Hi lift cam and compression

[makeitfit]

350 miles in on Black Pearl's project power engine and an interesting thing has happened !
I did a compression check 200 miles back and all were fine and dandy, 400psi nothing more than 3% between them.
Handbrake cable has just gone and we noticed that the engine will not hold on a hill when left in gear
I'm wondering if the valve overlap is such that it can allow a bit of roll chuff, roll chuff ? :nenau

 

[macabethiel]

350 miles in on Black Pearl's project power engine and an interesting thing has happened !
I did a compression check 200 miles back and all were fine and dandy, 400psi nothing more than 3% between them.
Handbrake cable has just gone and we noticed that the engine will not hold on a hill when left in gear
I'm wondering if the valve overlap is such that it can allow a bit of roll chuff, roll chuff ? :nenau

Certainly sounds like the valve overlap is responsible. I guess Formula 1 cars have the same problem !

 

[solarman216]

No I do not think that the cam can be the reason, compression is compression and should hold in a low gear, if not then compression may not be as good as it could be, Rick

 

[makeitfit]

I guess it's IC off again :doh

 

[solarman216]

Yep test those compression's again, if they are OK them just maybe your big wheels are just too much for this aspect of a test, ie too much leverage, Rick