2nd gen head swap, 1st gen G54b

[JimmyTheSaint]

So I have to replace my cracked cylinder head again on the old 79 D-50 2.6

I do not want to go back to the jet valve head. Non jet valve heads are offered for the second gen G54b, but I need to know if it will fit my 1st gen engine. I will be replacing the timing chain this time as well and they seem to be the same length chains from 1st gen to second gen, but the parts stores list them as different part numbers.

Ive searched here but no specific info readily available. Im sure someone here has done this and can shed some light.

[pennyman1]

the difference between the 1st and 2nd gen heads is the intake manifolds - 79 - 80 have 2 bolts at the front of the manifold, the 81 - 89 have only 1 bolt in front and one below the thermostat housing. The intakes are not interchangeable. The 85 - 89 heads also have hydraulic lash adjusters, the 84 and older are manual adjusters. All non jet valve heads are 81 up style.

[BradMph]

I installed the 2nd gen '87 intake on my 1st gen '86, I also took the oil pump from the 2nd gen since it was a bigger gear pump and just better.

[JimmyTheSaint]

the difference between the 1st and 2nd gen heads is the intake manifolds - 79 - 80 have 2 bolts at the front of the manifold, the 81 - 89 have only 1 bolt in front and one below the thermostat housing. The intakes are not interchangeable. The 85 - 89 heads also have hydraulic lash adjusters, the 84 and older are manual adjusters. All non jet valve heads are 81 up style.


Ok so if I swap intake manifolds with the head I should be fine. I think at one time I read the valve covers may be different as well?

This sucks. I dont want to pull the trigger on a non jet valve head and not be able to find the intake/valve cover to make it fit, and its next to impossible to find a good first gen head.

I really dont want to go through this again with another cylinder head. I replaced the one thats on it about 7 years ago and it went through 4 different junkyard heads before I found one that wasnt already cracked. Now they are all gone. I havent seen a running 1st gen truck in my area in nearly a decade. I just want my ole truck back on the road, but Im getting too old for all this part chasing now. LOL

Thanks for the info.

[JimmyTheSaint]

I installed the 2nd gen '87 intake on my 1st gen '86, I also took the oil pump from the 2nd gen since it was a bigger gear pump and just better.

I may end up going that route as well since my ole truck is having a hard time keeping oil pressure when idling unless im using some really heavy oil. Thanks.

[pennyman1]

Bradmph is talking about a g63b, not a g54b - the motors are 2 different engine series

[elsupremo]

There is new head available for the G63B. It is the head for the fork lift version of the engine and does not have the jet valve.
it is identical to the truck head otherwise. I am finishing the installation right now. I bought it a year or so ago off eBay.
it came complete with valves. I had to transfer the cam and rocker assembly from old head that was cracked.

i machined a soft aluminum rod and drove it in the damn EPA passage from intake side of head to #4 exhaust port through the head blocking it off. I’m running Weber carb. I don’t want my engine breathing it’s own ass-gas.

[pennyman1]

I did forget to mention the 81 up valve cover is different from the 79 - 80 valve cover.

[elsupremo]

All went well.

[geezer101]

There is new head available for the G63B. It is the head for the fork lift version of the engine and does not have the jet valve.
it is identical to the truck head otherwise. I am finishing the installation right now. I bought it a year or so ago off eBay.
it came complete with valves. I had to transfer the cam and rocker assembly from old head that was cracked.

i machined a soft aluminum rod and drove it in the damn EPA passage from intake side of head to #4 exhaust port through the head blocking it off. I’m running Weber carb. I don’t want my engine breathing it’s own ass-gas.

I lopped off the EGR gallery from my intake manifold on my G63B and I had a workshop thread a hex key grub screw into the head to seal off the port passing through the head. I got pics of it on the site somewhere...

[elsupremo]

I elected to fill the entire passage and polish the exhaust port smoothing out the spot where the hole was. My reasoning was that only plugging the intake end might be causing a hot spot in the head.

Probably overkill, but what the hell.

[geezer101]

Fair enough. It "shouldn't" cause a hot spot but you stayed on the better-to-be-safe-than-sorry side. Overkill? After I cut the entire EGR gallery off the intake manifold? :lmao:It would be good to be able to get the heads before they drill the gallery through them...

[elsupremo]

I got to take the “little truck” out today and put some miles on it with my 95# GSD (Germanic Sheep Herding Dog) riding shotgun. He got his picture taken twice by passers by. When I park and go in shopping he gets behind the wheel and sits there waiting on me. People are fascinated by it.

i have my fingers crossed that this forklift head is going to serve me well. After a first run in the garage for about an hour I shut it down and let it cool overnight. The next morning I removed the valve cover and retorqued the head bolts. All but 2 moved a good bit. I may do it again.

[elsupremo]

I have some 250 or so miles on it now.

i took a 130 mile trip today at average of 65 mph and got a good mileage check today. 28.37 mpg on 10% “alkyhall” regular.

i like it. :thumbup:

[geezer101]

Nice. No leaks, everything behaving itself and getting good MPG's. :thumbup:

[elsupremo]

Well I made it a little over a year and now #1 cylinder is dead. I’ve had it with the 2.0 engine. I’m considering a swap to 2.6 or maybe some other engine. Anybody got ant suggestions?