DonW

I ran across an L98 TPI Motor / Trans combo complete with all wiring and ECM from a low mileage wrecked 1990 Corvette. The seller was a local parts yard that warranted the engine for 90 days, and the transmission still hooked up to it is a pretty fresh GM reman 4L60 (non electronic) unit. All sensors are still on the motor. Got the whole combo for what I consider to be a good deal at 1300 bucks.
The car its going in is my 83 Z. Shes got the worst LG4 made at 145hp The gains will be phenomenal to me being used to the old sluggish 305. However, I want to get the most potential out of the 350 TPI motor, and am trying to wrap my head around whether to just drop it in as is, or reuse my current HEI setup that has a new Holley 600vs sitting on a Eddy Performer intake.
Im putting this in the Carb thread since allot of you guys know how to make a Carbed car and have probably been down this road before.
So what are the pros and cons of each setup in your opinion?

TTOP350

iTrader: (8)

I rarely say this but since you are carb now, that would be easier to do.
Go efi later if you want.

Abubaca

iTrader: (3)

Since there's really no right or wrong, I'll throw in my two cents. We all have reasons, sometimes good ones, sometimes not, as to why we do what we do. For me, on my 89, it came with TPI, so for some reason I feel like I can't change that. I HAVE to keep it. That being said, I've always loved the beauty and simplicity of mechanical carbs. It's just "cool" that they're almost as good as EFI, yet a HUNDRED years older! I just think that's cool! Ultimately your goals, budget and area of expertise will make one choice better than the other.

dmccain

iTrader: (2)

Being the car is already setup for a carb I would have to go that route for simplicity and you should make more power also. I love a nicely tuned TPI engine but too easy to just put your carb on and go. Shes gonna be a strong runner with that L98! Good luck!

rusty vango

its getting hard to keep a TPI car running . especially if you have a MAF car. parts are being discontinued . or very spendy , when you do find them . that being said . i love my TPI car . now if i could just get it to idle right !!

lt500r55

I agree with ABUBACA I also have an 89 IROC an I'm grinding on an extra tpi base right now trying to figure out why they made what they made an why I'm sticking to it. if I did not feel like keeping it stock I would probable throw it as far as I could an go carb. take it with a grain of salt I'm a little tired of looking at. it's got restricter plate genes .Dan

DonW

Abubaca, lt500r55, I dont blame you guys for keeping the stock setup. No need to mess with a good thing! I would definately be all about originality in your cases as well. Mine was decomputerized when I got it, and a hack job at that. Right now, I have it running pretty good on the HEI-carb setup after following Sofas Holley sticky this past summer. A few weeks ago, the trans started spilling fluid from the servo, and already had a small leak from the front pump. For the cost of getting the trans pulled, rebuilt and reinstalled was going to be close to what I paid for this whole engine / trans setup. And in the end would have just wound up with the same weak early version of the 700R4. The 4l60 should be better. It was a win win.

From what Ive read on here, the TPI is a limiting factor in upper RPM's. Is that true? Will the carbed setup be better in upper RPMs? You guys definately have me leaning toward keeping it carbed with all of your input, and it makes sense. The only two things I think Im going to run into are fuel supply (not sure if this motor has the cam lobe provision or even the hole for my mechanical) and speedometer, since Im sure the vette it came out of was digital.

DonW

Your gettin an old man all excited now... This car currently wont pass, well, anything else on the road...lol

five7kid

iTrader: (14)

For the trans, you're going to have to swap the tailshaft housings regardless, since the Vette and f-body are different. Swap the speedo drive gear while you're at it - problem solved.

The carb will make more power above 4500 RPMs (to 5500 RPMs if you have an Edlebrock Performer, not Performer RPM, intake). The TPI will make more below 3000 RPMs. TPI will yield better fuel economy (assuming it operates properly). TPI wins the butt-dyno competition.

Unless you get the complete TPI system (harness, ECM) from the Vette, you're probably better off just putting your intake/carb/distributor on the L98 longblock. Hopefully you already have the geometry corrector bracket for the TV cable, and a means to lock up the torque converter clutch in cruise conditions.

Something nobody mentioned is the '90 Vette L98 had aluminum heads with the older SBC all-90-degree mount bolts, same as your '83.

I'm not sure if the '90 L98 cam had the fuel pump lobe. My guess would be it does. Only way to know is to check.

I also hope you don't plan on using any of the LG4 exhaust (with the possible exception of the hangers). LG4 exhaust will turn the L98 into a disappointment.

five7kid

iTrader: (14)

Define "old"...

DonW

five7kid, thanks for the input. It hadn't occurred to me to just swap tail shafts and speedo gear...excellent. I do have the complete wiring harness and computer from the Vette. Carb is looking like the way to go though, especially since you just pointed out that my Edelbrock performer will bolt right up. The exhaust was the first thing I changed when I got the car. It went straight to the exhaust shop and got a cheap set of flowtech shorty headers and all new bigger pipes and flowmaster muffler. I did that because I knew when the day came for a new small block, all I would have to do is spread the headers out and reinstall on the new engine. Sounds like I will be winding up with a pretty straight forward swap, even if I wind up having to do some sort of external elec fuel pump. I really dont want to have to drop that tank again. I just had the rearend replaced with a rebuilt 3.42 unit and paid a pretty penny to have a fuel level sender replaced...lol Lord willing that tank aint comin outta there again!

