Race Engine Forum UK

Hello Guy,
I've left a post on another thread about compression testing and then read quite a few other post and then re tested my compression and I seem to have some strange results.

To refresh my engine specs

2.0 Fiat TC
CR about 9.2:1
Std Cams (132)
3 angle valve/seat work
Port & Polish
At this stage 34 DMS Weber (until I sort out my twin IDFs)

Now the engine is very fresh, probably only an hour old.

The Compression results were as follows

For a start all 4 cylinders were within 5% of each other on all tests.

Cranking test was all plugs out and throttle fully open with a reading of 145 psi

Idle test was 60 psi and when I blipped the throttle it shot up to 130 psi

Does this seem about right to you or does it seem a little low? The engine seems to have great torque and is very responsive.

Even with the engine fresh I thought it would be a bit higher or am I expecting too much? Do I waffle too much

Thanks Guy

Kindest Regards
Gill

145psi - with engine hot?

GC

Hi Guy,
Yes engine is hot.
I'm kind of hoping my compression guage is not calibrated terribly well.

Gill

Gill, hi

OK -they seem on the low side but it could easily be the gauge. Frankly I just would not worry overmuch. The acid test is a) it drives well and b) doesn't smoke or burn oil, other than a modest useage during break-in (bedding-in/run-in), say 1/2 pint in 500 miles.

I'd just carry on driving it and see how she goes. I will stress that I use Flex-Hone brushes for finish honing and they give faster break-in than any other method. An engine honed by any other method will take longer. I'd give the engine several hundred miles and test again. If you can get Sealey products there they do a nice screw-in compression gauge, not costly and accurate too.

GC

Hi Guy,

Ok, I feel a little better now.
The motor does run well, cylinders are all even, it does blow any smoke and it doesn't have any of the other telltail signs of leaky valves or rings.

I'll test again when its has had a real good run and in the mean time I'll test the gauge and probably get a better one. I admitt mine was a cheap gauge.

Thanks Guy

Gill