Is it true that all K motors had the weaker connecting rods? If it is possible that some K motors came with the bigger connecting rods how would one identify that it did? Are there any markings or numbers on the engine?
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1988 760Tic - electric fan, HD radiator, boost gauge, a/f gauge, remote start, BP7ES plugs, brown top injectors,tuned AMM, MBC@14psi - 158,500 1966 M-B 230 sedan - 98,000 1982 Rx-7 - 201,000

few things:
Dick, no, not all K blocks got big rods, infact engines manufactured before 6/89 I believe did *not* get them, they were a running change somewhere around then. if the car is a late 88, figure on most of the stuff having been assembled mid to early 88, so more than likely not the big rods unless a P.O. has added them (i.e. assume your motor has small rods and be pleasantly surprised if they're the big ones).

Most people are up to speed on these things, but I'll hit the list real fast:
85-early 88 B230f/t non k-series key features:
thrust bearing at the #3 main instead of the back, Apparently this allowed for crank flexing towards the front, hence a lot of people break the #1 rod

Early K block(somewhere early 88 on):
redesigned mains, the thrust bearing has been moved to the #5 journal, wider main journals.

Late K block (~mid 89 on):
13mm connecting rods as opposed to the early 9mm rods

L block:
Longer piston skirts, piston oil squirters, same 13mm rods, same main bearing layout (its all interchangeable after the k block was introduced, however you wouldn't gain anything by switching to a later model rotating assembly aside from the longer skirted pistons=less prone to slap. oil squirters greatly reduce the chances and onset of piston slap as well).

That should clear things up a bit

It should be noted that the 13mm rods can be put in any year b230, I checked this on a whim once this past winter

-k.

.....figure on most of the stuff having been assembled mid to early 88, so more than likely not the big rods unless a P.O. has added them (i.e. assume your motor has small rods and be pleasantly surprised if they're the big ones).

This caused me to remember something... the 2nd owner of my car was the Owner of a Volvo/Saab Indy shop. There are no service records for this 4-5 period. All I have is the receipt of purchase and the owners I purchased it from statements. It is believed though that the car received a fresh paint job and it is known this was the shop owners daily driver. If any mechanical work was done I am sure the PO wouldn't have known. It is possible he might have changed out the bottom end. I should see if I can get in contact with him.
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1988 760Tic - electric fan, HD radiator, boost gauge, a/f gauge, remote start, BP7ES plugs, brown top injectors,tuned AMM, MBC@14psi - 158,800 1966 M-B 230 sedan - 98,000 1982 Rx-7 - 201,000

Talked to the shop owner and he was pissy about the whole subject :). Said he'd never touched the engine or messed with the connecting rods. Proceeded to tell me that if there were any problems with the car it was the fault of the punk 16-17yo kid whose parents bought the car for him. So he may have though we was in line to get sued for something and covering his ass or he was telling the truth.... probably both.
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1988 760Tic - electric fan, HD radiator, boost gauge, a/f gauge, remote start, BP7ES plugs, brown top injectors,tuned AMM, MBC@14psi - 158,800 1966 M-B 230 sedan - 98,000 1982 Rx-7 - 201,000

Good post, but my experience has shown that the L engines do not have longer skirt pistons. I am overhauling a 1994 L block, and the original pistons were the same length as the very early B230FT pistons.
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john

Volvo introduced the K block as a running change early in the 1988 model year. The K block motors have the 63mm (instead of the 55mm) main bearing journals, and the thrust bearing moved to the rear main bearing (it was in the center). Early in the 1989 model year Volvo made a running change to the 13mm connecting rods, from the crack prone 9mm connecting rods. The next change was sometime in the 1993 model year, when the L block was introduced. The L block motors have piston oil cooling with the same crankshaft and the 13mm connecting rods from the K block engines. There is also a later and very scarce R block version of the B230FT. It is supposed to have more block strength.

I doubt that your 1988 model year engine has the 13mm connecting rods.

The picture shows a couple of 9mm connecting rods from a overboosted 1988 B230FT.

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john

How hard would it be to swap out 9mm connecting rods for 13mm? I am running 94 octane and brown tops so I doubt i'll do what John did. I don't have any pinging.
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1988 760Tic - electric fan, HD radiator, boost gauge, a/f gauge, remote start, BP7ES plugs, brown top injectors,tuned AMM, MBC@14psi - 158,500 1966 M-B 230 sedan - 98,000 1982 Rx-7 - 201,000

When you are overhauling the engine, it is easy to install the 13mm connecting rods.

Although the connecting rods in the picture were damaged from overboosting the engine, the 9mm connecting rods are quite prone to cracking under normal use in the turbo versions of the B230. I have two 9mm connecting rods which were cracked when I overhauled the 1987 B230FT in my wife's 1986 car. Magnafluxing inspection detected the cracks. The original engine in my wife's 1986 car broke a connecting rod at about 55,000 miles.
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john

But those are both pre-K block engines. Weren't they even weaker? I thought that pinging was the main culprit in bending the smaller rods. I would figure that aslong as I avoid pinging I should be ok at my current boost level?
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1988 760Tic - electric fan, HD radiator, boost gauge, a/f gauge, remote start, BP7ES plugs, brown top injectors,tuned AMM, MBC@14psi - 158,500 1966 M-B 230 sedan - 98,000 1982 Rx-7 - 201,000

The connecting rods are all the same from the introduction of the B230 series of engine (1985) until early in the 1989 model year when they were upgraded to 13mm.

Like I wrote before, the early rods are prone to cracking the the subsequent breaking. Overboosting will bend the rods, or make them fail catastrophically.
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john

What are the chances that mine are actually bent? How much is a reasonable price for new 13mm rods or used ones? Is used ok? How easy or hard is swaping them? What else needs to be bought to do it? Is this something I could do myself or should I have a mechanic do it?
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1988 760Tic - electric fan, HD radiator, boost gauge, a/f gauge, remote start, BP7ES plugs, brown top injectors,tuned AMM, MBC@14psi - 158,800 1966 M-B 230 sedan - 98,000 1982 Rx-7 - 201,000

I doubt that any of the connecting rods in your engine are bent unless you have seriously overboosted the engine. It is more likely to have a cracked connecting rod.

To install the 13mm connecting rods you must remove the pistons from the engine.

I sold two sets of used 13mm connecting rods for $50 per set in the last month. If they were reconditioned rods, they would have been worth more.
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john

Someone will have more info that I do, but the K block was the first step back to the B 23 style bottom end. It is sig better than the 85 through early 88 models. Turbobricks has a more complete description of all the engines.

dick

My car is a late '88 model with a K block. It is my understanding that some of the late '88's and early '89's received the beefier connecting rods. I just need to know how you can tell without ripping the engine apart.
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1988 760Tic - electric fan, HD radiator, boost gauge, a/f gauge, remote start, BP7ES plugs, brown top injectors,tuned AMM, MBC@14psi - 158,500 1966 M-B 230 sedan - 98,000 1982 Rx-7 - 201,000

You cannot tell without removing the pan.

If it is a K block it has the larger surface bearings and I believe the larger con rods.

dick