tr7triumph.com

ok fitted 4 branch manifold with big bore silencer no centre box fitted gaskets to manifold an sealed all the joints when starting the engine i get a backfire the she idles at 1000 revs if i drop the revs she idles iratically an wants to cut out ive been told i must uprate the needles to the carbs an fit KnN filters in conjunction with the 4 branch manifold to run smooth has any1 else experienced uneven tickover when puttin 4 branch manifold n bigbore exhaust [B)]

stephen j dark

You changed the breathing of the engine,
so you must change the carb's needles.

<center>
<font color="blue"><i>1980 TR7 DHC (my first car, now restored and back on the road)
1981 TR7 FHC Sprint (better known as 't Kreng)</font id="blue">
<b>[url="http://www.tr7beans.blogspot.com/"]<u><b><font size="2"><font color="red">My Weblog</font id="red"></font id="size2"></b></u>[/url]</b></i></center>

have ordered uprated needles an knn filters an givin the engine a service [:D] thanks beans

stephen j dark

Stephen, I did not have a problem with idle, after doing the exhaust, & inlet. It was at higher revs I needed the richer needle. The thing would not rev past about 3500 RPM without those needles.

Was your backfire through the carbs, or the exhaust? I have found backfire through the carb is usually caused by closed up inlet valve clearances, or indeed a riding valve.

Backfire through the exhaust has usually been down to sucking air in somewhere it shouldn't, or one of those damn fool air pumps pumping it in.

Bad idle has usually been down to unbalanced carbs. One doing all the work, & the other admitting very little, or virtually no air at all at idle, or the float level being so far out on one carb, that it provides little fuel, so its cylinders are running very lean, below 1250 or more RPM.

Unless it's a spark plug problem, or a coil or a lead or------, well you know the rest.

Of course you still must uprate those needles.

Hasbeen

the backfire was thru exhaust put some new fuel in it an cured backfire tho still running up n down at idle doing a service on her 2morro see if that cures it then friday new needles n filters i was told that the small pipes leading to the air filters i could block off as im running k n ns is it better with or without pipes ???

stephen j dark

Some pictures how I solved that in my weblog (labels <i><u>SU</u></i> and <i><u>8V engine</u></i>)

<center>
<font color="blue"><i>1980 TR7 DHC (my first car, now restored and back on the road)
1981 TR7 FHC Sprint (better known as 't Kreng)</font id="blue">
<b>[url="http://www.tr7beans.blogspot.com/"]<u><b><font size="2"><font color="red">My Weblog</font id="red"></font id="size2"></b></u>[/url]</b></i></center>