

Pretty normal to utilize sub-1000cfm carbs on engines of less than 800bhp I think.
Probably a crossover gray area in there somewhere above 600 of course, so maybe I'm over analyzing it with bad, or limited info on my part. But what size are they talking? An 800cfm carb? Maybe an 850, or even a 1000cfm carb? Or something in-between?
Using the same intake, or going with a larger footprint? If the same, then I'm guessing they're keeping it below 900cfm.

I was curious before, but now I'm REALLY interested!
Can't wait to see the video either, and see the News at 11 too!

Paul

I double checked and it was a Edelbrock 650 I had originally installed.

Bumbera racing knows far more about engines than I do and I'll trust them if they say I need more. It's a trick flow stage 2 cam, trick flow twisted wedge cnc ported aluminum heads, 1.6 or 1.8 (can't remember right now) trick flow rockers, a weiand dual plane intake, balanced rotating assembly, bored 30 over, flat top pistons and long tube headers. I'm aiming to spin it up to 6500rpm. Once it gets out of the body shop it's going on the dyno.

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