I recently bought an 84 Z28 with the 305(non H.O.) and a 700-R. I am asking for everyone's honest opinions on motor swaps.

I have been thinking LT1 for Mainly Gas mileage, but I don't know if i want to go through the trouble of all of the conversions. I have a 350 right now with flattops that came out of a truck. Right now it has an RV cam in it, which of course is no good for my application. Now, my conflict is that I have the motor, and I can pretty much rebuild it for a little bit of nothing, but a Holley is not exactly going to help with my gas since this is a daily driver. I was wondering if a tpi swap would help on the gas enough to make a difference, and still make power. If I build up the motor I already have, i'll probably put new rings in it, leave the flat top pistons in it, a mild cam (maybe a 268), 1.6 rockers, and ported heads. I want to know if yall think i should Put a TPI on it, buy a LT1, or just slap a holley on it and go
all your 2 cents will add up, thanks

 

Of course. TPI or some form of fuel injection will absolutely help with the gas mileage problem.

I wouldn't really bother with TPI in stock form. I would go aftermarket since you have a carb right now. Or if you do go TPI I would at least get the aftermarket intake. Fuel rails and so fourth. I personally love fuel injection.

 

I wouldn't put a stock TPI in it, that would make no since. But I really don't want to drop a lot of money in something like that. Couldn't I port the stock runners, add bigger injectors, port the intake, and slap a bigger throttle body on it and still make the needed power? The big question is the computer...my car only has a Quadrajet on it right now so it has minimal computer control. Is a computer going to hit me in the wallet hard?

 

It will take next to nothing to get the stock CC q-jet to work with the 350 (secondary rods/hanger tuning). What you'd have to do to get the TPI to work is quite a bit more. You should absolutely improve the exhaust (throw all of the stock stuff away, get '86-'90 TPI single-cat application headers on-back).

What heads are you planning on using? Most factory truck 350 heads are worse than factory LG4 heads.

With port matching, the stock intake will work fine, too. Or, a GM performance q-jet manifold, or Weiand Action+ would be good improvements.

The RV cam would probably work fine. Especially for gas mileage concerns. But, a good computer-compatible cam from Comp or Crane would improve power without hurting mileage too much.

 

I don't want to use the quadrajet just because of the coldstarting/gas mileage. That RV cam is not good for anything except local cruise in night. I already put a 3 inch cat, 3 inch pipe, and flowmaster on it becasue the original exhaust was like swiss cheese. I will probably put a set of heddman headers on it.

 

I don't know what heads im going to use yet....you are right, those factory castings are boat anchors
any suggestions on heads? Are the bolt holes at a different angle on the TPI heads?

 

I wouldn't bother with the tpi... an older stock setup probably will need new injectors anyway. a new bigger TB is pretty expensive also, but probably the main limitation are the runners. those 3 are 1000$ allready! and yes, an older tpi setup CAN run worse than any well tuned carb.
the only thing the tpi is good at is showing off- it does look neat!

 

You can definatley get good gas mileage with a carb. If you put a mild cam in the engine with some nice aftermarket heads like the World SR Torquers or something like that, and a 500-600 cfm carb, you should be fine with about 20 mpg. TPI is good for low maitnence but converting can be a pain. There was someone selling a complete TPI setup in the classified section for like $450.00 and that had the computer and stuff with it.

 

There are aftermarket induction sets you can get.. like a MiniRam or Holley's(?) fairly good TBI peice.

 

the ECM you can get used for like $30 the chip and the wireing harness will kick you in the *** pretty hard.

 

:hail: get the Hooker 2055's :hail: comes witht he 3" high flow y-pipe

 

I would suggest a some sort of aftermarket DFI setup. I mentioned TPI because it will feed a stock 305 plenty and they are cheaper than aftermarket for a complete setup. You can mod it to flow better and work ok on higher HP motors. Personally I think TPI with a different intake and plenum, runners and so fourth could be cheap enough and be ready for good high HP engines.

If you are serious about making alot of power than I would say that DFI of some sort will be needed to keep good gas mileage. However the cost will go up. I have never seen a high HP motor pull good gas mileage out of a carb.

I don't know much about carbs. I have never seen one that would give consistant and comparable gas mileage to FI. I notice that they need to be tuned all the time. I know that the newer electic choke helps for starting on cold days and things like that.

My TPI runs the same on cold and hot days. Just my $0.02.

 

Gas Mileage with a carb shouldn't be too awful...My dad can still pull 21 MPG in his truck...Its a 350 with double hump heads and a 650 Holley....Just gotta know how to set everything up!