Project: Iron block 5.6 - Page 14 - PeachParts Mercedes-Benz Forum

Tony H · #**196** 10-26-2022, 01:34 AM

You can use a combination of offset woodruff keys/tooth skipping to achieve any valve timing you wish. Not sure how one would arrive at the correct amount of advance to introduce without profiling the cams. The 26/27 are quite retarded. 15deg more retard that the 02/03 cams I'm using for my project.

Quote:

Originally Posted by badgator

Is there a problem advancing 560 26/27 cams 1 tooth (10 degrees) since they are retarded so much?

Tony H · #**197** 10-31-2022, 09:36 PM

I needed to determine very precisely the needed compression height of the replacement pistons. First I calculated the 0 deck CH with the 4.5 block and 5.6 crank. It came out to 1.187". I wanted to verify using the actual block, crankshaft and rod so I machined the top of my 4.5 test piston very precisely until I had 0 deck at TDC. Then I removed the piston and measured the pin to top of piston and added 1/2 the pin dia. It was 1.184"-only .003" from the calculated height. I may set it up again and see if I get the same results. Now I add whatever additional for squish (+.010 in my case) which will give me .040" squish with a .050" head gasket. So if I use the calculated CH the pistons might be .003" too tall but it's still conservative for a low speed engine.
EDIT-I just realized I had my rods big end resized and that could have changed the rod length. I have another set of rods I can check with.

Double edit. Same with another rod. Happy my Measurment is close to the calculated figure.

Tony H · #**198** 11-21-2022, 11:10 PM

I think I have everything necessary to order the pistons. Contrary to what I was originally told they will build the pistons around the 5.6 pins including fitting the pins to the pistons. I do have a minor unknown in that the 5.6 pins are 2 different weights with one pin 10 grams lighter. The different weight pins were used to weight match the pistons. I will check with the machine shop to see if they can hone the ID to match the weights. The amount to be removed is probably in the few thousands range.
Edit: pins are lightened frequently so no deal. They are tapered on the ends where strength is not as critical.

rwd4evr · #**199** 12-30-2022, 04:20 AM

I just saw a VQ37 runs a 95.5mm bore. Does that leave comfort room in the block? Not trying to derail but I'm going 5.6 alloy in my drift car but I'll tell ya. That ole iron block sure has taken a beating well. I may have to build if the alloy doesn't like it.

Tony H · #**200** 12-31-2022, 04:49 PM

Hey Jason,
Not sure I get your "drift" (no pun intended-well just a little maybe) concerning the Nissan engine. Are you are asking my opinion on a 95.5mm bore on the iron block?

rwd4evr · #**201** 01-10-2023, 03:10 PM

Yes exactly that.

Tony H · #**202** 01-11-2023, 03:03 AM

I think it would be fine but I am no authority on cylinder wall thickness-just what I read on the net. I think my block I bored to 96.5 would have been fine even though it had a few spots less than .1" but since I have to have pistons made I wanted to be safe and use a smaller bore. The main reason I want a bigger bore is so I can use the 5.6 heads. The intakes will hit the cylinder wall with a smaller bore. What I found on both my blocks is the cylinders are bored off center on one bank(as evidenced by the head gasket). If the bore center was corrected it would minimize the cylinder wall thickness loss. If you look at the pictures of my "new" block the cylinder wall thickness readings from the right bank (2nd picture) the bores are all shifted to the upper left by an equal amount. The head gasket confirms it. It would gain some thickness (prevent some loss) if the overbore was centered on the gasket bore.

rwd4evr · #**203** 03-13-2023, 01:17 PM

Did you find any truth to the distributor being installed at a slightly different angle and having a corresponding different gear on alloy and iron block front covers? I've read this but never actually measured them.

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Tony H · #**204** 03-15-2023, 03:27 AM

I have never had any reason to check it. I plan on using a modified 5.6 distributor for FI/ignition cam sync but never posted any of it since I did not get it done. I do have the ignition cam sync plug (made from a 5.6 distributor) done if you want to see it. I will have to check if the distributor fits the iron block timing cover and the gears match.

rwd4evr · #**205** 03-15-2023, 06:13 PM

Quote:

Originally Posted by Tony H

I have never had any reason to check it. I plan on using a modified 5.6 distributor for FI/ignition cam sync but never posted any of it since I did not get it done. I do have the ignition cam sync plug (made from a 5.6 distributor) done if you want to see it. I will have to check if the distributor fits the iron block timing cover and the gears match.

Yeah as far as I know it fits perfectly but I've read that the angle of the distributor is slightly different on the alloy block and the corresponding gear has a slightly different angle on the helix. It would make sense being the alloy block dissy is way bigger diameter.

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Tony H · #**206** 03-16-2023, 11:01 PM

5.6 distributor fits and turns in iron block engine but mine is modified without the large upper portion. I looked at some cam sync plugs and made my own. The SS nuts are welded onto the dist shaft, one ss bolt is drilled for the flying magnet (have not installed as I don't know which pole is needed yet) and the other is a counterweight. When I decide which FI/Ignition system I am using I will buy the sensor for it.

rwd4evr · #**207** 03-18-2023, 11:45 PM

Oh cool. You are going to run COP ignition, Or coil near plug individual coils?

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Tony H · #**208** 03-19-2023, 01:31 AM

Probably CNP. The coils will fit under the air cleaner for a cleaner installation. I'm a way from that but always planning.

Tony H · #**209** 12-21-2023, 08:16 PM

Been a while since I have been here. Project is still alive and well. Been hung up with various life issues. Hopefully I will have an actual shop in the not to far future. I know I have been saying that for years but the actual building is finally there but needs a lot of renovation. Working out a few last details on the engine such as what bore to use and wrist pin weights. Custom piston manufacturer will make pistons around 5.6 wrist pins which makes this so much more feasible. I have a lot of 5.6 pins but not 8 of the same weight. I have at least 2 different weights. I'm thinking I can have the pins weight matched when I have the engine balanced.

Matt at Pelican Parts · #**210** 12-28-2023, 04:25 PM

Hey Tony,

Thanks for the update. Looking forward to seeing the project move forward some more!