69-80 SB Chevy 350

[nixtux]

I'm looking into a Fuel Injection System for my truck. Any suggestions/Advice would be appriciated. I'm basically a n00b; I'm not sure what I'm looking for. I'd welcome advice.

The main issue i have with the truck is sometimes (about 25%) it'll choke out under heavy throttle. Which a friend of mine said, "old quadra-junks are well know for that." He's a smart with this stuff. Too bad he lives 3000 miles away.

I was looking at this one but I don't know if it'll work.

http://www.barrygrant.com/bgfuel/default.aspx?page=63

I'd really like to maximize power. Ideally it'd be nice to have good fuel economy on one hand and a lot of power on another. Not that it has good fuel economy but it'd be nice if it didn't get too much worse.

Maybe even slap a supercharger on her?

1973 GMC Super Custom

350 .03" bore (355)
rods and main .010"

From Comp Cams Limited Warranty Card

Value lift .47 .480
Duration .006

value timing open close
at 0..6 INT 28 BTDC 60 ABDC
EXH 74 BBDC 26 ATDC

Cam specs
AT 106 Intake center line
Intake Exhaust
Duration .050 224 230
Lobe lift .3180 .3200
Lobe separation 110.0

Flattop pistons - 9/1 Compression
Comp Cam 242 Extreme Engery
Rochester quadrajet Carb <--- shit
Headers 2 1/4 pipes /w mufflers (not too loud)

T350 /w shift kit
Torkmaster 2000

3.73 Gears - 12 bolt rear-end

Truck:



Engine:

[geoffinbc]

Edlebrock sells one of the most affordable systems and they are pretty plug and play. You should not need any extras.

[jp_grasshopper_007]

well if you can't make a quadra-jet work you don't need carb based fuel injection. Edlebrock, Holley, and others have whole kits w/ computers. if you want something badass look here http://www.ronsfuel.com/index.cfm not something you would need but it's cool. really you could just save alot of $$ by having someone rebuild your carb. people that say they're junk just don't know how to fix them, as far as a carb for a daily driver goes the quadra-jet is your best choise

[nixtux]

I did some tuning on the carb yesterday and it's running quite a bit better. I also filled up and ran some seafoam.

Granted my knowledge of carb systems is quite limited but I did some reading and with the advice of a friend made a few changes here and there.

What fuel should I run with it? I typically run 87 but I filled up with 89 cause 87 was out of order. It seems to run better /w 89 but I didn't run it hard before the seafoam/tune.

The damn thing felt like it wanted to do a wheelie between shifts. The shifts were far more aggressive /w much better throttle response. It was a welcomed change.

My understanding with adding a FI system would be improved fuel economy and more power. The truck typically isn't my daily driver; I've been using it lately while my car is out of commission. Even at that it's a mere 20 miles a week. In three years I've only put around 1,500 miles on the truck. About 9,000 miles in 6 years. My parents used it more than me.

Normally I drive it when I feel like having fun. Or just in the mood to feel some torque.

You make a good point in respect to price. They seem to run between $2000-3000. That isn't an ideal price unless it improved mileage/power enough to pay for itself in a few years. +1-2MPG would in fact pay for itself. Provided I maintain my current driving habits (city.) In general that's the real question. Will the benefits out weight the price.

I may be getting ahead of myself as I am also buying up parts for my Cutlass; It is turning out to be quite a bit more expensive than I originally thought. But all this stuff is fun and it gives me something to do.
I love learning new things. Thus the experience pays for itself.

Thanks for your advice.

well if you can't make a quadra-jet work you don't need carb based fuel injection. Edlebrock, Holley, and others have whole kits w/ computers. if you want something badass look here http://www.ronsfuel.com/index.cfm not something you would need but it's cool. really you could just save alot of $$ by having someone rebuild your carb. people that say they're junk just don't know how to fix them, as far as a carb for a daily driver goes the quadra-jet is your best choise

[jp_grasshopper_007]

yes, making the switch to injection will increase your mpg but, on something that doesn't get drivin that much I don't think the cost is worth it. if you want to try to rebuild the carb yourself most carb kits come w/ an exploded veiw of the carb. if it's just bogging under heavy throtle (does fall on it's face and pick back up?) it's prob. just the sec. opening to soon to far. they open w/ vac, check the tens. on the top flaps. if the truck runs a little rich all the time and can't be leaned out enough by adjustments to the air bleeds (2 screws front/bottom of carb) it will need to come apart. air tubes in the top plate are loose or 1 or more has fallen out.

