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1987 Tbi 305?!?!

M

mertresvaag

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I am looking to buy a K5. I recently ran accross and add that I am not only interested in the truck but just seems off. It says it has a fuel injected 305. Now I thought the 305 wasn't even an option in 87. Secondly if the motor was swapped out for a 305 would it not be a huge PITA to make a 305 run correctly since the TBI is set up for a 350? Was there any crossover? Did the 305 make it into come 87s?

Thanks

Mike
 
Hate to say it but it is wrong even my resto pack says 305 standard! I believe the 305 was the official standard engine for fleet fuel economy reasons. I am looking for where I saw that. Here id this to document it came standard.


1987
GM changes name designation on the C/K line of pickups. The previous 4x2 C series is changed to the R series, and the 4x4 K series is changed to the V series. Chevrolet also introduces TBI equipped engines and computer ignition controls (although carburetors were still available in some models). 1987 was also the last year for the "stepside" bed, starting in 1988 GM refers to it as a "sportside". The end of a 15 year run for the rounded line C/K pickups, however, the rounded line body style remained until 1991 on Blazers, Suburbans, and one-ton trucks.
http://www.73-87.com/7387info/7387differences.htm

blazer8.jpg

 
Well alright. I guess that solves that mystery to me.

Thanks for the reply.

I see in your sig you have the 305. What do you think. If you were buying again would you shy away from it and look for the 350?
 
i know this wasnt directed at me but .. my 305 just seems to lack the balls some time. personally if i was to do it again id go 305, but im to attached to my truck so ive started rebuilding a 350 in my garage that im gonna slap in their when my 305 goes boom
:wink1:
 
lunchbox said:
i know this wasnt directed at me but .. my 305 just seems to lack the balls some time. personally if i was to do it again id go 305, but im to attached to my truck so ive started rebuilding a 350 in my garage that im gonna slap in their when my 305 goes boom
:wink1:
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Is it a huge PITA to swap in a 350 for a 305 when it has TBI? Do you need to swap out the CPU too?
 
Me too. I have an 87 TBI. It's got plenty of power. It's got enough power for what I do. Spins all four 38 " swampers on rock and dirt while climbing and plenty for the street. Probably a little weak for mud. Oh yeah. I'm running 410's and a sm465.
 
yea i have to swap out the cpu. i have it all i got a tbi 350 from a 92 silverado.from what im gathered swapping in the 350 is just like swaping in another 305 its the same size block all the accesorys bolt into the exact same locations .everything is basically the same,
 
Swapping a 305 to 350 is easy. Everything is direct bolt in. Wireing harness and TB are the same The only things you need to change are
1. 350 and 305 ECMs are the same but you need to remove the 305 chip and install one for a 350.
2. You need to pull the 305 injectors out of the TB and replace them with the 350 55lb hr injectors. Both are simple easy jobs.
 
mertresvaag said:
Well alright. I guess that solves that mystery to me.

Thanks for the reply.

I see in your sig you have the 305. What do you think. If you were buying again would you shy away from it and look for the 350?
Click to expand...

Well for most of my driving being street it is fine. I am happy with it and have driven large motors most of my life. From my fathers company trucks with 350s and my Z-28 and being a retired cop so I base off that. The gearing in my truck is not for speed or power. It was a highway truck from North Dakota so it was set up for economy but still able for pursuit.

With all that said, it bogs down in the PA hills on the turnpike and drinks gas in the hills. I get 15 mpg on highway here in mainly flat Ohio/Mich and 10 mpg in town. Get me on the PA turnpike hills it is 10-12 mpg.

When I go out west to Colorado to have a drink I will get a better highway mileage run. Also as I like to tell people "If I wanted economy I would of bought a VW and if I wanted performance I would of gotten a Lamborghini."

So would I swap motor not really. Now I did have a 1989 with a 350 and 4:08 (i think) in it and it ran like a raped ape. I sold it to jekquistk5 but if something had happened to my 305 I would of swapped the 350 being as I had it already. Hope that helps some and not confuses you. :doah:
 
Thunder said:
Swapping a 305 to 350 is easy. Everything is direct bolt in. Wireing harness and TB are the same The only things you need to change are
1. 350 and 305 ECMs are the same but you need to remove the 305 chip and install one for a 350.
2. You need to pull the 305 injectors out of the TB and replace them with the 350 55lb hr injectors. Both are simple easy jobs.
Click to expand...

I would assume the chip is easy to pick up from vendors. It is socketed or soldered?
 
AFAIK all the stock chips were soldered in.

Of course, matching auto or manual trans PROM(chip) is necessary, and I personally would *prefer* a chip that matches the 350 in question, since cam specs, compression, heads, exhaust, and so on ALL affect the tune.

I wouldn't get too far away from the same year chip, it wouldn't be a surprise that there are some changes in hardware. I'm not even sure if the '747 ECM was used after '91.
 
Last edited:
Every stock Pre 92 TBI chip I have ever seen had a socket. The sockets are soldered but the chip is not. Simple to replace. Pull old chip. Plug in new chip. Juse be sure to touch a ground with your hand before touching the ECM or chip. A static electrick charge or spark will fry the ECM / Chip. Chip will only fit one way dont force it.
And the chip is easy to find. Just make sure you get one for the year ECM you have. They made changes in the early 90s to a faster ECM and a diferent chip(MEMCAL) because of the 4l60E trans. I believe these are the ones with the chip you need to solder in.

Also should have said in my other post. If you swap in a 350 it should be a TBI 350. A regular crate 350 doesn't have a computer compatable cam.
 
Thunder said:
Every stock Pre 92 TBI chip I have ever seen had a socket.

Also should have said in my other post. If you swap in a 350 it should be a TBI 350. A regular crate 350 doesn't have a computer compatable cam.
Click to expand...

So if I am looking for a donor I am looking for a 87-91 with TBI. Will any 350 in this range do? ei car truck doesn't matter?
 
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