1984 Bronco build thread

[StraightSix]

I'm sorry that it didn't work out. That is a bummer! But I think you are right, the cam must be flat. However, I would check before I tore it down or even pulled the cam out.

Getting the engine out is easier with the hood off, but people have done it w/o pulling it. However, the boom on the engine hoist will have to be really close to the engine or it'll hit the hood before the engine clears the crossmember.

As for what to do, I think it is probably time for a new engine. However, I've come to the conclusion that it is better to buy at least a short block, if not a long block from someone that does this routinely. Having said that, I don't know of someone that builds the 300 "routinely". But, when I asked Scotty The Mad Porter about it a couple of years ago he said he does build them.

On the head, I'm not sure that oversized valves are what you want for a low-RPM engine. Certainly you want good valves and seals, but larger valves are usually needed for engines are going to spin pretty high.

And on the compression ratio, there is another variable - quench or squish. If you get the piston-to-head clearance down to less than .040" then that results in the air/fuel mix being swirled in the combustion chamber, which is supposed to reduce the tendency to detonate. So you need someone that knows what he is doing when you pick your engine builder.

Gary in particular and everyone in a general sense-

The engine is out, and a thank you mexican dinner has been bought for everyone that helped. We removed to hood and the radiator to do it. Neither would necessarily be required, but both made our lives easier.

My engine builder of choice is backed up 14 weeks, and Im not ready for the bronco to be down until 2022. Does anyone know a reputable engine builder in georgia, or even the south east? I sold myself on building a fresh block, but now Im back to a cam, oil pump, and anything else that I find and doing it in my garage. If I do that, Ill leave the head, the crank and the rods/pisons alone if I can. Ill take them apart if I have to.

More details and some pictures tomorrow when I know more and have slept some. Thanks!

[Gary Lewis]

Gary in particular and everyone in a general sense-

The engine is out, and a thank you mexican dinner has been bought for everyone that helped. We removed to hood and the radiator to do it. Neither would necessarily be required, but both made our lives easier.

My engine builder of choice is backed up 14 weeks, and Im not ready for the bronco to be down until 2022. Does anyone know a reputable engine builder in georgia, or even the south east? I sold myself on building a fresh block, but now Im back to a cam, oil pump, and anything else that I find and doing it in my garage. If I do that, Ill leave the head, the crank and the rods/pisons alone if I can. Ill take them apart if I have to.

More details and some pictures tomorrow when I know more and have slept some. Thanks!

Glad you got it out.

Before deciding on what to do, and before pulling it apart, I would do a leak-down test. Harbor Freight has a tester that looks pretty good, but there are others as well. To me, a key thing for them to have is an on-board regulator and two gauges.

A leak-down tester allows you to inject air into the cylinder via the spark plug hole when the cylinder is at TDC, meaning the valves are closed. The air comes in via a tiny orifice and if there is leakage you'll see that as lower pressure due to the drop across the orifice.

It will determine if you have valve leaks, head gasket leaks, or a cracked block, and how tight the rings are. If your engine passes on all of those things then just pull the cam and lifters and replace them.

[FuzzFace2]

Glad you got it out.

Before deciding on what to do, and before pulling it apart, I would do a leak-down test. Harbor Freight has a tester that looks pretty good, but there are others as well. To me, a key thing for them to have is an on-board regulator and two gauges.

A leak-down tester allows you to inject air into the cylinder via the spark plug hole when the cylinder is at TDC, meaning the valves are closed. The air comes in via a tiny orifice and if there is leakage you'll see that as lower pressure due to the drop across the orifice.

It will determine if you have valve leaks, head gasket leaks, or a cracked block, and how tight the rings are. If your engine passes on all of those things then just pull the cam and lifters and replace them.

A leak down test is a good start but I would look into why no oil to that rocker?

I would pull that rocker & rod and distributor so I could spin the oil pump and see if oil comes out the lifter.

If not pull the lifter and see if oil comes out the block.

If you don't get oil out of the block the garage rebuild will be for nothing.

Maybe that should have been done before pulling the motor?

Good luck

Dave. ----

[Gary Lewis]

A leak down test is a good start but I would look into why no oil to that rocker?

I would pull that rocker & rod and distributor so I could spin the oil pump and see if oil comes out the lifter.

If not pull the lifter and see if oil comes out the block.

If you don't get oil out of the block the garage rebuild will be for nothing.

Maybe that should have been done before pulling the motor?

Good luck

Dave. ----

My understanding is that oil to the rockers comes up the push rods as the lifter is pushed up by the cam. So my assumption has been that with a wiped cam lobe there won't be much pushing up of the lifter, hence little if any oil to the rockers.

And speaking of wiped cam lobes, I've been reading lately of problems with Comp's cams having that problem. I don't know if this is because they sell a lot of cams so there's more chance that people don't break them in correctly, or if they are having problems. But I'd research whatever manufacturer I was considering before buying.

