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PV, 120 (Amazon), 1800 General Forum for the Volvo PV, 120 and 1800 cars |
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My Amazon on a rolling roadViews : 4309 Replies : 22Users Viewing This Thread : |
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Nov 22nd, 2008, 16:59 | #1 |
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Last Online: Jun 28th, 2021 20:58
Join Date: Jan 2006
Location: Leigh-0n-Sea, Essex
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My Amazon on a rolling road
Ever since I replaced the single Stromberg carb on my Amazon with a secondhand twin SU set up I have had mixture problems. It would start easily when I enriched the mixture but soot up the front two plugs in a month or so, or if I weakened it, it would run a lot better but become almost impossible to start.
I met a guy who had just started a rolling road tuning business and was keen to resurrect his long experience of tuning SU's on his new high tech set up. As a birthday present my family gave me the cash to do it so last week I took the car to ATSPEED in Rayleigh Essex (01268 773377). I know lots of you may have already had your car on a rolling road but it was new to me and I found it a fascinating experience that I would like to share. He started by welding a plug for a lambda sensor in my exhaust downpipe, and the car was then strapped down on his rolling road. The first run showed it was running rich and recorded a maximum of 65hp at 4400 rpm, and would not rev much higher. A check of the carbs followed and the ATF in the dashpots was replaced by 20/50 engine oil, and the mixture roughly set. The next run showed the mixture was nearer the optimum but still not quite right so the jets were adjusted while the car was running at about 60 mph (try doing that on the road!) until the optimum was reached. A full power run now showed 78hp at 5000 rpm, but they thought there was a bit more to come so the needles were shaved a bit by hand and max power went up to 83hp at 5000rpm, but there was a slight flutter at cruising revs, so to make for the best driving experience a little more was shaved from the needles and this gave an extra 5bhp between 3000 and 4000 rpm. To see (and hear) my car doing 100mph in an enclosed space is exciting and this video gives an idea of the experience. http://rides.webshots.com/video/3045...58258802VJqrgw Original specs say my car should have 115 bhp at the flywheel, and losses to the rear wheels should equal 15-20% plus 10bhp, so mine should have 82-87hp at the back wheels. To hit this figure on a 38 year old engine is a credit to the longevity of Volvo engineering. The car is transformed, from a lumpy idle, occasional misfiring, and no real top end power, to a crisp engine that pulls like a train. All in all one of the best birthday presents I could have hoped for.
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Brian M 1970 Volvo Amazon and 1978 Safari 14/2 |
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