Early AJP rebuild
Discussion
I have bought an early 4.2 Cebera from a customer in France that is partly dismantled and thought I would share some of the mods I am doing along the way .
The engine had a head missing but another was supplied so I had most of the major bits. I was going to rebuild the engine trying to improve power , fuel consumption and reliability .I basically stripped the engine down completely and ended up replacing one liner and the valve guides in one head .I skimmed the heads , ported them and balanced the chambers and modified the pistons .
Forward to the crankshaft which is the early small counterbalance one . I could not find another crank and as they are a week point decided I would need to do something even though the crank and bearings were in perfect condition. I looked at a crank that had snapped and all the fractures were at the front of the crank which suggested ,to me, it broke because of resonance and not power so I set about finding a crankshaft damper that would work . After speaking to Vibration Free about their " Sterling Damper " I was informed that it would not work on the uneven firing order and that I should go for a fluid damper as they do not need to be tuned to the engine.
I found one that I thought I could use on Ebay and gave had it modified to fit on the nose of the crank And I have had a pulley made for the aircon that I am going to shrink onto the damper
.
I am waiting for a new oil seal as I have had to modify the housing to clear the damper . I will let you know how I get on .
The engine had a head missing but another was supplied so I had most of the major bits. I was going to rebuild the engine trying to improve power , fuel consumption and reliability .I basically stripped the engine down completely and ended up replacing one liner and the valve guides in one head .I skimmed the heads , ported them and balanced the chambers and modified the pistons .
Forward to the crankshaft which is the early small counterbalance one . I could not find another crank and as they are a week point decided I would need to do something even though the crank and bearings were in perfect condition. I looked at a crank that had snapped and all the fractures were at the front of the crank which suggested ,to me, it broke because of resonance and not power so I set about finding a crankshaft damper that would work . After speaking to Vibration Free about their " Sterling Damper " I was informed that it would not work on the uneven firing order and that I should go for a fluid damper as they do not need to be tuned to the engine.
I found one that I thought I could use on Ebay and gave had it modified to fit on the nose of the crank And I have had a pulley made for the aircon that I am going to shrink onto the damper
.
I am waiting for a new oil seal as I have had to modify the housing to clear the damper . I will let you know how I get on .
Sounds like you have everything in hand, I would have been worried that there would be parts missing that would be nearly impossible to replace
When I first bought my car, another owner was kind enough to show me how to remove the gearbox by spinning it around as per the WSM (which I've never been able to do, I always remove the manifolds first)
While I was there he showed me the crank he had removed
I'm sure you already know, but the early AJP8 had a different front crank seal carrier, the later version allows the seal to be changed easily, is that a modification you will be including?
When I first bought my car, another owner was kind enough to show me how to remove the gearbox by spinning it around as per the WSM (which I've never been able to do, I always remove the manifolds first)
While I was there he showed me the crank he had removed
I'm sure you already know, but the early AJP8 had a different front crank seal carrier, the later version allows the seal to be changed easily, is that a modification you will be including?
Interesting route. I couldn't find anyone to rebuild my engine with the small bearing crank and offer a warranty so had to have it converted to the later large bearing. £1750 for the crank, £600 machining n the engine (in total for everything) meant that was an expensive route to go...
I spotted this guy in germany has a lot of 4.2 parts going very cheap, pistons, liners
https://www.ebay.co.uk/sch/donner-schrauber/m.html...
I spotted this guy in germany has a lot of 4.2 parts going very cheap, pistons, liners
https://www.ebay.co.uk/sch/donner-schrauber/m.html...
Byker28i said:
I spotted this guy in germany has a lot of 4.2 parts going very cheap, pistons, liners
https://www.ebay.co.uk/sch/donner-schrauber/m.html...
Selling valve springs, with no mileage indication - weirdhttps://www.ebay.co.uk/sch/donner-schrauber/m.html...
I have a full set of used springs with perhaps 60k on them
Free to anyone who wants them, excluding postage, and a donation to any NHS worker charity
Luckily I have a few spare parts knocking about . I did not know there was an earlier oil seal housing as there was not one with this car so I am getting one copied from a spare 4.5 I am building . I also had the valve guides manufactured from colsibro as the main suppliers did not specify what their`s were made from.
In the end I removed the prop and engine mounts to get the pulley on so a bit of a stuggle.
I did see those oversize pistons but the ones i had looked good and the car has only done 25k miles .What was the reason for your rebuild ?