[FuzzFace2]

My understanding is that oil to the rockers comes up the push rods as the lifter is pushed up by the cam. So my assumption has been that with a wiped cam lobe there won't be much pushing up of the lifter, hence little if any oil to the rockers.

And speaking of wiped cam lobes, I've been reading lately of problems with Comp's cams having that problem. I don't know if this is because they sell a lot of cams so there's more chance that people don't break them in correctly, or if they are having problems. But I'd research whatever manufacturer I was considering before buying.

This was the exh. Valve IIRC so if not opening the exh would back up into the intake and cause a pop from cam over lap was there a pop more so under load?

Still easy to measure pop the side cover and check the lifter movement to the others.

Dave ----

[StraightSix]

This was the exh. Valve IIRC so if not opening the exh would back up into the intake and cause a pop from cam over lap was there a pop more so under load?

Still easy to measure pop the side cover and check the lifter movement to the others.

Dave ----

Ok folks - here's the update for today. We drained the block and ran the leak down test. We used 80 psi for the air feed. All cylinders were between 30 and 40 psi oyher than #3 which was at about 66. So not great, I presume :( several valves had a fair deal of blow by but we never heard any air moving in the water jacket so I think the head gasket is fine.

Next we got the pan off and had a look around. Just looking at #2 intake lobe, I wouldnt have assumed it was "flat", but then again we knew it was moving the valve some. There is still crosshatching in the cylinders. No gunk on the pickup screen. Ultimatly, other than the eing blow by that we already new about the bottom end looked really healthy to me all things considered. We didnt pull a main or a rod cap, but I may. I do have a steel timing gear.

After much discusion with my friend, I think Im going to take my second block to the engine shop to be built with the expectation that I probably wont get it back until January 2022. Ill be taking it over sometime this week. In the mean time Im going to make this block servicable and put it back in. My preference is to leave the head, crank and rods in place. I plan to address the cam and the valve train, the oil pump, maybe a water pump because its easy, and other little things I find. I plan to seek out a stock cam. The goal for this block is to get through the 10,000 or 20,000 miles between now and January.

I know ignoring the ring blow by and the valve blow by long term is not acceptable, but Id rather not have the vehicle down for 6 months and this is the best idea I have been able to come up with.

Thanks for reading! Opinions and recommendations are more than welcome as always.

[Gary Lewis]

Ok folks - here's the update for today. We drained the block and ran the leak down test. We used 80 psi for the air feed. All cylinders were between 30 and 40 psi oyher than #3 which was at about 66. So not great, I presume :( several valves had a fair deal of blow by but we never heard any air moving in the water jacket so I think the head gasket is fine.

Next we got the pan off and had a look around. Just looking at #2 intake lobe, I wouldnt have assumed it was "flat", but then again we knew it was moving the valve some. There is still crosshatching in the cylinders. No gunk on the pickup screen. Ultimatly, other than the eing blow by that we already new about the bottom end looked really healthy to me all things considered. We didnt pull a main or a rod cap, but I may. I do have a steel timing gear.

After much discusion with my friend, I think Im going to take my second block to the engine shop to be built with the expectation that I probably wont get it back until January 2022. Ill be taking it over sometime this week. In the mean time Im going to make this block servicable and put it back in. My preference is to leave the head, crank and rods in place. I plan to address the cam and the valve train, the oil pump, maybe a water pump because its easy, and other little things I find. I plan to seek out a stock cam. The goal for this block is to get through the 10,000 or 20,000 miles between now and January.

I know ignoring the ring blow by and the valve blow by long term is not acceptable, but Id rather not have the vehicle down for 6 months and this is the best idea I have been able to come up with.

Thanks for reading! Opinions and recommendations are more than welcome as always.

That is quite a bit of leakage, but that's roughly what Big Blue's engine had when I pulled it out and it was running quite well. So I think if you get the cam problem sorted you'll be fine for 20k miles.

But on the valve or cam problem, I'd do as Dave suggested - pull the side cover and measure the lift. I sure wouldn't want to pull the cam only to find out it isn't bad.

Otherwise I think your plan is solid.

[StraightSix]

That is quite a bit of leakage, but that's roughly what Big Blue's engine had when I pulled it out and it was running quite well. So I think if you get the cam problem sorted you'll be fine for 20k miles.

But on the valve or cam problem, I'd do as Dave suggested - pull the side cover and measure the lift. I sure wouldn't want to pull the cam only to find out it isn't bad.

Otherwise I think your plan is solid.

Dave and Gary,

Thanks! Thats a straightforward way to check lift and it should be a quick and easy check with the block on the stand. It may be a day or two before I get a chance to try but Ill post results here asap.

Im still sorta hoping to identify a shop that could turn the block around by September or so. Id prabably just swallow the down time at that.

[FuzzFace2]

Dave and Gary,

Thanks! Thats a straightforward way to check lift and it should be a quick and easy check with the block on the stand. It may be a day or two before I get a chance to try but Ill post results here asap.

