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06-08-2009, 03:41 PM | #1 | |
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Re: Tbi swap build thread
Quote:
2) SBC and BBC harnesses are nearly identical with few exceptions: a) BBC used different IAC motor and connector is different - four wires. b) TPS may be different, early BBC used lever style TPS adjustable, while later used throttle shaft style - similiar to cars. Different connector. c) Some HD BBC did not use knock sensor (KS) and ESC modules - these engines used 1228747 ECM and can be positively identified by broadcast code printed on ECM label (four letter code). 2-1) You'll have to use 454 TBI ECM with your swap to keep things easy. In general 1227747 ECM (when loaded with appropriate BCC EPROM) was used with V6 (4.3L) and 305/350 SBC V8 and some 454 BBC. The 1228747 ECM has identical harness interface minus KS functionality for HD application. You can swap out your SBC 7747 ECM for 8747 when you perform the swap. Other than aforementioned points 2a and 2b SBC harness is good to go. //RF
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"The Beast" 1975 Chevrolet C20 longbed 350/700R4! with 3inch body lift Dual Flowmasters Super 40's! TBI retrofit completed (2007-07-29) New 383CID (+030) 08-304-8 9.5:1CR x36,005 (2012-12-17) |
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06-08-2009, 03:54 PM | #2 | |
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Re: Tbi swap build thread
Quote:
Thanks for the help!
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Bob 1970 Chevy K10 LWB "Goldie" 350/TH350 next project!! 1981 Chevy C10 LWB 355/TH350 - My son's truck LS SWAP FORUM! Tons of LS swap info here! PLEASE CLICK HERE TO SUPPORT THE GREATEST BOARD ON THE NET! CLICK HERE FOR THE FAQ INDEX by KRUE Last edited by glock35ipsc; 06-08-2009 at 03:55 PM. |
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06-08-2009, 05:01 PM | #3 | |
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Re: Tbi swap build thread
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The reason being that the BBC TB has 50mm bores and 80 or 90 lb injectors vs. SBC TB 46mm with 40/55/64 lb injectors depending on engine size. You may be able to get 454 started, but the moment you ask that 454 to deliver power it will lean out and fall on its face. IMHO the swapping harness connector ends is straight forward, except for IAC which may require pin swapping. I believe that I have a set of notes related to this issue. To me revamping harness to mach sensors (2x) is not that difficult. Take a look at two TBI (SBC/BBC) setups first before jumping to any conclusions. //RF
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"The Beast" 1975 Chevrolet C20 longbed 350/700R4! with 3inch body lift Dual Flowmasters Super 40's! TBI retrofit completed (2007-07-29) New 383CID (+030) 08-304-8 9.5:1CR x36,005 (2012-12-17) |
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06-08-2009, 05:31 PM | #4 |
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Re: Tbi swap build thread
Thanks for the info! I know getting a little ahead of myself here, as I haven't taken possession of either truck yet. Just trying to refresh my knowledge of these TBI's after not messing with them for 20-some years.
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Bob 1970 Chevy K10 LWB "Goldie" 350/TH350 next project!! 1981 Chevy C10 LWB 355/TH350 - My son's truck LS SWAP FORUM! Tons of LS swap info here! PLEASE CLICK HERE TO SUPPORT THE GREATEST BOARD ON THE NET! CLICK HERE FOR THE FAQ INDEX by KRUE |
06-09-2009, 08:50 AM | #5 |
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Re: Tbi swap build thread
Excellent, thanks for your time and effort in this thread! And cjracing15 too!
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Bob 1970 Chevy K10 LWB "Goldie" 350/TH350 next project!! 1981 Chevy C10 LWB 355/TH350 - My son's truck LS SWAP FORUM! Tons of LS swap info here! PLEASE CLICK HERE TO SUPPORT THE GREATEST BOARD ON THE NET! CLICK HERE FOR THE FAQ INDEX by KRUE |
06-12-2009, 02:12 PM | #6 |
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Re: Tbi swap build thread
Hey guys I put on a summit brand fuel fuel pump that is rated at a free flow rate of 43 gph and a max pressure of 85 psi will this work as is or should I regulate it somehow?
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GO BIG GREEN GO DUCKS MEMBER #6377 72 k-5 daily driver 6'' lift 35'' 350-350-205 slowly getting rust free. Project "7DEUCE" check out my build http://67-72chevytrucks.com/vboard/s...d.php?t=267665 Tim Powell..R.I.P EastSideLowlife..... R.I.P.. |
06-12-2009, 02:27 PM | #7 | |
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Re: Tbi swap build thread
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//RF
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"The Beast" 1975 Chevrolet C20 longbed 350/700R4! with 3inch body lift Dual Flowmasters Super 40's! TBI retrofit completed (2007-07-29) New 383CID (+030) 08-304-8 9.5:1CR x36,005 (2012-12-17) |
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06-12-2009, 03:04 PM | #8 | |
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Re: Tbi swap build thread
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Walbro is one of the few mfg that publish their performance curves. and another But you get the idea...
