1986 F-150 complete rebuild ,from the ground up - Page 2

jonmark1985 · 12-27-2007, 01:51 PM

Your about 180° off. if your looking for low end tourqe and grunt you gotta work torwards in a different attitude. You actually need a less agressive small cam. Peak tourqe usually occurs near your highest volumetric efficency. You run the bigger cam your putting more air into the motor. At lower speeds the air charge speed is going to be slower because the demands of the engine are not near as great, but at the higher speeds you effectively fill the cylinders, but low end tourqe suffers. If you wanna make the truck truly fast your will disregard low end tourqe, grab the biggest longest duration cam you can find, port (in all actuallity hog out) the head, put huge valves in it, a completely free exhaust with a tuned header, and either a wild stall converter (4500-5000 rpm). This way you will gain the most horsepower because your making a gob of tourqe at wild rpms. This won't be a streetable combo in the pure sense, but boy it would smoke tires and run.

For this motor I'd reccomend getting a truck camshaft, that will help fill the cylinders from 1500-4000 rpms. Run either a stick shift or a slightly stalled automatic. 4.11 gears will greatly multiply the tourqe and you'll be able to have enough tourqe to pull a barn. But don't scimp out and get the smallest camshaft you can find. When you improve the induction exhaust and the head your are going to need to move more air into the motor, more than the factory camshaft will allow at the RPM the altered parts will let you.

The goal is to rather build a RPM to shoot for. Right now the motor is pretty much built for tourqe at off idle, basically your want to slightly elevate this, and get the VE (volumetric efficency) to around 100%, instead of the stock ~70%.

davetruck · 12-27-2007, 02:39 PM

Thanks bro,
I've got a lot to think about and lots to consider before I commit to anything.

But one thing I got from what you said was volumetric efficiency, is this basically getting the most efficient air flow?
I've read that these inline sixes are great but it's biggest downfall was poor airflow... or, it starves for air??

is that what you are getting at?

cam with long durartion and big valves for lots of horse power?

you think I want to smoke tires? Damn Right I do !! I want lots of horse power from the second I hit the gas, One thing thats always been missing from my previos vehicles was no ablity to sprint off the line , I'm talkin my driving to work vehicles , my gettin around cars, but this truck ain't gonna be for daily driving just for drivin around and showin off , layin rubber everytime I see another guy in a truck.

They all like to squeal their tires around here so I will too

Any how got the garage 97% cleaned out, got some tools layed out but will get a wall set up for us to hang them on, got a corner set aside for the engine hoist and stand I need to buy.

Napa is still closed until the 28Th in the mean time I bought a part cleaning tank (5gal)
My son and I will put it together tomorrow.
I'll get some pics of the cleaned out garage(it was filthy,sawdust everywhere, the guy I bought this house from had a wood shop in there)

In the mean time I gotta think about what ya said jonmark1985,

Dave

jonmark1985 · 12-27-2007, 06:29 PM

100% VE is filling the cylinders completely.

Say with the motor stock appearing your gonna run 80% peak VE @2500 rpm. The best the motor fills the cylinders with fuel is 80%. Then lets also say that above that VE drops off pretty fast. At 4000 rpm VE is 60%. Your tourqe will actually be lower at 4000 than at 2500, but you may make more horsepower at 4000 rpm than 2500 rpm. This is because your speed of your engine gives your the power.

In this second scenario lets say we have the motor properly modified for a truck. This time we have 95% VE at 2500 rpm. Tourqe is increased and horsepower is increased from stock. At 4000 rpm VE is 80% and horsepower and tourqe are greatly increased.

In this last and third scenario lets say the motor is wildly souped up for a drag car/truck. At 2500 rpm VE is around 97%, but the amount of fuel flow the heads/cam/induction/exhaust are capable of surpasses what the engine is capable of requiring. The speed of the fuel traveling through the runners is sluggish and tourqe is slightly lower than in the previous motor for this given rpm. At 4000 rpms VE is 95%. Tourqe is very strong and with the combination of higher revs horsepower is through the roof. This point is the VE peak, and also peak tourqe. The speed of the fuel is moving at a good rate. At 6000 rpm VE drops down to say.. 75%. Tourqe drops off, but your engine still has some speed and horsepower still slightly increases. Finally lets say at 8000 rpm the VE drops to 60%. Tourqe finally drops off enough that horsepower drops off as well also. The fuel is moving so fast through the induction and head that it crashes against the bowls of the head. At this point a down shift would pay off.

jonmark1985 · 12-27-2007, 06:55 PM

Ok now lets get some parts figured out for you. Lets start at the carb.

I'd reccomend a 600 cfm 4160. Being that the engine is on the smaller side and your not really going be revving the motor over 5000 rpm you wont need a large carb. Make sure that you get a vacuum secondaries carb. A larger vehicle won't like a double pumper very much.

Then you want to hunt up a good 4V intake manifold. I'd opt for one without EGR is you don't have to worry about being emmisions compliant. EGR will warm the intake up and make your fuel less dense than it can be. You also want to find an intake with long runners. Short runners, or long tuned runners (tunnel rams) are designed to move fuel fast through the intake. The long runner will have to maintain an appropriate fuel speed in order to meet the demands that the later part of your engine is requiring.

