The Stovebolt Site Forums The Shop Area Engine Shop 261 with TBI Drove it today

Did a 261 with TBI in my 55 pickup. Took out the 327. Drove it for the first time today. What power, the 3.90 rear has to go. Did a T-5 with 3.50 first and .78 OD. Thinking about a 3.08 posi out of caprice police car that I have. Any body running a 3.08 and this transmission ratio ?

What kind of TBI setup did you fit to a 261?

I used a TBI system from a 91 astro van that had a 4.3.

Do you have any photos and more info? That sounds like a good combo. Pat

I have some pictures I could e mail you, I do not have a photo sight. The engine is a 261 .040 over bore. 261 cam. 848 cylinder head with 9.5 compression ratio, fenton headers to y pipe with 3inch muffler and exhaust, clifford hot water heated intake with tbi adaptor, 4.3 tbi system and T-5 transmisson. If some has a photo sight and would post them I could send them the photos.

There is a man with a heavy diesel repair shop near me that has a 57 Chevy 4dr that has a 235 with an old Borgwarner OD trans and a 3.08 rear. The BW unit is a full 30% OD while yours is 22% but I was amazed at how well it pulled through some rolling hills, no pinging or lugging. It has a tach an if I remember right 65mph was around 1600rpm. Your 261 should be a gem with shallow gearing.

This is not fair....... you can't just wet our appetite with "is running" without showing pictures and telling us how you did it and what you broke doing it......

what about calibration.... or whatever is the equivalent of adjusting the jets to proper size.....???

How do you operate a TBI in a 40 Chev 261 which never heard of a on board "pewter"......

what is the down side....??? good bottom end torque or top end revs....?

All kind of TBI conversion kits for sale on EPay but only for late 1985 to recent computer GM vehicles.....

Curious and interested....

Bob C.

I bought a 91 astro van for $150 with a bad engine. Took out the wireing from the computer to engine and cut out the circuts I didn't need. Like the wires to the automatic transmission. The program is the stock one that was in the computer. I tried the 4.3 throttle body but the injectors leaked badly so I put a 5.0 tbi on it. It the same tbi only the injectors flow more fuel. I'm going to repair the 4.3 tbi and retry when I have time. I used the map sensor, distributor,temp sensor ect.. from the 4.3. The new engine has a lot of torq It sound cool revs up nice and is a blast to drive. Has more pulling power than the 327 did. fist gear is all most like a granny gear, thats why I thinking about the 3.08 rear end. The engine looks impressive to, will try to figure out how to post some pictures..

28 Chevys - I am running a 292" six with a MY6 trans behind it. In case you're not familiar with MY6, it is a 4-sp., 3.09, 1.67, 1.00, & 0.73 O.D. I have a 3.08 axle set behind this. It's in my daily driver, also have done a couple 500 to 600 mi. road trips in it. Pulls great, I like it. I'm running one big YF adapted off a 300" Ford. This is in my '55 Bel Air. I've seen back yard adapted injection systems on inlines for many years at B'ville. Nice to hear of someone doing it on a street motor.
Doug

28chevys,

I would be be glad to post your photos if you PM the jpgs to me. Sounds like you have a nice setup. Right now, I have a 261 running with five Srtombergs, and my next 261 is scheduled to run with three Strombergs on a Harper maifold. I may be a little too ancient to go to a computer-controlled engine, but who knows. At my job I work with computer-controlled engines. I must admit that a good TBI should be "better" than seventy-year old carburetors.

I just sent some pictures to KCmongo he going to post them. Let me know what you think of it..

Here's the Pics:

Mongo

Thanks for hosting the pics, Mongo. And nice work there, 28. Gives me lots to think about for the future.

Nice Job

28 Chevys - Looks good, I like it.
Doug

This is pretty amazing! I guess the computer adjusts the fuel flow base on the feedback from the oxygen sensor. Is that correct?

The computer controls the fuel based on the program it has untill it warms up. It looks at engine temp. RPM. engine load and throttle postition to set fuel flow. After the engine warms up to operating temp. and the O2 sensor is up to temp. it goes into closed loop, at that time it adjust the fuel to 14.7 air fuel ratio by useing the O2 sensor. A lot of more things happen in there but thats the most of it in a nut shell.

Thanks for the update. Is there a source where I could read about the program logic?

Truckernix, http://www.msefi.com is a good forum for DIY fuel injection. It is based around the MegaSquirt DIY fuel injection computer but also covers a broad knowledge base of people who are using and modifying factory fuel injection systems.

'28, what intake manifold are you using? Are you using the stock distributor? Where in your exhaust do you have the O2 sensor installed? I'm planning to put a GM TBI on my GMC 302 with a Megasquirt computer but I haven't collected all the parts yet.

Thanks for the link. I will be doing some reading!

I'm running the cilfford hot water heated intake with the tbi adapter on it. The 261 had a theromstat bypass hose so i came off of those ports with stainless tubing to the intake. There is a web sight that has a winALDL program that you can down load for free. With this, a lap top and a cable. That you can build or buy. You can hook up to the ALDL port. This lets you look at what going on with the control system and has a data loger so you can store and look at the data. I,m going to do this but haven't got to it yet. I'm hopeing that I don't need to reprogram. The 4.3 is 265 ci. and my 261 .040 over is about 265. The fuel and timeing tables should be close. I used the dist. out of the 4.3 .

Have you run this much more since last post? Is yours a solid lifter motor? If so did you use the knock sensor?

The TBI is a very simple system and should work well. Looks good.

I drove it a few more miles and pulled out the rear axle. Put in the 3.08 posi rear end out of a 93 caprice. I just got it back on the road today. I need to put in my new electric speedometer next to tell how fast I'm running. The 3.08 gears don't seam to high. This engine has a lot of torque. I'm running the 261 cam shaft and knock sensor. The knock sensor does not pick up the solid lifter noise. I thought this might be a problem.

Location of a knock sensor has a lot to do with its function. Where did you mount yours?

I put it in the block drain plug so it's in contact with the coolant. The 4.3 had it in the drain plug.