1984 Bronco build thread

[ArdWrknTrk]

Hi Guys! here are some photos to go along with the story from yesterday.

bearing damage - I suspect machining debris from the original rebuild was captive in the crank or block at first fire of the engine in early 2022.

The new Engine

I ported the intake, I only have this before photo showing the alignment issue between the spacer and the inlet flange.

The new heads intake and exhaust ports - I was really pleased with these.

Finally, the Holley 390. this carb has a few upgrades to include a rear metering block, a quick fuel adjustable vacuum canister (white spring installed), and a mechanical choke. I dont recall my jetting at the moment, but its somewhere in the neighborhood of 54s in the primaries and 58s in the secondaries. Ill try to verify. Its running an 8.5 power valve. The carb was running great when I pulled the engine. I took it apart and cleaned everything up at that time so it should be ready to drop on and run. hopefully the new cam wont play too much havoc on tuning.

That Offy C and 390 is a great combo for the 300!

I gave one to a CT member from FTE (Josiah) with the Holley (black) cap.

So, was it you, or your machine shop that didn't scrub out the engine before assembly?

That's got to be frustrating, to lose a fresh engine. 😖

[StraightSix]

That Offy C and 390 is a great combo for the 300!

I gave one to a CT member from FTE (Josiah) with the Holley (black) cap.

So, was it you, or your machine shop that didn't scrub out the engine before assembly?

That's got to be frustrating, to lose a fresh engine. 😖

Hi Jim!

Unfortunately, that was the machine shop. I picked up a completed long block from them. The issues are better documented on ford six, but I had to go into that block before installing it to retime the cam ("yeah, we timed the cam, it was right at zero" - whatever that was supposed to mean) as well as resealing the oil pan gasket and a few other issues. I feel much better about the shop that did the work this time around but its hard not to be nervous after my first experience!

I still dont know what was causing my come and go loss of compression on Cyl 5. It is made especially odd by the fact that it made zero PSI, not just low pressure.

I really like my 390. My guess is that the primaries are actually flowing about the same amount of air or just slightly more than the factory 1 barrel leading to great throttle response at part/light throttle where most driving actually happens, but the secondaries are there when you want them. If someone made a smaller 4 barrel, or even some kind of vacuum actuated staged 2 barrel (think half of a 600 cfm 4 barrel) Id be mighty interested, but out of the commonly available options I like the 390 a lot. Assuming the vehicle stays carbureted I dont anticipate ever replacing the 390.

[ArdWrknTrk]

Hi Jim!

Unfortunately, that was the machine shop. I picked up a completed long block from them. The issues are better documented on ford six, but I had to go into that block before installing it to retime the cam ("yeah, we timed the cam, it was right at zero" - whatever that was supposed to mean) as well as resealing the oil pan gasket and a few other issues. I feel much better about the shop that did the work this time around but its hard not to be nervous after my first experience!

I still dont know what was causing my come and go loss of compression on Cyl 5. It is made especially odd by the fact that it made zero PSI, not just low pressure.

I really like my 390. My guess is that the primaries are actually flowing about the same amount of air or just slightly more than the factory 1 barrel leading to great throttle response at part/light throttle where most driving actually happens, but the secondaries are there when you want them. If someone made a smaller 4 barrel, or even some kind of vacuum actuated staged 2 barrel (think half of a 600 cfm 4 barrel) Id be mighty interested, but out of the commonly available options I like the 390 a lot. Assuming the vehicle stays carbureted I dont anticipate ever replacing the 390.

😳 Yeah, that's definitely their problem.

I don't know much about timing the geared cam in a 300.

I assume you can get offset keys, like my Ducati bevel's?

"Straight up" or zero with a 460 is when the crank and cam keyways are pointing directly at one another.

If you are thinking about a 2-Barrel consider a progressive Weber.

Some hate them and some love them. 🤷‍♂️

I remember when the Ducati 906 Paso came out with one. They worked really well.

 

[StraightSix]

😳 Yeah, that's definitely their problem.

I don't know much about timing the geared cam in a 300.

I assume you can get offset keys, like my Ducati bevel's?

"Straight up" or zero with a 460 is when the crank and cam keyways are pointing directly at one another.

If you are thinking about a 2-Barrel consider a progressive Weber.

Some hate them and some love them. 🤷‍♂️

I remember when the Ducati 906 Paso came out with one. They worked really well.

Jim,

You hit the nail on the head! Offset keys are really the only option for adjusting 300 cam timing these days. I believe there were adjustable timing sets of some kind in the past but Ive never seen one.

Ive read a bit about the webers! That is an exciting concept to me, but I think I would rather it be vacuum actuated than mechanical. Then again, Ive never tried one. Thry might be dandy

[ArdWrknTrk]

Jim,

You hit the nail on the head! Offset keys are really the only option for adjusting 300 cam timing these days. I believe there were adjustable timing sets of some kind in the past but Ive never seen one.

Ive read a bit about the webers! That is an exciting concept to me, but I think I would rather it be vacuum actuated than mechanical. Then again, Ive never tried one. Thry might be dandy

Weber is huge. They owned all the Carter and Edelbrock patents for decades.

