Old vs New Nelson Q500 case
05-01-2003, 02:37 AM
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Old vs New Nelson Q500 case
In the last year or two, a slight modification was made to the Nelson Quickee engine. It looks as though the carb sits a little higher, and the bottom of the plastic carb seems a bit different.
Not sure if anyone will give me a straight answer on this, but is the newer case design better/faster??
I can't imagine a change being made, unless it was for the better. My engines are all the older design, but work well.
Someone give me a reason to buy a new nelson
Not sure if anyone will give me a straight answer on this, but is the newer case design better/faster??
I can't imagine a change being made, unless it was for the better. My engines are all the older design, but work well.
Someone give me a reason to buy a new nelson
05-01-2003, 07:05 PM
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Old vs New Nelson Q500 case
Dave:
I believe the change was made for two reasons. The first and most important was to beef up the front of the block. The Q40 engine (both the Q40 and Q500 use the same casting) has a history of cracking, even the 2nd design, in the area of the front reinforcing web. The second reason is to provide more support for the carb/venturi. The part of the carb which goes into the block is about 1/8 inch longer. The old design had a tendency of the carb/venturi getting loose which could affect the needle setting. With the new design there is a problem with the spray bar/fuel line interfering with the Q500 air valve shutoff. Nelson has now come out with a new spray bar design with the fuel inlet on the same side as the needle. This really works well on the Q500s. There have also been a couple of other changes in the last two or three years. The crank air passage now has a radius and I beleive the intake transfer ports were raised a little (not so sure about the ports but the timing seems to be slightly different).
Barry
I believe the change was made for two reasons. The first and most important was to beef up the front of the block. The Q40 engine (both the Q40 and Q500 use the same casting) has a history of cracking, even the 2nd design, in the area of the front reinforcing web. The second reason is to provide more support for the carb/venturi. The part of the carb which goes into the block is about 1/8 inch longer. The old design had a tendency of the carb/venturi getting loose which could affect the needle setting. With the new design there is a problem with the spray bar/fuel line interfering with the Q500 air valve shutoff. Nelson has now come out with a new spray bar design with the fuel inlet on the same side as the needle. This really works well on the Q500s. There have also been a couple of other changes in the last two or three years. The crank air passage now has a radius and I beleive the intake transfer ports were raised a little (not so sure about the ports but the timing seems to be slightly different).
Barry
05-01-2003, 08:01 PM
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Old vs New Nelson Q500 case
Thanks for the great explanation Barry.
After talking to Dave Schadel this afternoon, I decided to buy one. He said the differences in regards to performance are very small, but the change in the crank accounts for at least a 50 rpm gain.
Not much, but I need all the help I can get chasing you guys. Dave said he'd pick a good one out for me
After talking to Dave Schadel this afternoon, I decided to buy one. He said the differences in regards to performance are very small, but the change in the crank accounts for at least a 50 rpm gain.
Not much, but I need all the help I can get chasing you guys. Dave said he'd pick a good one out for me
