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Beginner 300 moderate rebuild

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Beginner 300 moderate rebuild

Post #1 by buckingbronco » Sat May 23, 2020 8:03 pm

This post is to document our progress on our 1980 Bronco rebuild that my son and I are doing.
The primary reason for the rebuild was excessive blow by that was covering the engine bay with oil let alone burning it.
Since we had to repair something on the inside we will also be upgrading intake to Offy dp, efi exhaust manifolds, 4bl Holley 8007 carb, improved cam(tbd), and do some mild porting.This will hopefully improve hp performance so going down the highway is easier.

We already received a lot of great advice on prepping for the build from this post

I attached images but I am not sure how to insert them... :?:

We took the front end of the truck off vs taking the hood off since we wanted to do some rust restoration work on the front end.
We followed the removal steps from the Ford 1980 engine manual...only real question was how much to raise the transmission to get the engine off. We had to raise it about 2-3 inches to get the engine mount bolt to clear the frame before we could get the engine off the transmission. It just took some iterations on the jacking.

There was an interesting gasket for the air intake to the carb.. old mason jar lid...which will not be needed in our rebuild :lol:

We had guidance to take a picture of the distributor with #1 at TDC and those are attached as well.

after we had the engine on a stand (HF 4 point stand is working well for us so far), we removed the head to find that this engine was already rebuilt once with sleeve inserts.
We also saw from the head picture that #2 cyl had much heavier deposits as you can see on the head picture.

We rotated the engine... and quickly found out that the hydraulic lifters can just fall out... rookie mistake... we removed and labeled them the best we could.. there are 4 that fell out that may or may not be in the right position. :oops:

We then took the pan off and saw some ring parts/chips in the bottom of the pan.. maybe a dozen small 1/4 pieces.
We took off #2 piston and found the broken ring with the guides in the piston also broken...
We took the rest of the pistons off and #1 also had broken rings but the rest of the pistons were all good.
The rod bearings almost all 5/6 had some score marks... I'm guessing pumping fragments of rings and piston is not the greatest for them. :|

So now the questions for some wisdom from the group...
1- Can you bore out a sleeve or are we now looking to find a new block? I intend to take the block to the machine shop Tuesday to get their opinion. The cylinders all look good from an appearance standpoint. you can see cross hatching... there are some scratched that you barely can feel with your finger nail. see img3403 in attachments
2. We have not yet removed the pilot bearing from the crank... do we need to do that or does the machine shop do that? and is that something that you automatically replace or do you reuse?
3. We have not yet taken the timing gears off. Do we need to definitely take them off before sending crank to the machine shop?
4. Do we take the rocker arm studs off or leave those on?
5. It was recommended to remove casting marks in the block... I see the ones on the main web for the crank. see img3400 and I'm guessing the ones underneath the camshaft will also be obvious.
6. we will also be doing some mild porting but I was going to start a separate post for that to make sure we dont mess that up.

Thanks for the help again!!

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Re: Beginner 300 moderate rebuild

Post #2 by bubba22349 » Sat May 23, 2020 8:50 pm

Not a problem on the lifters being wrong unless you had planed to reuse them along with the cam, since you said your going with another cam grind then you will need a new set of lifters to go with it. The timing cover will need to come off to remove the crankshaft and the camshaft removed if your taking the block in for cleaning and boring with the crankshaft. With the metal that when through the oil system the crankshaft will need at least a polish or it might need to be ground undersize depending on its condition.

1. Yes a sleeve can be bored out

2. The pilot bushings can sometimes be reused it would depend on if it shows any wear in the hole, as far into this as your going you probably should just replace it with a new one they are low in cost. You can remove it by packing it with wheel bearing grease the use a Rod that just fits it the hole strike end with a hamer to Hydrolicly push the bushing out you will need to pack the grease back in several times. You can also use a slide hamer tool or even have the machine shop remove it. Good luck :thumbup: :nod:
A bad day Drag Racing is still better than a good day at work!

