I have a 84 K5 blazer that i am wanting to inject. It is a 350 with 10 to 1 forged pistons, vortec heads, and mild comp cam. My question is will stock tbi run okay with the compression ratio and cam or will i need to go projection or propane?

It will run but may not be perfect.
You can perform a simple fuel pressure adjustment on the regulator to help.

Or you just have a chip burned for the engine.
There is no need to change the entire engine management system.

For $130 you could also start tuning and tweaking your own chips if you really wanted to play with it!!


Either way you should get a data cable or build one for $6 and then download winaldl and log your engine data while driving.
That will tell how close your fuel tune is.

If none of this make sense to you then I recommend a google or try looking at the link in my sig.

This is all assuming you are referring to bolting on a GM TBI system from a 350 chevy.

To run a stock chevy tbi you need about 17 in of vaccum at idle. Bill seems to be full of information, and on line with his info.Good luck, Billy

Thanks for the info

How mild is your cam? The knock sensor may not get along with it. Also if you have vortec heads, chances are you may want to just run TPI and deal with MAF instead of cold/speed density.....either way the patch cable and chip thing is almost standard in modified cases...at least to make it run the right way the first time.

Im not sure on the cam numbers. I bought the blazer with the engine already built and the previous owner didnt know the cam specs.

How mild is your cam? The knock sensor may not get along with it. Also if you have vortec heads, chances are you may want to just run TPI and deal with MAF instead of cold/speed density.....either way the patch cable and chip thing is almost standard in modified cases...at least to make it run the right way the first time.

Sounds like he has a built engine, the MAF setup will only account for about 10% change from stock, (talking airflow) and I bet he's past that, so custom tuning is a must.

There is a way to get past burning and swapping chips, but it'll cost about $360.
http://www.dynamicefi.com/

Something else on the MAF setup... Make absolutely sure, if you do go that route, that you get the sensor and air inlet tubes. The sensor is on the air filter housing, and I think that the ECM is tuned to the inlet hose. The MAF is a $200 sensor new.

Im thinking it will be easier and cheaper to go with projection or propane

Im thinking it will be easier and cheaper to go with projection or propane


You haven't said what you have now......

as for cost....
a complete used TBI set up or a used mechanical propane setup will be about the same.
If you are trail only then propane will be OK.
If you plan to drive it and use it on the trail...you may want to re-think the TBI.

But it appears you buy rather then build your stuff so depending on your skills...either conversion may be out of your reach.

You may seriously want to look at complete bolt on kits rather then DIY conversions.

Right now it has an air gap intake with a 750 carb on it. Its in an 84 k5 blazer. I have done a chevy tbi swap into a jeep wrangler before so that isnt an issue. I just dont want to put tbi on it not run right.

Whatever you do is going to take some tuning.

I lot of these replys are referring to tpi not tbi. go to www.TBIchips.com for tuning info.