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Inlet manifold bolts torque value

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Howard3180
Posts: 2
Joined: Tue Sep 04, 2018 1:49 pm
Location: Laleham Englandpurchasing

Inlet manifold bolts torque value

Post by Howard3180 » Wed Jul 03, 2019 4:33 pm

Hello, I’m currently trying to solve a misfire in my SP250 and have done the following - rebuilt carbs, distributor cap , rotor arm, plugs and found a leak in the inlet manifold. Sparks are good - I’ve used one of those transparent plug extensions to see the sparks. Carbs are set up broadly right, according to SU HD6 instructions? Yes, the engine is coked up from too much REALLY rich running on the old carbs. I’ve replaced the inlet manifold gaskets, as the right cylinder bank had a leak and have managed to make the misfire worse, so it is off with the manifold again. Darn it!
Two questions at this point please, first what is the torque setting for the 16 inlet manifold bolts as I can’t see that in my manual and second might a decoking service like TerraClean help? As a side note, Barry Thorne suggested checking that there isn’t any crud in the inlet manifold holes that might stop the bolts from reaching the bottom and creating a seal properly. I thought that I’d done that check with my screwdriver and a bit of kitchen towel, but no doubt worth trying again, especially as some good of my bolt are slightly different lengths
As I’m a Surrey resident, I’ve got the car booked in to Russ Carpenter in Nov/Dec, so really want to achieve a decent interim improvement without doing a significant amount of overhaul myself.
Suggestions welcome.
Thanks, Howard

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Vortex O'Plinth
Posts: 841
Joined: Fri Feb 12, 2016 8:15 pm
Location: Gloucestershire

Re: Inlet manifold bolts torque value

Post by Vortex O'Plinth » Wed Jul 03, 2019 7:19 pm

Daimler gave no torque setting for the inlet manifold bolts (actually set screws) but I believe they are 5/16 - 18 UNC going into the aluminium heads. I'd suggest a safe torque for these would be 7-10 ft.lbs. but in reality this is one of those applications usually done by 'feel'.

I've no experience of TerraClean but in the 'old days' pouring generous amounts of Redex into the carbs while running would produce satisfyingly dense clouds of white smoke from the exhaust and - allegedly - get rid of some carbon deposits. Whether it worked or not you'd only really discover after removing the heads.
Nick

"Open the pod bay door Hal".

fireboss
Posts: 39
Joined: Wed Feb 24, 2016 10:20 pm
Location: Whitby, Ontario

Re: Inlet manifold bolts torque value

Post by fireboss » Wed Jul 03, 2019 8:37 pm

This from BT, hope it helps:

All the listed torque settings for the SP 250 are as follows:-
Cylinder head where studs fitted with nuts - 40/45 lbs. ft.
or where Bolts are fitted – 50/55 lbs. ft.
Connecting rod nuts – 28/30 lbs. ft.
Main bearing nuts – 25/30 lbs. ft.
Oil Sump screws – 10/13 lbs. ft.
Flywheel bolts – 43/48 lbs. ft.
Clutch to flywheel bolts – 14/16 lbs. ft.
Pinion bearing nut – 95/105 lbs. ft.
Differential bearing nuts on caps – 35/40 lbs. ft.
Crown wheel bolts – 50/60 lbs. ft.
Road wheel nuts – 60/65 lbs. ft.

Ian Hastings
Posts: 104
Joined: Tue Mar 15, 2016 3:00 pm

Re: Inlet manifold bolts torque value

Post by Ian Hastings » Wed Jul 03, 2019 9:51 pm

Nick's suggestion works well but I would also add that copious amounts of Redex in the fuel tank and take the car for a serious "Italian Tune" will clear a lot of crud out and improve the gas flow!

Howard3180
Posts: 2
Joined: Tue Sep 04, 2018 1:49 pm
Location: Laleham Englandpurchasing

Re: Inlet manifold bolts torque value

Post by Howard3180 » Thu Jul 04, 2019 12:37 pm

fireboss wrote:
Wed Jul 03, 2019 8:37 pm
This from BT, hope it helps:

All the listed torque settings for the SP 250 are as follows:-
Cylinder head where studs fitted with nuts - 40/45 lbs. ft.
or where Bolts are fitted – 50/55 lbs. ft.
Connecting rod nuts – 28/30 lbs. ft.
Main bearing nuts – 25/30 lbs. ft.
Oil Sump screws – 10/13 lbs. ft.
Flywheel bolts – 43/48 lbs. ft.
Clutch to flywheel bolts – 14/16 lbs. ft.
Pinion bearing nut – 95/105 lbs. ft.
Differential bearing nuts on caps – 35/40 lbs. ft.
Crown wheel bolts – 50/60 lbs. ft.
Road wheel nuts – 60/65 lbs. ft.
Thanks for this. I'm working on it now...

csm1406
Posts: 45
Joined: Sat Feb 13, 2016 6:06 pm
Location: west sussex

Re: Inlet manifold bolts torque value

Post by csm1406 » Thu Jul 04, 2019 3:29 pm

Hi
Re Misfire - if one of the valves is not seating well - because of carbon build up or wear this may give the impression of a misfire - at tick over on my vehicle I get a chuffing noise on one side which I am fairly sure is a valve not seating properly.

Good luck.
Cameron

silverdart
Posts: 166
Joined: Sat Feb 13, 2016 10:49 am
Location: West Midlands

Re: Inlet manifold bolts torque value

Post by silverdart » Thu Jul 04, 2019 5:25 pm

If you have not changed your condenser, I would do this. For about £14 it recently transformed the running of my engine.

Dave.

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