49-53 mercury rods

[matthewejacob]

It won't let me post in the wanted forums in the swap meet section so I guess I'll put it here. I am having a time trying to find a set of stock rods for a 49-53 merc crank. Had no idea how hard it would be. All i can find are the H-beam rods that are over 100 bucks a piece. Does anyone no any vendor at all where I can find a set of stock rods? This is not a drag strip engine that i'm building but I'm kinda locked in at this point. I have a genuine merc crank and .125 over merc pistons (not sure if the wristpin position is any different on the pistons or not) I'm kinda new in the flathead world. This is my first one and it's going in a 53 f100 I'm putting back together.

[richard crow]

all the 8ba rods are the same the difference is the pistons.you must use merk pistons

[tubman]

Originally Posted by matthewejacob

It won't let me post in the wanted forums in the swap meet section so I guess I'll put it here. I am having a time trying to find a set of stock rods for a 49-53 merc crank. Had no idea how hard it would be. All i can find are the H-beam rods that are over 100 bucks a piece. Does anyone no any vendor at all where I can find a set of stock rods? This is not a drag strip engine that i'm building but I'm kinda locked in at this point. I have a genuine merc crank and .125 over merc pistons (not sure if the wristpin position is any different on the pistons or not) I'm kinda new in the flathead world. This is my first one and it's going in a 53 f100 I'm putting back together.

No difference between the late ('49-'53) Ford rods or Mercury rods; they are the same, the difference is in the pin position in the piston. If you are using a Merc crank, stock rods will be just fine. There are plenty of stock rods floating around out there,. It will probably cost more to get them reconditioned than the rods them selves. I seem to remember some outfit was selling new French Ford rods for cheaper than the cost of reconditioning. An internet search may be in order. (I believe the French 4" stroke rods are different from the Ford units, so be careful.)

I would imagine you could find a set of rods on eBay, or the swap meet "For Sale" sections on here or the H.A.M.B. If all else fails, I save the good ones and could probably put together a set if all else fails.

If you really want to use the aftermarket rods, it's different ball game. Ford probably used better grade of steel than they do now days, though.

EDIT : Given you are assembling a rotating assembly from a number of different sources. it would be a good idea to have the whole thing balanced.

[KiWinUS]

I have sets of nice used 8ba rods if you need a set.

[Karl Wolf]

Originally Posted by tubman

No difference between the late ('49-'53) Ford rods or Mercury rods; they are the same, the difference is in the pin position in the piston. If you are using a Merc crank, stock rods will be just fine. There are plenty of stock rods floating around out there,. It will probably cost more to get them reconditioned than the rods them selves. I seem to remember some outfit was selling new French Ford rods for cheaper than the cost of reconditioning. An internet search may be in order. (I believe the French 4" stroke rods are different from the Ford units, so be careful.)

I would imagine you could find a set of rods on eBay, or the swap meet "For Sale" sections on here or the H.A.M.B. If all else fails, I save the good ones and could probably put together a set if all else fails.

If you really want to use the aftermarket rods, it's different ball game. Ford probably used better grade of steel than they do now days, though.

EDIT : Given you are assembling a rotating assembly from a number of different sources. it would be a good idea to have the whole thing balanced.

The 8BA rods are 8" center to center. (Some of?) the French rods are 7 7/8". This means one could use the Ford pistons with 7 7/8" rods and a 4" stroke crank.

Karl

[matthewejacob]

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Some of you have pm'd me but I can't reply because I don't have enough posts. If you om me you'll have to leave your number so I can reply. As for the rods being I the same, my stock Ford rods do not fit this crank. The rod journals are 1.999 and my rods are larger. So could my crank be an early one and not 49-53? I don't know the difference other than the guy that listed the crank had it listed as 49-53. Like I said I'm really green with flatheads so this is all new to me. It's definitely a stroker crank. Has the wide counter balances. Not like the Ford crank that I have.

[big deuce]

Does it have one, or two oil holes per rod journal? One hole is early, two holes is 8ba. Does it have cleanout plugs, in the crank, and what size?

[Ronnieroadster]

With that 1.999 diameter rod journal that's the size for the early cranks. Latter cranks 1949 to 1953 rod journals were ground to that 1.999 size when the stroke was increased from stock. To determine if your have the early or late crank first thing to answer is how many oil holes do you see on the rod journals. If its one then you have an early crank which needs floater 21A rods and double wide floater rod bearings. If you see two oil holes you have a latter crank that's been ground down with an increased stroke. The rods you need would be those used on the early cranks 21A and the wide floater bearings.
Ronnieroadster

[matthewejacob]

it has two holes. and micing the journals it looks like they are actually 1.990 so someone has taken them down to .10 under it seems. so I would need the early rods with the later crank?

