Rebuilding my Flathead random questions

[busmania]

Thank you. Found that on google too! Appreciate it.

I may have made a MISTAKE. please advise if I should redo my rod bearings. In the book it says to fit the main bearings to the crank via some persuasion from a hammer. It didn’t say that for the rod bearings but I fit the rod bearings with the crank but then they seemed a little loose (some not all) in the rod journal and rod cap. Should I have not fit these bearings to the crank and left them snug in the cap and rod journal? If so, I may buy new bearings. Or am I overthinking it? Essentially, some of the rod beatings seemed a little loose (or just not snugly fit) when I put them in the cap and rod.

[Mart]

I'm no engine builder, but as long as the rod bearings are not loose when torqued up, they will work as intended. They should fit into the rod and cap without too much resistance but not be so sloppy they are falling out, though they can sometimes fall out when sliding the piston and rod in. You need to watch and check when fitting. Like I say, I'm not an expert, but this is my (limited) experience.

[flatjack9]

You never use a hammer on the main bearings. Floating rod bearings - yes.

[Bored&Stroked]

You're building a 1940 engine, with a 4" Mercury crank and 8BA rods. You do not touch ANY of the bearings with a rubber hammer! Since it sounds like you've already applied the hammer to potentially BOTH (rods and mains), you'll need new bearings for both.

The 8BA rods use insert style bearings - so there is no hammering involved. Each 1/2 shell should sort of snap into the rod cap (they can only go one way) and rod end and be snug - they will not be loose or move around in the least. The same goes for the mains - the rear one will be quite tight (sometimes I use a little wooden block to knock it down on the edges - never on the bearing surfaces).

On the rods, the chamfers on the edges need to be toward the outside of the journal - in case you need crankshaft fillet clearance. I haven't seen your rods or crank, so I don't know how things were prepped/machined. When in doubt, post some clear close up pics of a couple rod caps as well as the rod journals on your crank - then I can tell you more.

Checking Clearances: You should at least PlastiGauge the mains and rods to see what your approximate bearing clearances are. I like to have .001 or so of clearance per inch of journal diameter. You do this checking without the rope seals in place.

So .002 to .00225 on the rods and .0025 to .00275 on the mains. PlastiGauge isn't super accurate, but you should be able to ascertain if you're in the ballpark. Do not skip this step!

Tip: Take some heavy duct tape and cover the ends of the crankshaft main studs - that way when you man-handle the crankshaft into place (multiple times), you don't nick the bearing journals by hitting them on the sharp edges of the studs. The same goes for the rods - when you're installing the pistons/rods it is very easy for a rod-bolt to hit the crankshaft journal, making a nice ding in it. Protect your journals at all cost! LOL

It is critical that your bearing clearances are correct and that your crankshaft end-play is within spec (about .004 to .008 or so). When you use PlastiGauge, you do NOT put oil or lube on the bearings or journals and you must be careful not to turn the crank or move the rod when taking things back apart. Carefully take things back apart and use the little paper guide to see what your clearances are. I'd check all three main bearings and all 8 rod bearings - it is a good practice to be sure!

If they are too tight, you'll score and wipe out the bearings . . . to loose, you'll knock and then wipe out the bearings.

When you believe you have everything correct, install the main bearings (and the crank) and lubricate them well (again, without the rear seal plates). Then use 3 torque cycles to creep up on the torque spec on the main bolts/studs - and then see how the crankshaft feels - it should easily spin around just by grabbing the snout and twisting by hand. If is does not - do not proceed, something is wrong and you should not assume it will "fix itself" when you run it.

If the crank spins easily, then take it back out and put the seal plates in the block and the cap and reassemble it. Now you're ready to put in the pistons/rods. Lubricate the heck out of everything.

Okay, enough babble out of me for now . . . I'm sure there will be more later on! LOL

B&S

[busmania]

Bored&stroked, thank you so much for ramblin on and taking the time to write that. It helps so much. Everyone else, thank you as well. I know some of my questions may be dumb or noobish but I’d rather it be right than not ask. Sometimes I probably overthink these things.

Anyway, here is the page in the book that had me taking a hammer (rubber mallet) to the mains. Is this just wrong? I thought everyone considered this book one of the best? Frankly, I find it to be missing many of the details (which is why I’m here).

I will buy new bearings and do it again. That doesn’t bother me one bit (though I do it with my tail between my legs).

I did plastiguage the mains and take end play readings along the way. The bearings thus far have been really my only f up.

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[Mart]

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That "main" bearing is a floating rod bearing from a pre 8BA type motor. Hey, you're learning and that's good.

[busmania]

Yep, I clearly didn’t pick up that detail on the book. Dang. Learning is fun. 2 steps forward, one back.

[fortyonerag]

Originally Posted by busmania

Yep, I clearly didn’t pick up that detail on the book. Dang. Learning is fun. 2 steps forward, one back.

Glad you're asking the questions. I'm gearing up for this exact job myself right now.

Much obliged.

[Bored&Stroked]

What that book is showing are pre-49 full-floating ROD bearings - a completely different animal. They were NOT talking about the MAIN bearings - which are the three that go in the block and in the main caps.

If you didn't hammer those three main bearing sets, then you can reuse them. If you hammered the smaller rod bearings (which are NOT full-floaters), then you will need to replace those. They're not super expensive, so just some $$$ spent on education.

