RBtwin

Belt tension is not the problem. I will put a strobe on the balancer tonight and I believe I will find it oscillates a few degrees for and aft. Will let you know. I will also try and film the belt and post it up.

You've made a smart move there. You should slap yourself for the first choice

Okay the Dayco one went on. The harmonic has moved but its still there. Its not as bad- there is no noise, but it really sh1ts me. There is one at about 1500rpm and one at about 2600rpm. The belt goes through the harmonic because down the long side it gets a wave to it that has an amplitude of about 5mm each way at a guess. Can anyone verify a harmonic? You need someone to look at the belt while you rev the motor up slowly. Mine only lasts for 50rpm or less. You can see it between the cam gears but easier to see down the drive side of the belt. I am using a VL balancer- nothing flash and I have tried two different ones. The tensioner and idler have bearings in VGC. If this isn''t the problem the next port of call is to test rig the cam/spring combo. I don't want to do that! lol

Thanks for checking guys I have a dayco on its way to me now. On their web site they list two types of belts- a polychlorosomething and a HSN. Any idea which one you have or even what the difference is?

You would know if it does. It makes a fairly cranky noise like a bearing is cactus or its valve bouncing. It only lasts for 50rpm or so.

Has anyone had harmonic problems in the timing belt? I have an issue at about 2000rpm where the timing belt vibrates fairly badly. It goes away after that and has some smaller harmonic periods further up. Just wondering if anyone has had the same problem? RB30/25 Tensioner up top in the block Gates timing belt P.s. I don't know how to search this thread to find specifically where info is and I can't read 155 pages- I may die

I have some RB25 head studs for my RB30 and they are too long in the shank. Just wondering if the Rb25s have a recess below the block deck of a few mm before the thread starts. By my calcs they are about 5mm too long in the shank. Thanks

I guess I'll have to take some relief valve pressure out of it because I don't have oil squirters so that would cause higher pressure.

You guys made my day!!! I was just about to pull the sump off and I really wasn't looking forward to it! The gauge is TEMPORARY for tuning- autometer pro comp liquid filled mechanical gauge (not that it makes much difference) and i bled it properly. I might try and get some thinner oil to start with now to drop it a bit. Thanks.

Hi just wondering what oil prssure you have. New motor RB30/25, RB25 oil pump, RB25 oil feed restrictors in the block. 110psi cold with 20W-50 garbage oil for run-in. Haven't got much oil temp in it yet to see if it goes down. Does anyone else get high pressure cold? Has anyone experienced by-pass valves sticking in the pump? The pump was pulled apart and looks to be in VGC before install. Please help. Thanks.