In the end I removed the prop and engine mounts to get the pulley on so a bit of a stuggle.
I did see those oversize pistons but the ones i had looked good and the car has only done 25k miles .What was the reason for your rebuild ?
On my car I was starting to lose compression on cylinders 1&2 which turned out to be worn valve guides. I think Jason at Str8Six said the early engines had chrome valves and brass guides, but when he turned the head over to show me valves and guides fell out...
I ended up having the whole engine refreshed, rebuilt. New Cams, Crank, Valves, valve guides, everything done...
What have you in your heads?
I ended up having the whole engine refreshed, rebuilt. New Cams, Crank, Valves, valve guides, everything done...
What have you in your heads?
Might be hard to prove seeing that it has already lasted 25 years . I just wanted to address the potential problems while I had it apart . This included mainly the crank and taking some load off the auxilary shaft by converting to electric steering pump .
On a previous Ajp I built some monkeys overskimmed the heads and it suffered badly from detonation . on this engine to help prevent this I ground a radius off the raised part of the piston as this was likely to be the hottest part . I think it will also speed up combustion and reduce the surface area of the combustion chamber so should incease power slightly on both counts and also a slight reduction in piston weight . I am building a 4.5 also and am planning on milling a fair bit more off.
On a previous Ajp I built some monkeys overskimmed the heads and it suffered badly from detonation . on this engine to help prevent this I ground a radius off the raised part of the piston as this was likely to be the hottest part . I think it will also speed up combustion and reduce the surface area of the combustion chamber so should incease power slightly on both counts and also a slight reduction in piston weight . I am building a 4.5 also and am planning on milling a fair bit more off.
Edited by plasticman on Sunday 26th April 22:49
Flatplane8 said:
Hi,
My 1997 4.2 has 178k miles, no rebuild yet. Had it 20 years next month. ??
Simon
Wow, just Wow!My 1997 4.2 has 178k miles, no rebuild yet. Had it 20 years next month. ??
Simon
As far as a rebuild is concerned, I don't think there are any issues with rebuild parts
The problems are with repairs and replacements of damaged rather than worn parts
For instance, good luck finding a new oil pump housing
Hi, thats good to hear. I need to take the body off my car to refurbish the chassis, which will mean taking the engine out. I'm going to check the engine over (leakdown test etc.) but there are a few oil leaks to fix, mainly the alternator drive shaft. As mine is a 1997 Cerbera I'm guessing its got the small journal crankshaft, which means I'd rather not go the 4.5 or 4.2 route. 4.2 pistons and liners seem to be unavailable, but maybe some other pistons could work. I'll cross that bridge when I get to it.
Depending on how it all looks, I may rebuild the engine myself. I have done some engine work, most recently big end bearings, rings etc. in a 6 litre marine diesel https://youtu.be/k3YQ6sE32F0?si=tTxH2Ri2zIkh7dR3
I was interested in this thread as it looked like a creative approach to a rebuild.
Depending on how it all looks, I may rebuild the engine myself. I have done some engine work, most recently big end bearings, rings etc. in a 6 litre marine diesel https://youtu.be/k3YQ6sE32F0?si=tTxH2Ri2zIkh7dR3
I was interested in this thread as it looked like a creative approach to a rebuild.
Caveat - all this was true at the point I had my engine rebuilt...
Liners and pistons are available for the 4.2 but I think only from Dom at Powers, because he got hold of the designs, had some made etc Depends on the mileage as to how the pistons and bores look.
Heads/blocks are available from either the usual scrappies, or engine rebuilders have some used bits stored, but expect these to need a full rebuild.
My 4.2 had the small bearing crank which had done 50K+ miles without any issues, but noone would warrenty the engine without the change to the large bearing crank. That was expensive!
On the early 4.2, look for wear in the valve guides, compression test etc. Thats what prompted my rebuild was the valve guides were worn (two valves easily fell out when the head was turned upside down...
Liners and pistons are available for the 4.2 but I think only from Dom at Powers, because he got hold of the designs, had some made etc Depends on the mileage as to how the pistons and bores look.
Heads/blocks are available from either the usual scrappies, or engine rebuilders have some used bits stored, but expect these to need a full rebuild.
My 4.2 had the small bearing crank which had done 50K+ miles without any issues, but noone would warrenty the engine without the change to the large bearing crank. That was expensive!
On the early 4.2, look for wear in the valve guides, compression test etc. Thats what prompted my rebuild was the valve guides were worn (two valves easily fell out when the head was turned upside down...
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