[HayesPerformance]

What we always do, is scrap the quadra-jet and put on a #1406 Edelbrock carb with a electric choke.

Its MUCH CHEAPER then going EFI.

Also scrap the points and drop in a later HEI ignition.

WATCH AND SEE THE DIFFERENCE JUST THOSE ITEMS MAKE.

If you need those Items I can give you a deal on a whole package to wake that engine up so it runs better, starts great, more power, etc. and with that carb under NORMAL driving conditions you will see a MPG gain.

We specialize in restoring/building classic cars and have many, many years of experience.

This is one example of a 58' Buick limited that we have been 4 years on.

We still have TONS of work to do on it, the engine if far from done.

[jp_grasshopper_007]

a 1406 is ok till it needs rebuit then you'd be better of w/ the quadra-jet. and yes if you still have a points dist get rid of it. get a hei vac adv.

[jp_grasshopper_007]

if you're going to put a square bore carb on that motor you need to change your intake or get an adapter plate (the 1 inch style not the metal ones they're junk)

[nixtux]

I don't think the carb will need to be rebuilt since it was back in 2002 (9000mi ago.)

I adjusted the air lines yesterday and that helped quite a bit. It improved overall power and the throttle response seemed to improve between shifts making them much stronger than normal. Which is a welcomed suprise.

Normally when it's below 0F it tends to run a bit "lean" but that wasn't the case yesterday. The cab cold but the truck ran like a champ.

You are correct it simply bogs then revs up and bogs until I let off the gas. It didn't do it once yesterday. It acted like it for a brief second during a shift but other than that I didn't notice too much.

I'll take it for a longer cruise today to see if it I can get it to bog again and if it does I'll make some more minor adjustments. Also sometimes it'll "keep running" for a couple spits after I turn it off. That's only about 30-35% of the time.

I have a couple errands to run today and I'll make a couple videos of the truck taking some hard runs. In an attempt to compare.

Thanks for all your advice it's greatly appreciated.

yes, making the switch to injection will increase your mpg but, on something that doesn't get drivin that much I don't think the cost is worth it. if you want to try to rebuild the carb yourself most carb kits come w/ an exploded veiw of the carb. if it's just bogging under heavy throtle (does fall on it's face and pick back up?) it's prob. just the sec. opening to soon to far. they open w/ vac, check the tens. on the top flaps. if the truck runs a little rich all the time and can't be leaned out enough by adjustments to the air bleeds (2 screws front/bottom of carb) it will need to come apart. air tubes in the top plate are loose or 1 or more has fallen out.

[jp_grasshopper_007]

"Also sometimes it'll "keep running" for a couple spits after I turn it off. That's only about 30-35% of the time."

That could be 1 of 2 things (carb related) either the throtle plates aren't shutting all the way or the base plate is wore @ the throtle shaft (vac leak). To check the latter grab your throtle (where your cable hooks on) see if you can move it up/down or side/side. If you can some but not sure if it leaks take some carb clean and spray @ the shaft (w/ eng running) it will pick up rpms if it leaks. You can check other spots that way (vac lines, base gasket,upper carb gasket)

[nixtux]

I'll get some carb cleaner in a bit and check that out.

From examination it appeared the throttle area is solid but at the time I wasn't exactly checking. Once my feet regain feeling I'll check it out.

After the tuning it didn't bog repeatedly. It will bog once then just take off. The below video is a 0-65MPH run. It briefly bogged after it shifted into 2nd. Barely noticable in the video.

http://www.youtube.com/watch?v=-5ibYomJyPU

"Also sometimes it'll "keep running" for a couple spits after I turn it off. That's only about 30-35% of the time."

