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1500 Spitfire engine tap/rattle


Conor L
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Just had a little play around with no joy I'm afraid. @Pete Lewis just tried to push the gearstick into all 4 gears without the clutch which made no difference unfortunately. @Iain T I've previously ran with no belt (runs so smooth amazing what a difference it can make) again no different also listened with the stethoscope all seemed normal. To check my theory of mixture I backed off the fast idle screws so the revs wouldn't increase when the choke was pulled. Drove it around my close (clocked up a mile now aha) and only made a difference on full choke which is when it ran rough (expected) I did also hold the revs right up (3k) and you could hear a slight noise then too then it was tick tick tick tick as the revs come back down. Thought that was enough for the neighbours and put it away

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On 10/03/2021 at 19:32, johny said:

is it possible that some mechanical fuel pump operating arms arent touching the cam lobe the whole time? If so when running you'd get a click each time they make contact... 

I guess the problem there is how do you prove it?. Swap out the pump?.

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And the new pump could be the same design.

I think you can probably tell if, as youre putting the pump into place on the engine, you can feel the lever giving resistance as it comes into contact with the cam. Of course this is only valid if the cam lobe peak is away from the lever but if thats the case it would then prove the lever is constantly in contact....

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Haven't had the chance to take a look as I've been working and the weather has been awful. Will have another listen around with my stethoscope later on. I know the fuel pump lever arm is in the right place but I'll still listen anyway. Something that has been previously mentioned is piston slap which has gotten into my mind however I would've thought I'd have seen that on the bores when the head come off 🤔

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Well I've had a listen today with my stethoscope and cannot put my finger on this noise! To be honest I've got to the point now where I'm just going to leave it and focus on sorting other things out before it goes back to have the rest of the panels painted. It's running nicely after a fiddle with the carbs and pulls really well so hopefully the engine is strong and whatever is rattling around will eventually fall off and the noise will go haha. Many thanks for all the advice it has been invaluable! I know this isn't the right page but I'm in need of some richer fuel needles as I can't get these ABT 1s rich enough when trying to set the mixture. Specs are stainless tubular manifold, foam filters, mk3 profile cam, head skim (if that'll make any difference) what would you guys recommend based on experience? Also will the dashpot springs need changing too?

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Re needles. Do you mean they need t be richer at idle? If so changing needles is unlikely to help, they are all pretty similar at the idle end/top. AAR or AAU can be useful, or better still a rolling road will reprofile needles to suit the engine perfectly (looks brutal, but when I had one done the chap took a file to teh needles, and in 2 goes got a perfect mixture over the entire rev range, transformed the car, more power/torque, plus more economical.)

As to the mods, the cam will need  slightly richer needles, but we need to know which foam filters. Some are free flowing, others are worse than the paper type. If they are "good" (pipercross etc) then a pair of inlet trumpets and stronger carb springs may well be beneficial. MGBs were fitted with nice little trumpet/bellmouths and are rather good.  And cheap....

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