Puma 1.7 big end bolts - removal tool


Help Support ProjectPuma:

This site may earn a commission from merchant affiliate links, including eBay, Amazon, and others.


New member
Jan 16, 2019
My engine oil pressure gets really low when the engine is hot - and it's getting worse! To resolve the issue I've got a set of new big end shells but now I have a problem.

Can anyone let me know the tool required to undo the original Ford fitted big end bolts? - They don't look like Torx as they appear to be 12 sided rather than 6!

Any ideas?

Shouldn't a normal socket fit? I have sockets with 6 & 12 points so I'd assume (correctly or not) that the 12 point ones would fit perfectly UNLESS what you're saying is they are Female Torx bolts? NOT Male which I'm thinking of which may be other Ford engines I'm getting mixed up with.

In which case, you can buy 12 point torx bits pretty easily too. Just give them a search on the web (Google etc or even Ebay/Amazon) & I'm sure you'll find what you need as I had a quick search & found an abundance of them. :eek:k:
Did the same job on my Celica. Same sort of bolts for Conrod caps but I used a standard 12 point socket to remove. Think it was a 10mm but Puma probably different.

Most 'standard' (non impact) sockets tend to be 12 point, at least from what I've seen, so they shouldn't be hard to get.

Hopefully the big ends shouldn't be too scuffed but if they are it's possible to polish them up with some fine wet & dry and a shoelace - check this video for the technique: https://youtu.be/IlRmz1W-zL8

I used Plastigauge to check clearance between shell and bearing surface once the new bearings were fitted - luckily within spec but you should use the correct shell depending on clearance.


  • IMG_20210407_145248176~2.jpg
    1.2 MB · Views: 91
Well, that was interesting. Thanks for your input yippeekiay and grogee - you're right it was a 12 point 8mm hex, I just didn't have one. So, bought one and then an 8mm spline socket which was a tighter fit. So, I removed the bearing with the engine in the car and they looks a bit poor!

So, with various advice, I bought new bearings from Burton - no tabs, apparently they only fit the FRP. I bought a set from a someoneSpeed - which were Mitsubishi items - tabs on wrong side so they don't fit. Finally I bought a set as described by Coyote in a separate thread, from Suzuki - yeah, they fit, they're in and work fine (so far). Oil pressure when hot is about 1.5 bar, rather than the FA on the worn out ones.

So, other than being best part of £200 quid lighter, the engine is now tip-top!

Thanks everyone for the input.

Now I have a R53 supercharger to fit - off with the Jenvey's and on with the blower!


  • IMG_2677.JPG
    1.1 MB · Views: 71
Good work. Out of interest, how did you measure the oil pressure?
Ah - I'd replaced the oil pressure switch on the engine block with a "T" piece so I could connect an oil pressure light switch and a sender for an electric oil pressure gauge.

Apparently :-
Oil Pressure
Oil pressure (minimum, oil temperature 80 degrees C) at 850 rev/min bar 1,0
Oil pressure (maximum, oil temperature 80 degrees C) at 6000 rev/min bar 4,0
Pressure relief valve opening pressure bar 4,3

and big end bearing torque setting are:-
Big-end bearing cap to connecting rod, Stage 1 15 lb-ft
Big-end bearing cap to connecting rod, Stage 2 45 °
Nice work! Happy to see you're going on with a supercharger. I have a billet mounting bracket for a r53 eaton m45 if you're interested. I bought it from a guy in the Locost forum. I'm going for a Rotrex so I won't need it. If you're interested you can pm me. Good luck with the build!

Hi Siju - Thanks for the offer but I've already done the fabricating part!

Ducting next ....


  • IMG_2673.JPG
    936.1 KB · Views: 44
Nice job on the bracket! It's also good that you've accounted for the oil filter and starter motor. Looking forward for this to finish!