Monday, March 26, 2012
A Small Relief
Saturday, March 24, 2012
Summer Has Arrived
Update to '99 Miata Head on '94 Engine - Fuel Rail Issues
In this photo you can see the fuel pressure regulator. When installing the '99 Miata head on the '94 block, it's necessary to use the '99 fuel rail with the '94 fuel pressure regulator (FPR) because the '99 is a returnless system, while the '94 uses a return to the fuel tank from the FPR. The '94 FPR can only be oriented one way, due to a vacuum port that has to face out. That's no problem, but it dictates the routing of the fuel hoses. You can see this one sticking straight up, and the other one sticks straight down. The '94 fuel rail has an input that has a flared end on it so the fuel hose with a clamp on it will be nice and tight. The '99 uses the newer style fittings that click into place and require a special tool to remove, so the input to the rail has NO FLARE. The '94 FPR has an output on it that is flared, and so must be a clamped connection. Being ignorant when I embarked on this project, I blithely bought the first spool of high pressure fuel hose I found online and simply clamped the hoses to the fuel rail connections and on the other end to the fuel hardlines from the tank. It worked for 2000 miles.
Here's the assembled hose and fitting. It JUST fits in the space under the fuel rail. The connector gives a very reassuring and positive click when engaged. This shows how I ended up routing the hoses. It had to change a bit with the 90 degree bend at the end of the supply hose. From the hard lines on the left, they both run back behind the intake manifold and then run forward right on top of the fuel rail. Finally, the supply line goes forward and makes a gentle 180 to go under the end of the fuel rail and make the supply connection. It's not ideal as I'd rather the fuel hoses were more concealed, but I had to take the route with the least sharp bends and the right approach direction to the fittings. You might find a suitable route under the intake manifold, but there's very little room to make the connection down there and I was being conservative because I needed this to be fixed!
Saturday, March 17, 2012
Not What I Needed
Wednesday, February 29, 2012
Flat-bed Blues
Sunday, January 22, 2012
Hella FF50 Driving Lights
Saturday, January 21, 2012
Photo update.
Sunday, January 08, 2012
Camshaft Fix and Finished Paint.
Monday, January 02, 2012
New Steering Wheel
Friday, December 30, 2011
'99 Miata Camshaft Confusion!
With the help of a couple friends, I figured out why my new '99 head was making such a racket. It's got the wrong exhaust cam in it. I got the '99 head from a friend of mine. It's been in storage for over 10 years and its exact history is a little fuzzy. It came completely assembled but the cams were just loosely held in the journals with the bearing cap bolts finger tight. As seen much earlier in this blog, I took it apart and lapped the valves, checked the bottom surface for straightness, and put it back together.
What I've been hearing since I first started it up was what sounded like excessive valve lash. It was quite loud so I knew something wasn't right. I had checked all the clearances when I installed the head and they were pretty good. If anything a couple of them were on the tight side, not loose. Nevertheless, I figured I had screwed something up so this morning I popped the valve cover off and measured the clearances. None were above the maximum spec, but a couple were below the minimum, so I fired up my spreadsheet and plugged in all the numbers and identified 4 shims I could swap with each other that would bring everything within the factory specs. I was able to get the shims out without completely taking out the cams or having to re-do the timing. If you loosen the bearing caps and rotate the engine you can sneak the shims out from under the cam without removing the timing belt.
I was very glad to get the clearances better adjusted. Most of the valves are in the bottom half of the range. Alas, the noise was unchanged, so I put out a mayday to some gearhead buddies. One of them asked if I was sure I was using the right cams because the cams for NA and NBs have a different profile due to (or at least coincident with) the change to solid lifters in '99. I just used the cams that came with the head, but I realized that I took it on faith that they were the right cams.
From Solomiata.com:
Note the NB cam on the left has a more rounded profile, while the cam on the right from an NA is more pointy.To seal the deal, I spotted the marking on the intake cam, BP4W, which is indeed the correct intake cam for the head. On the exhaust cam is BP06, which is an NA cam. Bzzt. Wrong cam. So I'll be ordering up an NB exhaust cam and I'm debating whether to also order the BP5A (aka Mazdaspeed cam) for the intake side. Would be easy to swap it out as long as I'm in there swappin'. Hope this helps save someone some trouble sometime. Never assume!