Connecting rod question

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Model T Ford Forum: Forum 2014: Connecting rod question
Top of pagePrevious messageNext messageBottom of page Link to this message  By Jamie Holmes on Friday, March 21, 2014 - 09:25 pm:

I apologize if this has been covered before.

I am rebuilding the engine in my 15 T Runabout and am considering purchasing pre-poured babbet connecting rods.

Any experience with these?

Thanks

Jamie


Top of pagePrevious messageNext messageBottom of page Link to this message  By Jamie Holmes on Saturday, March 22, 2014 - 08:23 am:

No opinions?


Top of pagePrevious messageNext messageBottom of page Link to this message  By Roger Karlsson, southern Sweden on Saturday, March 22, 2014 - 08:57 am:

You mean replacement rods from the vendors?

How's your crank? Is it round with a nice surface at the rod bearings? Is the motor down for full restoration, then you should also check the crank for cracks with the magnaflux method before you can decide if it's worth reusing and can decide what size babbitt you need in your new rods.

Someone who rebabbit lots of rods may be able to match them in groups of four by weight of both small and big ends. Sometimes it's almost impossible to grind enough for proper weight matching of a given set without risk of weakening a rod.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Roger Karlsson, southern Sweden on Saturday, March 22, 2014 - 09:01 am:

If your '15 has original rods in an original engine it has heavy rods. When sending in rods to get replacement rods they want only post 1920 light weight rods, something you may have to find first at some swap or here in the classifieds. Light rods are very common and should be cheap - and are better for your engine than the heavy originals.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Dave Hjortnaes, Men Falls, WI on Saturday, March 22, 2014 - 06:46 pm:

Additional question re: above.

If a rod is 10% oversize, does that mean it has more babbit than usual to correct for the smaller size of the crankshaft due to wear?


Top of pagePrevious messageNext messageBottom of page Link to this message  By Kerry van Ekeren (Australia) on Saturday, March 22, 2014 - 07:04 pm:

yes and no, the crank needs to be ground to the over size babbitt.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Aaron Griffey, Hayward Ca. on Saturday, March 22, 2014 - 09:09 pm:

No, The crank has to be ground until it is round and then the rods have to be bored to fit the crank.
After the flaming I got a couple of weeks ago I will not mention anything about my experiences of buying rebuilt rods.
But the great god of engine rebuilders says you can not buy decent rods.
Even if you do get some you have to send them to several machine shops to have them checked. I don't know how many.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Jamie Holmes on Saturday, March 22, 2014 - 09:34 pm:

Thanks everyone for the responses. I appreciate that everyone has different experiences and therefore opinions not wanting or trying to start a flamefest.

Ok onto to answering your questions, everything has been magnafluxed, block, head, crank, flywheel, transmission drums, rods.

Couple of small cracks in the block, pressure test is next to see the extent of the damage and repair required.

Thanks for the heads up on the rods. I will look for the a newer/lighter set even if I decide to have them re-babbited as I had intended on using aluminum pistons in order to reduce reciprocating weight and be kinder to the crankshaft.

Crank journals are still at standard size and the crank needed a minor straighten,

As a tech by trade (35 years) I know by my own experience that not all parts are created equal and I also know that not all Babbitt is created equal. Having poured Babbitt myself (agricultural application) I have no intentions of doing this myself. I was just considering the pre poured rods as a way of speeding up the rebuild process. I would have my machine shop guys check the rods for weight, straightness and pin+ bearing size before any assembly.

I will search the forum for a discussion on aftermarket rods, no need to stir the pot

Thanks as always for the info and if anyone has some later rods for sale let me know.


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