Need help bad series 1 and series II

[Twobonnie]

I have a 1990 bonneville that i and trying to build but the head gaskets are blown and i was just given a 1997 olds 88 with a series II engine with the top end just being rebuilt. i was wondering what would i have to do to make the engine work in the older car or would it just be better to pull the heads and just use the series II heads? I am new to this site and i hope someone here can help ive owned my 89 bonnie forever and now i have another but it needs alot of help so anything would be helpful thanks

[RJolly87]

The two engines are incompatible in the sense that you wish to use them. You can swap the entire drivetrain, computer, etc into the Bonneville body however. Also keep in mind that the LN3 is 'Pre-Series 1'. 'Series 1' started with the L27/L67. You can swap parts over from the L27, but cannot cross over in to Series 2, or the L36/L67.

[Twobonnie]

So basically i cant swap the intake and use the motor and odds and ends id just have to swap the whole motor and ecu? And if i do just swap the motor would the trans bolt up to the block 440t4 trans i think thanks for the help so far man im just trying to see if there is any possible way i could use the motor without alot of stressful work

[redzmonte]

doing a SII swap in a SI Car is going to be a bigger headache then fixing the SI. you can do the swap but you will need the ECU, Harness, Fuse boxes, Transmission and axles out of the SII car.... then the hard part starts.. I did a SII L67 swap in a 91 Z34 lumina and it wasn't as easy as just plugging it in to make it run...

S

[Twobonnie]

I understand it not that easy but given i was just wondering couldnt i just swap heads from the sII to the LN3 i have or is that impossible im just trying to cut a corner. Quickest rout would be? Does anything swap over from sII to SI? I am trying to build my car quick as possible

[RJolly87]

The heads are not interchangeable.

The 3800 does not blow a head gasket without a good reason (usually catastrophic overheat) and there is typically an equal chance of other damage as well.

You must find compatible heads. I am fairly confident that the L27 shared heads with the LN3. The internet also suggests that 3.3 heads could be the same.

My vote is sourcing a used engine/block based on the failure, because of the possibility of other damage.

[Twobonnie]

Hmm thats bummer i was really hoping that i could have used the heads so now im at a cross roads does anyone know of a build thread for a SII swap in a older 87- 91bonneville that I could follow? And thanks for the help guys im just stuck because there same motor 3800 231c.i. Motor but they don't cross is it kinda like LS motors compared to old 350's i know its apples and oranges but anything helps thanks guys.

[MattStrike]

As far as a build thread, nothing really that I'm aware of. It's really straightforward though. Anybody (dare I say it) that can pull a motor can do one of those swaps if they had the service manuals. I have been working on the schematics for an adapter for the firewall pass-through.

[95naSTA]

does anyone know of a build thread for a SII swap in a older 87- 91bonneville that I could follow?

http://www.gmforum.com/your-ride-gm-pic ... ne-217534/

There you go.

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