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Discussion in 'The Injection Section' started by az_762_nato, Aug 11, 2016.
This is going to be the "pre-winter" mod I guess, because remote start!
Looks like a driveway full of fun
Yikes. Why do I hate electrical stuff so much?
I hate electrical too, but my love for easy starting when it's 5 degrees outside, and remote start having the truck and heater warm for me won out this time. This stuff is going to go in the 73
Looks like a lot of your wires are marked so that will help. I've done a couple of these conversions, so post up here if you need assistance
Yup, I've been going through and deleting unneeded things from the harness and labeling each circuit as I go. The only thing that I'm really not too clear on is which TBI adapter plate I'll be using. I don't know which one (front, center, or rear mount) works best with the factory cables and brackets
Is the throttle cable (at the carb) an eyelet with the circle clip or the stud & ball?
I changed the cable on my 72, but the 77 I only had to make some minor mods to use the factory bracket and cable assembly
It's the stud and ball. This is what it all looks like now, all factory except the hei swap
On that I pulled the cable (not the sheath) from a newer and strung it through the original sheath, so it would match the TBI throttle control
I finally got the time to finish marking and modifying the harness. I took your suggestion and grabbed a cable inside from a parts yard truck. I still have to order a universal kickdown cable and cable bracket, plus find someone (preferably local) who can flash/program/magic spell the ECM to make sure its right for a 350 with auto trans and get rid of the EGR function.
Minus the EGR removal, a stock prom will work.
I had it removed from mine, as well as the VSS. If you have means to run the VSS, it's nice.
I had Howell Engineering flash my last 2, they are the original designers of the system. Runs a little over $200 for a new prom, but I haven't found anyone yet that was unhappy with their work.
If you plan any engine mods, do them before you get it burned
I'm gonna leave the VSS out for now, but will probably be adding it in at a later point. I'd have a shop do the egr removal for me, but can't afford the $$ for just that (waiting on the VA), that's why I'm hoping someone local is set up, or someone from ck5 that I can mail the ECM to. Truck is staying stock '73 350/th350/203 with no mods under the hood, and no lift or gears
If you dont run a vss, you will want it programmed out. I would do some price checks before committing to anyone doing the chip.
There are several different ways that guys program the chips. Some of them range from tricking the temp to make it run more fuel, jumpered reprogrammable chips, or a complete tune setup on a new prom.
Might looks at moates.com, they offer a way to burn the programmable chips. I didnt find it cost effective for me, but it does show how a lot of guys do their own. Additionally, it is how quite a few of "tuners" will adjust your prom.
All interesting, and an enlightening way to help decide what is best for you
Honestly hoping someone on here has the ability to verify the BIN is 5.7 with auto and shut down the egr, I don't do electronic stuff and thanks to the VA I'm not in a position to drop a few hundred bones on tuning, it's just a stock 1973 350
What's the "BCC" (Broadcast Code) on the PROM? Take the small cover off the ECM (two small screws) and you should be able to see it. SOMETIMES the BCC is on the sticker on the outside of the ECM housing. The PROM comes out easily if you need to remove the blue cover to see the BCC. This may help you: http://www.gearhead-efi.com/BCCFind/
Be a bit careful thinking you can just do X and Y without causing issues. These setups run like they do because they are a system. When you start removing things that are part of that system (VSS particularly, EGR is not an issue) then you are detracting from the factory programming. Separately, the MAP systems rely on volumetric efficiency calculations to fuel the engine...a 1987 TBI engine undoubtedly has different VE than what you put TBI on.
Not saying it won't run ok, not saying it will be so terrible you'll hate it. Just that it's only going to run *right* if it's on the exact same engine combination it came off of, if it's not tuned. Compression ratio, CC of heads, head flow, combustion chamber and intake runner design, exhaust, it's all going to affect VE. Timing is another animal. It gets fairly complex, not necessary to really comprehend the intricacies if you are having someone else do the work, suffice it to say, the only real problem on a fairly stock engine of same displacement is going to be how it runs cold, and the air:fuel ratio when you are on the throttle. Those are the two places the system can't compensate for minor changes on its own. VSS is possibly going to cause issues with deceleration and mileage, but if you want to keep the truck fairly stock, your only option there is one of the VSS generators as sold, or to swap in a later speedometer, and I can understand why you wouldn't do either of those.
Definitely not saying it's the end of the world. Just offering some advice that might give you a slightly different viewpoint.
In your case, I'd look at Howell for tuning, since it sounds like they are doing a good job. Chip burning on these old ECM's is tedious and the tools costly, and if you don't like dealing with electronics and what not, probably wouldn't like that learning curve. Besides, if it's programming once or twice, I just don't see the cash and mental energy outlay offset by the result.
I do have a VSS I'll be using, it attaches to the speedo cable. My ECM is a 7747, and BCC is ABHL which should be a 305 with an auto
I'd have to look at the truck PROM's to see, but suffice it to say that the fueling and timing will both be quite wrong. Never got into the 305/350 differences, but if the injectors are different, that's a no-brainer that it's not going to work as-is. None of the differences are insurmountable with basically stock engines, just going to need a tune to remove EGR and burn a chip that gets you close enough. (What I mean is, you will have to have a chip burned to remove EGR anyway, so a tune at that time makes sense)
Bad thing is, anyone worth their salt is going to want a datalog, and I'm not sure how cheap you can get an ALDL cable anymore. Anyone close to you that has an ALDL cable?
Datalogs are good, but a stock 73 motor is almost identical in cam/compression as a 7747 ECM 350. No data log is needed to just remove the EGR
@az_762_nato I have a stock prom for a 7747 350. Let me see what it is exactly. You're welcome to it if it works for you. I'll be in the springs tomorrow as well
210HP and 9.3:1 compression for the L05 1/2 ton variant is a substantial amount more than what a 1973 engine had, 155HP and 8.5:1 compression for the 1973: http://brochures.slosh.com/index.shtml?1973
~26% difference in output. That's more than I expected actually, and gives me pause. But going backwards, the problem will be rich, not lean, so a different issue.
You'll smell it on cold start, if it's an issue.
I plan on eventually having the stuff to datalog the obd1, and eventually il have to learn the TBI programming, my 75 that Shawn is building has a TBI engine.
@bent72 , thank you! I really appreciate it and it should get me up and running once I start the install on Monday morning
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