Reply
Hi Brian. No problem at all. The tool is actually out on loan now. I wont have it back for about a week, so dont move too quickly LOL...
Dont worry too much about not having a parts diagram. The factory one is actually quite vague and inaccurate. Really only good for identifying parts # - and not so good as an assembly guide...
You had asked on the forum a while back about things you could do while the engine was apart to gain a bit of performance if possible. I meant to respond there, but your post quickly morphed into a full blown turbo discussion. Not I think what you were looking for...
But yes, there are certainly some simple things you can do - while you have the engine apart - that are not radical and are compatible with (and wont overwhelm) the stock fuel injection system. You will get many opinions on this subject, and I am certainly not an expert on the subject, but here is my 2 cents worth anyways...
Firstly, these engines were designed to have a CR higher than what we got over here. It was lowered for the NA market for 2 reasons: to meet emission regs, and to make the engine a non-interference design.
A quite noticeable increase in power and torque can be obtained by raising the compression to at least euro specs, which was about 9.2. The NA spec was about 8.5.
This can be achieved by several methods (different head, different pistons), or simply by shaving the head/and or block. Each have their advantages and pitfalls. And should match the fuel you intend - and are able to - run.
Here in Ontario the highest octane available is 94. Probably ( ???) good for a CR in the upper nines. BUT....these fuels (to the best of my knowledge) all contain varying amounts of ethanol. Which your fuel injection components were never designed for. I have seen the effects myself, and it is not pretty....
However.....Shell 91 (their highest grade) contains NO ethanol. The only fuel I have found here that doesn't. The safest bet in my opinion. This should work well with a CR in the low to mid nines.
So...aim for that. It will be safest for the injection system. And then optimize the engine for that octane. Will provide a decent power boost too.
Easiest way to achieve that is to simply shave the head. I sure hope you are intending to have the head skimmed anyway to ensure flatness and reliability, so just have them skim it a little more.
You can calculate the amount of shaving needed. My distant memory says it is about .025" or so. I would have to do the calcs again to be sure.
Disadvantages of shaving the head ? Some say it weakens the head, but I think that little amount doesn't. It will alter your cam timing slightly, but for that little shaving it should not be significant. Would be best to invest in an adjustable cam pulley to correct it and even add another couple of degrees of advance (that helps too). And if you shave too much, you will run out of tension adjustment on the timing belt. You will be okay if you only shave the head a bit. Any more and you will have to use a 1300 tensioner bearing (it is slightly bigger). And it is possible that shaving the head too much will turn the engine into an interference design. Not a problem if you change the timing belt at recommended intervals.
Secondly....the NA engines had a really mild cam - for emission reasons.
You can get a nice increase by changing it (really easy to do when you have the engine apart !!! ) to a euro spec one (pretty easy to find and get these days on Ebay UK or Germany or Italy ) or something like PBS SX1 type grind. Just dont go too wild like a 40/80 cam - the stock FI system wont like it, and your X will idle like a dragster. Something like a euro cam will really make a difference, and still give a nice smooth powerband.
These two above things would certainly give you the mild increase you are looking for. And at a pretty reasonable cost. And now would be the time...
And while the engine is apart, some mild porting/polishing/matching would certainly yield some benefits for almost no cost if you can do that yourself.
Next up would be to free up the exhaust. With a header or double outlet manifold for a '74 US or any euro X. And a lower restriction cat and muffler. A good gain to be had there.
I will stop rambling now..... If you have any questions or need any help, just ask. Doug