If you want to learn a bit more about how one tunes actual full-floater bearings - when running pre-48 rods, here is a short video I did a few years ago - just to help folks. Again - you don't have these!

https://youtu.be/CyVLsPdbhS8

[Bored&Stroked]

Also, post some pictures of the insides of the big-ends of the rods and rod caps. I'd like to see if they have chamfers or not.

[busmania]

I understand floating bearings verse non. I just over read that detail when reading the book. I probably would have asked here first had I caught it. I also in my head figured i was working on installing the crank and main bearings so took it to mean those bearings. Whoops! But now it all makes sense!

Got it apart while I wait for new parts. Blessing in disguise. Realized I must not have seated the graphite rear seal and instead of sticking out a slight bit, was actually 1/32 of an inch or so below where the two halves meet. That definitely would have leaked.

Here’s photos of the big ends of the rods. My machine shop put the rods and pistons together for balancing and also stamped arrows into the top of the pistons and said “make sure they all point to the front.” They also stamped each rod and rod cap with cylinder number so they can’t go on backwards or mismatched. Happy about those small details from them!

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[Bored&Stroked]

Good that the machine shop is doing its job and keeping you honest.! Sounds like you're on the right track.

On the rear or front main seals, put a dab of automotive silicone sealer on the ends of each - right before assembly. This helps prevent weeping past the ends of the seals.

[busmania]

Moving right along. Got then pistons and crank
all re assembled and measured out. Everything was within spec!

Onto the next issue. I started putting the timing cover on but noticed the cam gear is recessed and this caused me alarm so I grabbed my distributor. Sure enough, the distributor gear is not long enough to engage the cam. Surely I can’t be the first to run into this issue?
Looking at my stock cam, the slot is basically flush with the end of the cam gear. On the new heat and cam, the slot on the cam is about 1/2” to 3/4” recessed so the distributor gear won’t engage. HELP? google didn’t help much!

First photo is stock cam.

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[38 coupe]

Ford made the front of the cam shorter in 1942, and made the distributor deeper to match. There is a piece made that fits between the later cam and the earlier distributor to fill the gap. I'll see if I can find a link to one.


Edit, part number 11A-6280 available from several vendors including one who regularly contributes knowledge to this forum: https://thirdgenauto.com/product/193...termarket-cam/

[busmania]

I figured that would be an easy one. Thank you 38 coupe!

Next item up...oil pump. I was hoping to use a new pump. Well, the new pump I bought from speedway and screen hit the baffle in the oil pan. It seems no one sells the screen I need (sits right next to the pump versus all of the ones I see online (and that I bought) kick the oil pick up screen slightly forward about 6", thus hitting the baffle in the pan). What are y'all using? Or do I need to trim up the baffle (not preferred obviously)?

Thanks!

[tubman]

I found the Speedway pumps to be deficient. See this thread : https://www.fordbarn.com/forum/showt...light=speedway.

A good stock Ford pump is the best choice.

[busmania]

Originally Posted by tubman

I found the Speedway pumps to be deficient. See this thread : https://www.fordbarn.com/forum/showt...light=speedway.

A good stock Ford pump is the best choice.

Thanks. I’ll start to clean mine up and see how she looks. Are the stock pumps Rebuildable? When I removed the screen tube, the area around the whole was broken so I will have to replace that at a minimum.

[Bored&Stroked]

I'd run a 49-53 pump and use the pickup that Speedway sells - then make modifications. It is one of those "mods" that you need to make - to modify the baffle so the screen and tube fit. You want the bottom of the screen about 1/4" to 3/8" off the bottom. On my first flathead, I had to cut/weld up the tube between the screen and the pump to get it where it needed to be.

[busmania]

Thanks. Was just reading about that. I see someone modified the baffle and a lot remove the baffle all together. I’ll probably modify the baffle as it seems simple enough. Edit, I see that someone is you!

More? Haha. I’m getting really close. Water pumps and front cover on. Without head gaskets, my pistons hit and raise the new edelbrock heads .030”. Checked with dial indicator and feeler gauges. I am reading a .050” Piston to head clearance is ideal which means I need to find .080” of space. I’m really wondering, is it ok to install heads AND gasket and torque it all down to measure everything and then re use the copper gasket at final assembly? Most of what I’m reading seems to indicate most gaskets are about .050” which means I may have to have some work done on my heads.

Appreciate all the info.

[Mart]

If your pistons are lifting the heads .020", things are pretty tight. Sure it's not the valves?

Some pistons have a "pointy" dome. not a true dome. The heads can sometimes have a true dome. This is the situation in french pistons for instance.

When I had this problem I filed the heads of the pistons in the middle to reduce the pointiness. If you assemble the head on with the gasket dry you ought to be able to use it again after checks.

I wouldn't go full torque though, 20 or 25 lbs ft would be enough to check for clearance.

Bear in mind you want 40 to 50 thou clearance, those final few thou when going to full torque can be borne in mind.

I use aluminium foil crumpled into balls held in place with grease (vaseline) when checking clearance. All around the piston and on the dome.

Bear in mind I am not an engine builder. Others may have other methods that they prefer.

I am surprised the pistons are lifting the heads, though. Have the heads been heavily skimmed?

Hope any of this helps.

Mart.