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Triumph TR6 - Rebuilt Engine - Stock Cam?
|Hello all. |
I came across this BBS a while ago and have been reading it almost daily. A great wealth of information and fun.....not as good as driving but a good way to spend the winter dreaming and planning.
I have kind of an odd question.....I recently had my 1969 engine professionally rebuilt. When I picked up the car, it idled very roughly....would stall without the choke out and even when warmed up, it idles rough (with the choke in). The rebuilder says everything is adjusted appropriately but has a strong suspicion that the cam he was sent was not stock but a mild "street cam". When he checked with his supplier, he couldn't get a definate answer but based on the packaging it was a distinct possibility. Upon driving it the rebuilder feels it seems to have acceleration consistent with a mildly hot cam. He did offer to get a stock cam and replace it if I wanted.
So two questions:
1) does the explanation seem plausible....any easy way to verify??
2) If it is not stock, should I get it replaceed. (My thoughts are that I am quite happy to put up with rough idle for more performance). This car is a daily driver(summer anyway).
Really appreciate any advice or feedback!
|I recently had very similar symptoms as you Fred with my tr6. It would not idle without choke, it would die after warmed up without choke...It had been running fine. I remembered checking the damper oil just before it started running bad and the level seemed ok (according to the manual). A week or so later I decided to try adding a little damper oil to the carbs and voila...Anyway, you might check that out. I know you are ready for that new rebuilt motor to start singing.|
|Fred--Welcome! As a quick check, set-up a dial indicator on an intake/exhaust pushrod pair and take some lift measurements. Compare those int/exh lobe lift measurements with what you think you have (vendor specs). Try bumping the idle rpm up to the 1,000 - 1,100 rpm range to see if that improves idle quality. If it's bearable, leave the cam in and enjoy the increased performance.|
|try advancing the timing to smooth out your cam. do it in 2-3 degree increments and test drive. just stay out of detonation (pinging). if you have a hi po cam it would help to have your distributor recurved by a knowlegable triumph guy. things can be adjusted like the rate of advance (need quicker) and limit the amount of advance so you can have more intial advance.I heard "goodparts" can do it at a fair price, around $80. what is your compresion ratio? more cam needs more compresion. At idle compresion is bled off with more duration and overlap of the cam lobes but make up for it at hi rpm's. Thats why more timing helps at idle but not necesary at hi rpms.|
|Thanks guys. I really appreciate the ideas. Now I just have to wait for break in the weather.....semi-blizzard out there as I type!|
|I always liked the old description of how a hot cam would idle ... "rumpa rumpa".|
This thread was discussed between 09/12/2004 and 12/12/2004
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