starting a restoration

[Southpaw]

I'm getting motor rebuilt  is there a spark plug that works better  in the 4.0?? what about oils  synthetic a good choice this motor is fuel injected newer gas sucks  anybody use enzyme fuel additive thanks 

[fiatslug87]

I've always use Champion Copper Plus RC9YC with no problems. I like to keep it simple.

[AZJeff]

There really isn't anything better than the original equipment type plugs from Champion.  The AMC/Chrysler 4.0 is an engine that isn't very picky (nor does it respond to) fancier spark plugs.

 

Synthetic oil is very useful in some environments.  For example, down here in PHX, where temperatures regularly reach 110* or more in the summer, a synthetic oil will not break down under heat nearly as readily, and that makes it worthwhile.

 

I am not familiar with enzyme fuel additives, so I won't comment.

[Limeyjeeper]

If you want use a synthetic I would use Amsoil Z Rod 10W30. It works great with the Jeep flat tappet lifters and cam.  Jeep lifters like some zinc in the oil to help with wear. 

[Southpaw]

13 hours ago, AZJeff said:

There really isn't anything better than the original equipment type plugs from Champion.  The AMC/Chrysler 4.0 is an engine that isn't very picky (nor does it respond to) fancier spark plugs.

 

Synthetic oil is very useful in some environments.  For example, down here in PHX, where temperatures regularly reach 110* or more in the summer, a synthetic oil will not break down under heat nearly as readily, and that makes it worthwhile.

 

I am not familiar with enzyme fuel additives, so I won't comment.

i lived in phx for a couple years i was a roofer i still go to bullhead  for a couple weeks in the winter   thanks for the info

[Southpaw]

9 hours ago, Limeyjeeper said:

If you want use a synthetic I would use Amsoil Z Rod 10W30. It works great with the Jeep flat tappet lifters and cam.  Jeep lifters like some zinc in the oil to help with wear. 

thanks 

[Southpaw]

14 hours ago, fiatslug87 said:

I've always use Champion Copper Plus RC9YC with no problems. I like to keep it simple.

thanks i will give them a shot 

[Limeyjeeper]

2 hours ago, Southpaw said:

thanks i will give them a shot 

Gap to .035 no more.

[Pete M]

yup, copper for the plugs, full syn for the oil.   

[BeatCJ]

57 minutes ago, Pete M said:

 full syn for the oil.   

On a new rebuild. I have heard that switching to full synthetic on a high mileage engine can lead to new or worsening leaks.

[Pete M]

yeah, I've heard all sorts of other old wives tales too.   I went back and forth in my 88 depending on what was on sale.  never noticed any changes.

[Torq_Shep]

13 minutes ago, BeatCJ said:

On a new rebuild. I have heard that switching to full synthetic on a high mileage engine can lead to new or worsening leaks.

So the theory is with switching to Syn on an old engine:

 

Synthetic tends to have better detergents and cleaning properties than dyno oil. Old gaskets (specifically cork and rubber) tend to collect impurities that help block leaks as the gasket deteriorates. Switching to Syn will help clear those impurities and potentially make a vehicle leak more. 

Is it true? It has some validity in that Syn will almost certainly clean better than most dyno oils. However, if your gaskets are silicone or some sort of synthetic you probably won't see any difference in leaks. 

[BeatCJ]

Sure. I've never swapped back and forth, so I have no personal experience. Just seemed like it would be good to throw it out. 

[Tex06]

Copper plugs, spending more is just throwing $$$ out the window, imo.

 

I run the cheapest stuff around  for oil (usually Wal-Mart's SuperTech) and a FoMoCo FL-1A filter. If you're changing it every 3k miles, the oil doesn't really matter (gets plenty hot here in S. Louisiana). If you like to go longer between changes, go full synthetic. Buy a good filter.

 

On an older motor, as stated above, swapping from dino oil to synthetic can "cause" leaks due to the detergents in the oil. Not super common, but I blame that for finding out my original cork oil pan gasket had a leak (early in my ownership of my MJ I thought that synthetic would be "better". Ended up only doing the one oil change with synthetic, noticed my Jeep started marking it's territory in my driveway....the roommate and owner of the house was PI$$ED. Replaced with gasket the blue Fel-Pro, bought some more cheap oil because I didn't have $40 for another oil change, and never looked back).

[Pete M]

if gunk is somehow keeping your engine from leaking, then I figure you've got bigger issues than finding out a gasket needs to be replaced.  

 

it's all theory and conjecture.  I've yet to see legit research on it, so I file it under the mechanic's version of old wives tales. 

[fiatslug87]

People tend to forget correlation is not causation.

[Southpaw]

8 hours ago, Pete M said:

yup, copper for the plugs, full syn for the oil.   

 

3 hours ago, fiatslug87 said:

People tend to forget correlation is not causation.

thanks  now how do i get the pig tails off injectors  everything on you tube is for newer motors thanks 

[Southpaw]

4 hours ago, Tex06 said:

Copper plugs, spending more is just throwing $$$ out the window, imo.

 

I run the cheapest stuff around  for oil (usually Wal-Mart's SuperTech) and a FoMoCo FL-1A filter. If you're changing it every 3k miles, the oil doesn't really matter (gets plenty hot here in S. Louisiana). If you like to go longer between changes, go full synthetic. Buy a good filter.

 

On an older motor, as stated above, swapping from dino oil to synthetic can "cause" leaks due to the detergents in the oil. Not super common, but I blame that for finding out my original cork oil pan gasket had a leak (early in my ownership of my MJ I thought that synthetic would be "better". Ended up only doing the one oil change with synthetic, noticed my Jeep started marking it's territory in my driveway....the roommate and owner of the house was PI$$ED. Replaced with gasket the blue Fel-Pro, bought some more cheap oil because I didn't have $40 for another oil change, and never looked back).

thanks for the info

[Southpaw]

7 hours ago, Torq_Shep said:

So the theory is with switching to Syn on an old engine:

 

Synthetic tends to have better detergents and cleaning properties than dyno oil. Old gaskets (specifically cork and rubber) tend to collect impurities that help block leaks as the gasket deteriorates. Switching to Syn will help clear those impurities and potentially make a vehicle leak more. 

Is it true? It has some validity in that Syn will almost certainly clean better than most dyno oils. However, if your gaskets are silicone or some sort of synthetic you probably won't see any difference in leaks. 

thanks  I'm having the motor rebuilt  

[fiatslug87]

For injectors: There's a little wire clip around the connector you have to remove, I use a pick, then the connector pulls right off. They're pretty springy so make sure you don't loose them.

[Southpaw]

I'm not finding it  this is an 87 but thanks for the info and i will try again .. 

[Southpaw]

17 hours ago, Pete M said:

if gunk is somehow keeping your engine from leaking, then I figure you've got bigger issues than finding out a gasket needs to be replaced.  

 

it's all theory and conjecture.  I've yet to see legit research on it, so I file it under the mechanic's version of old wives tales. 

thanks  this motor leaked  pretty bad  I'm guessing rear main  but there is alot of build up on the front of the motor also... but with a rebuild  seals should be upgraded???

[Southpaw]

17 hours ago, fiatslug87 said:

People tend to forget correlation is not causation.

well that made me stop and think for a minute 

[fiatslug87]

2 hours ago, Southpaw said:

I'm not finding it  this is an 87 but thanks for the info and i will try again .. 

Maybe this will help, it's the little wire the pick is pulling on.

 

[BeatCJ]

3 hours ago, Southpaw said:

well that made me stop and think for a minute 

That's OK, just don't forget to start again.