Hey,
I'm new here so I'm sure I'll get flamed for this but lets give it a shot anyways lol. I have a '91 K5 Blazer with a factory TBI 350 engine in it and I'm looking for some low end torque for 4 wheeling. The engine has about 160k on it but doesnt use too much oil and is very reliable. I was looking at a couple of options and was hoping to get your opinions.

1) Replace the 350 with a crate 383 and hope the computer runs it ok

2) Modify my current motor (grind out or replace the throttle body, new intake, headers ect.)


some background notes:

I've replaced both axles so now I have 1-ton gears (4.10)

I run 35x12.5x15 Super Swamper SSR's

I have a 700r4 transmission and an NP241 transfer case which works fine

I have done alot of external engine work( not on this truck) but very seldon have done internal work


thanks for all the help in advance

 

What kind of wheeling do you do? If ya are into rock crawling I would say look into a 383 conversion. If you are like me and like to go out into the mud and in general just play where ya actually need the 4x4 I would highly suggest going to a little bigger cam that lets your motor breath. The LT1 cam seems to be the hot swap around here because it will run with the stock computer just fine and pass emissions, but you will have to also find the roller lifter parts for your motor as it is a factory hydraulic cam. A good set of headers would also really wake up the motor by letting her breath. I dont think that low low end tork is really what ya are after with 35s because that isnt much bigger than what comes stock on a 3/4 ton chevy from the factory. I think that you would be happier with more power throughout the powerband unless ya are really into rock crawling. If you are trying to get into serious rock crawling I would suggest leaving the motor alone and start trying to find a later model SM465 muncie truck 4 speed that came in these trucks in the earlier years. They could be had with your transfer and feature a very low 6.54 first gear, 3.57 second, 1.7 third and 1:1 fourth. These trannies ran from 1/2 tons up to 2 1/2 ton trucks with the same internals other than input shaft/ bearings and output shaft (ie same internals). These things are impossible to kill tust me I know. Hope this helps ya out. Let me know if ya have any other questions.

 

If you wanna keep the 350 in there and add low end torque, try the edelbrock TBI intake. You could always make your own TBI spacer for pretty cheap as well, or you could buy one-won't be much improvement but it is good for more torque. LT1 cam might work good for you as it is pretty mild for a 350, computer friendly, and hyd. roller. However, most people say when they put it in their 305 they lose some low end but gain quite a bit up top. I'll finely find out for my self here in the near future!

 

I dont think that he needs low end torque as much as he needs a higher power output across the board. He is already running 4.10's so a little loss of idle wont kill him. I still say go with the bigger cam unless he is going to mohab. Just my 2 cents

 

Just a little note:
When I start my truck after its been sitting for a while (or sometimes when it hasnt) I get a little bit of blue smoke out of the exhaust. I think I read in another post that this is probably the valves....so would taking the heads off and replacing or improving the current ones be on my list of things to do ?? or could this be a combination of rings and valves?

this brings me to the point where I start looking at crate motors lol

 

the smoke that you are seeing is probably worn valve seals or possable a guide. This is fairly common on high milage chevies but is relatively cheap to fix. However I would suggest tossing the stock heads for something a little better.

 

he would need the rollers too

 

What brings a 4x4 off-road type person to an F-Body site?

 

the TBI knowledge

 

The guys at Coloradok5.com have tons of knowledge about 4X4 stuff but I feel better here asking about TBI stuff...cause this is where its @


Just to keep my options open...who sells a crate motor to fit my needs for about $1500?

 

www.sdpc2000.com

 

The reason there is such an interest around here is that the truck motors are identical to the f bodies except that the trucks wernt roller motors. I personnally have been hanging around here for about a year but started out on the TPI board because I have an 86 firebird with a swapped in 350 TPI and a 5 spd. When I bought my 89 LO5 4x4 I just started to monitor whats going on in this forum also. Now I have the truck maybe I will get the TPI running. O by the way I also have a 79 4x4 and a 1960 chevy truck with a 400 pushing 550HP. I am kind of a chevy nut LOL. O well sorry to ramble.

 

If your going to rock crawl then you may want to stick with a closer to stock cam and better heads. I would recommend a search on www.car-part.com and find a low mileage 96+ Vortec motor for around $750. That will yield you 50hp over a stock L05 without sacrificing low end torque. Combined with some 1 5/8" headers and good catback it should make a nice little engine. The Vortec engine is also a roller motor and there are a lot of nice cams available for it. The LT1 cam could be used to pull 300hp out of that engine as well.

 

Will my 91 TBI computer run a 96 Vortec motor? I like this idea alot if it will

 

Valve seals or possibly guides are a good bet here, but in '91 and '92 GM also had some problems with head castings that were not properly de-burred. Sometimes the oil return holes in the heads were partially closed off. Once the engine got some miles on it gunk began to build up around the return, eventually closing it off almost completely. This happened to my brother's '92 bird. Best solution is to pull the head and open the returns using a dremel and/or drill if that turns out to be your problem. I've talked to some that have done it with the heads still on the car by magnetizing a drill bit and cleaning it frequently while drilling, but this seems too risky to me.

 

Yeah the TBI will run on a vortec engine. You just need a good edelbrock Vortec carb intake and an adapter to put the TBI on top of it. You will probably need to increase fuel pressure slightly to compensate for the extra hp but you would have to do that anyway. Several people on here run the 350HO crate motor with TBI and its a Vortec motor with a different cam.