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Discussion Starter #1 (Edited)
In the good tradition of many „project“ threads on this forum I would like to share with you my Busso 3,75 V6 built project. It might be inspiration for some of you or just source of info and pictures for the others.

In the following text I will be deliberately calling the engine 3,8l as its easier to use but as I am using 101mm liners it will really be 3749,5 cc engine and I plan to have 3,75 GTA written on the plenum as in my eyes it fits better to Alfa pedigree (1750 engines…)

History:

A friend of mine owned a 3,8l 156 GTA built by Autodelta as their first or one of the first 156/147/GT 3,75 conversions. You may know it, it was the red one with full wide bodykit on the AD press pictures from Brooklands. 40k kms after conversion this engine suffered a failure of big end bearing on cyl.4. Basically the bearings grinded completely to a very thin foil, or maybe the half bearings started to spin, the conrod developed a huge play, engine started to knock and it suffered a crank journal failure. The engine was taken apart after, but never rebuilt again. It spent years split in parts in many boxes somewhere in a garage...

As during last summer my GTA was almost in a condition I couldn´t think about anything to do on it I was missing some “project” in my life so I decided to give a try to the 3,8 rebuilt. Other reason to go for this engine was also that I don’t need to touch my GTA and take any parts of it and I can be building a second engine under no time pressure. Once the 3,8 is finished I just swap it for my current 3,2. In case I don’t build it right and something goes wrong I can always swap the 3,2 back in.
As mentioned, I started the project in summer 2011 with a time plan for the rebuilt of “about a year”.

These are the main specs and components of the engine:


  • 3,2 Busso engine block modified by PS Schulze (Germany) to accept 101mm liners
  • cylinder liners and seals made by PS Shulze
  • custom casted pistons and piston rings made by Pistal Racing (Italy)
  • multi layer steel headgaskets made by PS Schulze
  • heads ported, and gasflowed including regrind and enlargement of the valve seats (done somewhere in London by some workshop/supplier of Autodelta but I can’t get any detailed info about it)
  • stiffer valve springs
  • Balzuzzi (Italy) intake camshafts with 10,9mm lift (compared to 9,3mm OEM) and OEM exhaust camshafts
  • carbon intake plenum ( @selcuk – looking forward to it )
  • F430 TB 84mm
  • complete custom made intake, oil catch tank….
  • GTV manifolds, EQ pipes, Supersprint..... + stuff that is already on my car now
  • remap


Here is the stuff I brought home:




I especially liked the “box with all bolts” that came out of the engine…. I cursed the people who were disassembling it years ago….

The first step was to clean some small things and make a little of order in the parts to be sure what I have and what I miss and make a plan in my head.



The main problem with this engine was the crankshaft and its journal on the con-rod nr4. It was oval , scratched and grinded well under spec… I know a place that could repair it, put new layers of hard chrome on the journals, nitride the journal surface and grind the journals to spec, but the price was quite steep and I was not sure about the result. So I needed a “new” crank.

ePer lists crank available as new unit and also as a refurbed unit. I had confirmed by Alfa UK and Alfa Slovakia that the “refurbed” units are new ones anyway, they just sell them to dealers for better price for engines where they failed shortly after warranty. So I ordered a refurbed unit in UK as the price was better there. After few days I got info they don’t sell them anymore. So I tried Alfa in Slovakia and got the same feedback, part is not possible to order for refurbed price due to low stock. They were willing to sell it to me only as a new unit. And the price was more than the whole engine or even a whole car from a breaker. After 2 months of hunting for a crank by Alfa breakers around Europe it became clear that the easiest way will be getting another engine as parts donor. Luckily I found one breakers yard in Hungary that imports cars from UK and Italy for parts. They had a nice engine from side-crashed 3,2 GT with 40k on the clock. The engine looked horrible from the outside, dirty and with damaged wiring and all fragile parts broken as somebody rolled the engine over on the floor few times in the warehouse during long time storage.



But we removed the sump and it was just perfectly clean inside, no debris in the sump and clean golden oil everywhere, basically looked brand new inside.

So including the engine in my GTA I now have 3 pcs Busso V6 at home.

Here I would like to thank my friend yetyGT who helped me a lot to find and get this engine. Thanks mate. And now we have plenty of spare parts for our cars.