Im still sorta hoping to identify a shop that could turn the block around by September or so. Id prabably just swallow the down time at that.

as I said in my other post when you can measure the lobe(s) from the side cover area so you know if the cam is good or bad.

I think if I had it down this far I would pull 1 or 2 main & rod bearings so I know what they are like.

To throw a set of bearings in it would not be hard at this point.

I would also measure the holes to see if they are factory or been bored over size and maybe throw a set of rings in it after running a hone to break the glaze this way the rings will seal good.

On the head and you saying the valve had leakage I would check on either a replacement head from one of the local parts stores or maybe pull yours apart and lap the valves so you know what you have.

Maybe check to see what the turn around is on a valve job on it.

Yes it is a quick rebuild without the machine work and other than the head would last longer then the 20k you might put on the motor and even if you do get the other built you have this as a spare.

BTW I did a quick rebuild on a AMC 360 motor I had never heard run when I got it.

All bearing were showing copper but the crank measured factory so a set of bearings fixed that part.

I forgot to check the cam bearings but did not have a way to change them anyway.

All the rings were stuck in the pistons and i had to break them to get them out. I used the broken parts to clean the grooves. I picked up a new set of rings but the gaps were large, I was in a time crunch and went with them anyway.

I had a set of heads that were good to bolt on, same on the oil pump as it is partof the timing cover.

I went with the largest lift cam kit I could with out machine work, did I say I was building this for my drag car?

I cleaned the block for hours as it was really bad.

Ran a hone in the holes before the pistons went back in and did all the measuring just like you would when rebuilding a motor, even coil bind for the cam.

I got to say the motor ran strong, great oil PSI even hot idle, did not smoke at all I was kind of shocked because of the ring gap.

Other than the money for the parts and time I think in my case was all well spent.

Dave ----

[StraightSix]

as I said in my other post when you can measure the lobe(s) from the side cover area so you know if the cam is good or bad.

I think if I had it down this far I would pull 1 or 2 main & rod bearings so I know what they are like.

To throw a set of bearings in it would not be hard at this point.

I would also measure the holes to see if they are factory or been bored over size and maybe throw a set of rings in it after running a hone to break the glaze this way the rings will seal good.

On the head and you saying the valve had leakage I would check on either a replacement head from one of the local parts stores or maybe pull yours apart and lap the valves so you know what you have.

Maybe check to see what the turn around is on a valve job on it.

Yes it is a quick rebuild without the machine work and other than the head would last longer then the 20k you might put on the motor and even if you do get the other built you have this as a spare.

BTW I did a quick rebuild on a AMC 360 motor I had never heard run when I got it.

All bearing were showing copper but the crank measured factory so a set of bearings fixed that part.

I forgot to check the cam bearings but did not have a way to change them anyway.

All the rings were stuck in the pistons and i had to break them to get them out. I used the broken parts to clean the grooves. I picked up a new set of rings but the gaps were large, I was in a time crunch and went with them anyway.

I had a set of heads that were good to bolt on, same on the oil pump as it is partof the timing cover.

I went with the largest lift cam kit I could with out machine work, did I say I was building this for my drag car?

I cleaned the block for hours as it was really bad.

Ran a hone in the holes before the pistons went back in and did all the measuring just like you would when rebuilding a motor, even coil bind for the cam.

I got to say the motor ran strong, great oil PSI even hot idle, did not smoke at all I was kind of shocked because of the ring gap.

Other than the money for the parts and time I think in my case was all well spent.

Dave ----

Dave,

You're rebuild on the 360 sounds awesome. Id very much like to do that some time. What became of it? Thanks for all of the sound mechanical advice you’ve given me over the last few days.

All,

Im a notoriously slow decision maker and its not unusual for me to labor over a choice for days or weeks before making a decision that was ultimately pretty straightforward from the start. With that being said – Im changing my plan one more time. Im just going to take my block to an engine shop to be built. Sure, that means the vehicle probably wont run again until December at the earliest, maybe March at the latest, and I hate that.

This will give me a chance to rebuild the transmission and transfer case myself, possibly paint the tub, and do the headlight upgrade. By the time the engine comes back ang goes in I will have rebuilt the entire drivetrain other than the front axle and the vehicle should be road worthy enough to take me anywhere without worrying too much about mechanical problems. If the goal is a rebuilt driveline, this is the fastest, cheapest, and lowest effort route to that goal. It just means 6 months or so of downtime.

I can also take advantage of that time to fix other things that Ive been failing to find the time for Like my living room trim, or my snapper engine. Maybe a bit of life balance for a few months is a good thing!

I have canning to do tonight (we froze 14 quarts of cream corn and about 50 ears whole yesterday), but I should be able to sneak into the garage for a few minutes to finish stripping my engine for the trip to the machine shop. Hopefully Ill have it dropped off sometime this week. Im sure there will me more to come in the next few days! Tentatively, Id like to work out the transfer case and transmission rebuilds in August and September.

As always, thanks for reading!