JMG2

I have a ~1988 block, which came (I believe) from a 1988 c1500. that I dropped into a jeep cherokee. I'm posting in here because you guys have the most experience dealing with these types of blocks...


Far as I can tell, the motor was spec'd at ab out 210hp/300tq from the factory in 1988. I put in a crane cam (specs below), a holly terminator EFI, headers, single exhaust( thought it's mandrel bent, 2.5" on each side into a 3" y-pipe), stock heads.

Just curious, roughly what HP/TQ would you rate this motor?

EDIT: finally pulled the valve covers to check the heads.

I confirmed I have 193 heads (14102193). the Cam is:

crane
SB-Chevy 262-350ci
Lift: .420''/.442''
Duration: 278°/288°
RPM Range: Idle-5500

and I have short tube headers. Efi (not that that makes a differnece), edlebrock performer intake.

Tom400CFI

Not enough information to make a good guess, but a couple things.

L98's never went into trucks...though they certainly should have!
An '88 truck w/an 350 would be an "L05". Those were only offered with pretty terrible, "swirl port" 193 iron heads, carb looking/style intake and TBI. They were offered with two different cams; one giving 190 hp the other giving 210 hp.

I didn't see the cam specs in your post, we don't know what intake you're running, or what kind of headers. The "Holley Terminator EFI" is an engine control system, so no power from that...

We need more info, but it sounds like you're got an LO5 with headers, exhaust and a cam of unknown specs. I highly doubt that you're doing any more than 230hp from the limited info given.

Bendeco

250 hp.

JMG2

ok, I may be confused as to the motor.
I ran the stampings down as much as I could, and the best I could find is that it is an L98 block. I assumed this was something different than the l98 motor they put in vettes... especially since it has iron heads and a carb. did GM ever make an l98 block that was used in differnet applications, that is different than the l98 in vettes?

Anyway, the date stamp on the original motor puts it at 1988. It is a 4-bolt main, with center bolt valve covers.

How can I tell what kind of heads I have?

Also, the cam specs are :

Crane
SB-Chevy 262-350ci
Lift: .420''/.442''
Duration: 278°/288°
RPM Range: Idle-5500
View Graph
350-2102

I'm running an edlebrock performer intake, fwiw.

Tom400CFI

O.K. Now we've got something. Intake and cam are very close to stock replacements. A little better....but only a little. I'm still at ~230hp. Those heads are HP killers. Terrible. You can confirm the heads by pulling the valve cover and looking at the casting number. If it ends with a "193", that isn't good.









L98's came in 'Vettes and F-bodies and that's it. No aluminum heads in the F-bods though and other slight differences such as lower intake bolt holes, exhaust manifolds, etc.

JMG2

Thanks... this is all very helpful. I just had the @#$@# valve covers off last week-- I believe there's a casting number by the distributor, I'll see if I can find that when I get a chance.

I'm with you on the 230ish number.. I'm comparing this by seat-of-the-pants to my 1998 5.9 motor jeep grand Cherokee, which had about 230hp/340 tq in a heavier package... this motor (the one we're talking about) seems to pull just a bit harder, which could either be due to more power or the lower weight of the Cherokee.

Anyway, my guess is all very unscientific, but you're in the range I would have guessed.

how much do you think on torque? The truck seems really good on low-end torque (which was my goal-- this thing sees most of its time offroad, and hardly ever is over 10 mph)... offfoading I barely touch the gas to drive over rocks .... I'm guessing around 300 ft/lb?

Also, I basically have a stock, small-cap HEI distributor. I'm considering upgrading, but wondering if this would be worth it. My thinking is that upgrading to an electronic distributor that can connect to the terminator EFI will give better throttle response/possibly more power, but not sure it's worth it

And by the way, I am a 'vette guy (I have a c2 and a c5)-- this just happens to be my project of the moment -- I started this over ten years ago, and when I did this swap I was young(er) and stupid, and had 350 hanging around that "must" be better than the i6 in the Cherokee, and decided to drop in... if I had thought this through more, I would have spent a few extra $$$ and went with a real l98 or a lt-1 (ls motors were still pretty expensive when I did this swap).

Tom400CFI

I'll bet that '80's style Cherokee feels fantastic w/a V8 in it! I used to have the '88, red, 4.0/5 speed package (that was so popular) and it was no slouch -for the time. Mine wasn't even the 190 hp "HO"...I think mine was 170hp? Yeah, one w/a V8 would be a hoot!

I'd guess you're around 320-340 tq. That engine was rated at 300tq, the cam and header (especially) probably helped tq a little and also probably moved the tq peak UP. I doubt that any of the parts hurt the low end tq (tq @ ~1000 RPM), but probably improved it in the 3000 RPM area. Especially if the headers are long tube. The heads would actually help the LOW end tq...but it's obvious in the pics how they aren't helping high RPM breathing. Watch out for drive shafts and rear ends; I blew both on mine...w/the 6 cylinder. I don't know WHAT the deal is w/the drive shafts. I turned 3 of them into "candy canes" with the stock set up...one of them I twisted on dirt!