That could be 1 of 2 things (carb related) either the throtle plates aren't shutting all the way or the base plate is wore @ the throtle shaft (vac leak). To check the latter grab your throtle (where your cable hooks on) see if you can move it up/down or side/side. If you can some but not sure if it leaks take some carb clean and spray @ the shaft (w/ eng running) it will pick up rpms if it leaks. You can check other spots that way (vac lines, base gasket,upper carb gasket)

[jp_grasshopper_007]

I watched the video. Is that w.o.t. ?

[nixtux]

Yea it was WOT. The launch, I didn't rev very high. It can launch much better than that. Also I have really good tires. The old truck isn't anything special. I'm sure it could push a lot more with good tuning.

I've considered getting a blower for it - for fun. But I'm not sure if it's a good idea because of the flat top pistons. It's also 9:1 compression as is. I'd hate to destroy the motor to get a little more power.

I have the "spit" and "bogging" gone. --- no spits --- but it'll kind of bog (run rich maybe?) It's just powerless until I get off it then WOT it; then it HAULS ass. I had a Jeep Cherokee next to me on the highway. He was pulling away from me during 1st but I got off the gas and opened it up --- pulled away from him no problem.

A screw was loose on the throttle assembly. I tighted the screw which made the metal bracket stiff instead of loose. It'll downshift anytime I'm under 50MHP. Which is what it should do. Before WOT wasn't opening it up all the way. It's a vast improvement.

I almost have the idle perfect. It's a bit lopey yet. I figure a quarter turn or less on the choke screw should achieve the ideal idle. It'll push and pull when stopped at a light.

*UPDATE*

I moved the screw slightly (a millimeter maybe two.) The idle improved. Driving was a great. I stopped and got gas. After that it had a high idle. I went home turned the screw back and it was lopey again. But the issue with it not getting power correctly under WOT the first attempt is strange. And I had a issue where it died while I was at a light. It started back up though.

Monday I'll run some cleaner in it (I spaced it out yesterday---work was insane so I didn't get a change to go to the parts store.)

Check for leaks. If it doesn't appear to have any I'll probably make an appointment to get the choke/carb checked by someone who knows what they are doing. It almost seems like the electric choke isn't functioning correctly. But I could be wrong.

Again, thanks for all your advice. it's been a fun experience playing around with this.

I watched the video. Is that w.o.t. ?

[nixtux]

No vac leaks. Carb tuned pretty well now. Turns out the high idle was from the cold...

However, the 73' started even when it was -50F while a brand new Ford Focus did not and required a jump from elder. So that was amusing. Now that it's a bit warmer (around 10-25F,) she runs really well. A nice lopey idle and starts up every time, anytime I give her WOT she down shifts instantly unless I'm over 50-55MPH then it stays in 2nd until 3rd shift.

The only issue that still exist is sometimes it seems to run lean during hard acceleration, however, since I don't typically beat on it I never really notice. And it's also not predictable.

I'm sure it could use a bit better tuning which I may decide to take it in for a check up. Before I do that I'm going to change out the spark plugs/wires (still haven't done that.) But I'm doing it tomorrow. Also marking distributor and going to try to turn it a bit and see if that helps any.

I'll report back Monday when I return from the cities.

[JohnnyReb]

L98 tuned port is the only way to go. A little bit of work but worth every bit of it. I have swapped TPI motors into several vehicles including 2 trucks. Cool thing about the chevy truck is it was offered with TBI so you can buy a direct fit gas tank and sending unit and also use a speedo with a optical vss. The long individual runners on a TPI make it a excelent choice for a truck motor, plenty of low end torque. I have a 83 in the garage now with a L98, 700r4, 35's, 4 inch lift and 4.56 gears that will do 17 city and 23 hwy. It seems a little confusing when you try your first swap but everything bolts right in and you can use 100% factory parts. The only thing you have to be creative on is fuel lines and upper radiator hose. My last swap I bought a flexible stainless upper radiator hose and made that part easy. You also need the washer resevoir that mounts to your upper inner fender, I think like 86 up chevy trucks. You need the intake duct from a GTA that will mount where your old washer resevoir is now, or fab your own. I don't like speed density systems but that makes intake duct easier, had to go that route on a Astro van. Nothing sweeter than a older Chevy truck with fuel injection on those cold snowy days. Put on a pot of coffee and hit the button on the remote start before its time for work.