L18 8.1L swap resource thread

[Larry]

Larry,
I have some questions on what you are doing to remove and install the engines.

the manual says to attach J36857 to the heads using 9428217 and 15650963.

Do you have an alternate method that might be more easy to procure?


Thanks

I just lift them like any other old big block by bolting a chain to the heads. If you have any of the old lifting brackets that used to come on older SBC and BBC I would suspect they would work fine as well. I didn’t have any of those around. The tool numbers you posted are designed to help stab these engines into the GMT800 trucks where the engine fits deep under the firewall. If I recall those brackets also require the intake to be removed. They would be nice to have but not necessary for install into an older rig.

I didn’t use the orange equalizer bar on the burb (and actually haven't used that dumb bar in years). That bar used on the K10 tends to beat up the firewall while you’re trying to stab the engine. Don’t let the upside down hook in the picture at the front confuse you. The chain is bolted to the head with a large washer. The hook is just laying there

 

[efituned]

Looking to get a new/rebuilt alternator for an 8.1 I am rebuilding. The alternator that came with the engine doesn't have any part numbers. I am unsure which amp alternator to order. Are the housing different between the two amp ratings or will they both bolt up?

01 8.1 seems to have come out of a pickup.

 

[Larry]

Looking to get a new/rebuilt alternator for an 8.1 I am rebuilding. The alternator that came with the engine doesn't have any part numbers. I am unsure which amp alternator to order. Are the housing different between the two amp ratings or will they both bolt up?

01 8.1 seems to have come out of a pickup.

I like to use the 140 AMP CS144 series alternators from the older GMT400 trucks. Mine are from around a ’98 K3500 7.4L spec.

Or you can use as AD series like the GMT800 trucks used that would be stock to an 8.1L. These came in variety of amperage's from 105 to 145 amps. There may be other alternators that fit the bracket, I’ve just never checked because I prefer CS144’s. CS144's just don't get packed with dirt and crap like these AD's do.

 

[coloradoblazers]

I just lift them like any other old big block by bolting a chain to the heads. If you have any of the old lifting brackets that used to come on older SBC and BBC I would suspect they would work fine as well. I didn’t have any of those around. The tool numbers you posted are designed to help stab these engines into the GMT800 trucks where the engine fits deep under the firewall. If I recall those brackets also require the intake to be removed. They would be nice to have but not necessary for install into an older rig

I am planning on pulling this weekend from its doner....
Off the top of your head, do you know the size/thread of the bolts?

 

[Larry]

Not for certain but I suspect M10 x 1.50 since most everything else is that size and pitch on these things

I am planning on pulling this weekend from its doner....
Off the top of your head, do you know the size/thread of the bolts?

 

[zombiyjay76]

Not for certain but I suspect M10 x 1.50 since most everything else is that size and pitch on these things

Larry is right, just checked the bolts on my 8.1 that is currently on the engine stand.

Need to get mine installed already.

 

[efituned]

I'm in the process of assembling my engine and I am getting close to installing the intake. I ordered a victor reinz head gasket set, should I use those intake manifold gaskets? Should I replace my silver bolts with the updated bolts?

So far I've got the short block and heads assembled. Is there anything I should do differently then normal reassemble?

01 8.1

 

[-stew-]

I need to get cracking on my swap.

 

[Larry]

I'm in the process of assembling my engine and I am getting close to installing the intake. I ordered a victor reinz head gasket set, should I use those intake manifold gaskets? Should I replace my silver bolts with the updated bolts?

So far I've got the short block and heads assembled. Is there anything I should do differently then normal reassemble?

01 8.1

Sorry for the late reply….I was gone fishing for a few days.

Ya, for 2001 to early 2004 engines GM recommended replacing the intake bolts with 65MM 12561518 bolts. There are also 72MM bolts dealers often order by mistake. Take my word for it…those will break off in the heads on earlier engines when you go to torque them down. Ask me how I know


If you already have silver 65MM bolts just use what you got.

 

[efituned]

Sorry for the late reply….I was gone fishing for a few days.

Ya, for 2001 to early 2004 engines GM recommended replacing the intake bolts with 65MM 12561518 bolts. There are also 72MM bolts dealers often order by mistake. Take my word for it…those will break off in the heads on earlier engines when you go to torque them down. Ask me how I know


If you already have silver 65MM bolts just use what you got.

Those are the bolts I currently have...I'll use them. Does the oil pan touch the cross member between the frame rails with stiff engine mounts (ie. energy suspension)? Also, what's the best way to install that rear main seal without the special tool?