At the head I would try a hand at porting the head. Begin by gasket matching both the intake and exhaust ports. Smooth out any bumps or casting flash in the ports, but the objective for this motor is not to change the shape of the ports and remove as little material as possible. Then spend a very good amount of time blending the bowls directly below the vavles. Leave the valve guids intact, but make the area around the guids smoothly meet the rest of the port. In the chamber you may want to unshroud the valves. Try to imagine the fuel leaving the head and how it will travel. Look for any obvious obstructions, Don't cut too much out of the chamber though, or you will compromise your compression. Then polish the exhaust ports to a chrome like finish. A three angle valve job will also be worth while.

An RV or "tourqe" camshaft wil prove quite adequate here with this motor. Long duration will not match the rest of the package, and will want to breathe better at a higher rpm. As for gross lift stay modest, unless you have access to a flowbench. If you do have the head flowbenched you will want to have the camshaft's gross lift set just slightly below the point at which the fuel's speed becomes turbulent. Remember too that a large lift will make an unstable valvetrain if it takes an aggressive nature. A short duration with a large lift will have a very steep lobe, and could be more prone wear. Also valve springs, retainers, keepers, rocker arms, and possilby even valve guides will need to be either reworked or replaced with performance parts. A truley adjustable valve train will also pay off.

For the header you will wan to have a long runnered semi small tubed design. The long runners will help synchronize the pulses of the exhaust with the somewhat lower rpms this motor will be accompanied to.

A good free flowing exhaust with a good quality turbo muffler will also be in line. 2 1/4" or 2 1/2" will be adqeuate. 3" will not be need for the amount of power you are going to make.

davetruck · 12-28-2007, 06:45 AM

that's a lot of info bro,
thanks
what about the bottom end of the engine I imagine a new crankshaft and bearings would be in order.
I'm thinkin hone out the cylinders and go with high compression pistons

I'm starting to wonder where exactly to start but I think we"ve already started , gettin the work area set up I'll get the engine out get it all apart an start rebuilding after I get the block inspected for cracks......

I'm under the inpression I want to choose the cam first and then build around that?
what do ya think?

I'll be out in the garage set up my parts cleaner, hangin tools and then I'll get some pics...

Dave

jonmark1985 · 12-28-2007, 07:03 AM

Have the old crank magg'd and have its old journals cleaned up and checked. Then have the entire rotating assembly balanced. Flat top pistons help with air flow better than domed pistons. CC the heads and get an idea on your compression with either a set of flat tops or domed pistons. Get the steel timing gears. Basically the 300 has a completely bullet proof bottom end, and again you don't plan on revving this motor to the moon so forged pistons probably aren't needed. Make sure to get a good set of moly rings. I like Speed-Pro.

davetruck · 12-28-2007, 07:28 AM

so if the old crank is good it's reusable?

what does 'cc' mean?

what's 'journal'?

sorry but I'm new to this and I need to learn the termenology.

do you know a website where I can buy a better manual right now I only have the 'Hanes, repair manual"

It's based upon a complete teardown and rebuild but not meant for making the engine high performance.

so much to learn , but thats what I'm here for
I can and will do this
Dave

jonmark1985 · 12-28-2007, 07:37 AM

CC stands for "Cubic Centimeter". The industry standard is to measure the volume of cylinder heads in CC's. Intake ports, exhaust ports, and chambers are almost always measured in CCs. You will need a buret, alcohol, dye, and a peice of plexi-glass in order to find CC's in a suitable manner. I have done it with just a syringe before though.

If your motor doesn't have bearing problems your crankshaft is probably usable in a performance motor. The journals are the parts where the bearings ride on. These will need to be measured with a micrometer and made sure they are within specifications.

I own this book, and I think it would be a great help to you. It doesn't have much information on the six cylinder, but still general info that would help you.
Amazon.com: How to Build Max Performance Ford V-8s on a Budget: Books: George Reid

davetruck · 12-28-2007, 12:45 PM

I've been looking for a specific book on the Inline 6 300 but closest I saw so far was this ford falcon book that deals more with the 200/250

Falcon 6 Performance Handbook

I'll likely get that one you mentioned from amazon

Well we got the parts washer together , bought a jug of degreaser, and ordered an engine mount, soonest I'll see that is monday.

The engine hoist was $450.00 so I opted instead to hang a chain come along from my rafters.
Knocked a hole in my ceiling and put a good sized 3x6 timber across 4 of the rafters, the rafters are close together so I think it's all solid enough,
I'll go buy the hoist tommorrow since my son went to the nearest "city" an 1hr and 10 away, with my wife .

He'll want to come with me to pick one out.

Let my 10 yr old son drive the truck in an empty feild yesterday, he had a blast!

here's a couple of pics, I have room to work on one side and room for the truck, you can see were the hoist will be....

Dave

davetruck · 12-30-2007, 08:20 AM

Well....
I now have both those books on order , both will be shipped on monday.

Bought a 1.5 ton chain comealong , tested it on a 200 lb peice of scrap iron and not even a slight wimper from the beams so I'm confident it'll pull the engine out with out any problem.

still researching....

I know for sure I want this thing to "jump" off the line.

can't wait to do that smoke show.

Dave