A guy was asking me if it could be done and for what cost.He said he has a 87 firebird.He wants to convert his carb setup to TPI.He said he was given a TPI and comp.Is this possible?What will he have to do and what will he run in to doing it.Probs/drawbacks and what shortcuts will aid him?
Thanks guys.

 

as long as he has all teh sensors, ecm, harness, and hardware he is ready to go.
eh will have to oval out the center 2 bolt holes on each side of eh intake to mate up to his older pattern heads, no big deal.
he will have to run all teh wires, my suggestion is to get an assembly manual to see how they were run from teh factory, that will save a lot fo headaches.
the only thing i cna see holding him back is his stock cam. teh tpi wil compensate for it, but even a stock tpi is set up for a bit larger cam than any of teh carb motors came with. if he switched his cam whiel he had the engine apart he coudl make huge gains, soemthing liek a comp cams xe268h woudl eb great in a 305 using stock tpi.

good luck with the swap.

later
tim

 

The automatic TPI cars had the same lousy cam as the LG4 low output carb motor. That tiny little peanut cam is chomping 25+ hp bare minimum out of the motor. From 85-86 305 TPI cars lost 25hp from nothing but that lousy cam, the infamous peanut cam that most of the other base model cars came with for awhile. And there is still room for improvement over that factory 85 cam with a good aftermarket grind... Tell him to swap it out while he's got the intake off (can be pulled out with the engine in the car, just remove the radiator, unbolt and pull out of the way the A/C condenser (leave the lines hooked up so you don't have to recharge the freon) and the cam can slide out the front). For a 305 behind an automatic something like a 204/214 @.050, .420/.442 lift cam is perfect, if your buddy had of had a pre 87 he'd be set with that for $100. I believe even the base models motors all went to roller cam setups that in 87, could be off. Unfortunately I think he needs to try to score a good yet still cheap roller cam from somewhere now. Tell him to look in to a used L98 cam or maybe a LT1 cam. If he has a 5spd he can go slightly larger, but for a street car I wouldn't go much bigger at all (I'd stick to 210/220 or under if it were me...)

If he swaps to the TPI intake and adds a decent cam he can look forward to probably around a real world 40hp at least over a stock LG4 carbed setup (not because TPI is so great, but because the cam and the stock LG4 intake is weak as all hell...) If he switches on headers at this point he will be rewarded with even more power, as the small pipes on the LG4 will be really be holding it back as well.

Tell him to check out this interesting article about a LG4 buildup. www.inter-scape.com/ray/305buildup.htm They picked up 35 hp over stock with a Performer RPM intake (20 with Performer), and 40 something HP over that when they added a decent cam, all with the motor already having headers with the stock heads still (270ish hp total at that point). He probably won't pick up quite that with the stock TPI intake, and he'd want to go slightly smaller on the cam so he'd give up some power there, but it's worth a few ponies over the stock LG4 setup (someone's dynoed the TPI intake swap alone, and it was worth some decent power, I forget the numbers though...)

If he doesn't have the whole wiring harness, the injectors, and all the sensors already it will probably be pretty expensive to get it all together for the TPI swap. Really if I were him I would sell off the TPI parts, and use the money to upgrade the intake, cam, and exhaust keeping the carb setup. It can make plenty of power, as per the article above.

Good luck

 

i put in a 93' vette LT1 cam in my 305, i haven't had a chance to run my car again at the track, but im hoping i picked up a solid 30+HP.....

 

Dont forget the fuel pump. That needs to be changed out for a TPI pump. The LG4 pump wont give you anywhere near enough pressure.

 

I removed my pump and it in a dump somewhere.

 

Thanks guys I'll pass on the info.

 

I did this swap on my car last year.
Cost me about $1500 since I did a lot of things to the engine at the same time I did the swap. I had the MAF setup converted to Speed Density, installed a new cam, 87 TPI heads, in-line fuel pump, MSD 6A, Eprom Programmer and tuning software, etc..

Went from this Carb Setup

To this,
TPI Setup

After my bottom end went out, I sold the setup and installed it on the buyers Camaro. Did the entire swap in less than 10 hours.
That included removing the carb setup, installing the TPI, re-doing the fuel lines, installing an inline pump, and all the wiring, plus drilling out the 4 center intake manifold holes since he had 86 heads and my intake was 87+.
I have a partial parts list on my site on what was needed for the swap, www.transamws6.com.

 

Dont forget you need to add in a fuel return line too.

 

Car already has a fuel return line stock.
The only mod you have to do to the fuel lines is cut them when they go over the trans tunnel and add more line and keep it on the drivers side of the car.

 

Really? Carb thirdgens have both feed and return fuel lines? I didnt know that.

 

Mine did and so did the Camaro I did the other swap onto.
Feed was 3/8 and the return was 5/16.
Not sure if you can tell but here is picture of my underside of the chassis, Fuel System.jpg
Both of our cars also had mechanical fuel pumps on the block.
I have heard that some carbed 3rd gens had low volume electric pumps in the tanks, I just haven't seen them personally.

 

Yeah, Kevin ... those are the lines I had to replace on my Z28 with TPI lines. There are three lines coming out of the fuel pump (IN, OUT, Return). Just they go over to the passenger's side, rather than the driver's side. I didn't want mine to look like a butchered job, so I got the entire lines (from rear to front).

That is actually false. They were later (dealer warranty?) equipt with a pump to help vapor lock, but not from the factory. Also, the GM 350HO conversion kit comes with this upgrade ... could be where the rumor go started (converted cars).