I don't think changing the type of distributor will gain you anything. Gains aren't typically made in the ignition system....if they were, you'd see A-B dyno graphs all over showing it....and you don't. This is especially true on a lower RPM, lower cylinder pressure engine such as the one you have. HOWEVER, it sounds like you are thinking about this for timing control. What is controlling timing now? Mechanical/weights? Or is it and electronic HEI that you're running with static timing? If it's not connected to the Holley, and you don't have the Chevy ECM running it, what runs it?

JMG2

Yup-- 170 hp, 212 tq in that year. It's deifnitly a hoot to drive-- sounds like a nascar going down the road, although my offroad club hates being in back of me on the trails -- the exhaust note can get a little mind-numbing after awhile.

Thanks. I haven't yet figured out what kind of heads I have, but given my luck, they'll be the crappiest kind GM offered that year. the headers aren't long tube, unfortunately. engine bay in the Cherokee is a bit cramped, I'm lucky I found an outfit that makes parts specifically for swapping a 350 into the Cherokee.

Right now I'm only running 32" tires, and have a "super" (30 spline) front and rear diff, w/ 4.11 gears and a Detroit. The Detroit solves many of the issues of the stock 35, as obviously does the increased spline count.
That being said -- a Ford 8.8 and 35" tires are definitely in my future (I hate going to ford, but the 8.8 is practically a direct swap in for the Cherokee, is stronger than a dana44, and are dirt cheap.)

I'm currently running a stock small cap w/mechanical+ vacuum advance. I'm thinking of doing an MSD with electronic control -- the holley EFI has a direct hook up for electronic ignition and can control it directly.

Thanks for all the input!!! now if I can just identify exactly what kind of block I have ... I'll see if I can't find the casting numbers on the block.

Tom400CFI

Copy all that....sounds like a FUN project, to me.

I built a Jeep YJ for my bosses boss (the GM of the resort); junk yard 350, NV3500 5-speed, stock 231 T-case, Re-arched springs, 35" tires, outside the frame long tube headers, bullet muffs and turnouts (side pipes) with a 3" crossover pipe...man, that thing sounded delicious!

I posted up the whole conversion on a Jeep forums, and everyone lambasted me for keeping the stock D30 rear. Well, that rear has been in there for over 10 years now...still going. IDK WHY the rear in my Cherokee died. I developed a grumble noise on a road trip. I checked the pinion and it was totally loose. That was the end of it. Stock sized tires even. (?)

Moving to an electronic distributor will give you more control over timing curve; it can become "3D", which is nice if you're interested in fuel economy, EGR, etc. If you're not going to exploit those features, then you won't gain any peak power or tq that you couldn't gain by playing with weights and springs. Since your engine controls support timing control though, it's almost a no-brainer to swap to an electronic distributor.


W/regard to the block, all '80's GM blocks are functionally the same. The block from an "L98" may be identical to one from an L05. The only changes that I can think of at the moment are:
*R or L dipstick location,
*2 or 4 bolt mains
*one or two piece rear main seal, and
*flat tappet or roller cam blocks.
As far as strength, buildability, parts interchangeability etc...is concerned they're all pretty similar/interchangeable.

JMG2

ok, so I got my head under the hood, and tried to decipher the stamps on the driver's and passenger's side.
Pictures are below (as well as a few pics of the entire motor). far as I can tell, the driver's side is either GM 87LG sg1 or GM 57LG sg1
The passenger side looks like 318 1486, but I put pics below for people that are more familiar with deciphering these stamps.

JMG2

sorry to resurrect an old thread.
Finally got around to pulling the valve covers off.
So I confirmed I have 193 heads (14102193). the Cam is:

crane
SB-Chevy 262-350ci
Lift: .420''/.442''
Duration: 278°/288°
RPM Range: Idle-5500

and I have short tube headers. Efi (not that that makes a differnece), edlebrock performer intake.

I've done some research on these heads-- I'm using them in a low-idle offroad, crawling application, looking for low end torque, from what I read, these aren't terrible heads, but I'd love to hear thoughts on them. I'm itching for a winter project to do, if I can get a decent amount of more low end torque out of a swap, a may do it.

cv67

4bolt block wasnt from an L98 but a bonus if you have it
Heads for off idle grunt and rock crawling probably fine
Wont make any real hp with them but for a jeep who cares go play

Tom400CFI

The most practical way to get more low end tq is with more compression. IDK if your combo can take more compression w/o detonation....a more modern/aluminum head would help in that regard, but you'd be spending $1500+ to gain what...20 lb-ft at 1000 RPM? Probably not worth it.

Money could be better spent on a stroker kit.