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"The Beast" 1975 Chevrolet C20 longbed 350/700R4! with 3inch body lift Dual Flowmasters Super 40's! TBI retrofit completed (2007-07-29) New 383CID (+030) 08-304-8 9.5:1CR x36,005 (2012-12-17) |
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06-12-2009, 02:43 PM | #9 |
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Re: Tbi swap build thread
I have 3/8 return line so I should be ok then sweet..
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GO BIG GREEN GO DUCKS MEMBER #6377 72 k-5 daily driver 6'' lift 35'' 350-350-205 slowly getting rust free. Project "7DEUCE" check out my build http://67-72chevytrucks.com/vboard/s...d.php?t=267665 Tim Powell..R.I.P EastSideLowlife..... R.I.P.. |
06-12-2009, 03:47 PM | #10 |
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Re: Tbi swap build thread
Very nice....
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GO BIG GREEN GO DUCKS MEMBER #6377 72 k-5 daily driver 6'' lift 35'' 350-350-205 slowly getting rust free. Project "7DEUCE" check out my build http://67-72chevytrucks.com/vboard/s...d.php?t=267665 Tim Powell..R.I.P EastSideLowlife..... R.I.P.. |
06-17-2009, 08:42 PM | #11 |
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Re: Tbi swap build thread
Ok guys heres an update I got her running but not very well Im in the process of tracking down the check engine light and varrious odds and ends.. Can anyone tell me where this green box goes? And whats the deal with the light at then end of it?
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GO BIG GREEN GO DUCKS MEMBER #6377 72 k-5 daily driver 6'' lift 35'' 350-350-205 slowly getting rust free. Project "7DEUCE" check out my build http://67-72chevytrucks.com/vboard/s...d.php?t=267665 Tim Powell..R.I.P EastSideLowlife..... R.I.P.. |
06-28-2009, 10:48 PM | #12 | |
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Re: Tbi swap build thread
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The green box and light you asked about are the VSS signal from the speedometer to the ECM. The light hooks into the back of the instrument cluster at the speedo drive and a gear in the cluster (a reluctor I think it is called) causes the light to pulse at a speed/frequency that is proportional to the vehicle speed and the green box converts that light pulse into a 2000 pulses per mile square wave DC signal to tell the ECM how fast you are going. rfmaster discusses the importance of VSS in post #46 of this thread (I also use the JTR VSS signal generator hooked up at the tranny due to speedo cable wind-up). Mark |
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06-28-2009, 11:55 PM | #13 |
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Re: Tbi swap build thread
Great project. I am just about done with my TBI transplant myself. I have a 1976 1/2 ton fleetseide that had a 250 I-6 in it. I installed a 1988 GMC 454 TBI with a TH400. I used the 1988 wiring and computer and I modified all of the interior and exterior wiring to work with my original equip. Very healthy set up. just need more traction!!!
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06-28-2009, 11:57 PM | #14 |
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Re: Tbi swap build thread
I had to use a 1987 RV fuel tank and fuel sender assembly for the fuel injection. Works great. I just have to figure out how to use a speedo cable in ther TH 400 with the speed sensor. If you have any ideas let me know.
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06-29-2009, 07:52 AM | #15 | |
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Re: Tbi swap build thread
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I originally installed a 2PRS at the end of the speedo cable that hooks into my cruise control transducer because it was easy to get to and install, but my speedo cable is pretty long (or worn) and the speedo cable wind-up resulted in wildly fluctuating signals to the ECM at low speeds. By wind-up, I mean when the friction in the speedo cable builds/twists up and releases the tension at low speeds - if your speedometer needle swings back and forth (especially at low speeds), you have wind-up. To get a good low-speed signal, I ended up mounting the 2PRS at the speedo cable output on the transmission itself. If you had a later model truck (which I do, but didn't go this route), you could also get an '87-'89 instrument cluster with the VSS optical sensor built in. This option also requires the green box thing and light pickup mentioned a few posts back. Good luck, Mark Last edited by brontotx; 06-29-2009 at 07:56 AM. |
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06-29-2009, 08:18 PM | #16 |
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Re: Tbi swap build thread
Do I really need the vss hooked up to the speedo? As I have no speedo just a tach... Also any tips on what wire is for the check engine light? I assume it plugs into the back of the cluster?
