401 Rebuild help

[flyusmc]

Hi all,

I'm hoping for a little advice in rebuilding my engine.

I have an stock 88 GW and am buying a 78 401 out of a Cherokee to put in it.

My Priorities are this:
1. Price
2. Low down Torque (I would like 400-500) for towing
3. Reliability.

Can you recommend an all inclusive rebuild kit or parts? I have around 800 to spend (not including machine work.)

Thank You,
Flyusmc

[JERSEYJOE]

If you are in doubt of the condition and you do not want to just rebuild the entire engine, do this:

1. Find someone that can do a leakdown test to see if the engine in it's current condition has a reasonable seal. If it does then you can conclude that the rings / valves are healthy.
Also have them remove the oil pan and look at the rod and main bearings. If you are lucky you might be able to just replace the inserts without any machine work.

2. Replace the cam with any one of the many RV grinds available although the stock 401 stick is fairly lively.

3.Swap the intake for an Edelbrock Performer and use either the matching Edelbrock carb or a Holley Truck Avenger 670.

4. The stock exhaust manifolds are decent so just have a true dual exhaust with a crossover done for max torque.


I know that some people will just poo poo this and tell you to start from scratch and rebuild the whole motor, and without knowing the condition of yours you might need it. I have seen people buy used motors that were still in very decent condition and they were able to use it as is. You could spend a lot of GREEN once you go with the start from scratch route as many guys will tell you. There are a lot of guys here that can help you every step of the way. Listen to them and bre realistic about how the motor is going to be used and don't be tempted to " over modify" it.

Good Luck.

[jeepsr4ever]

I think a RV cam and a edelbrock 600 on top of a factory 4bbl would give you gobs of torque. If you want it to develope low then you want to keep the intake runners small and use a larger carb to get more fuel at lower rpms. The performer is a good midrange intake manifold but for that 800-1800rpm range the stock intake and larger carb will out run the eddy. From there the performer outruns the stock intake.

[Goose]

Now thats interesting.. I guess I had never even given the stocker consideration.. but what you say is true.. but a question.. If you go too big on the carb wouldnt you be undoing the advantage to the smaller stcok runners??

(he sits here thinking of all the stock 4 bbl manifolds for AMC he has pitched over the years.)

[JERSEYJOE]

Yes I threw out at least 4 this year alone.

[flyusmc]

Okay all here is what I have so far. Let me know if this sounds like a matched plan

Block - Stock 401
Pistons -Stock if I dont' have to overbore (I'll see when I pull the engine
Cam- Sum K8600 and lifter set
Roller Timing Chain
(I'm gonna buy) MC's smaller diamater rocker arms and pushrods had HD oil pump parts
Stock intake
Edelbrock 1406- (I've never tuned a carb and can't afford someone tuneing one for me, so I was told this was the safest bet?)
I have both Headders a stock exhaust manifolds. Which one should I use? I am leaning towards the Headders.
HEI dizzy.

-Am, I missing anything? How does this combo sound for towing/torque?

Thanks.
FLYUSMC

[JERSEYJOE]

I would skip the ehaders and use the stock manifolds with true dual exhaust with a crossover.

The 1406 should work great out of the box.

Did you find someone to check the motor you have?

[pablorg]

I would skip the ehaders and use the stock manifolds with true dual exhaust with a crossover.

JERSEYJOE, can you explain what "true dual exhaust with a crossover" exactly means? :oops:

I currently have Edelbrock Headers with dual exhaust on mine...

[Rhinolined360]

lol or save some money and get a chevy 350 with less problems

[Goose]

uh oh...

[fifesjeep]

It's not a Jeep without an AMC Motor. :?

[Patf10]

how does a crossover effect performance, i have true duals on my cj. and where should a crossover be placed, does it matter how close to the engine it is?

[Goose]

Well on a vehicle as short as a Cj location on a crossover is where you can fit it.. but in front of the mufflers is the needed location, "Dynaflow" I think its is dynaflow anyway has a new crossover muffler out.. where the x pipe is incorporated intothe muffler for our application that would be pretty handy.. only one to hang and find space for.



Chevy?? in a Jeep?? on this board?? OMG.. :shock: Duck dude, duck.
:mrgreen: :mrgreen:

[tufcj]

If an "H" pipe is used with headers, generally, the closer to the collector you can get, the better the low RPM torque. As you move it back, it helps gain HP in the higher RPM ranges.

NASCAR teams did a lot of research on "H" pipes.

The problem on Jeeps is they usually have to go under the trans, forward of the skid to be of any real use. Right where they are most open to being crushed.

I run an "X" pipe on my AMX. I don't know if there are any real gains, because that's the only way it's been while I've had it. It does sound nice though.

Bob
tufcj

[JERSEYJOE]

I HAVE A PICTURE OF MY EXHAUST FABBED UP BEFORE I SENT IT TO BE JET HOT COATED. I CANT POST IT, CAN SOMEONE POST IT FOR ME IF I SEND IT?

[82Waggy]

Can't imagine a non-previously rebuilt 401 not needing to be bored - they are all worn out.