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TBI to Carb Harness

M

MDCrawler

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Location
Maryland
About 5 years ago I decided to pull the motor out of my V20 and give it to a "reputable":doah: machine shop in my town for a rebuild. It was just due. Any way, hopped it up some and it ran so/so for bout 2 months and melted holes in the pistons because he stuck 10.5 to 1 pistons in the thing and kinda left out that information when I picked it up. Mentioned "it'll be fine on pump gas" after I've told him on the initial build that I want to burn the cheap stuff, anyway got rebuilt again and never has really run right and to be honest with you he gave me a list of all the parts he put in but I'm kinda calling BS and decided not to let him fix a sandwich let alone my truck. I have no idea whats in that motor and I've made sure the whole town and surrounding states are aware of this guy. The motor problems are identical to Y5mgisi's thread where he's been through the entire thing and keeps finding gremlins that you hope and pray are it and it makes no difference.

Sorry bout rambling on a bit here, bare with me.

Anyway, The ol truck motor and I had a nice long talk about a week ago when it cost me $25 bucks in gas to go 7 miles to work and back and I had just come across a nice 4brl intake ( The clouds parted way and the angels sang as a brilliant ray of light fell apon a bow tie dual plane with the 73* intake bolts to fit the factory tbi heads, spread or square and no egr for "scrap":bow:(didn't even know it existed)) and fresh holley 600 ($45). Decision was made to carb it. So after bout a $300 summit order to collect the rest of the parts needed for the swap, it hit me, what has everybody been doing with the TBI harness when they switch to carb??? do they just wrap it up nice and leave it or cut the whole thing out??? I don't want to just hack it to crap because I might eventually want to go back to TBI (maybe find another motor down the road and can start fresh again or tinker again, want to leave my options open because I do believe that it def has advantages.) I don't care how it looks, it's a working truck, not a mall crawler, but not a XRCC entry either. I'm just worried about if I leave it that everything will corrode and be worthless anyway and if I cut it out then well it's worthless too. What would YOU do or do you have any other suggestions?

PS, would love to mention the "reputable" shop name but didn't know if it violated CK5 policy or not and just decided to keep it out of this thread but if your from MD, WV, or PA I would be more than willing to give my feedback. PM me.
 
More details on the motor? Heads, cam, pistons, etc

What distributor are you planning on running now?

There is no censorship here on CK5, feel free to speak your mind
 
well I do know that the heads are factory tbi heads. pistons are flat tops but who knows what the ratio is, I've just ran high test to be safe. The cam is comp computer friendly, I want to say .444/434 lift, I couldn't tell you the LSA or duration off the top of my head. Was told stainless valves, stiffer springs, 1.6 roller rockers.Long tube headers into 2.5 and flomasters, I think 40 or 50's, came with truck and never looked really. The rest is pretty much stock(intake, valve covers....) I've been through this motor time after time. Been over fuel pressure, rebuilt TBI (throttle shaft not leaking), new injectors, intake gaskets, dizzy and coil, compression test, leak down wet and dry, timing(cam and spark) new egr and cleaned passageways, O2 is new and sealed from any exhaust leaks, tune up stuff. Computer is seeing correct data, had scanner hooked up. Was told (by guess who) that I didn't need a chip, knew better, got one.... didn't help, well I take it back WOT is impressive now. Still stalls tho.

I've just reached the end of my rope for now and been threatening a carb for a while and one just fell in my lap. I'm planning on running just a factory HEI 4 pin dist. The last time it stalled it took 3 light cycles to fire up again and that was when I said no more. I'm well aware of how a carb runs and not afraid of them at all. A 68 rambler was my first car for like the first 6 years I was driving and now I'm in a 85 Monte Carlo. I've already made up my mind and it's going to get carbed, just kinda wondering about the harness for the TBI.
 
I have went ffrom carb to tbi a couple tmes I leave the harness intact tie strapped out the way of everything and unplug the computer so there is no service engine soon light

Mine runs way better on a performer intake and 600 carb
 
gonefishin: I ran across a 14096242 intake for scrap. I figured this had to be in the same ball park at a performer only it's cast but I said so what, it's still not as heavy as a big block. What carb are you running???
 
I am running a 600 edelbrock not the best for crawling but its not too bad for the mud I have the offroad needles and seats in it also

I would say an easy 60 hp difference between carb and tbi

Another thing to think about is fuel your in tank pump puts out too much pressure so you either need a regulator or I just hooked up another tank with a mech pump
 
Ok I am running a 355 sbc flat top pistons I call it an rv cam but its a crane 210/216@ .050 and then I added 1.6:1 roller rockers which put it just a smidge over .500 lift so actually its prolly a little bigger than an rv cam it has a slight lope at idle

I was running this on a stock tbi tune with stock injectors don't get me wrong it ran but could have been tuned way better I am sure I just don't have the time or money for tbi tuning
 
gonefishin said:
Ok I am running a 355 sbc flat top pistons I call it an rv cam but its a crane 210/216@ .050 and then I added 1.6:1 roller rockers which put it just a smidge over .500 lift so actually its prolly a little bigger than an rv cam it has a slight lope at idle

I was running this on a stock tbi tune with stock injectors don't get me wrong it ran but could have been tuned way better I am sure I just don't have the time or money for tbi tuning
Click to expand...


Yeah. My point is that correctly tuned the TBI can make just as much power as a carb.
 
I've busted that myth in here before.... a carb certainly doesn't produce more power... it's a fuel supply system.... a proper running motor has a certain fuel demand, it doesn't care if you spray it in there with a garden hose....

now, what those cylinders want, being dictated by a different cam, heads, etc, THAT is a power difference..
 
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