Tappet gap

[Robbie224]

Hi. Like to ask more experienced owner what are the tappet gaps on a A series engine on a 1971 1275gt? Are both inlet and exhaust same gaps?
Thanks

[surfblue63]

Servicing data dated March 1972 gives the cold valve clearance as 0.012". Inlet and exhaust are the same.

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[Robbie224]

Handy reference. Thank you

[Minimat20]

Anybody know what an A+ metro engine would need? 12G940 stock head but lumpy cam. Always had a devil of a time dialing it in.

Cheers

[Exminiman]

As far as I am aware standard gaps are 12 thou, inlet and exhaust, for all pretty much all a series .......dare say that I will now be corrected

There is an argument for making the exhaust gap bigger at 15 thou, because of the extra heat.

[Minimat20]

Many thanks!

I do have them set at 15thou as we speak. Just wondering if anyone knew "for sure".

Cheers

[MiNiKiN]

Depends on the cam you are using. Minispares suggests the following for their Evolution001-Cam:
"Valve clearance should be 0.014" (0.35mm) on inlet and 0.016" (0.4mm) exhaust"

[Minimat20]

Thanks for the replies!
I had the cam ground almost 20 years ago now and can't seem to remember the specs on it. I know it was a "racier" type as I wanted to put it in when the engine was being rebuilt, as other bolt on stuff could come later.
Any way I can tell what the specs are with it insitu?

Cheers

Matt.

[Polarsilver]

ok not applicable to this post ..other than the mention of the Minispares Evo1 Cam tappet clearance as advised by MS .. after setting up my MS evolution1 cam to get the advised 0.014 & 0.016 thou tappet clearances & faffing with various feeler gauge set ups to get the advised tappet clearances .. lets face it an odd plus or minus Thousands of an Inch tappet clearance aint going to break a road engine & will i notice the difference in performance or tappet rattle .. so i set my evo1 cam with both tappet clearance set at 0,015 thou and all is ok .. well Colin at Southam did not tell me off when he set up this engine .. anyway if you lot tell me off for straying away from suppliers instructions ..i can reset Tappets to MS Evo1 cam spec; when i get around to pull down the head

[Peter Laidler]

PolarSilver is dead right....... your engine is just a simple heat machine and a few .000" here or there within the valve train is going to make no mechanical difference. To be really accurate, feeler gauges ain't the way to go either! For truly accurate tappet clearance - if you REALLY need it - is a dial test indicator set up to measure it

[OzOAP]

Tappet clearance affects cam timing and lift.
The manufacturer does not just pluck a figure from thin air so they don't rattle.

[Polarsilver]

OZ .. i agree & will set them Tappets up with my DTI when i pull the head down

[OzOAP]

DTI has to be exactly above rocker/valve contact patch.
If too far forward or back it will give inaccurate reading.

[970s]

Hi, anyone had the experience of the 1982 -1984 MG metro cam tappet setting?
Lots of argument and different figures quoted in the Haynes manual, some recommend 17 thou for exh and 14 for inlet , some required 14 thou both exh and inlet, some 12 thou, quite confusing, I had try both 12/12 thou and 17/14 thou setting, makes not much difference, mine 83 1275 std metro engine use the stage 1 kit from minispares, expect to boost a little extra power for my heavy estate.
Any advise is appreciated!
Thanks.

AL

[Spider]

Tappet clearance affects cam timing and lift.
The manufacturer does not just pluck a figure from thin air so they don't rattle.

Quite;-



As simple as they may appear, they are a complex bit of geometry. Too tight and there's a risk of burning valves, too slack and they'll hammer the valve train to death.

As already mentioned, with the exception of the MG Metro Cam, all Factory Tappet Clearances were 0.012" Inlet and Exhaust. The MG Metro was 0.012 to 0.014" on the Inlets and 0.015 to 0.017" on the Exhausts.

If you have a non-factory Cam, you really need the Grinder's Data and advice on the clearances, though, without that, it can be worked out form checking / measuring the Clearance Ramps, though you'll need some experience in interpreting the measured results to get right.

[970s]

Thanks Spider, seems I have to re check my tappet gap and set it to 13/16 inlet/exh thou.

Al