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GO BIG GREEN GO DUCKS MEMBER #6377 72 k-5 daily driver 6'' lift 35'' 350-350-205 slowly getting rust free. Project "7DEUCE" check out my build http://67-72chevytrucks.com/vboard/s...d.php?t=267665 Tim Powell..R.I.P EastSideLowlife..... R.I.P.. Last edited by FRENCHBLUE72; 06-29-2009 at 08:19 PM. |
06-29-2009, 11:03 PM | #17 | |
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Re: Tbi swap build thread
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If you decide to replicate a VSS signal, you do not need a speedo. The JTR 2PRS signal generator can hook to the side of your tranny (or wherever the speedo cable normally hooks to in your truck). As for the check engine light wire, it is normally the brown w/ white stripe wire going to terminal A5 of the 1227477 ECM. Since my '82 instrument cluster did not have a check engine light, I pushed a stripped wire end into the choke light terminal on the back of my cluster. This made my choke light (which wasn't being used anyway) into a check engine/SES light. Another option is to install and wire any 12V light as your check engine/SES light. Please note that this light has 12V+ with ignition on and the brown and white stripe wire from the ECM switches the ground. Hope this helps and good luck, Mark |
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06-30-2009, 12:13 AM | #18 |
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Re: Tbi swap build thread
So basically I just need the wire from A-5 on the brain wired to the ground side of a light of some sort with power going to the positive side of the light when the ignition is on??? correct?
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GO BIG GREEN GO DUCKS MEMBER #6377 72 k-5 daily driver 6'' lift 35'' 350-350-205 slowly getting rust free. Project "7DEUCE" check out my build http://67-72chevytrucks.com/vboard/s...d.php?t=267665 Tim Powell..R.I.P EastSideLowlife..... R.I.P.. |
06-30-2009, 02:02 AM | #19 |
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Re: Tbi swap build thread
Correct... see rfmaster's circuit diagram in post #108. The only caveat is that the light you use should not be a grounded internally to its mount or it will be on whenever IGN is on.
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07-07-2009, 07:10 PM | #20 | |
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Re: Tbi swap build thread
Quote:
As for the vss you will keep getting a ses light untill you install one. Ask me how I know .
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The fleet 94 Chevy 4x4 reg cab 2018 Traverse (wifes car) 1977 SWB stepside 1949 Chevy truck Last edited by cjracing15; 07-07-2009 at 07:12 PM. |
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07-07-2009, 07:46 PM | #21 |
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Re: Tbi swap build thread
I am running the vss just not hooked to anything..... As far as the adapter I used one and just put the sensors close to where they were stock.... I ran a stock coil so I cant help ya there....
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GO BIG GREEN GO DUCKS MEMBER #6377 72 k-5 daily driver 6'' lift 35'' 350-350-205 slowly getting rust free. Project "7DEUCE" check out my build http://67-72chevytrucks.com/vboard/s...d.php?t=267665 Tim Powell..R.I.P EastSideLowlife..... R.I.P.. |
07-08-2009, 09:22 PM | #22 |
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Re: Tbi swap build thread
It has taken a bit longer that expected to get this TBI swap done.
After going 4 wheeling to a hard t rail here in Colorado I was motivated again to get this TBI swap done. The blazer would die and be hard to start and would not run on its side. This was a huge hassel and made the trails harder. So needless to say I am going to get this swap done. Ordered the VSS and the 4 wire O2 sensor. I will pick up a KS and I should have everything. I decided to use the stock intake and just drill/machine out the 4 center holes. This solves the issue of coil mouint and sensor mounts. I will have a question when I wire the O2 sensor when I get it. I have the relays but do not know what color O2 wires go to what parts of the relay? I bought the AC delco AFS75 O2 sensor and the relays are off a 83 ish caddy. I am hoping to start wrenching on it next weekwend. Thanks again for all your help and all the great information in this thread. |
07-07-2009, 09:35 PM | #23 |
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Re: Tbi swap build thread
SEEEE I told Ya.
I knew RF would have a very good answer.
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07-08-2009, 09:36 PM | #24 |
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Re: Tbi swap build thread
I understand what you mean about taking longer than you think it will to do this swap. It took me about two months longer than I thought it would take. What takes longer than anything is the little things you just thik of untill...
Good luck and if you have any questions just ask. We all will try to help ya out.
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07-12-2009, 12:28 AM | #25 |
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Re: Tbi swap build thread
I like all of the information about your TBI swap. This is very interesting. I'd like to share pics of my swap. It is not quite done yet but is driveable. I have a 1976 c-10 long bed that had a 250 I-6 and installed a 1988 454 TBI in it. It has all went fairly well so far. I hope the pictures work. I had to use a fuel tank and sending unit from a 1987 RV to work for the fuel injection system. I have to complete the wiring conversion for the instrument cluster. I used the complete wiring harness from the 1988 GMC 3500 Dully.
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