[big deuce]

Early rods, and expensive floating bearings. Or, find a regular 8ba crank.

[matthewejacob]

I don't believe it's a stock crank that was ground down. it has the smaller hole in the end and the counter balances are quite a bit wider than my stock crank. it's definatley a merc crank i believe. so from what i'm gathering, it should have had the same journals as the ford crank and someone has ground them even more? wouldn't that give an even longer than the stock 4" stroke then?

[matthewejacob]

i think i'm kinda stuck and in too deep to even go back to the stock setup without having to buy another set of pistons. i had the block bored .125 over and purchased merc pistons from h and h flatheads. so if those wristpins are in a different place than the ford pistons i'm stuck having to finish this thing expensive or not. if i can get a set of early rod at a reasonable price maybe i won't have to take a loan to get the bearings!

[tubman]

What they did back in the day was offset grind the rod journals on a Merc crank down to the early size yielding a 4 1/8" stroke using the early rods. This, along with the 3 5/16" bore yielded 284 cubic inches. If you bored it out to 3 3/8", you had the legendary "3/8 stroker" yielding the classic 296 inch flathead. The only other alternatives back in those days was a welded stroker setup. Nowadays, we have aftermarket (SCAT, etc.) stuff that'll go even bigger than that (with a appropriate price tag).

Big time professional race stuff. In any event, you are going to need special pistons no matter what you do. If this is your first flathead, it may be beyond your means (especially if you're on a budget). I'll bow out now and leave it to "Ronnie Roadster" and the real experts, who should be able to help you out.

[matthewejacob]

I may be ok. I did a quick search on ebay for 21a rods and they aren't too bad for a set. the bearings are a little more but still way under 900 bucks for the h-beam rods. I guess now really the question is given it's been ground down that far, will the pistons i've already baught have interference issues. the rods are affordable enough if they don't work I guess i'll have to bite the bullet and by the pricey ones with the correct length. I definatley don't have unlimited supply of money on it but i did anticipate it costing as much if not more than all the rest of the build (body panels etc.) but i want it done right internally so i'm not pulling the engine back out cause i wished i had done this or that later. you guys have been an imense help. had i not posted on here i think i would have made some costly mistakes. at least i have a shot now of not having to keep re-buying parts. hopefully.

[matthewejacob]

I suppose the safe option since i have the pistons is just get a scat 4" stroker crank with the 2.138 rod jounals, which will allow me to use the stock rods i have already and be certain it would work. roughly 300 bucks for old style rods and bearings and i have to deal with the floating bearings or just fork up the money for the crank and use the newer rods and know i won't have clearance issues with the pistons on the heads.

live and learn i guess. wish i found this forum before i baught the crank.

[tubman]

I don't know if you can get the newer SCAT etc. rods for the smaller crank pins. You should check. 4 1/8" is an odd stroke and you WILL need new pistons. I hear the "hot ticket for aftermarket strokers is a SCAT crank with Eagle rods.

Basically, you have an "old school" stroker crank that probably is incompatible with the newer rods. You will have to use the old style rods with "full-floating" bearings. Do you have a good grasp of what "full-floating" bearings are? They are hard to find, expensive if you do, and you need a skilled craftsman to install them.

[tubman]

Our posts crossed. It sounds like you're on the right track now. One question. Are you sure your pistons are for a 4" stroke Merc, and are they new? Buying a new aftermarket stroker crank so you can use a set of old pistons doesn't make a lot of sense.

[matthewejacob]

they are brand new .125 over egge pistons specifically for 4" stroker crank. so the scat crank should be ok with them. but it should at least allow me to use the rods i have which i have plenty of. i have two more spare flatheads sitting out there as well to pull from. the thing i was trying to avoid was buying those really expensive rods on a street engine. the money I think would be better spent on a new crank.

The floating bearings really just made me take a step back on it and rethink this whole thing because i've heard some not so great outcomes with those. nor do i know anyone experienced with them to even help guide me on them. I think what i may do is just put the crank up on marketplace or something and see if i can't get a hit, or maybe even trade something for it. better than it gathering dust.

[matthewejacob]

scat offers a crank with the 2.138 rod journals in a 4" stroke. I think that may be the ticket.

[tubman]

I think you're on the right track. If the 4 1/8" Merc crank is in good shape and measures out right, it may be worth a lot to someone wanting to build a "classic" engine.