Okay gang... The motor on the Track Roadster's gonna see some attention in the next couple of weeks, as the crank and rods are done and ready to be picked up. The motor's torn down as far as it can go - the only pieces left in it are the oil tube for the cam bearings - and that teeny fuel pump pushrod bushing. Since the Roadster's getting an NOS AC Sparkplug 6V fuel pump to feed the '94's, the fuel pump pushrod is about as uesful as tits on a boar hog. Soo...it's gonna get ditched. Now...with the pushrod gone, the void left means oil pressue will suffer. What's the best way to plug the hole? The junk block had a bolt in the hole; I'm tempted to cut down a discarded head bolt and JB weld it in place - but that seems hokey. Tried pushing the bushing out so's I could braze it shut (all that cast iron around the hole takes for-freaking-ever to heat up) but the bushing wouldn't budge. Tried running a tap thru there, but the bushing's hardened (!?) steel. Lemme know, Chuck.
Flathead Jack sells a nifty little aluminum plug specifically for that purpose. Couple o bucks. Had to do this on mine too.
Several folks have simply run a cut down fuel pump pushrod. Cut the bottom off so it won't ride on the cam & cut the top off so it won't bother the breather...
If you had access to a lathe you could turn down some brass into a fine tapered plug and swage it in the hole. A couple thou interference should keep it there. Flatman
I'd use a shortened push rod tube if you are using the breather. I believe the cone is a baffle to deflect the oil spray away from the breather tube. It's not just the oil from the push rod hole. It may not be necessary but Henry put it there for a reason.
The pushrod that came with the motor didn't have the cone; I thought that odd. the brass plug is a good idea - I think I'll run that down - along with Flathead Jack's plug.
If the push rod bushing is in place, then you shouldn't lose oil pressure without the push rod. Nothing wrong with plugging the hole, but you shouldn't need to. If the bushing is removed, then you must rotate the cam bearing so the bottom hole for the push rod is covered and plug the top or you will have a huge oil leak. This was supposed to be an old racer's trick to keep oil from having to flow around the bushing and thereby having an unrestricted straight path to the oil manifold tube. If your push rod bushing has a tiny lubricating hole in it, plugging the bushing will keep oil from spraying out the hole, but the loss shouldn't be enough to cause an oil pressure problem. Plug it if you're worried.
Jim, I just fired a new flathead on my test stand, engine had good oil pressure but gauge actually had a jerk to it and oil pressure was a bit lower than usual. I didnt like the jerk in the gauge but ran the engine for a minute as well. The breather opening was covered with a piece of masking tape as i hadnt installed the breather yet. After some run time and coming to temp the tape blew off at about 2000 rpm and oil blowed out the hole. A friend had stoped by and seen this and said the fuel pump hole MUST be pluged to stop this. We pluged the hole with a plug made up on my lathe. The jerk in the gauge went away and the gauge shows 5-10 psi more than it did. On my engine the open bushing did change the oil pressure.??
The 8Ba push rods did not have the splash skirt, in fact the earlier 59ab pushrods were a smaller dia.
This is soo cool, guys! Where else would someone post up a drawing of an oil feed orifice? I ordered up a bushing from Flathead Jack, on account of Pop's not back from Arizona and I don't like using his shop when he's not there. Besides - the cost for gas there and back was about the same $$ as the plug from Jack! Jack was fun to talk to, BTW. I asked him the same questions...he said that back in the day, they plugged the pushrod hole with a cork and some glue! I told him about my original thought re: head bolt and JB - his comment was... 'are you sure you want a head bolt to come loose inside the motor?' GMC Bubba's right, BTW. Since the oil pump is a positive displacement pump and doesn't move all that much oil, a 0.050" orifice will allow oil pressure to pulse with the lobes - especially if you're running a stocker pump. A hi-volume pump would mask the leak, as the potential for oil delivery of the hi-vol would exceed the leak as presented by the orifice.
Ok...So we are getting mixed info here...some say plug it...some say don't botther..some say cut down the pushrod to avoid spray. I guess it can't hurt to plug it.... I have the early block..right now I don't have anything in there...I haven't noticed any splatter out of the breather.... Is there any reason that the late block should have the plug as opposed to the early block? Tim MBL
Glad Jack was able to help you. When I was building my flathead, he was a fountain of knowledge. A crotchety fountain, but a big help nonetheless. He used to race flatheads way back. He knows his shit.
I tried to use his plugs but there were not the right size. We made one out of aluminum.. If you do not plug it you get a lot of oil splashed up out of the breather.
I turned an aluminum plug on the lathe the same size as the hole. Leave a step or head on the top of it and drive it in with a hammer. Mine hasn't moved in four years.
Here's a starter discussion: http://www.btc-bci.com/~billben/oilflow.htm I've never paid any attention to this stuff as I like mechanical pumps and have never eliminated one... Routing of oil right there is different between early and late blocks, and only late blocks (and not all of them) have the tinly oil hole. Will try to find some info adequately describing... On early block there is absolutely no need to pluggit, but I would leave in a piece of rod with the umbrella...experience shows that leaving out ANY of the various pieces of tin Henry put in to block oil splash in the valley will immediately result in oil either overwhelming the valve guides or coming out somewhere you don't want it!
OK...so in my application (EARLY BLOCK) I should at least put the rod in to have the umbrella part to deflect the oil. I have the spare rod...how far from the edge of the umbrella should I cut the rod? Tim MBL
There are good pics of the late oil path in this area in the '49 Merc shop manual, which probably everyone here has, and good pics of the early in the Ford Pilot shop manual, which probably only I have...will try to check this out and describe properly. Anyhow, if no rod, shield the hole so no extra oil gets thrown about (Why this hole would cause that problem baffles me, but several reports show it does!), and blocking off that tiny hole would probably at least make you feel better...
Just probe the hole with the top end of the pushrod to determine how far down the pump drive lobe is, then make rod so it doesn't contact that... You could either shorten it so umbrella drops right down against block, or mke a simple spacer to place the brolly up a bit in its natural habitat, decision to be based on your very own SWAG about what the dynamics of oil flying around in there are... Note that the oiling issues here are mostly controlling all the random splash and fog within a running engine, NOT having to do directly with the pressurized oil system.
More on the early block: Oil flow is around that bushing via a cast passage, sealed on its inner curve by the bushing. Note that with an intact bushing, it remains sealed with or without a pushrod... Ol'Ron, one of the most experienced flatheaders on the planet, removes the bushing and ports that passage with a ball ended burr to ensure free flow. On pumpless engines, he removes the bushing permanently, taps the top of its hole to seal it, and plugs the bottom with the cam bearing below. This completely opens the area to oil flow.
I used a 7/16" freeze (Welch) plug from NAPA for my '49 Merc motor. There's a lotta oil that comes outta that hole if you leave it unplugged!
I know this is an old thread but does anyone know of a source for the Flathead Jack style plug since he is no longer in the biz? Also, the plug is or isn't required on a '48 motor?
This has been discussed thousands of times on Fordbarn. Do a search there and you will find the truth. https://www.fordbarn.com/forum/showthread.php?t=253112&highlight=fuel+pump+push+rod+hole
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