Carb or FI?

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rebelgtp

Master Mechanic
Mar 5, 2009
366
0
16
La Grande OR
I'm trying to decide which to use on my car a regular old carburetor or use injection on my Olds. Engine that is going in is a Chevy 355 early 70's 4 bolt main block, Z28 heads from same era. I found an inexpensive TPI setup off a Vette from the 80's (pre '87) and got thinking maybe go that way. It does not have an ECU with it but I was thinking Mega Squirt could take care of that for me.

Having not really messed with injection before what should I be looking at here? Seems like in the long run it would be less expensive to pickup the TPI and MS than it would be to buy a new manifold and carb. Car is mostly going to be used as a road runner and autox car. I would think I could dial things in a bit easier with the injection to improve mileage and maybe change the map for when I need to get a little more performance?
 

Bonnewagon

Rocket Powered Basset Hound
Supporting Member
Sep 18, 2009
10,540
14,217
113
Queens, NY
I love injection but it's hard to beat the simplicity and low cost of a carb. A well set up Q-jet does all things well. Plus the sbc intakes are a dime-a-dozen at swap meets.
 

79GP6.6L

Greasemonkey
Jul 7, 2006
218
0
0
Upstate NY
The long-runner TPI intake will give you a lot of low-end torque, but they don't do well above 5200 rpm or so. You can't change the physical characteristics of the intake through programming, so the easiest solution is to switch to an intake with shorter runners, like the Accel Superram or Holley Stealthram.

In the long run fuel injection will be more expensive, but will have better street manners. How complete is that TPI setup you found? If you have to buy things like a mass airflow sensor, oxygen sensor or fuel injectors, it will get expensive quick. You also need to plumb an electric fuel pump for fuel injection.

I have a fuel injected project and a carbed project, and the carb setup is definitely easier on the wallet.
 

rebelgtp

Master Mechanic
Mar 5, 2009
366
0
16
La Grande OR
I would need the mass air flow, and oxygen sensors and a ECU though I figured I would just build a Mega Squirt for the setup and knew I would need the fuel pump. Wouldn't I need to change out the fuel line as well for one that can handle more pressure? The guy is asking $125 for the setup.

The guy that I am getting the engine from said he does have an Edlebrock intake laying around as well that I could get for cheap just don't know what carb I would want to match up with that to feed the engine.
 

79GP6.6L

Greasemonkey
Jul 7, 2006
218
0
0
Upstate NY
The metal lines on the car should be ok as long as they are in good shape. The easiest way to go with everything else is to run braided fuel line with AN fittings. Does the TPI setup include the fuel rails and fuel pressure regulator? You will need those.

If you are in a hurry to get your car on the road, you could put a carb & manifold on it at first and accumulate parts for the fuel injection conversion as time and money permit.

I'll add one more thing about TPI. This is just my personal preference. I have run a stock TPI setup, a modified TPI setup, and now I run a Stealthram, all on a 350 in an F-body. TPI looks cool under the hood, but it is a PAIN IN THE *ss to work with! There are a lot of bolts securing the runners to the intake base and plenum. The lower ones can be difficult to get to, and even worse if you have tall valve covers. It is also easy to cross-thread the lower bolts if you are not careful. You have to watch out for vaccuum leaks where the runners meet the base and plenum, as multiple gaskets are required.

With the Stealthram, the plenum is off after 4 bolts, and it performs better than my modified TPI setup did. I am never going back to TPI! You can make a strong running engine with a TPI setup, but it is more work and the aftermarket components are expensive. I'm not trying to talk you out of it. Fuel injection is great. But there are easier ways to do it.
 

drknow90rs

Greasemonkey
Aug 12, 2009
117
0
0
Wittmann, AZ
If you are going to autocross, I would recommend the TPI setup. I have had TPI setups on many cars over the years and they are simple to work with and parts are cheap for them. If you go to www.thirdgen.org you will find that there are lots of good parts for sale at good prices. That said, 125.oo is very cheap. I usually sell the same thing for 200.oo +. The superram and miniram are better, but you will pay a lot more. I autocross with my 86 IROC and I'm rarely over 4500 Rpm. Good luck!
 
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