Tightening up the valve lash to .014 Int, .015 exhaust made a marked difference in smoothness, but not neccessarily butt dyno improvement.

Always run the intakes loose unless you have too much compression & are detonating. Tightening the intake lash only dumps compression & should only be used for a diagnostic tool.

Exhaust lash, run it as loose as is mechanically reliable. Only tighten it as a diagnostic tool.

Hello, There are compressions that the engine sees.
1. measuredchamber cc + swept volumn in cc divided by the camber cc= Static comp

Static compression is what you physically measure, but it is completely meaningless without knowing the camshaft events.

2. Effective comp when the int valve closes. High V.E. about 7-1 ratio and 9-1 with about 60% V.E. or alky fuel with aluminum head.

This is static compression + camshaft events. Because the inlet valve closes as it is rising up the bore, the compression you see on a compression gauge at cranking speed is determined by the cam & static compression.

Also, you can run more compression with an aluminium head (You actually have to run more compression to make up for the fact that the aluminum head wastes more heat)

If you are using alcohol, you can run much higher compression. (Which is all good)

3. Dynamic comp is when the engine is running at max TQ and that is when the V.E. is increased.

VE, Volumetric Efficiency is is the ratio of cylinder capacity to how much air you actually trap & it varies with engine speed. Peak torque happens when VE is close to it's highest highest.

Most companies advertise seat duration at the cam and lifter interface. Only a few will give duration at the VALVE due to rocker ratios and valve lash differences.....

Seat to seat timing is the only timing point that is not affected by rocker geometry. When your cam is advertised as 274° 'Seat to Seat' on a pushrod 4-cylinder Ford which has practically the same ratio as a B20 Volvo, then it should have 274° in a Volvo too.

When he says that your cam does not have 274°, but infact has 290°, then the lobes he has given you are pretty much the same as an Isky VV-71 for all intents & purposes.

A lot of my engine builder customers will check the intake centerline when installed or check at .050" tappet lift fo the cam duraton @.050" and the int lobe centerline.....

I check it @.050", .100", .150" & .200" to check the quality of the cam.

When the cam design has easy clearance ramps that allows you to adjust the int closing point...

Cam profiles which have long clearance ramps are typical, but far from ideal.

I'm not impressed with the fact that he gave you a single pattern cam. About the only time a single pattern cam is OK is when you have a large exhaust valve.



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Three 164's, Two 144's, One 142 & a partridge in a pear tree.