1989 Mighty Max engine rebuild

I got a brand new head from Clearwater Cylinder Head with the cam and valves installed, ready to bolt in for $375. My engine was rebuilt a year ago and the head wasn't replaced at that time.( It was a reman that I had put on 5 years ago to replace the original that was cracked). 8 months after the rebuild I was going through coolant again. I never had coolant in any of the cylinders like you have in the pic, just one really clean cylinder. I bought a new head from Clearwater and installed it myself. One thing I noticed was that the top of the block had been machined flat during the rebuild. That was never done when the first head was replaced as the engine stayed in the truck. I've since been told that could have been the reason for my subsequent troubles. I would check the top of that block to be sure its perfectly flat before you put a new head on it. Torquing the head bolts again when the engine is hot is also important.

Ok, i'll keep that in mind, i'm about ready to put the head in but i noticed that i may me missing some pins that go between the head and the block to line everything up. Can anybody shed some light on if they are needed and where i can maybe get new ones?

After much research I noticed there should be dowel pins to align the head gasket and head to the block. Got my local machine shop to whip me up some, but I noticed a bad vacuum line going from the brake booster to the intake. Any help where I may get one of these from. Local auto parts store said junkyard. Any other ideas out there floating around?

If its a hard line, make it out of a length of fuel line tubing the same size from the parts store - use vacuum hose and clamps to hook it up.

I seem to remember the alignment pins being hollow alignment tubes. There was one at the front and one at the rear. This pic shows them clearly. Attachment 12419. Fluid probably needs to flow through them, coolant or oil. These were the only pins on my 2.6

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Originally Posted by asmyser

So I took it down and it looks like a cracked head. I'm taking it to a guy for a second opinion. The question next is, where do I get another?

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TopEnd Performance (vendor that sold me my Weber) has 2 NEW heads that will drop on these motors (mine same as yours). Both are machined w/out Jet Valves ( very good idea if replacing a head). Last time I checked (2.5 yrs. ago) the least expensive was just over $300. The more expensive head designed for Turbo setups, so not really needed for G63B naturally aspirated motors.

Just a FYI: should replace head bolts (if you don't have studs)... some people reuse old, but those threads collapse on 1st torqueing and do not torque accurately or hold torque after 1st use. I just replaced my head, had difficulty finding head bolts. Found 'em at HeadBolts.com (owner was extremely helpful: did not have 'em when I first spoke with him but he found them for me).

FYIW II: I'm new working on these old Mighty Max trucks (used to restore old SAABS for a hobby, maintained small fleet of Chevy/GM trucks when I used to swing a hammer for a living: eg. have experience and can figure things out, but these truck have their peculiarities/uniqueness). Mostly because of time constraints, just finishing my truck up last few weeks. Full motor rebuild. After getting acquainted w/my MM (mostly reading here) also decided to spring for the Weber and install an electric fuel pump.

Just finishing final testing today, but had it out for +/- 30 miles of driving in last few days and it's... sweet. Runs smoother/stronger by a good margin on the Weber. I largely decided to go with it because, although several local Carb shops said they could rebuild my Mikuni... after reading up found out practically nobody had one of those successfully rebuilt (for many reasons).

Ok, just my $0.186 (and falling).

Good luck w/your truck.

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Originally Posted by BradMph

It's not hard to replace carb. Weber gives all the directions and we also have manuals here you can download on an install also.

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Is there a specific location on our site where the manuals you mention, and others are located?

I've also seen references from experienced posters here they have a "page" or "file" on specific subjects, but through this last few weeks getting my truck spruced up finding these has been hit or miss. I've found/read your wiki articles (very helpful), but that's only tech articles I found in one spot.

All manuals and other source reference can be found here. http://www.mightyram50.net/vbulletin...esource-Center

ok, so i got it all back together.Howqever she doesn't run. I either have a timing issue. although the marks by the belt are both spot on. And i replaced my mechanical fuel pump and i may have switched the lines going to the carb. Does anybody that knows mikuni carbs know which line goes to what location on the carb.

what i need to know is: does the red line hook up to the top line or the bottom line on the fuel pump. I know i have the intake line properly installed.

Attachment 12497

Are you sure you have the mechanical pump arm in the right way onto the cam - are you getting fuel flow from the pump to the carb? The big line coming from the frame goes to the inlet side of the pump (bottom), the line to the carb is the middle, and the small top fitting goes on the line back to the tank.

well that confuses me, because i have three that are about the same size, and then a smaller one on top the fuel pump. The one coming directly frum the fuel filter from the tank i believe is the one that goes on the arm of the fuel pump that is single. Its the other arm that has two more hookups that i may have gotten confused on.