Here are some pictures from the disassembly of the spare engine, no need to comment, I just undid every bolt I have seen, took the parts apart and then put bolts back exactly as they were not to lose or confuse them:











 

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Discussion Starter #2 (Edited)
And here is finally what I was going for:




I took the crank assembly to the workshop for balancing, flywheel skim and flywheel balancing as well. I didn’t want to lighten the flywheel as I don’t really want to weaken the casting in high rpm. I was offered a custom made very light flywheel milled from steel, but I don’t think I would need it on a road car.
The outcome from the workshop was that the crank is in perfect condition, needed only minimum work to balance it perfectly and the imbalance was probably just normal material fatigue after the 40k miles. Flywheel needed a skim as the clutch on the GT was probably not seated right and was wearing more the center of the flywheel than the outer part. Looked a little like an unevenly worn brake disc. Now it’s perfect.

While the crank was in the workshop I cleaned and polished the 3,8 pistons. There are many discussions online if this has some positive effect on less carbon buildup on the pistons or less heatsoak by them but I don’t really care, I just wanted the clean polished look






Rings were also fine, needed just a good clean



The 3,75 liners looked fine, no wear, no lip, there were still perfect honing marks on them, but due to the long storage on free air they were a bit rusty inside of the cross shaped honing marks. They had some vertical scratches in the area of piston skirts as well; I guess some metallic particles got to the oil when the bearing failed. I took them to the workshop as well to measure them with the pistons and suggest whether to clean the rust chemically or mechanically. We couldn’t use honing stones on them again as this would make them too large for the pistons so I just had them slightly lapped. They are fine now, with some minimum hairline scratches, but according to my workshop fine to use. I was offered new 3,8 liners for 110 EUR each, so I passed.



I also took the pistons for weighting and rods to check if they are perfectly straight and same length, both ends parallel and for balancing of both ends. I decided to use the rods from the GT engine as they had less mileage and were not stressed by a 3,8 engine before. They were perfectly straight, just needed to remove a little from the small end counterweight so that they clear the 3,8 pistons. After that both the small ends and big ends were balanced separately to have even weight distribution of the rods. I finished with 617g con-rods.

Here are all the parts ready to be installed:



Due to different piston design I am using shorter and lighter gudgeon pins than 3,2 engine what lowers the moving weights as well. Pistons are also lighter.



As the pins have much less play in the pistons they couldn’t be just pushed in by hand as on the 3,2 but I needed to heat up the pistons to about 120 degrees in the oven, freeze the gudgeon pins in the freezer and then quickly put them together. They just slid in nicely. Now the con-rod is floating on the pin, but pins are solid in the piston, secured by lockrings.




Here is also a video from the pin install:
Conrod gudgeon pin install.avi - YouTube

Then I installed the piston rings and weighted all assemblies (piston, piston rings, gudgeon pin, pin lock rings and con-rod). I ended up with 2x1109g, 2x1110g and 2x1111g assemblies. So all my moving parts are within 2g tolerance from lightest to heaviest what I find pretty OK for my use

 

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Discussion Starter #3 (Edited)
To work on the engine I wanted to have some engine stand. I didn’t really like those I could buy in the shops. As this is just probably a one-project item for me, I designed and with help of a friend welded some simple stand by myself. It’s not exactly straight and the pieces are mostly cut just by eye few millimeters less or more…, but it holds the engine, I can turn it upside down and work on it from any angle




I gave the block a hot bath in some degreaser and a good clean






I actually really gave the block a bath and brushing in a plastic basin and later I found out that it fits nicely into my utility shower in the basement. And that the shower hose fits the oil filter outlet so I was able to clean oil pathways in the block with hot water. Some black gunk went out, so I am happy I did that. Otherwise it would end in my bearings or heads…. I let the hot water flow for some time:

GTA engine block cleaning.avi - YouTube

I got a new set of bearings for the engine, the standard size, red color code as I could still see some red color marks on the crank. Just to be sure I did a test crank install with the new bearings and checked the clearances with plastigauge. I came to 0,030mm clearance on all bearings. The ideal value should be around 0,025mm. Just to be sure I got one set of blue color code bearings that should be about 0,004-0,006mm larger and tested these as well. Plastigauge showed the very same result, but crank was not turning so smoothly so decided that playing with 0,005mm differences in home conditions is probably too much to ask and I will stick with new bearings according to the crank color code.






 

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Discussion Starter #4 (Edited)
Now I finally started to assemble the bottom end. I put new seals on the liners and inserted them in the block. The liners are different from 3,2 as they have a cutout at the bottom to clear the crank that needs to line up with the cutout in the block so they can’t be rotated and can be installed only in one direction.







To prevent the liners to come out or turn, I locked them in the block. I didn’t have the right tools, so I just used 4 pieces of steel water piping with some large washers welded in. Works just fine:



And here are all the new bearings, mains, big ends and trust washers.



