Allardyce's charges are without a win in four Premier League games ahead of Saturday's clash with Jose Mourinho's side at Upton Park.
West Ham's lack of firepower was evident once again when they dominated much of the first half of their defeat against Norwich City before the international break, but only had a Ravel Morrison goal to show for it and Chris Hughton's side came from behind to win 3-1.
Andy Carroll has been sorely missed by the London outfit and Allardyce has picked a side without a recognised striker in recent weeks, but the former Newcastle boss insists tactics are not the reason for the disappointing form has left his side level on points with third-bottom Fulham.
Having beaten Chelsea 3-1 in the corresponding fixture last season and with Mourinho's men having failed to win their last two top flight games, Allardyce is eyeing a repeat performance.
He said: "In terms of our goals it's not that we're not creating chances but we're not converting them. Our chance conversion is among the worst and that has to improve.
"We played against Spurs and scored three goals, we could have scored more goals against a lot of teams.
"In the striker area, they are not delivering goals in the game. We have outplayed a lot of teams since we have played without a striker.
"The tactical side of it has worked, but we haven't taken our chances.
"To take the pressure off us all we need results. We haven't achieved that so far, and we need to turn the performances into results.
"With those two results for Chelsea there's a chance to see where their weaknesses lie."
