performance parts for an off road build

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woejise
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performance parts for an off road build

Post #1 by woejise » Wed Dec 27, 2017 11:15 pm

im about to start a build up of a 300 out of an 83 bronco, i want to build this engine for maximum torque for off road/mudding purposes. what is a good cam to go with? ive been looking at the clifford 6=8 but sounds more for road use

pmuller9
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Re: performance parts for an off road build

Post #2 by pmuller9 » Thu Dec 28, 2017 10:17 am

Need to know more about the engine build.

Bigger valves and port work?
Which Intake manifold and Carb?
Headers or EFI exhaust manifold?

Superbum
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Re: performance parts for an off road build

Post #3 by Superbum » Fri Dec 29, 2017 3:43 pm

Clifford makes good intake manifolds but their cams are old tech. I like Lunati cams because they tend to have more lift than their competition. Which one depends on how much compression what valve/port size and what carburetor you intend to use.
I'm running a 82 Bronco with 9.2:1 compression a Lunati 61002 and 1.94/1.60 valves with port work. The carb is a 470 cfm Holley Truck Avenger. It will have plenty of torque for towing and off-road use.

woejise
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Re: performance parts for an off road build

Post #4 by woejise » Sat Dec 30, 2017 11:56 pm

still working all the details out of what i want to do. im just starting my planning for the build so any input is greatly appreciated. i will most likely put it in an older jeep as an off road/mudder.

pmuller9
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Re: performance parts for an off road build

Post #5 by pmuller9 » Sun Dec 31, 2017 6:08 pm

For off road mudding purposes do you need the engine to rev and make power around 4000 to 5000 rpms or rock climbing torque at low rpms?
Are there also concerns of the carburetor being able to operate at extreme angles?

86f250straight6
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Re: performance parts for an off road build

Post #6 by 86f250straight6 » Sun Dec 31, 2017 9:44 pm

first thing, like pmuller said, is a carb going to be an issue with how you plan to use it? I have noticed with carb trucks inthe past that when im on and off the throttle in short bursts on a hill avoiding trees that the carb floods. in rough terrain like climbing a hill an you slide sideways a bit and have to stop to miss a tree youre forced to somehow push the clutch and brake together and rev it up to keep from stalling. If you get a 4 barrel intake manifold a chevy tbi setup can bolt right on and takes up no more space than a carb. 87-96 300's had multiport fuel injection, and is a significant gain over a carb even in stock form but the intake manifold is huge and not going to fit in your jeep without some cutting. either one will make more power over a carb and be 100% more reliable (it will literally run upside down)
I'm trying to build a truck that I can't break :bang:

woejise
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Re: performance parts for an off road build

Post #7 by woejise » Tue Jan 02, 2018 1:42 am

after doing some research sound like a TBI is definitely the way to go. not sure sure which one but im sure a little diging will point me in the right direction. thanks

pmuller9
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Re: performance parts for an off road build

Post #8 by pmuller9 » Tue Jan 02, 2018 9:44 am

This will be available in a few months.
https://www.dropbox.com/s/iesz74irdlgll ... l.pdf?dl=0
It is 450 cfm and will handle from 100 to 400 horsepower.
Uses 4 injectors for better low speed fuel control.
Annular discharge.

This is the Holley
https://www.holley.com/products/fuel_sy ... ts/550-849
Cost more, smaller CFM rating, supports 350 HP, uses two 100 lb injectors and is not annular discharger.

There are various GM TBI conversions.

For off road mudding purposes do you need the engine to rev and make power around 4000 to 5000 rpms or rock climbing torque at low rpms or something in between?

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Shorty
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Re: performance parts for an off road build

Post #9 by Shorty » Tue Jan 02, 2018 11:20 am

need to spin tires to clear treads, so 4-5000 rpm would be helpful. Depends on mud type, around here it is sticky clay. Sandy loam would need much lower rpms or you just dig yourself in.
85 F150 on 78 bronco frame C6 np205 welded dana44 front, trussed posi nine inch rear. EFI exhaust manifolds into one 2 1/2" rolls on 35x12.5x15 Maxxis Trepador.

pmuller9
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Re: performance parts for an off road build

Post #10 by pmuller9 » Tue Jan 02, 2018 1:05 pm

Shorty wrote:need to spin tires to clear treads, so 4-5000 rpm would be helpful. Depends on mud type, around here it is sticky clay. Sandy loam would need much lower rpms or you just dig yourself in.


Use one of the 22cc "D" shaped dish hyperuetectic pistons at zero deck.
Take a .025" cut off the head for a 9:1 compression ratio.
Use the Howards 280996-10 cam. .501”/.501”, 221/221, 275/275, 110deg LSA.
Install it with the intake lobe center at 106* ATDC

Installing bigger valves with some port work would give additional power.

woejise
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Re: performance parts for an off road build

Post #11 by woejise » Tue Jan 02, 2018 3:29 pm

I plan on taking advantage of low end torque. I dont plan on rock climbing but id like to clear an obstacle or 2 and climb a decant hill

pmuller9
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Re: performance parts for an off road build

Post #12 by pmuller9 » Tue Jan 02, 2018 3:53 pm

woejise wrote:I plan on taking advantage of low end torque. I dont plan on rock climbing but id like to clear an obstacle or 2 and climb a decant hill

That is why the cam is being advanced 4 degrees with the intake lobe center at 106* ATDC
This combination will give you plenty of low end torque and a wide power band for climbing long steep slopes.

If you want to come down a notch, Howards 80936-10 cam. .480”/.480” 213/213, 267/267, 110 deg LSA
The compression ratio would need to come down to 8.8:1 which eliminates the .025" head milling.

The reason for the Howards cam in this case is most of the other cam companies move out to a 112 LSA and the 110 LSA offers more midrange power with either headers or the stock EFI exhaust manifolds.

On a Ford 300, head modifications that improve airflow such as bigger valves and bowl work can actually add torque everywhere in the power band with the proper selection induction components.

pmuller9
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Re: performance parts for an off road build

Post #13 by pmuller9 » Tue Jan 02, 2018 10:57 pm

Let me explain the camshaft selection.
The stock cam has 268 degrees of advertised duration and only 192 degrees of .050" duration.
However it is retarded 4 degrees with the intake lobe center at 114 degrees ATDC
The intake .050" lobe closing point is 30 degrees ABDC and the intake advertised closing point is 68* ABDC

Torque well above the idle rpm is mainly determined by the intake .050" closing point as long as it is not competing with a lot of valve overlap.
If we use the second choice, Howards 80936-10 cam. .480”/.480” 213/213, 267/267, 110 deg LSA installed 4 degrees advanced with the intake lobe center at 106 degrees ABDC, the .050" closing point will be 32.5 degrees ABDC which is only 2.5 degrees more than the stock cam. Plenty of low end torque.
The higher lift will produce more torque and the longer duration will give you a wider power band.

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