Time for a general progress report on my never ending fiddling with the car.
I made a list of things that needed attention last fall and slowly marked them "complete" throughout the winter. Probably the most important item was the tinny ticking sound that I could not identify, but I found it. When I first put the engine together, I knew the rocker arm geometry would need to be set by getting the proper length push rods. I was slightly off on the lengths and the contact pattern on the valve stem tip showed it, but I deemed it "good enough". Unusual for me. So taking a look at the wear pattern after a summer's worth of driving was high on the list. See pictures of what I found.
I will blame 98% of what you see on run-of-the-mill rebuilder's not using higher quality parts. The intake/exhaust valve were different length and the guides had been "hogged out" to .015 over to match the standard over-size of the rebuilder valves. If the heads had been used on a stock Caprice with stamped rockers and low lift cam, they would have probably lasted to the end of their warranty. But they weren't and they didn't. The valve stems were too soft for the magnified pressure of the rocker tip roller, combined with more spring pressure than stock. My 2% is not following Comp Cams lifter preload directions. I have had the habit of setting the preload at 1/4 turn, C/C said their lifters should have 1 full turn. My light setting might have let the rocker bounce on the end of the valve stem a little, maybe yes, maybe no. Back to the machine shop for new Manley valves, bronze guide inserts to bring them back to stock size, and new seals. We went with 2.02 intakes to allow for a better shape around the seat, the 1.94 valves would have been a little to sunken after the heads had been rebuilt ?? times. Ticking is gone and runs very well. I've detailed this issue a little more to help those who are considering mail-order rebuilt heads with the intentions of going beyond stock with the valve train, I learned a lot.
I have always considered the steering to be very quick and require an uncomfortable amount of concentration to keep the car from waving around like a flag in a brisk breeze when making any kind of slight correction on the highway. I want to thank a very knowledgeable member of this Forum for reminding me that if I wanted a car that handled like a race car, I bought the wrong one. These were meant to be gentleman auto's. But I needed to make some kind of improvement. I installed a set of shims in the relief valve of the power steering pump, 5 in all. According to the literature, that reduced output pressure from 1350psi to 700psi. The steering is still very easy, but more refined maybe. Then I took the time to tighten up my camber settings. My right side was .5 negative and the left side was .7 negative. I could actually see the difference sighting down either side of the car. I removed 1 shim on the left side which brought it to .4 negative, a noticeable difference on the highway. Then I decided to increase the tire pressure after I could see the only side to side motion was strictly the flexing of the tire side walls. Again, I carry about 32psi in the tires of my Suburban and Escalade with good results, much bigger tires though. My 215R60-15 94H tires are a lot smaller and 32psi wasn't enough to firm-up the side walls apparently. Maximum psi is 51 and I am now running 45, again with noticeable improvement. I am as happy as I'm going to get with the handling now, more fun to drive.
Drive line angle got my attention next, a little shudder on initial acceleration and at higher speeds too. I've made more adjustments than I can count to the center bearing and have best results with the bearing all the way to the left and stock 5/8" spacer replaced with one 3/8" thick. One last comment here, I have 100% poly bushes in the front suspension and this creates a non cloud-like ride. I can feel every pebble in the asphalt on the highway and this has made it harder to sort out some of the jiggles and jaggles.
I hope this post will aid some of you who may have similar issues. I still love the car and will never sell it! My short gravel "homestead" driveway is ankle deep in mud, but the Jag still gets driven to town for morning coffee every day.
LTI, good for you getting it right and bad luck on the valves.
I feel that 45 psi is far too much pressure than should be needed to get the car to run straight easily. Have you checked toe in and castor? AS well as this I feel 0.5° negative camber is on the limit, 0.2 might also help.
Secondly, poly will certainly make the car far more "jumpy", so it might be worth considering using OEM lower sishbone bushes (but ONLY metalastic) LnR has a threaad on this.
Finally, what sort of rack bushes are you running? And FULL MARKS for using the car every day!
LTI, good for you getting it right and bad luck on the valves.
I feel that 45 psi is far too much pressure than should be needed to get the car to run straight easily. Have you checked toe in and castor? AS well as this I feel 0.5° negative camber is on the limit, 0.2 might also help.
