This really is a great thread. Hands on no service shop DIY work! Keep up the great posting!!!

 

Appreciate the insight. I’m glad I went with donor. Everything about it just seems like it was an old car that got scrapped for non engine mechanical reasons. No evidence the engine was ever overheated so that’s nice. I’ll find out eventually lol. I found a few TSBs from Ford and Mazda of the era that had an extended warranty because of a head gasket issue. As far as I can tell it was a gasket material flaw or lackluster design. I’m hoping that by sourcing the latest tech that was at one time available for this engine it’ll address all of that. The fel-pro kit I sourced looks like it’s a more modern mls gasket. In the very least it’s definitely more modern than the original.

I can only speculate what the cars history was before me, but it looks like someone was having overheating issues, bought a redone head and slapped it on. Then that overheated severely and they gave up.

It’s unfortunate but I think a big part of the problem was a plugged intake. I noticed when I did an initial teardown of the engine it had, the manifold tees were plugged solid with junk. And I noticed the fan shroud was missing which I’m sure exasperated the issue. The coolant not being able to fully circulate was probably the original cause of the overheating issues, and it was missed because they probably just tore the head off and left everything in tact so they missed the blockage in the hoses and tee.

 

Just make sure if all looks well use a good quality head gasket and retorque it after some time running. Even the socalled monotorque gaskes shrink and will tighten with a retorque. When retorquing I always back the bolt off first then tighten. As I said most of those engines got scrapped because of head gasket issues.

 

Will do. Reminds me that I noticed the official torque procedure is to tighten to a higher torque value after initial warm up. Really highlights how far things have come.

 

So I’ve realized this has basically turned into somewhat of a build journal. Things that have progressed:

I wanted to get some measurements on the valve springs. I can’t really find new ones (that I trust are the right ones), I’ve looked. But I wanted to make sure I wasn’t way off to where I would be forced to address it and go with some Frankenstein option.

Some background. The donor engine was from an 84 B2000. Using partssouq.com, I realized that engine used a different spring for 83-84. I’m assuming the outer was made longer for more strength since the outer free length is longer than the free length spec in the ‘79 manual. The inner seems unchanged.

I looked at getting a valve spring pressure tool, but they’re pricey. Even the Amazon/eBay aftermarket is a bit much for what it is. So I put together a barebones version. Just a 1” piston/bore to give a 1:1 reading on the psi gauge.




Seeing how the spec I have in the ‘79 manual isn’t going to be the same since the springs are different, I decided to compress each spring to the same lbs the manual calls for and just take the measurements as relative to one another. I’m happy with the results (especially because there’s no off the shelf option) I’m sure there’s a bit of an error margin but again, it’s allll relative 😎


So yeah, I’ll take it. Not like I’m building a race car with the whopping 77 hp…

Other than that, I got the new valve guides in. Will have to ream them, but that’s for another day.

 

Looking at your measuring, . Springs also act differently in the valve train then simple measuring anyway. As you said it is minor and unless you are intending to spin the motor above 5k it is not likely to even be noticed in normal driving engine operation.

As for not finding replacement springs... well there are spring replacements for just about any engine.....It just takes a little more research from suppliers of spring or better the actual spring manufactures using their specification charts instead of applications information.

 

Yeah I’m no valvetrain expert, I mainly did this to satisfy my curiosity, and because both engines valve stem tips had a bit of wear like they were spinning. Could have been a lack of oil at one time in their lives too, or incorrect lash etc.

I did look into the possibility of an off the shelf aftermarket spring, but the spec at 31.4 lbs etc is some oddball thing as far as I know. Springs are measured and rated much higher off the shelf, so I’m guessing I’d have to characterize the ones I have and go back and forth with suppliers to find what I wanted. I’m just glad they’re good enough and likely not the cause of why the valve tips wore down. I’m replacing all of the valves, but I don’t want the same thing to happen to the new ones is all.

 

Interesting device you made to check the springs. The ones we used were all mechanical and you just set the test length and compared the springs. Other tests you can do is line them up and compare the free length and also up against a 90 degree square check for warpage but like callisto said it probably won't make any difference unless your going to rev the nuts out of it. You could just add a shim under each spring to make up for valve and seat machining.

 

I got the idea from these “hobbyist” type ones that I see around now on Amazon. If I were to improve it I’d make it liquid filled so travel length and accuracy would be better, but yeah it was an excuse to use the lathe more or less.

I did think of shimming if it needed it, but I’m gonna leave that up to a machine shop when they do the valve job. Where I’m at the prices for machine shop work have really seemed to go up over the years, so I like to take care of what I can now to keep overall cost down. And it’s nice to have an idea of what to expect going in. And I’m a tool hoarder lol

 

I’ve also somehow sourced what I was lead to believe is mostly unobtainium.




I am in no way a carb specialist. I believe this is the CARB approved carburetor offered by Weber as a bolt on upgrade for these Mazda engines. Executive order D-133-12 if you want to look it up.

I plan on using the Nikki carb initially since the car was known to have ran with it before the hg went. I don’t want to give myself too many variables at once when trying to see where things are when I get the engine built and the car running. But I couldn’t pass up the deal and I never thought I’d come across one of these in the limited research I’ve done, so it’s a work in progress. I did source a rebuild kit and over time I’ll familiarize myself with it more.