It's likely the YFA that came on your truck was made in their factory.....

 

[Gary Lewis]

Weber is huge. They owned all the Carter and Edelbrock patents for decades.

It's likely the YFA that came on your truck was made in their factory.....

Late to the party as I've been driving all day. But those bearings look BAD! That's a bummer!

But you are well on your way to having a great engine.

[ArdWrknTrk]

Last Summer I developed a miss at idle.

.....cylinder 5 made 0 psi. I started the truck up and drove it into the workshop where I discovered that unplugging the #5 plug wire with the engine running caused an immediate reduction in idle speed, quality and vacuum as well as causing the wide band O2 to show leaner - so cylinder 5 was indeed combusting and doing something. I repeated the compression check and found that cylinder 5 was still making 0 psi. From there I decided to pressurize cylinder 5 with both valves closed to see which side the air came out through - there was a small puff of air under the paper towel covering the carb inlet, then a clicking sound, and then the cylinder started to build pressure. A subsequent compression check showed 150 psi like the other cylinders.

.......from there I decided it was either a bent/sticky valve or a valve seat issue

I never did find the root cause of my miss at idle, the valves were straight and felt very good in the valve guides, no apparent seat issues.

If the valve went click when you did a leak down and made pressure after that, it wasn't a seat issue.

Tight, sticky, something...

 

[StraightSix]

Last Summer I developed a miss at idle.

.....cylinder 5 made 0 psi. I started the truck up and drove it into the workshop where I discovered that unplugging the #5 plug wire with the engine running caused an immediate reduction in idle speed, quality and vacuum as well as causing the wide band O2 to show leaner - so cylinder 5 was indeed combusting and doing something. I repeated the compression check and found that cylinder 5 was still making 0 psi. From there I decided to pressurize cylinder 5 with both valves closed to see which side the air came out through - there was a small puff of air under the paper towel covering the carb inlet, then a clicking sound, and then the cylinder started to build pressure. A subsequent compression check showed 150 psi like the other cylinders.

.......from there I decided it was either a bent/sticky valve or a valve seat issue

I never did find the root cause of my miss at idle, the valves were straight and felt very good in the valve guides, no apparent seat issues.

If the valve went click when you did a leak down and made pressure after that, it wasn't a seat issue.

Tight, sticky, something...

Jim, I would have bet anything you were right before taking it all apart but I never found anything sticky. The valves felt perfect in the guides sliding and spinning. Like floating on a film of oil. You must be correct but I sure dont know what part is to blame.

Gary, the positive outlook is always appreciated, and for a chronic worrier like me, needed.

Lots of good progress on dressing the engine tonight. I got the water pump, thermostat housing, fuel pump, dip stick, ps brackets and intake/exhaust studs all installed. Now the intake is in a soapy bathtub full of hot water heat soaking, Im trying to get all of the fine chips from porting the inlet out. Thats probably where Ill leave it today!

I plan to take the transmission and transfer case down before flying the engine in, maybe Ill get that tomorrow! I also need to verify TDC against the balancer marks. I may be able to get all of that tomorrow which would leave me ready to fly the engine this weekend! It might still take the better part of next week to finish dressing the engine in the engine bay (intake, exhaust, carb, PS, wires and such. Im feeling pretty good about getting it going in the next 10 days or so!

[ArdWrknTrk]

Jim, I would have bet anything you were right before taking it all apart but I never found anything sticky. The valves felt perfect in the guides sliding and spinning. Like floating on a film of oil. You must be correct but I sure dont know what part is to blame.

Gary, the positive outlook is always appreciated, and for a chronic worrier like me, needed.

Lots of good progress on dressing the engine tonight. I got the water pump, thermostat housing, fuel pump, dip stick, ps brackets and intake/exhaust studs all installed. Now the intake is in a soapy bathtub full of hot water heat soaking, Im trying to get all of the fine chips from porting the inlet out. Thats probably where Ill leave it today!

I plan to take the transmission and transfer case down before flying the engine in, maybe Ill get that tomorrow! I also need to verify TDC against the balancer marks. I may be able to get all of that tomorrow which would leave me ready to fly the engine this weekend! It might still take the better part of next week to finish dressing the engine in the engine bay (intake, exhaust, carb, PS, wires and such. Im feeling pretty good about getting it going in the next 10 days or so!

Can you just take the sticks and transmission mount off and slide the TC/gearbox assembly back out of the way on the crossmember?

I've done this quite a few times and it saves me having to fight it back up into place.

Of course I'm usually working without a lift or even a proper transmission jack so it might not be a big deal for you.

[StraightSix]

Can you just take the sticks and transmission mount off and slide the TC/gearbox assembly back out of the way on the crossmember?

I've done this quite a few times and it saves me having to fight it back up into place.

Of course I'm usually working without a lift or even a proper transmission jack so it might not be a big deal for you.

Jim,

Thats a great idea. I am working with a transmission jack, but your suggestion would still possibly be a time saver. Ill look at it when I get under there!