mark kibort

got it....

ok, forget about the 4.5 engine.. that is a losing proposition to put that on the euro stuff. why.. just tossing out 20 to 40hp right off the bat.
the valve reliefs are quite large on the 79s, probably fine, but who cares ... you don't want the US 4.5

the 4.7 is the most straight forward. use the 79 rods . tip and tale balance them all and then have the entire rotating assembly balanced .. assemble.. use stock rings, bearings and head gasket. use the torque measure ... im sure the studs are fine. the angle torque was for the non stud bolts.. Use of cometic gaskets is tricky and not for the faint of heart... you use angle torque on that gasket and you will have a huge gasket leak. Its a short story and we ran down that road with the stroker successfully.
Now, the only thing left to question, is that while you got all this apart, why not go to a 5 liter? they are cheap, probalbly can find one in great shape. the cylinder walls are thick and the ONLY tricky thing is cutting valve reliefs in the pistons. THEN you also can use the piston offsets to your advantage. (that was shown to provide another 10hp on 911 engines according to greg brown)

I have an entire thread of when I built Scots motor. he was in your boat.. had a 4.5 and wanted 80 more HP. we got him almost all of that and then some.

Fresh

Thanks. What you are saying makes sense. Either a 4.7 or a 5 liter is best. Things must be balanced and work in harmony. Plus the old adage about there being "no substitute for cubic inches". I had just put a lot of thought into the 4.5 liter thing... and I had the block and other parts just lying around taking up space. I was just curious about the 4.5 with euro top end; what parts were used, mods done and how it turned out.

I am 52 years old. My son's been on me for 8 years to get our 79 black on black 5 speed going again. I gave it to him when he was 15 when the head gasket blew, with the promise that we would resurrect it.. you know, like the raising of Lazareth. Well, the car's been sitting ever since. When we saw that the 4.7 euro bottom we recoiled in horror.

My son said "dad lets just throw the 4.5 back together and get the car running. At least we'll have SOME fun. Right now we are having NO fun". Hence my exploration of the 4.5/euro combo.

I always tend to over complicate things. Being 1/2 German myself, I always want to try and experiment ... to re-invent things. It usually turns out undesirable... I really need to tattoo the words "Keep It Simple Stupid" on my forehead.

Fresh

Thanks for the info. I don't really understand all of that bit about torque angle and such. I will read up on this or youtube it. NO WONDER all of my engines blew like krackatoa! I probably torqued them wrong.

However, I get the bit about the bad technique. The wife tells me this every time. Oops! this is a G rated forum.

mark kibort

just use the stock spec.. it works, especially on the older studded motors.
20, 40 and then 60ftlbs or Nm or something like that , all in the order shown in the manual for the head nuts. the spec is in the little book or the manual

mark kibort

I get it.... then, start building the 4.7. (forget about the 4.5) with the parts you have. use all the old rods . the euro 4.7 has a much better crank too, with larger oiling for the bearings. the 4.5 is worthless... just toss it.
if you need rods .... I have a bunch left over from my builds . I think I have a full set of euro 4.7 pistons too minus about 1 or 2 if you need them.

Hilton

Good work asking questions before doing stuff like using scotchbrite or hones! Too many people come in saying "I did this, what do y'all think?" by which time they've done damage.

Correct on the pistons.. no soda blasting. Soak the pistons in marvel mystery oil, and use a soft nylon bristle brush to clean the pistons up and remove any carbon. They're iron-plated (process called Ferrostan IIRC) and the coating is both very thin, and very important for avoiding galling against the alusil walls.

The bores may not be as bad as they appear - old merc's also used Alusil, so if you can find a mercedes-friendly shop, they may have the correct sunnen pad and paste to polish up the bores. Do not let any old shop "hone" them!! anything which leaves visible honemarks has destroyed the cylinder walls.

First steps should be dismantle and clean everything.. then assess which bits are usable, which bits can be saved with some work (decking/welding heads if corroded around old fire rings, polishing bores etc.), and which bits are garbage. Then plan from there.

As far as gaskets go.. the factory head gaskets are excellent quality and last 25-30 years (yes, seriously that long, sounds crazy I know). I'd just buy a complete engine gasket kit, which includes all the seals, o-rings, gaskets for the whole motor. You'll come out way ahead versus just buying the ones you think you need at the start.

Fresh

Cool, will do and thanks for the tip.

Rob Edwards

Anyone that gives you a torque spec that includes the phrase 'or something like that' is probably not someone you want to take critical fastener torque advice from. Mark means well but his 20-40-60 Nm numbers refer to the M12 girdle nuts,not head studs.

