paul mc Posted January 15, 2012 Share Posted January 15, 2012 After 175,000 miles on my 1987 3.5efi engine I have decided it is way past needing new cam, so i bought a 3.9 cam and tappets, as well as new head gasket (tin) and other top end gaskets. But while i have the top off is there anything else i really should be doing? Should the cam shaft need new bearings? I have decided this needs doing as the engine seems very underpowered, i struggle to do 60mph on motorways and drop down to 50mph on hills. It is an automatic as well. Beforfe stripping the top end i also did a compression check, all of the cylinders are achieving a consistent 150psi, with the exception of the cylinder nearest the driver which achieves only 135 (although jumps to 155 with a squirt of oil). Does this raise any particular alarm bells? I ground the valves last time i had the head off when i first bought the car (only about 500 miles ago to go into my hybrid project). unfortunately i didn't ever take the donor rangie out for a long run at full speed as it was not road legal, so don't really know how it was behaving prior to transplant, but around the farm it seemed to run well up to about 30mph, which was as fast as i could get. any help much appreciated. Paul Quote Link to comment Share on other sites More sharing options...
Escape Posted January 16, 2012 Share Posted January 16, 2012 At that mileage, the timing chain will need replacing, good idea (and quite cheap) to change both gears as well. For the gaskets I would an do use composite rather than tin. And if you have the heads of and want to spend some time, you can match the in- and outletports. With a Dremel or similar multitool you can enlarge the ports a bit, to make for a better match (and thus flow) between heads and manifolds. The gaskets give an indication how much you can gain. Shortening the trumpets is also an option. I did all of this when replacing the head gaskets on my 4.6, certainly didn't regret it, but can't say it made a world of difference either (a new timing chain definitely will make a difference!). Greetz, Filip Quote Link to comment Share on other sites More sharing options...
Bowie69 Posted January 16, 2012 Share Posted January 16, 2012 As above, but the timing chain,if you are planning on keeping it for a long time, put a duplex true roller type in, something like a Cloyes timing set, it is more money, but the old Rover setup is pretty dire, and at that mileage your timing could be 5 or more degrees out. Quote Link to comment Share on other sites More sharing options...
paul mc Posted January 16, 2012 Author Share Posted January 16, 2012 I was going to stick with a new tin head gasket so as not to affect compresiion, is this not necessary? Quote Link to comment Share on other sites More sharing options...
Bowie69 Posted January 16, 2012 Share Posted January 16, 2012 Composite will drop the compression, staying with tin is fine, but they are less reliable, but do not require a skim. Up to you Quote Link to comment Share on other sites More sharing options...
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