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2019 NORRA M1K Bronco Build

landshark

Active Member
#1
Long time lurker, first time poster.

Thought I would post my Bronco build to run the 2019 NORRA Mexican 1000 in the Pioneer class, figured this would be great audience to garner more knowledge and recommendations along the way. I am admittedly a newbie to the desert racing scene but not to Broncos, have some exposure to Baja, most recent being a part of a chase crew the Baja 500 in May among other experiences. I have been bending the ear of several veteran Bronco racers and others for quite a while now and look forward to it finally coming together.

Picked up a Rolling Bronco chassis a few months ago and stripped it down and started repairing body/rust areas - recently finished most of the repairs and plan to remove the body form the frame and start re-enforcing areas, build the suspension then drivetrain. Happy to share more plans on the build if there is any interest in knowing the details as I have allot of irons in the fire as they say. Anyway - some photos of what I started with and where it sits as of last night:

IMG_5122.jpg IMG_5126.jpg IMG_5136.jpg IMG_5158.jpg IMG_5167.jpg IMG_5168.jpg IMG_5304.jpg IMG_5451.jpg IMG_5454.jpg IMG_5700.jpg IMG_5703.jpg IMG_5711.jpg IMG_5708.jpg IMG_5682.jpg
 

Chris_Wilson

Well-Known Member
#2
Pioneer 4x4s
The spirit of this category is to provide a home for production based 4x4 Trucks / SUVs that raced in the 1967-1975 era.

The body style must have existed in this era.
Example: A 1977 Bronco can be legal in this class since its body style was introduced in 1966.
The chassis must be stock.
Must have solid front axle 4 wheel drive.
The suspension must be stock including mounting / pivot locations and spring mounting locations.
Spring rate is open but leaf springs and shackles must be stock lengths.
The maximum shock diameter is 2” (OD). No coilovers. No bypass shocks (internal or external).
The maximum tire diameter is 35”.
No rear links.
 

landshark

Active Member
#3
Pioneer 4x4s
The spirit of this category is to provide a home for production based 4x4 Trucks / SUVs that raced in the 1967-1975 era.

The body style must have existed in this era.
Example: A 1977 Bronco can be legal in this class since its body style was introduced in 1966.
The chassis must be stock.
Must have solid front axle 4 wheel drive.
The suspension must be stock including mounting / pivot locations and spring mounting locations.
Spring rate is open but leaf springs and shackles must be stock lengths.
The maximum shock diameter is 2” (OD). No coilovers. No bypass shocks (internal or external).
The maximum tire diameter is 35”.
No rear links.
Yup. That’s the class i am building too!
 
#4
Whats bad is how limited space is for a radiator in those. Ive been working in the cooling system industry for 45 years and built a lot of custom cooling systems. A common misconception is put a thicker core in it! If you think about it say the H20 temp is 180 degrees by the time that air reaches the last row of tubes its the same temp as the H20 in the radiator which is redundant. Its what gets first air that's important. Over the road trucks,passenger cars and pickups today have large radiators and are only 1 or 2 rows thick. Another thing is electric fans you want to use a Spal fan its high rpm and wide blades, stay away from flex fans the blades flatten out above 2000 rpm. If you want to run a engine driven fan find one that is used on a vehicle that had aftermarket a\c they are readily available. (at least they are here in phx) If you choose a aluminum radiator steer clear of the ones that have the tubes epoxied into the header plate after time the epoxy cracks from the constant expansion and contraction of the tube to header joint and cannot be fixed. I have a friend who has a 74 bronco whos putting in a 351c motor in his, I will post pics of radiator and fan we are going to use.
 

landshark

Active Member
#5
Whats bad is how limited space is for a radiator in those. Ive been working in the cooling system industry for 45 years and built a lot of custom cooling systems. A common misconception is put a thicker core in it! If you think about it say the H20 temp is 180 degrees by the time that air reaches the last row of tubes its the same temp as the H20 in the radiator which is redundant. Its what gets first air that's important. Over the road trucks,passenger cars and pickups today have large radiators and are only 1 or 2 rows thick. Another thing is electric fans you want to use a Spal fan its high rpm and wide blades, stay away from flex fans the blades flatten out above 2000 rpm. If you want to run a engine driven fan find one that is used on a vehicle that had aftermarket a\c they are readily available. (at least they are here in phx) If you choose a aluminum radiator steer clear of the ones that have the tubes epoxied into the header plate after time the epoxy cracks from the constant expansion and contraction of the tube to header joint and cannot be fixed. I have a friend who has a 74 bronco whos putting in a 351c motor in his, I will post pics of radiator and fan we are going to use.
The cooling space is definitely limited and appreciate the advice. I own a 69 bronco with a 400 in it as well and have a large 3 pass (if i remember correctly) aluminum radiator with a 7 blade fixed fan, it does very well 95% of the time. Only issues i have are when I am at a stand still in high heat and/or altitude for long periods of time (20-30 minutes) idling. A few years ago I installed two electric pusher fans in front of the radiator and they work perfectly in those situations. I will dig up a photo of the engine/radiator and post up.

I plan to run a similar radiator but will be running a metal explorer fan
 

landshark

Active Member
#8
being asked by the engine builder what I want to do about crank case ventilation, whats the ideal scenario for this running in the desert/NORRA?
 
#9
I've been using p.c.v. with an oil separator inline. The one like you use on an air compressor. Cheap simple and effective. Most if not all oil vapor is trapped in the separator. This is on a 422 inch f.e. engine 10.5 to 1 cam duration of about 300 degrees with a 110 degree lobe separation and 104 dgree intake center line with 4 degrees of advance.
 
#11
After doing some research on p.c.v. systems I discovered that oil vapor contaminating the intake charge poses some tuning issues when trying to control detonation. Anyway this variable can be removed will allow for easier and more consistent tuning especially with a carbureted engine and more compression.
 

landshark

Active Member
#12
Finished working on most of the frame, cutting off what I don’t need, track bar drop bracket, stock shock mounts etc. turned out the stock track bar bracket was junk so cut that off too and used a heavy duty drop bracket I had laying around and fabbed up a new one.



Re-enforced some spots on the frame, leaf spring hangers, radius arm frame mounts, both sides of the frame where the steering box mounts and a few other spots. Threw a quick coat of paint on it.



Mounted the rear springs, axle is under it but still have to cut out some of the back brace to make room for the spring perch and u bolts and burn in the rear brake brackets.





Working on the Dana44, should have it rebuilt tomorrow and hopefully get it mounted under the frame manãna.
 

Moss2

Well-Known Member
#16
We found that running the progressive coils in front of our 79 we ran into coil bind just about the same time as the stops. Those extra few coils they put in make it worth measuring carefully and allowing a little extra for articulation. It makes a mess of the lower spring mount and isn't to good for the coils either.
I like the build, hope to see it run.
 

landshark

Active Member
#17
I think running on 16x 2" wheels is risky in the rough stuff :D
yes but that's 16 more wheels to go bad rather than 4 :)

We found that running the progressive coils in front of our 79 we ran into coil bind just about the same time as the stops. Those extra few coils they put in make it worth measuring carefully and allowing a little extra for articulation. It makes a mess of the lower spring mount and isn't to good for the coils either.
I like the build, hope to see it run.
I am worried about that, i will be doing some major measuring to set the bumps. Good thing about coils is that they aren't too expensive. Bad thing is everything else is... I will figure it out - appreciate the advice.
 
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