Project: Iron block 5.6 - Page 15 - PeachParts Mercedes-Benz Forum

Tony H · #**211** 12-29-2023, 09:40 PM

I'm kind of hoping to get it done while I can still drive

It's the dreams that keep us going. Once you have everything you want you lose your incentive-or at least I have heard.

Tony H · #**212** 07-30-2024, 01:04 AM

Trying to keep making progress on this project. One obvious unknow has been using 560 heads on an iron block. I decided instead of having heads rebuilt and adding one more unknown I would find a pair of good, used heads from a running engine, clean them up, replace the valve guide seals. I found a pair of really clean heads, no stuck ball studs, old head gaskets still stuck on that protected the mating surface. Kind of a crap shoot with used parts, the last pair of heads I bought had stuck ball studs and needed new seats. Once the engine is sorted, I can consider having the heads rebuilt-the guides are a little loose as they all are.

Roncallo · #**213** 08-06-2024, 09:11 PM

Quote:

Originally Posted by Tony H

Trying to keep making progress on this project. One obvious unknow has been using 560 heads on an iron block. I decided instead of having heads rebuilt and adding one more unknown I would find a pair of good, used heads from a running engine, clean them up, replace the valve guide seals. I found a pair of really clean heads, no stuck ball studs, old head gaskets still stuck on that protected the mating surface. Kind of a crap shoot with used parts, the last pair of heads I bought had stuck ball studs and needed new seats. Once the engine is sorted, I can consider having the heads rebuilt-the guides are a little loose as they all are.

How are you going to deal with the bolts that are at an angle. Have you considered sleeving the head holes and re-pocketing them?

Tony H · #**214** 08-06-2024, 11:30 PM

I considered relocating the bolt hole in the block but the discrepancy is small and modifying the heads is easier so Post #148 shows how I addressed the issue. Basically, I tapered the hole (just enough) to an oblong to match the 4.5 bolt location. The photo shows how much needed to be removed-not much. There is still plenty head gasket heat ring at the relocated hole. I only did one hole as a test on a junk head to prove the feasibility before I went on. On the picture I used the wrong side head gasket so the other holes don't match.

rwd4evr · #**215** 08-21-2024, 12:59 AM

Hey! I haven't been here in awhile either but always good to hear of progress. Have you decided on the final bore size yet? I'm so interested to see alloy heads on the iron block because, man, my 4.5 is an absolute unit. 6000+rpm all day. Forget the cooling fans and see 270° last event without a pickup, not to mention it just ran 230° for years on grid before I went electric. I have very little faith that the 5.6 that's going in there will have the same indestructibility. I'm thinking 5.6 heads and cams on the 4.5 with a blower or turbo. We'll see.

Anyway I came here to give you a heads up. I just went to swap to an aluminum ps pump from a 560sl onto my 4.5 and the adjuster bolt with gear was too short for the almost identical pump. The lower boss is just a few mm thicker. So I tried to swap the entire slightly different alloy mounting bracket from the 5.6 and discovered that the mounting holes on the front of the iron k jet heads are not all in the same place. I did not look at the d jet setup since I know the pump is considerably different so I can't honestly say if it matches either. It also moved the pump lower and inward a bit which is a problem for me and the vacuum advance distributor and my electric fans.

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Tony H · #**216** 08-23-2024, 01:09 AM

I'm trying to keep making progress. Regarding the bore size-I was thinking in the range of 94.5mm to keep the minimum cylinder wall thickness in the .150 range. If I can have the bore center moved I could go with a larger bore-maybe 95mm since the cylinders in one bank are thicker on one side. The bore center is off the same amount in relation to the head gasket. The larger intake valve will be closer to the cylinder so I will need to check that out. I have not got far enough to evaluate engine accessories but I plan on using the 3.5 PS pump and a K-jet 4.5 alternator. Still not ready to pull the plug on the pistons.