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1985 Buick Riviera Swap 307 to olds 350


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Hello Everyone I plan on swapping out my 307 for a 68'-77' Olds 350 and eliminating SMOG bs. I know I have to get a non-CC Carb and Distribtor with advanced vaccum canister. (what I was told)... What else is needed and other tips would be great! Thank you!

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I replied to your PM on the other forum, but in case others are interested, here's that info:

 


The 350 is pretty much a bolt-in. Note that unlike every other 1968-1990 Olds V8, the 307s used with the TH325L4 transmission in the FWD cars used a smaller diameter flexplate. You'll need to transfer that flexplate to the 350 for the swap. Balance should be the same. Use the FWD oil pan and pickup from the 307. Transfer the entire water pump, pulley, and accessory bracket setup from the 307 to the 350 to ensure everything lines up. The two motors are externally identical. You'll also need to use the 307 FWD exhaust manifolds on the 350. You'll need to transfer the oil filter adapter from the 307 to the 350, as the FWD installations use a different adapter to change the oil filter angle. Note that because of this, the gasket between the adapter and the block is different. FelPro no longer lists the correct Toronado gasket, and most vendors (like RockAuto) incorrectly show the RWD gasket for this application. That is not correct. You can cut your own from gasket stock, or spend big bucks and get one from the GMC motorhome parts suppliers. What I find frustrating is that FelPro still includes both style gaskets in their engine rebuild gasket set, but they do not list the Toro gasket separately. I've probably thrown a dozen of those away over the years.

Deleting the ECU will have a couple of other minor impacts. The biggest is that your lockup torque converter won't any longer. You'll either need to live with this or get an aftermarket lockup kit. Similarly, the evap purge system won't work any more since the ECU controls the purge solenoid. You'll need to rig up a timed port system the way they did it in the 1970s if you care. Finally, since I assume you'll be deleting the A.I.R. system, that means that you won't get cooling air blown to the converter when the ECU is in closed loop mode. Eventually this can cause the converter matrix to melt down and plug the exhaust. An aftermarket converter can solve this problem (if you plan to retain it).

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While I really like the Olds 350 (had a 69 Rallye 350 for a while), for the Riv I'd tend toward rebuilding the 307 to '85 LG8 specs. '86 got roller lifters but not as good a cam. Both had contemporary emissions certs and is a lot of information on ALDL ECMs. With a 200 or 700R4 tranny it would be a nice cruiser.

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22 minutes ago, padgett said:

While I really like the Olds 350 (had a 69 Rallye 350 for a while), for the Riv I'd tend toward rebuilding the 307 to '85 LG8 specs. '86 got roller lifters but not as good a cam. Both had contemporary emissions certs and is a lot of information on ALDL ECMs. With a 200 or 700R4 tranny it would be a nice cruiser.

 

No, you didn't either. The Rallye 350 was 1970 only. And Olds started using roller lifters (and the crappy 7A heads) on the low-perf VIN Y 1985 307s. The OBD I ECU used with the CCC system is pretty stupid and has very limited telemetry. The TH325L4 that's already in that Riv is just a 200-4R bent in half.

I have to say, I really don't get the "easier to rebuild the 307" thing. The two motors are externally identical. I suspect the OP plans to delete the ECU either way, and 90% of the things I mentioned in my first post relate to that, not to the swap itself. You can run the 350 on the CCC system. Swapping the oil pan, flexplate, and exhaust manifolds is trivial.

Edited by joe_padavano (see edit history)
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Thank you, thought 69 but that may have been my mother's Cutlass 350, did not return from SEA until Feb 70. Remember most the screaming yellow and lack of chrome.

 

My memory of 50 years ago is more "what" than "when". I appreciate the correction.

 

I like the GM Computer Command Control, first series (pre-P4) was an 8 bit processor with 2K (AFAIR) memory. Do remember disassembling one in about 83-84 with a VAX. Have the printout.

Edited by padgett (see edit history)
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