What to do about my stock ECU

Do yourself a favor and put the hvac box in, or convert to the smaller heat only box. You'll like the option to defog.

Also, you don't need the ecu at all if you're modifying the engine. Ecu won't tolerate much if any modifications.
Just get a good name brand HEI distributor and a quadrajet rebuilt by a reputable company like Everyday Performance LLC. Not a parts store reman. Not a Kung pow Amazon special. Just because it's shiny doesn't mean it's good.
Also, because I think they're cool, progression ignition makes a distributor you can control with your phone. Timing tables, start retard, ignition lock out, vacuum advance, really neat units.

If you do have a lockup converter transmission, just get a non lockup th350. They're literally everywhere and have better torque converter availability. Unless you really care about the 300rpm drop when it kicks in, and feel like wiring up a system to make it come on and off in a not annoying fashion.

MrSony said:

Not a Kung pow Amazon special. Just because it's shiny doesn't mean it's good.

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ROFLMAO 🤣 🤣

MrSony said:

If you do have a lockup converter transmission, just get a non lockup th350. They're literally everywhere and have better torque converter availability. Unless you really care about the 300rpm drop when it kicks in, and feel like wiring up a system to make it come on and off in a not annoying fashion.

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i would go against that advice, just me, and wouldn't be 100% against either. i have a 200 4r and try to stay off highways as much as possible and mostly cruise backroads @45-50 mph in D but its nice to have the option i also have 3.73s stock. besides, hookin up a hommade switch or whatever is FAR more cheaper than than getting a new trans which was not expressed as being troubled. i hope it is a th350 of sorts specimin and not some other used in those yrs. FYI to OP lockup is good for keeping heat down & mpg up.

correct me if wrong with the lockup 200 4r when it goes into OD the circulating coolings system shuts off as goes into lockup cuz not needed for being a straight eng to rear sync system. how that translates to th350c idk.

MrSony said:

Do yourself a favor and put the hvac box in, or convert to the smaller heat only box. You'll like the option to defog.

Also, you don't need the ecu at all if you're modifying the engine. Ecu won't tolerate much if any modifications.
Just get a good name brand HEI distributor and a quadrajet rebuilt by a reputable company like Everyday Performance LLC. Not a parts store reman. Not a Kung pow Amazon special. Just because it's shiny doesn't mean it's good.
Also, because I think they're cool, progression ignition makes a distributor you can control with your phone. Timing tables, start retard, ignition lock out, vacuum advance, really neat units.

Click to expand...

just a FYI i once bought a GMPP their 330hp ho 350 and hooked it up to all 86 monte ss emissions ecm stock and it worked fine. maybe didnt quite get the full advantage of that motor even with TES (when those headers existed) but if lookin to start del emmisins equip just go all the way.

that was 22 yrs agoish, if i had a hyper chip in it and didnt know it that chip got smoked and a dealer put in a new GM chip. now i'm gonna put out my understandings and correct if wrong. all the ecu, ecm computer chip does is its programmed to basically monitot the system and keep emmissions within certain perameters for normal driving conditions. WOT, advancing timing, it cant adjust for with Qjet stuff but once WOT its not really there doing anything of significance making hyperchips of that era a scam for the gbody boys, it just sounded cooler than really was.

MrSony said:

and a quadrajet rebuilt by a reputable company like Everyday Performance LLC. Not a parts store reman. Not a Kung pow Amazon special. Just because it's shiny doesn't mean it's good.

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YEP! been there done that. A team performance roch qjet.... just a avg qjet that i bought to hopefully hurry along a engine swap while waiting for a jet performance AMAZON reg stage 2 to show up.... lol the A team a $300.00ish pos remove from box & throw in the trash. my mech put it on said car surged with no fix and found base plate where throttle pin is was hogged out from wear. i gave my jet perf Qjet and it works to this day. now i had previously bought a stage 2 Eqjet from jet for the 330hp ho (which had same compression as what have now) apparently not a fluke that not getting that teen angst of that deep high pitched YUHGLUGLUGLUGLUG we expect outta the 2ndaries the Qjet provides us in mid life crisis. both same result but they still scoot(ed) even 305 on same Eqjet.

this guy i seen recommend SMI think was? for qjets.... im not a reg fan of this guy nor any exp with anything he recommends. i just cant reccomend what i experienced.

If you ditch the ECM, make sure the A/C doesn't have a relay controlled by that. I ditched mine and bypassed it. The ECM has final say on giving the ground to power the compressor.

Hutch