I need to know where 3 and 4 go to on the card, i believe i either have issues with timing, or the fuel lines being swapped.I'm pretty sure i got the fuel pump installed properly with the pin installed properly and all that.

Attachment 12499

If You go to the Wiki page you will see a Fuel Management System forum. In that forum you will find a mechanical fuel pump diagram. Try pouring a bottle cap full of gas down the carb with the throttle wide open. When you close the throttle the choke should close. Then crank it over. It may take more rpm than your battery can give you to pull fuel all the way back up from the tank. If your timing is right and you have a spark it should fire and that will prime your fuel pump. You may have to repeat this a couple of times.

Yeah I've looked at that diagram a couple times but the return to tank also goes to the carb. Along with the line to the carb

An easy test for your fuel line hookups to pump is, disconnect top line coming out of pump at carb & get someone to crank the motor. If you are getting fuel, you've got it right.

As far as identifying which line is which: there's 3 lines connected to the tank. Supply, return and vapor.

- vapor line runs down firewall from charcol box, winds behind brake master cylinder (I have same year MM as you).
- Supply line comes into engine bay from frame a bit more forward then return line. The metal line (eg: where it connects to flexible line, just above motor mount if I recall) is slightly bigger then return line. The supply line flexible section to fuel pump has a hard, plastic section over it shaped somewhat in shape of a long "S" (maybe 18 inches long). This hard section is longer and has more twists then the one on return line.
- Again, return line comes into engine bay a bit further back towards firewall then supply line. If you can get a light down there (or get underneath and observe), you can visually see the smaller hard line (return).

I just finished replacing my Mikuni w/a Webber and do not recall fuel hookup locations for the Mikuni... I pulled Mikuni off and threw it away.

As far as timing goes: did you pull distributor out completely?

If so, I had to do something do get it back in properly I haven't seen mentioned here or in YouTube Videos on how to do this: eg. I had to remove thermostat casing from intake manifold. I installed my dist. several time before doing this, and that casing always forced me to turn dist. housing a bit clockwise further then seemed correct.... motor would puff and hickup like it wanted to start but never got past that. Read a bunch of stuff where others tried "guessing" tricks. Decided to pull that thermostat flange, distributor went in much more smoothly and motor fired right up afterwards.

Well that clears some stuff up. But from my last picture line 3 and 4 both go to the carb....and always have, even before swapping to a new one

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Originally Posted by asmyser

Well that clears some stuff up. But from my last picture line 3 and 4 both go to the carb....and always have, even before swapping to a new one

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Don't know if I can provide you certainty on this... sure one of more experienced hands here will chime in. I have no diagram of Mikuni fuel line locations w/me. If nobody helps, I take a look @ my Chilton's manual when I get home later today.

Here's a good diagram of fuel pump connections (posted by Brad).

yeah i got it figured out, got it all back together and it runs better then i remember. I went out this morning verified all timing marks, and crank it a dozen times or so and it started right up, it must have been flooded yesterday. I didn't take it for a spin since there's an inch of ice outside and the truck is two wheel, but it idles great... Updates when the weather is nicer. Thanks for everyones help thus far.

Success stories are what keep us going here, plus the billions of dollars in donations we get each quarter,jk!. Congratulations on a healthy running truck :clap:.

Well i can't guarantee its completely healthy yet, but hopefully this weekend will melt all ice and snow and i can take it for a ride. Speaking of donations, i did what i can.

Well iwas looking back at pictures and maxdsm posted the following picture on post number 120 and that pictures shows the same thing i have coming from my fuel pump, i think.
Attachment 12623

This is one ling thread that's for sure. Sorry I haven't been much help lately but for the slow season things have been real busy.

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Originally Posted by maxdsm

coolant...

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Correction
This picture the line in front of the block that attaches to the block is what goes to the fuel pump . it must be an overflow or breather for the fuel pump but it connect s to nothing .I slid the line over it and it fits perfectly.

Ok so the thing I circled in the picture in your truck also just goes under the engine and then nowhere, just like mine.

Ok, timing gurus out there. The truck idles ok, (its cold outside). I may or may not have an issue with my timing. And here's why i think this. The truck seems to run okay, but when i hook up the timing light to it, the mark shows up at about 10 or 11 o'clock. which is way outside of the "window" on the cover for the belts. Now, we had a hard time getting the thing to start the first time, Has anyone else ran into this issue before? When i turn the distributor so the marks get closer to lining up the engine almost shuts itself off. I'm not sure if this is something to be concerned about or not, Hopefully you guys can tell me.