Secondly, poly will certainly make the car far more "jumpy", so it might be worth considering using OEM lower sishbone bushes (but ONLY metalastic) LnR has a threaad on this.
Finally, what sort of rack bushes are you running? And FULL MARKS for using the car every day!
Thanks for the comments, Greg. In my head I think 45psi is too much also, but it helped and is well within the rating. The tread is nearly flat normally, but I planned to watch the center of the tread very closely for early wear. I may experiment by bringing the pressure down in the 35 to 40psi range and see how that feels.
Toe is right at 1/32 each side and caster is about 2.3 negative with no more adjustment possible. Likewise on the camber, upper control arm cross-bar is solid against the sub-frame bracket.
I can see that poly bushes would make the front very responsive and that, in itself, is not the real issue. It's the rear that sways greatly in a course correction, it runs straight and true in the straight ahead direction. Right at 0 toe on rear wheels and poly bushes on small end of control arms only. Nothing is loose. My rack bushes are also poly, but I remember your suggestion and explanation concerning stock bushes.
LTI
If the rear is unstable, something is wrong as the car should be very stable at the rear and track in corners perfectly. Candidates for the culprit are:
Outer fulcrum in the hub of the lower wishbone bearings worn. This is a very likely cause
Inner lower wishbone bearings worn, and or the dog bone castings that anchor it to the diff loose.
Diff loose in cage
not enough camber on rear wheels, try to get 0.25 to 0.5 degrees negative if you can
Radius arm bushes worn or fitted with poly instead of metalastic bushes
That is helpful to read about adjusting the driveshaft (and maybe still not getting it right). I had that same issue when I swapped in a 200-4r and am waiting to see if I have it with my 6 liter swap. after reading (most) of a 70 page thread on Toyota Tacoma forums about adjusting 2-piece driveshaft the conclusion that I've come to is that its basically a crap shoot if you get it vibration free.
That is helpful to read about adjusting the driveshaft (and maybe still not getting it right). I had that same issue when I swapped in a 200-4r and am waiting to see if I have it with my 6 liter swap. after reading (most) of a 70 page thread on Toyota Tacoma forums about adjusting 2-piece driveshaft the conclusion that I've come to is that its basically a crap shoot if you get it vibration free.
I spent more time than I wanted fiddling with my driveshaft. There was a noticeable shudder from a standing start with a little power on. I jacked the car up and crawled around under it for a couple of days with my digital level. Couldn't get the angles right without moving the transmission/differential angles, which I wasn't going to do. I decided to drive and adjust as necessary. I have poly bushes in the front suspension which transmits every imperfection in the road and makes it very hard to sort out other small shakes and jiggles. I finally found a stretch of new pavement about 30 miles away and after a few trips was able to feel the car, not the road. After many adjustments I have the setting at: carrier bearing all the way to the left and a 1/4" in spacer under it. Its very smooth from 0 to 90mph now and I'm going to leave it there.
Hey Dave, sorry to resurrect a thread after so much time but quick question. I have an '85 XJ6 with an LT1 and I'm hoping there is an easier fix for the throttle than me designing and 3d printing brackets... How'd you do your throttle from the stock pedal to the LT1 motor? Do you happen to have a picture or two?
Hey Dave, sorry to resurrect a thread after so much time but quick question. I have an '85 XJ6 with an LT1 and I'm hoping there is an easier fix for the throttle than me designing and 3d printing brackets... How'd you do your throttle from the stock pedal to the LT1 motor? Do you happen to have a picture or two?
No problem, glad to hear it still gets read.
The bracket on the intake is stock and came with the engine. The bracket under the dash is stock. I started with a complete cable from Lokar Performance, but had to make a new end for the gas pedal end. I think I started with a small allen-head cap screw and rounded the under side of the head with it chucked in my drill press. This part is a little tedious, but I live for the tedious. I drilled a hole through it and soldered the new end on the cable. On the throttle body end I used the small barrel nut they included with the cable, I had to drill out the pin hole in the throttle arm a little, but it turned out fine. Lokar shows a replacement inner cable with a ball end, but the ball is too big for the socket in the throttle arm and trying to drill out the arm proved too costly in drill bits. It's hardened steel. Here's a couple pictures and links to Lokar. I didn't take any specific pictures of either end of the cable.