New mains and trust washers in the block, they got a nice lube with redline assembly lube, crank got in, and caps screwed on.





All went in smoothly:

GTA crank install.avi - YouTube

Then I tightened the crankshaft caps. First to 25Nm and then turned them another 80 degrees:



Crank is in and turns smoothly without any rough spots and minimum resistance.

GTA crank turning.avi - YouTube

Than I got in all the pistons. OEM pistons have arrows on them showing orientation. Mine didn’t have anything. But the valve cutouts were not the same size so it was clear which side is going to intake side. Also the conrod pin axis was 1,5 mm off center so the pistons orientation was clear. I also put them together with conrods in the right way so that the letters stamped on the rods face the flywheel on the right bank and they face the timing side on the left bank.



Once the rings are compressed by the tool and attention is paid not to scratch the liner when passing the conrod through the rest is simple:

GTA 3.8 piston and rod install.avi - YouTube

Conrod caps are tightened to 20 Nm and then turned another 50 degrees
 

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Discussion Starter #5 (Edited)
Now the oil pump gets on. I got new seals for the pump-to-block connection pipe as the old ones were rock hard from the temperatures and oils… Pump than slides on the crankshaft caps and its distribution chain on the crank.





I am scared how little friction is between the crank and the oil pump chain drive. It’s very loose. I guess it’s locked on the crank later by a tap lock when I tighten the aux belt pulley that will press it very hard against the crank. I am just nervous about it and I would really prefer if the pump drive was locked on the crank by a pin as are the cambelt or aux belt pulleys.

GTA oil pump tap lock.avi - YouTube

Then comes the front cover with a new seal. Held by 6 bolts, 10Nm and now the block is almost complete.






There is still front and rear crank seal that should be pressed in, I just don’t have them yet so they will be installed later. I bolted on the flywheel to be able to turn or lock the crank easier and I put on the sump without silicone yet, just as protection.

For now, bottom end is mostly done, just the seals and sump silicone are missing:




And I love to see the pistons work:

GTA 3.8 bottom end assembled.avi - YouTube
 

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That is amazing and wonderful work. Keep it up!
 

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wonderful! you should start classes! i'd come along :)
 

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Excellent work Gotcha, fascinating thread, keep up the good work :cool: :thumbs:


A friend of mine owned a 3,8l 156 GTA built by Autodelta as their first or one of the first 156/147/GT 3,75 conversions. You may know it, it was the red one with full wide bodykit on the AD press pictures from Brooklands. 40k kms after conversion this engine suffered a failure of big end bearing on cyl.4. Basically the bearings grinded completely to a very thin foil, or maybe the half bearings started to spin, the conrod developed a huge play, engine started to knock and it suffered a crank journal failure.
I think this is the first example Ive heard of a 3.7/8 failing in some way... I think I have done around 30k kms with mine so far... any idea what caused the big end bearing to fail? a simple lack of oil possibly? :confused:
 

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I think this is the first example Ive heard of a 3.7/8 failing in some way... I think I have done around 30k kms with mine so far... any idea what caused the big end bearing to fail? a simple lack of oil possibly? :confused:
We had a customer mistakenly downchange into 2nd at approx 80mph which blew the clutch up, after replacing the clutch a big end bearing failed only a few hundred yards from our workshop, at approx 2,000rpm. Over-revving the engine can massively stress the big ends, causing potential for failure in the future.
 

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:wow::wow::wow:
absolutley stunning work
 

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Discussion Starter #15
Excellent work Gotcha, fascinating thread, keep up the good work :cool: :thumbs:




I think this is the first example Ive heard of a 3.7/8 failing in some way... I think I have done around 30k kms with mine so far... any idea what caused the big end bearing to fail? a simple lack of oil possibly? :confused:

I would have similar opinion as Dan. Engine was definitely driven hard and over revved on more occasions. I know the owner, he is careful about oil level and never revs cold cars, but once everything is warm he drives like crazy. With the cams and valve springs in this engine and remap it was revving up to 7500-7800rpm. I have no idea where was the limiter set. But I know that few weeks before the bearing failure the cambelt jumped in the limiter one tooth. Nothing was damaged, just the engine didn't run smoothly after and showed cam sensor failure. After this incident the engine had a complete belt job and only about 200-400 km after the belt job the bearing failed. So I guess something must have happened there as the belt jumped and bearing failed soon after... who knows the real truth...
 

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Have you given much thought to how you are going to set up the cams?
 

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I love reading these threads.....wish I had the knowledge to undertake something like this, must be very satisfying.......:thumbs:
 
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