LHR Connection - QR to UA

Hello,

I have the following connection at LHR in a few days and want see if any one has done it, and can provide any info on the connection process. Will I even make my connection?

QR 5, dep DOH 07:25a arr LHR: 12:05p
UA 931, dep LHR 1:35p arr SFO 4:30p

Thanks