The V8 Owners Forum -

Hi everybody, i am a new member and new to v8's ! i have a kit car with a rover 3.5 v8, the car came partly stripped with 2 engines from which i made one good one, the engine is running on hif6 su carbs, after rebuilding the engine and trying to start it, it started fairly easily and seems to idle pretty good, but it just wont rev up at all, i dont know if its a fuelling problem or ignition, but it does not make sense to me that if i adjust the ignition timing whilst its running it makes no real difference to idle and if i push the carb pistons up by hand whilst holding the butterfly open it has no effect, it doesnt stall or rev up ! what the hell is going on ?

Hi mate and welcome, saved your embarrasment with the multiposts,
Check the firing order its quite common to get the leads mixed,
and check the plugs, once they get wet from fuel they are a bugger to clean off

Is there any indication looking at the tailpipe if it's running rich when you try to rev it up? Or maybe it's leaning out.

What happens if you remove the linkage between the carbs and try them individually?

Chris.

What sort of distributor? if it is mechanical points, check condensor, if not is the coil duff? both can be OK at idle and low reve and die when reved.
What is the petrol filter like? could br blocked with gunk and starving the engine of fuel as you try to rev it up are the carbs full of crud? is the needle going up with the piston (had that one kept me foxed for hours!!).
Sorry running out of ideas but I'll keep thinking.
Mike

thanks for the suggestions guys !, i have checked and double checked the plug leads and also tried the plugs in each lead against the engine to check its firing, it smells a bit rich but so i tried adjusting the mixture screws and it seemed to make no noticeable difference, i have dismantled and cleaned the carbs well and have checked the jets and float levels, and the needle is definatly going up with the piston ! fuel tank was flushed through and new fuel purged in, can i test the dizzy or do i need to try a replacment ? i will try each carb seperatly as suggested tonight and let you know, thanks again for your help !

P.S. its not revving rough, its just not revving up at all, but sound good on tick over, imagine the throttle cable was snapped (but it isnt ! haha)

Which carbs SU's or Strombergs, if strombergs the diaphrams are prone to rotting out and if badly perforated could be the cause of your problem.

Kevin.

The mixture screws on the SU carburettors only alter the idle mixture. The taper of the needle sets the mixture for all rpm once off idle.

If it will not rev, so when you lift the throttle linkage, there is no increase in rpm?

Totally blocked aircleaners or a blocked fuel filter, or the fuel pump is in need of overhaul if mechanical or replacement if electric. Could also be totally blocked flame trap hoses and flame traps with the breather pipes on the carbs choked up with gunk. Replacement of the engine breather filter is always advised in such cases too.

Other than that, maybe the scew gear on the distributor or camshaft has totally failed, in which case you won't see any advance.

Blocked exhaust system?

Ron.