DonW

Well, Ford was President when I was born, and youll have to ask my wife or one of my six children the exact age. Thats what I have to do every year...lol

DonW

Or was it Nixon?....dang..cant remember!

sofakingdom

iTrader: (1)

That's my problem too:

"They" say your memory is the second thing you lose as you get old. Problem is, I forgot what "they" say the first one is.

DonW

Well there ya go. You help me, and I'll help you. First thing to go is the blatter...LOL

Galaxie500XL

iTrader: (1)

Your definition of "old" worries me just a bit....John F. Kennedy was President when I was born, and the last Project Mercury spaceflight occurred a week after my birth....and I actually remember watching Neil Armstrong walk on the moon.

Abubaca

iTrader: (3)

Ford was President when I was born too, lol. ...and I'm currently all laid up after knee surgery. Nothing like watching as your parts stop working!!!!

DonW

My wife tells me that I redefine the definition of old. Maybe it's because I grew up around my grandparents here in the south. Being old fashioned, coupled with 5 children and one on the way, with enough health ailments for a 70 year old, can sure make a man feel older than he is..lol
I don't exactly fit in with my generation if you know what I mean. I actually miss not having internet, and despise seeing grown men my age sitting around the house playing damn video games. I will never get that. My best freind I've known since childhood does this along with masses of others, So yeah, I feel old. Givem all the participation trophies they desire along with a kick in the *** I say... But that's just me,

DonW

Best carb thread ever.... Where's the beer and nachos?

DonW

I don't drink much, but sounds like beer and nachos is how I'd be taking advantage of your situation lol

dmccain

iTrader: (2)

five7kid

iTrader: (14)

Flowtech isn't the best choice out there. Their only quality is they're cheap - which is about the opposite of "quality". If they have 1-1/2" primary tubes, you might want to consider replacing them with a set of 1-5/8" primaries.

I believe you're also going to need to change the oil pan and oil pump pickup, as they the Vette oil pan doesn't play well with the 3rd gen f-body K-member. The bad news is I don't think your '83 305 pan will fit the later block (I could be wrong there). The good news is it shouldn't be hard to find a pan that does fit.

You'll also have to decide which accessory package to use. Putting the 305 stuff on the L98 will be a piece of cake. Using the Vette accessories will require some changes to the hook-up stuff in the car.

Even though this is the Carburetor forum, I really prefer EFI for a driver (I actually don't own a carb'd vehicle anymore). But, I'm thinking the payback for the hassle to convert the car over may not make it worth it to you. Putting the carb stuff on the originally-EFI longblock wouldn't be hard at all.

(And, since I started all the discussion about "old", I was born when Ike was pres - the Apollo 11 moon landing occurred the summer before I started high school.)

DonW

Trust me, I prefer EFI on my daily driver as well. Wouldnt have it any other way as my wife and I drive newer cars. I bought this car as a "date night" car for my wife and I and something for me to tinker on in the garage since I still have 3 girls (plus the wife) living in the house. Heck, even the two dogs we have are female! I needed something sinister looking in the garage! LOL
You couldnt be more correct about those headers. They are okay for now, and were an improvement over the stock manifolds, but something tells me I will be blowing a hole in those pretty soon after this swap.
I have a good list going now, thanks for the input on that oil pan!
Any suggestions for an upgraded cam kit since I will be losing a little on the bottom end grunt by removing the TPI? I might as well go through it, at least the top end while it is sitting in my garage floor now.

DonW

Who the heck is IKE???????

DonW

Just kiddin...thanks for makin a fella feel younger...lol

five7kid

iTrader: (14)

I think the best way to regain low-end grunt is with gears and increased stall. Then enhance that with a better cam.

The 113 heads will need better valve springs with most any aftermarket head (to say nothing of the valve springs being 25 years old). However, the '90 L98 had roller lifters (a very good thing), so if you get a cam kit you don't need one that includes lifters. The heads would also benefit from CNC porting, but you'll have to decide if you want to take it that far.

The Performer intake dies at 5500 RPMs, so unless you're willing to upgrade to a Performer RPM, that will limit your choices somewhat.

A lot of people get a LT1 take-out cam, which have the advantage of being relatively inexpensive for a roller cam. Comp makes some decent stuff in their "Xtreme Engergy" series cams, like this one http://www.summitracing.com/parts/cc...make/chevrolet which would match the rest of your combo well.

I was going to do this to my Gen I 350 http://www.summitracing.com/parts/na...make/chevrolet with Vortec heads and Performer RPM, but ended up going LS instead. A lot of people have used the LT4 Hot Cam, you may get some comments that there is better stuff out there. It certainly would be best with Performer RPM, at least 2500 stall. 3.73 gears would make it come off the stop lights pretty respectfully. This kit also has the advantage of getting rid of the factory stamped steel rockers.