4.2 & 4.0

[stroked88]

how do you distinguish the 4.0 from the 4.0. did the 4.0 every have a mechanical fuel pump?

 

[CanMan]

how do you distinguish the 4.0 from the 4.0. did the 4.0 every have a mechanical fuel pump?

The 4.0 is the same as the 4.0. :doh:

The 4.0 didnt have a mech. fuel pump.

 

[stroked88]

my bad i meant 4.0 from 4.2 ha
and so this engine in my shop having a mechanical pump should make it a 4.2 correct?

 

[Talyn]

As far as I know all 4.0L have an electric fuel pump. Do you have an engine block or head casting number?

What do you mean by "shop"?

 

[stroked88]

our personal shop where we work on our racecars. if it were i business i would hope i could tell haha. its just a motor we have in there idk where it came from but i blew up my 4.0 last weekend and was thinking about doing a stroker if this motor was a 4.2. im kinda new to the jeep motors so i thought i would come to the all know haha

 

[Talyn]

Yeah, I was going to say...

There were other inline 6s besides the 258. Your best bet is to pull the oil pan and find the casting number on the crank if you are looking into a stroker.

 

[stroked88]

besides im only 16 ha was there one specific casting number for 258 cranks or are there several? you seem pretty knowledgable so just thought id ask

 

[Talyn]

3 common casting numbers for the 258 cranks

258 crank casting numbers
1972-74__3214723________8120508 12 counterweights, 66lb, 64mm nose
1975-79__3214723________8125450 12 counterweights, 66lb, 64mm nose
1980_____3214723________8132619 12 counterweights, 66lb, 64mm nose
1981-86__3235477________3235444 4 counterweights, 46lb, 64mm nose
1987-90__3727___________53005535 4 counterweights, 46lb, 54mm nose

258 block casting numbers
70-'72: 3199962
'73-'74: 3218618, 3222380, 3213867
'75-'79: 3227445, 3224098
'80: 3235077
'81-'89: 3235444

 

[stroked88]

which is most desirable?

 

[gradon]

Auto/manual, street/offroad(%), low/high rpm?

 

[Dr. Dyno]

See if you can understand what this means:

4.0 + 4.2 = 4.5

 

[stroked88]

manual trans,street 75% off road 25% low rpm (below 2500-3000)

 

[stroked88]

looked at the block castings and it is a 258

 

[Talyn]

The heavy 12 weight crank would be better for you since you have a manual transmission and low RPM.

So, which crank does it have?

 

[stroked88]

according to the casting numbers it is and 81-89 and has the 4 cw crank and im not sure on the snout length. ill prolly have the pan off of it later this week. cant work on it till i get the racecar done and out.