stanghunter211

Hey guys, I have posted this topic before, but didn't get much feedback. I have long wanted to make my own 4bbl 350 HO like the one GM offers, but for half the price. But I love the pick up on FI cars. My question is , can I swap in a TPI 350 and keep it remotely smog legal? I have an 86 LG4. I would like to do the 4bbl swap, but the TPI just seems like a good all around package, and parts are more prevelant.

I need to know what exactly I would need, IE new fuel system? wiring? I know alot of places here that sell motor/tranny/wiring harness/computer combos... WOuld I need anything else > Any special wiring? Can it be done in the first place? On a car my age?

I am also planning on doing some suspension and structural support mods to help the car deal with more power. I will proly do those before I ever get a new motor. I just wanna know what are my odds here. Stick with the 4bbl HO dream.... or get a TPI setup?

Thanks guys

Will

Jim85IROC

As long as you use all of the OEM L98 smog equipment, it should be 100% legal.

Anyway, what you'll need is the entire TPI setup (throttle body, plenum, runners, base, fuel rails, injectors), upper radiator hose, water neck, computer & harness, all engine sensors, fuel sending unit, fuel pump, and fuel lines. The TPI cars may have a different length TV cable; I'm not sure.

I'm not sure whether it was 86 or 87 that the LG4 got the electric fan, but if you have a mechanical fan, you'll need the whole fan setup too.

Narcah

Basically you'll need everything related to the motor. However, it IS possible. And probably fairly easy. considering...

MRZ28HO

What Jim said is absolutely correct. "I" am going through that right now. Although my Z28 was an L69, it will be an "L98". Check out the Thirdgen.org forums for more specific help, also you can ask Dyno Don (L.) questions on the So-Cal forums there as well (regarding this swap). I would recommend going with the Speed Density setup if you can, it is the most advanced TPI setup that was available on thirdgens.

stanghunter211

Thanks guys. Yes 86 was the first year of electric fans, and I was gonna add a dual fan setup later on down the road.

Heres one of my main questions.

Do I NEED an "in-tank" fuel pump, or can I use an in-line model? I really dont wanna change my tank, as I have the biggest tank ever available on 3rd gens, 16.2 gallons. I would like to avoid changing that if at all possible.

So if I were to get it smogged, obviously, it would not pass under vin H. The tech would be looking for a carb, and all that other stuff. What would I do? Make a friend who smogs? Always beneficial. But what do you guys who have done this or plan to do this do>

Thanks guys, more questions later!

Will

MRZ28HO

All 3rd gen V8s and V6s had the same sized gas tanks (I4 had smaller ones), there are no "bigger" fuel tanks than other models. As for the fuel pump, you'll have to swap out the pick-up strainer for a fuel pump, the pick-up assy and tank are the same (carb, TBI, TPI).

stanghunter211

Pick up a chiltons manual, its right here in front of me, most got a 15.5 gallon tank, but the mid 80's Z's got a 16.2 gallon tank, I can copy it and mail it to you if you'd like

Will

stanghunter211

I've also got the fuel reciepts to prove it...........

Jim85IROC

If you're looking for accurate historical or technical information on your car, I suggest you look somewhere beside Chilton's.

But since you don't need to change your tank anyway, it's really a moot point.

stanghunter211

Hey , Can I use an inline fuel pump? I see several good pumps in Summit, and I wanted to know if I could use one instead of the intank setup. Also where would I mount it? Down under the car>?

Thanks guys

Will

Marc 85Z28

He's right. ALL carbed V8 cars got a 16.2 gallon tank, while the TPI and TBI cars got the 15.5 gallon tank. Not only have I seen the difference, my 1985 Chevrolet Camaro owner's manual confirms it...

Oh, and 16.2 is not the largest either. An 18 gallon was offered in the 1LE/B4C cars.

I every state you are allowed to swap in a newer engine from the same vehicle line, as long as you include all factory emissions parts.

And, yes, go with the inline pump. No need to install an expensive and troublesome intank unit with pickup.

Kevin91Z

Ahh yes, the infamous gas tank size debate. Lets just say that in my 4 years of being involved with thirdgens, not once has anyone proved they have a tank bigger than 15.5 or 16 gallons. The half gallon difference is not worth worrying about. GM probably wanted to put in an 18 gallon gas tank, but it never happened.

Bort62

Will,

I live about 70 Miles south of you in Morgan Hill. I Currently have my 85 sport coup LG4 completely dissasembled and going back togther, One aspect of wich includes a Speed Density Swap.

Feel free to email me with any questions, and I can help you out as needed.

Bort62@speedtoys.com

The best Route to do this would be to find yoruself a wrecked L98 car and Move everything over... I peiced my setup together over the net and It is a huge PITA.

stanghunter211

You know, that was the route I had planned on, finding a wrecked L98 car and just taking the whole works. But around here at least, there are not alot of L98's laying around. People snap em up quite quickly. I take it that you know about GM sports, since you live South around SJ. I have seen them put 5.0 TPI's out all the time and the occasional L98 or B2l, so I was gonna cruise by and check out what the prices were.

I met a guy over the weekend at a Bay Area GTG who just did an 82 T/A LU5(CFI???) to L98 swap. He said the biggest pain was the wiring, took him 30 hours, but everything works.

It looks like I will need a good week to do all the swap and stuff, but thats fine because I plan on going through the motor and adding some better parts while I have it out.

I also wanted to port the plenum maybe, add some headers, a better cam, but nothing too aggressive, so I can still pass smog. Maybe some other parts.

I also have plans for the near future, once this motor is in and all is well for a few oil changes, to add a vortec or similiar, maybe ATI, supercharger. I think an 86 with a blown L98 should make for quite the sleeper around here, and it will be smog legal, which is what I want

Thanks guys, I appreciate the insight. And I will follow up on you about your LG4 SC bro! THanks


Will

Sitting Bull

George,

I just love your red Z28. Have you taken any larger pics of it (other than the one on your site) and where might they be?