I am still hunting for a project car to build but with my current low budget it's not looking so good. My Ex- Fleet of Sixes these are all long gone! :bang: 1954 Customline 223 3 speed with O/D, 1963 Fairlane project drag car with BB6, 1977 Maverick 250 with C4, 1994 F-150 a 300 with 5 speed.

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Re: Beginner 300 moderate rebuild

Post #3 by sdiesel » Sun May 24, 2020 1:33 am

you can leave many of the parts you are concerned about right, where they are .
when crank goes in the caustic, if it does, the bushing disappears or the shop removes it before tanking. same with all other concerns. it takes but a moment for them to do it. it takes a lot longer for you to do it. get them to pull and install cam gear too.

if you grind casting flash do so early on, so their hot tank will hopefully clear out the metal shavings. the product called Awesome at dollar tree is, well, awesome for cleaning carboned castiron. drain oil, turn her over leave pan on, fill up the entire engine block with the stuff wait till morning turn block back over (engine stand inside a kiddy pool) and finish off with a garden hose and nozzle for a remarkable clean.
im assuming you still have head on and lifter cover sealed etc.

but most importantly: find a very good machine shop, spend the money, and if its a really good shop, have them assemble the long block for you. If you want the experience of putting together an engine, do so on the junk block.
the warmth you might feel by doing this in your shop becomes an aggravation if you get something wrong....
am i guilty of this? on almost every engine, I have had to backtrack into a finished block to double-check or change something i thought was a good idea
" did i forget to chase those threads ? or did i torque the cam retainer properly'' yea it's irksome, and when it's your first and you are hoping for a reliable run-forever machine.And likely its more expensive to do it yourself. if, for example, you wipe a cam. I have. i have done it.
. i ain't sayin your stupid like i am, but these things do happen.

sleeves: i personally would search for a new block. there are many available cheaply and likely less expensively than reworking a sleeved block. And you are relying upon the work of unknown individuals who originally sleeved that block to support the very expensive work you are about to do to their work....

I have found a superstar machinist. i turn the mess over to him ( mess figure of speech, he dont let greasy parts in the shop. i have to disassemble and tank or spray wash first). and i get back a complete long block in a month's time with a guarantee, something i won't get if i do the work myself. labor is but a paltry 500 or so to assemble. 2000. for complete machining roughly. piston hanging and custom work is more.

this is not universal advice. there is talent on this board that rocks, and they HAVE to build it their way. But in most cases their way is pretty specific and aiming for a precise outcome.
a long love affair with the 300 six.
my lastest and final fling is a fresh 300 in an 88 ford f350 dually 4X flatbed

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Re: Beginner 300 moderate rebuild

Post #4 by BigBlue94 » Sun May 24, 2020 12:34 pm

1. Does it really have sleeves in the cylinders? That's indicative of multiple rebuilds or a serious crack.

2. 3.& 4. Most shops want to do the teardown themselves, so they know what's correct, and they can see how the engine was treated. I sent my complete shortblock down, and the head, since I'd already removed it for a leaky head gasket.

5. Not necessary, but a good idea. It should be done before the block gets a final cleaning.

6. Porting without a flowbench is risky. But the guys here can help with that. Lengthening the radii and smoothing the bowl transitions is the biggest help.

Pics cant be attached here anymore. You must host them somewhere, like Facebook, imgur, supermotors, etc. Then copy and past the [img] tag here. When entered in the text box, itll look like this. I use supermotors, and they provide a copyable img tagged link.


Alternatively, you can copy a picture URL, paste it in the text box, and highlight it. Then click the small button above the text box that looks like a moon and two mountains. That will add the img tags to embed it. Or you can type the img tags on manually.
1985 Bronco. 309ci I6, NP435, 4.56 gears, Detroit locker and tru-trac, 4" lift, and 37" swamper tires. The 309 is 9.75:1 CR with a Schneider 140H cam, 4bbl, roller rockers, larger valves, and headers.

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