piston to valve clearance ~.100" delta between Int and Exh

[willyp42]

Hey everyone,
i ended up getting these results for a piston to valve measurements. and in not quite sure how i feel.
INT EXH
10 BTDC 215 250
7 BTDC 190 240
4 BTDC 170 240
TDC 153 250
3 ATDC 140 250
6 ATDC 134 250
10 ATDC 140 250

i am running 8.3 : 1 wiescos and kelford 276 HL cams.

would anyone feel concerned about the large delta in int vs exh?
the exh has .5mm less lift but timing means just as much as lift.
i dont have much experience at this so i am just wondering if anyone else has had similar outcomes or if this is normal.

thanks,
-Will

 

[DSMPT]

Did you use checking springs to measure the clearance? To me the intake numbers don't look right since your pistons have low compression dish-top (As I understood that [215] means [0.215"]). The exhaust numbers look more close but still the number's movements don't look right. I guess the indicator tip was sliding on retainer while you are pressing down the checking spring or maybe didn't check properly.

 

[willyp42]

Yeah I used checking springs had zero lash and zero’d the indicator. My intake is only .040 lift at 11btdc so I think that’s why it’s moving in an abnormal pattern for you

 

[willyp42]

i had to advance the intake 1/2 or cam degree after this,
this was my original p to v
20 BTDC .375
17 .323
14 .288
11 .268
8 .229
5 .206
2 .182
1 ATDC .176
4 .162
7 .155
10 .150
13 .148
16 .148
19 .152

after advancing i may not of been too thorough on the first pt or 2 but i definitely zero'd and repeated the measurement 3 times

-Will

 

[DSMPT]

My intake is only .040 lift at 11btdc

That's how it should be for this cam.

i am just wondering if anyone else has had similar outcomes or if this is normal.

I had the Kelford 276HL and a couple of engine spec sheets that I noted PTV clearance, I was looking for that but I couldn't find it. I stored it somewhere when I moved to a new place.
Anyways I sometimes degreed those cams and measured the PTV clearance. I couldn't find the engine spec sheet, so I can't tell exactly and all engines have different specs and the number would depend on by many factors, so wouldn't be the same as yours, IIRC the exhaust numbers were more or less similar to yours, but the intake numbers were much more. So I would double check the timing belt, maybe it's off.
And what I wanted to say in my first comment was the numbers in the green circles. The dial gauge shouldn't be moving like that if it is capable to read .001". It's reading the same numbers at least during 10 degrees after TDC. I guess this is probably the dial gauge or/and the tip was not set properly or was not functioning properly for some reason.

would anyone feel concerned about the large delta in int vs exh?

As long as if the mechanical valve timing (timing belt) is set properly and you confirm that you have a sufficient minimum PTV clearance, you wouldn't need to be concerned about that.

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[willyp42]

i get what you saying because the valve is nearly closed and the piston is moving away after the first few points my scrutiny went way down so they are probably wrong.