15 ftlbs, then 2x 90 degrees. There's a good discussion on head stud torques here:

https://rennlist.com/forums/928-foru...-question.html

And a good torque angle wrench for the purpose is the Gear Wrench 85074- can be had online for about $250:



:

Mrmerlin

FWIW what I found that cleans the pistons is to set them into a container of simple green for 12 hours this will remove the carbon,
the harshest thing you want to use is a toothbrush to scrub them

NOTE put the scotchbrite pads into the cabinet.

The cleaned pistons will have a dull green coating,
the skirts will look slightly polished.

NOTE be aware of the piston coding for tolerance.
There is a number stamped at the top of each piston and bore to signify the bore size and thus the size piston that must also be used.
I suggest to read the WSM for full instructions

Fresh

Thanks a lot, Hilton. I hate messing things up, especially expensive parts. I probably messed up my 4.5 pistons by over cleaning them. No biggie, probably not need them anyhow.

I am used to working on engines with steel sleeves, like small block Chevys and Fords (I know what you all are saying...Ahhh!). This alusil is new to me.

Pretty impressive stuff, though. I talked to someone the other day that had 310K miles on a 4.5 liter and the bore still looked great. The engine still ran great. That is just unbelievable.

The first time I tore into the 4.5 motor, I was so impressed with the design. The lower end being like 1 big stud girdle. Lots of studs versus bolts. It was so far ahead of it's time it made US built engines of the time look antiquated, in my opinion.

I can see why several people have suggested that I not split the block if I build another 4.7 or 5 liter. The mains probably last practically forever.

Fresh

Thanks Mrmerlin. Man, so much good information out there. I hope that I can remember it all! All I did so far was to pressure wash the 4.7 piston tops to get the funk off of them. Even so, they are still dirty. I hope I didn't mess them up.
Every engine I ever built up had forged pistons in steel bores. I am a green horn around these 928 engines, I need to keep learning.

mark kibort

Rob, when you say , "something like", it means "go look it up". edit: the spec is 20-50-80nm for the 2 valve heads.... yes the spec i gave of 20-40-60nm was for the girtle . ive used the torque value method successfully many times....im sure its a safe way to go with 2 valve studs.

and by the way, when you come off like you know what you are talking about , its a responsibility you should take seriously... the torquing sequence for for angle torque is not 20nm and 2 x90s, its 20nm then, 3 x 90s as shown in the m28-21 manual.... 4 steps, not 3 as YOU SAID!
If we follow your expert advice.... the guy is going to have a blown head gasket the first time out! (ask me how i know.... CT did that with scots motor)

now if you are talking about the 32valve with bolts... then you are right, but we are not talking about that engine here.... RIGHT ROB????? (yes, Rob means well here!)

Rob Edwards

Mark, read post #2 in the thread I linked above. 3 x 90 degrees is too much. If I have a choice between Greg's advice and your advice Re torque, I'm afraid I'm going to go with Greg.

mark kibort

Read his reasoning.. if you would rather go with greg then the factory, then go ahead.. so far my track record is the same or better than his on motors like this.... PLUS, did you read his reasoning? 3 x 90 was too much, so why not go back to how the factory originally did it, by using 20, 50 and 80nm? at least that way, you KNOW what the torque is.... again, sometimes you need to think about whats REALLY going on. did you think for a second that the studs after many heat cycles and one set of torquing, gets stretched? that means the 90 , 90, 90 is not going to work. as greg saw, way too much torque was developed.. or nothing changed on the last 90 meaning defomation issues... so, since the objective here is to have the heads pressing to the gasket with a certain amount of force, why not use the orginal factory method? 20 55 and then 75nm . that way you know what you got. I understand Greg got the same torque after 2 90s, as he did with 3..... that is very telling in the mechanical world, dont you think..... but, going to 2 might not be enough..you are betting a lot on Gregs guess/calculation/experience. Personally, i would go with the 3 torque's method...... My motors being raced have had no issues using this technique. its only 6 of them, but 6 all working fine under race conditions.

(as a note, think about the S4 motor with bolts. the entire thread set is moving in the block with as many threads in contact.... .on the nuts, you only have 5-6 threads in contact.. a lot more force distributed on the nuts and more deformation.. thats why they need 3 angles on the nuts, and 2 on the studs.... but again, do what you want.. but you have to admit...there is a good point there right? )

so, you can go with greg if you want.. i think the OP should do it the old factory way, because it works.

ask yourself this too... (and maybe greg can chime in) what happens to his test when ALL new studs are installed and then you do the 3 torque's technique? you dont think porsche ever did a test to validate their techniques with new motor builds?? just a thought there!

GlenL

Now that's Mark's here we can either stop responding or get drawn into unending and pointless arguments with him. RIGHT, MARK????

Fresh: Make your own decision. As you're new, you should know that Greg is a preeminent 928 mechanic and Mark is an enthusiastic know-it-all.