ok starting to run out of idea's
run down on the setup when i got it from sidedraft
A15 bored out to 1600, best of everything, Stewart Wilkins build, JTS head, twin forties, big bore extractors

now i have had it close to 2 years and just got it running a few months back
due to the time delay i got the webbers rebuilt
new fuel lines
new fuel pump
new elec dizzy from mal
new coil
new plugs
new leads
new sock air filters
drained the tank of old fuel replaced fuel with fresh 98 octain fuel
car has now been dyno tuned but the tuner couldnt give me the max horse power coz the dyno was old and doesn't give hp ? sound like BS ?
but it does rev better and have more power but the motor only revs to 5800 if im flat to the floor but if i eaze the gas peddal i can get it to rev higher .

the motor is ment to rev to 8500rpm

way can it bee ?
ill load a youtube video soon of the noise it makes when it hits the wall at 5800rpm

sounds like my old su's problem. they starved of fuel at full throttle, but ease the power on and all good.

What fuel pump you using? elec or mechanical.

also do you have a fuel pressure regulator on there?

elecy fuel pump was fine with a worked a14 but looked a lil old so i got the same elecy fuel pump again and the guy at the auto shop said its a good pump for wat i have , think he said 6psi

i have a fuel reg but dont have a pressure gauge so cant hook it up just yet but cant see how dropping the fuel pressure to say 4psi would help ? but ill get onto it asap :)

Does it do the same thing no matter which gear it is in? If it's fuel starvation, it'll be worse in the higher gears (because it spends more time at full throttle/full fuel consumption as it winds out to 5800rpm) . If it happens in every gear exactly the same, I'd be looking at valvesprings or secondarily cam timing/cam spec.

does seem to vary sometime's 5500 somtimes 6300 but normaly around the 5800 mark . ill take it for a test drive this arvo and see if i get more revs in higher gears

some one told me this morning i should try blocking the airfilters a bit to get more back pressure ? ill try anything

I'd say the same, sounds like it needs more fuel.

Why don't you put the old pump back on & see if it makes a difference. Webers are sensitive to fuel pressure & will blow the needle & seats open at 5 psi, which will cause the engine to run rich, not rev etc.
How many Klm's do you have on the motor? Is this a sudden thing or has it been there all along? Are the valve springs new? Are the spark plugs? What coil are you using with the Distributor? All of these things could be responsible. What cam are you running? Is it big enough to rev to 8500.I had a fully built race A15 that wouldn't go over 7000, though it should have gone to 7500. I now know the valve springs were pasted it in that motor.

My a14 did the same with twin su's 5500 max, I put in richer needles and now revs 7500. Would the a/f ratio lean out at max rpm if it is a lack of fuel problem.

The engine would go lean & stop accelerating (gaining revs) as that was all it could do with that amount of fuel. More fuel means it can keep accelerating (revs higher).

So if it leans out, the tuner should have picked it up on the dyno.