Reproduction Parts for 1916-1964 Chevrolet Passenger Cars & 1918-1987 Chevrolet & GMC Trucks
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I'm at that point where it's time to Plastigage the connecting rod bearings, and would love to get some confirmation of the orientation of the rods and dippers. When I tore down this engine, all of the embossed numbers on the piston tops were oriented toward the rear of the engine, except for piston #5. This put the rod clamping bolt and the matching numbers that correlate the bearing caps to the rods, facing the driver's side. All the rest are on the passenger side. Piston #6, although it's attached to the con rod and cap that are stamped "6", appears to be a replacement (?). Instead of a number, it has a very large "E", and a very small "Y" randomly stamped in different places at the top, with neither conforming to a decidedly rear-oriented position. I would like to confirm that all of the stamped rod and cap numbers, and therefore, all of the clamping bolts, should be oriented toward the passenger side, and the dipper openings also facing the passenger side? Thanks in advance for shedding some light on this. I looked in the closed chats and manuals, but couldn't find definitive information on the rod orientations. Andy
The location of the numbers is not a reliable indicator of the rod orientation. The key is the orientation of the dipper so it scoops oil into the hole on the bottom of the rod cap. According to the Repair Manual "The bearing cap should be installed with the oil hole away from the camshaft. The oil dipper mist be installed facing the cam shaft and should project into the oil tray 11/64". "
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Hello Andrew Baron,
Referencing 'connecting rod wrist pin locking bolts'
VCCA old forum (title) 1929 194
An answer by 'Chev Nut' 03/07/21 08:50PM #455247 "Bolts go to camshaft side."
Where the info is found in a manual, I don't know. I'm away from manuals I have. 1929 and 1931 orientations should be similar, an assumption.
In my 38 216 the wrist pin clamp bolts were towards the cam so I reinstalled them that way, as for the dippers I set them so that the opening was open on the leading side.
Tony
I'm at that point where it's time to Plastigage the connecting rod bearings
If you search the old forum, you will see a lot of posts telling that Plastigage should only be used as a rough guidence.
The final adjustment should be by feeling with hand and a 8-oz hammer.
Manuals of the time says the same.
1932 Chevrolet BA Confederate
I'm with Chip that the oil hole should be "away" from the passenger (camshaft) side. Personally I would consider that the trailing side. Yes, the dippers should face the camshaft to help throw oil up onto it.
@chip Thanks Chip. I wasn't aware that the number stamps couldn't be relied upon for the rod and cap orientation. I've noted your reply and will take a closer look at the position of the oil hole in the bearing caps, which I must assume should, in service, be at the far or rear end of the dippers for greatest benefit.
@arthur-p-sell Thanks again Arthur. I appreciate your chiming in on this.
@morten-c Thanks Morten. I'm beginning to figure out that the Plastigage can only go so far, and can sometimes be a little misleading. I'm just starting to rely more on the feel. I've read in a number of the old manuals about the hammer tapping method, but had not seen the photo and caption that you uploaded to these postings. What book did that image come from? It's nice to be able to see the approach demonstrated. Andrew
This is out of the 1934 manual Andy.
https://chevy.oldcarmanualproject.com/shop/1934/34crm021.htm
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@andrew-baron I was trying to send a PM to you. That hint about the direction of the holes in the connecting rods was in the hope that a previous poster would physically look at his conn rods. But once again I ran afoul of the web site.
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