Rover V8 Problem
Discussion
I've recently acquired a Sylva Stylus with a 3.5 litre Rover V8 installed.
Since owning it for the past few months I taken it out about 5 or 6 times (when the weather was up to it!) and what started out as a niggle seems to be turning into a larger problem.
There is a distinct hesitation when applying part throttle. A real noticable dip in power if you just squeeze the throttle - for example driving through the second half of a corner.
Applying full throttle seems to be fine but part throttle is a pain - not just a hesitation but a deceleration before picking up and actually accelerating.
The problem is usually not noticeable at the start of a journey (although I'm usually just letting the engine warm up and not on the kind of roads where I'd notice it so much) but gets worse.
I must point out that I'm a complete beginner when it comes to the oily bits of cars. Getting to grips with some of the theory but practice is something I don't have any of. One of the reasons for gettting this car was to build up that kind of knowledge so I guess it starts here!
A supplementary question would be do you know anywhere close to central Reading where a friendly mechanic would be able to have a look and not take advantage of my ignorance to rip me off!?
Thanks.
Since owning it for the past few months I taken it out about 5 or 6 times (when the weather was up to it!) and what started out as a niggle seems to be turning into a larger problem.
There is a distinct hesitation when applying part throttle. A real noticable dip in power if you just squeeze the throttle - for example driving through the second half of a corner.
Applying full throttle seems to be fine but part throttle is a pain - not just a hesitation but a deceleration before picking up and actually accelerating.
The problem is usually not noticeable at the start of a journey (although I'm usually just letting the engine warm up and not on the kind of roads where I'd notice it so much) but gets worse.
I must point out that I'm a complete beginner when it comes to the oily bits of cars. Getting to grips with some of the theory but practice is something I don't have any of. One of the reasons for gettting this car was to build up that kind of knowledge so I guess it starts here!
A supplementary question would be do you know anywhere close to central Reading where a friendly mechanic would be able to have a look and not take advantage of my ignorance to rip me off!?
Thanks.
Is the V8 fitted with twin SU's? If so check the pistons are sliding freely in the dashpots, any stickiness will cause hesitation. Make sure the damper rods are not bent, and ensure that the damper tube is filled with engine oil after putting them back together.
I think Haynes do a manual on overhauling the SU, but it's a simple carb and you should have no problems if you approach the work methodicaly.
I think Haynes do a manual on overhauling the SU, but it's a simple carb and you should have no problems if you approach the work methodicaly.
My Rv8 with twin su's had this problem, I cant recall now whether it was a rich or lean spot, but a change of needle solved it (thanks RPi) - Your 4 barrel carb will also suffer from the same problem, If it was a edelbrock i could give some tips, but ive never tuned a holley.
If at the time i had even a narrow band lambda sensor fitted, it would of been pretty easy to narrow it down to rich or lean, however for any decent tuning, look at a wide band.
Have read thru this, it explains how you can use a narrow band to tune your edelbrock.
www.telusplanet.net/public/gilesij/Volvord/edelbrock_1.htm
Becuase lambda sensors give instant feedback, I quickly learnt the the shortcomings and compromises that a carb has - i converted to fuel injection shortly afterwards.
eliot.
If at the time i had even a narrow band lambda sensor fitted, it would of been pretty easy to narrow it down to rich or lean, however for any decent tuning, look at a wide band.
Have read thru this, it explains how you can use a narrow band to tune your edelbrock.
www.telusplanet.net/public/gilesij/Volvord/edelbrock_1.htm
Becuase lambda sensors give instant feedback, I quickly learnt the the shortcomings and compromises that a carb has - i converted to fuel injection shortly afterwards.
eliot.
Ok, if it's a holley then it's probably your transition slots being over exposed. They control off idle tip in. Switch the engine off and look down into the primary chokes which should be the front 2 chokes. In the wall at the edge of the throttle plate there will be a slot cut into the choke housing. If you can see this with the throttles closed then it's set up wrong. You shouldn't be able to see these slots until you start to open the throttle blades. What they do is allow a small amount of air to bypass the plates as you move 'off idle' onto the main jet circuit. They give you smooth transition. Some people open the throttles to much to get a higher idle speed when really they should drill a tiny hole in the plates. Take a look and mail me if you like
bob42 said:
Right, I'll have a look tomorrow and see if I can figure out how your description relates to the real world! Having never really looked at a carb with the air filter off I'lll wait to see it in real life before sounding totally confused
When you look down into the carb the first thing you will see is the choke butterfly (if a choke is fitted). You will have to hold this open to see any further in to the throttle butterfly. This closes off the throat and will be sitting at a slight angle. Where this blade touches the side of the throat at the lowest point it should be covering the transition slots, which are cut into the sidewall. You should not be able to see these with the throttle closed.
Steve
Steve & Bob 42
I think I got it back to front (it's been a while since I tuned Holleys). You should be able to see nearly all of the transition slots when the butterflies are closed. The mistake people make is when they wind up the idle speed setting, thus opening the blades to much and using up all of the transition slot, hence no active transition circuit.
So long as the blades are near the lower end of the slots there will be some transition when coming off idle and on to the main jets. In other words there will be some progression and no stumble. Think that's correct
I think I got it back to front (it's been a while since I tuned Holleys
). You should be able to see nearly all of the transition slots when the butterflies are closed. The mistake people make is when they wind up the idle speed setting, thus opening the blades to much and using up all of the transition slot, hence no active transition circuit. So long as the blades are near the lower end of the slots there will be some transition when coming off idle and on to the main jets. In other words there will be some progression and no stumble. Think that's correct
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