 

[Larry]

Yep, the 8.1L oil pan will interfere with the square body 4x4 engine crossmember. Discussed HERE

On the rear seal installation I have no suggestions as I’ve only used the GM factory tools for the front and rear main seal R&R’s.

 

[efituned]

Yep, the 8.1L oil pan will interfere with the square body 4x4 engine crossmember. Discussed HERE

On the rear seal installation I have no suggestions as I’ve only used the GM factory tools for the front and rear main seal R&R’s.

Thanks, I'll get that cross member ordered. Which engine mount brackets are you using? Tall/short clamshell or does it really make any difference?

 

[Larry]

Thanks, I'll get that cross member ordered. Which engine mount brackets are you using? Tall/short clamshell or does it really make any difference?

On the Polar Bear Suburban the actual mounts are the same old mounts that were on the TBI 5.7L with Energy Suspension inserts. The K10 actually has BBC mounts with Energy Suspension BBC inserts. Hard to tell there is any difference unless you had them side by side. Either way, you’re fine with BBC or SBC mounts as long as you use the Energy Suspension inserts or something along those lines. I can tell you for sure that new off-the-shelf China’s finest mounts from Napa or any of dime store parts stores won’t last but a few months with an 8.1L. My K10 ate two sets of new BBC mounts until I just went with the Energy Suspension insert route in old OEM mount cases. Story on that debacle HERE

 

[Larry]

Check out Hot Rod Magazine's "How to Find an 8.1L Big-Block" article...its pretty much like reading this thread all over again o_O

 

[max 02]

At least they added your Name and CK5

 

[-stew-]

Hmmm.....

http://racine.craigslist.org/pts/5231209406.html

 

[Mark1968]

Having your work mentioned in hrm is like hall of fame celebrity status. Did they contact you in regards to the article or what?

 

[Larry]

No, actually one of my friends on Facebook posted a link to their story on my wall and said it looked like they used all the info from my thread on CK5. I wasn’t sure to be pissed or humbled but after a few days I decided I was pissed so I sent an email to some friends at TEN: The Enthusiast Network magazine group (HOT ROD, Peterson’s 4-Wheel & Off-Road, FOUR WHEELER, Motor Trend, Etc.) where they looked into it and agreed then added the CK5 blurb. They still didn’t give full credit to CK5, they only said “To see more more…..”

You know, the magazine guys are no different than anybody else and must research their info online like the rest of us but at least he could have given credit to the source where he acquired his information. It’s not uncommon to see the editors of 4-Wheel & Off-Road and FOUR WHEELER credit CK5 for story sources so it was shocking to see HOT ROD not following suit.

 

[efituned]

From the research I have done, seems that the 87 fuel pump unit is the one to have with a EP241 pump... Will this setup work in a stock 86 tank? I'm not wanting a external mounted fuel pump. Would it be easiest to buy an 87 fuel tank?

 

[Larry]

Well, sorta…..for a square body truck, a 1987 TBI tank (with baffles) along with a 1987 TBI sending would be needed to run an in tank pump. Although, the pump of choice is actually an EP381 rather than an EP241. An EP241 will run it but it is taking all that pump has to run any sequential port injected engine at wide open throttle. EP241’s were intended for TPI engines in old F-bodies and Y-bodies that required 43 psi (3 bar) fuel pressure whereas the EP381 has the correct rating to run 8.1L’s, Gen III LS engines, Vortec 4.3,5.0 & 5.7’s, etc. that require 62 psi (4 bar).

You may have read some really old threads where I stated that I used EP241 for the 8.1L in my K10 but that was in back in 2007/2008 when I ran a MEFI-4 ECM (Ramjet 502/Marine ECM), which batch fires the injectors on speed density fuel calculations rather than sequentially injected with MAF. Batch fire is exactly what the old TPI engines ran at 3 bar.

Long story short…..an EP381 is the correct pump to use on the 1987 sending unit and tank. Those bits may fit a 1986 tank but the 1987 won’t have the baffles for an in-tank pump where fuel could run away from the pump on turns and stops. I purchased new 1987 Spectra Premium fuel tanks through my local Napa store along with new Spectra Premium sending units. They’re expensive but Spectra builds top quality stuff 1000Xs better than the LMC China’s finest junkass fuel tanks.

Ya, don’t bother with an external frame mount fuel pump. Been there, done that and it isn’t a reliable and durable not to mention loud and annoying. Frame mount pumps are barely adequate and reliable for 12 psi (1 bar) fuel systems like old TBI engines let alone a 4 bar system.