I have a 1970 LT1 engine that has been stroked to 383 that I want to put my TPI induction on and drop in my 92 Z28. What is going to be the biggest barrier to try and overcome to pull this off. other than finding a place for the knock sensor, what else should I look out for? I know a completely re-programmed chip is in order. Thanks for any replies from people who have done similar swaps.

 

biggest problem will be the actual TPI itself, since it will choke a 383, especially one that "built"

this is an easy problem to overcome though, thanx to many different types of EFI manifolds availble



also, not too sure how well a solid lifter cam will get along with a GM ECM, i'm sure somebody else can chime in on this though

 

Yeah, I have the choking part covered, I think. I have an Accel/Lingenfelter intake, Fully ported upper plenum, SLP runners which I have also cleaned up inside, and 52mm throttle body. I am probably going to step up later to Holley's stealth ram, but for now I wanted to use what I have. I am not sure about the computer issues either.

 

The knock sensor might not like the solid lifters. You have modify the intake bolt holes to go on the LT1 heads, the center 4 bolt are drilled at different angle.

 

swap the Lt-1 cam out for one better suited to the intake.

 

The dipstick will be on the drivers side, might have interference issues with the exhaust.

 

I seriously doubt that this is an actual "LT1" engine.... sounds to me like this is a 3970010 block from who knows where, which is the same casting that was used in the LT1, that somebody has worked over, and sexed up and romanticized to the buyer for extra coins no doubt as a "LT1" block (at least they didn't say it was "from a Vette"); but most likely no other LT1 parts or any other connection to an actual LT1, including the heads or cam for example. I can't feature anybody grinding on a block to make it into a 383 and then sliding an old used cam back in it. So the whole LT1 ad-copy thing probably is a total non-issue in terms of reality, even though in reality even if it was a "LT1" block, it wouldn't make the slightest bit of difference to the matters at hand. It's just monkey-spank.

To put a 70s block in a later car, you need to be aware that the dipstick will be on the driver's side, and will absolutely not clear the exhaust manifolds; but will clear headers just fine. Also, you'll need a flywheel or flex plate from a 82-85 305, which will be the right diameter to fit your starter, and will have the right bolt pattern to fit the early crank.

All small blocks from 55 up have the knock sensor hole. Except, nobody realized up until 81 that it was the knock sensor hole. Before then, everybody thought it was just the right-bank coolant drain hole. I can hardly wait for somebody to post on this board that they have a rare 2-bolt-main block from a 375HP 350 that came out of a 70 Vette, that they paid extra for because it already had the knock sensor hole installed; I can feel it in my bones that it's coming.

 

This is indeed an LT1 motor that my father has had for many years. He ordered it from Chevrolet as a crate motor. He sold the 68 Chevelle it was in as a rolling chassis, and now I have a chance to either use it or bolt on some things to my L98 that is in it now. I would rather use his because I know it has some hell in it! Believe it or not, this is an LT1.

 

If now a 383, it no longer has the LT-1 crank in it. If TPI, it no longer has the LT-1 intake on it. You haven't said what heads or cam you're using.

I've had an engine with LT-1 heads and cam (although not the block), it was a low-RPM dog, required retarded timing with even the best pump gas, and wouldn't hold a candle to my current mild 396. Cam and head developement in the last 30 years have left LT-1 stuff in the dust.

It's "neat" that it was an LT-1 crate engine, but as people are trying to tell you, upgrade to new technology for the cam at least, and possibly even the heads.

 

Yeah, I agree with you about new technology with heads and camshafts. I just thought being this engine is available to me to use I would try and do something with it. Are you saying I should scrap this idea and build on the L98. I am sure it too has potential with the right head and cam combo.

 

The L98 has provisions for the factory roller cam; the LT1 will require you to either downgrade to a flat-tappet, or buy the original design roller system to retain that feature of the L98.

The L98 also already has the right crank for the flywheel or flex plate you already have.

Assuming that the heads on the LT1 are still LT1 heads (461 casting) the L98 heads flow about the same in stock form, port up similarly, and have the smaller chambers (higher compression). So there's no advantage to the LT1 heads over L98 ones.

The LT1 cam, if that's still in it, is a total mismatch for TPI. If you can imagine the worst features of the LT1 (poor gas mileage, rough idle, soggy bottom end) combined with the worst features of TPI (no top end whatsoever) then you'll get a pretty good feel for what will happen if you just jam the TPI on top of the LT1 long block; except that the tuning issues will be harder to overcome.

In short, there's nothing about the LT1 core that's any better than your L98 core for what you're doing, and alot of things about the L98 core that are superior. The mere fact that you can prove it's a "LT1" doesn't mean that it has any advantage for what you're wanting to do.

I would suggest using the L98 core as the foundation for your proposed build-up.

 

That is what I was thinking myself, I am not up for all the challenges this swap is going to present. I just wanted to hear someone else say it. I think it will be more sensible to use what is already there, and build it for what I want, which is a strong street/strip car. Thanks for the replies guys, I needed some opinions.

 

The main advantage of the LT-1 block is you can build it up as you continue to drive the car. But, RB nailed all the disadvantages.

But, hey, it's still a 350 block. I'd take it if offered. Probably worth more to a restorer, though.

 

Damn, who pissed in your Corn Flakes this morning?
He was just asking a question.


I would use the old short block if it's stroked to 383 and put your current heads and intake on it. It's kinda a trade off though, roller cam or another 30 cubic inches and a flat tappet cam. Cost of a flex plate and differant dip stick are pretty small compared to a stroker crank for you L98 block. Plus you can do all of that in the course of a day or two if this is your daily driver. Building up the L98 will mean the car is down for a while.

 

I'd sell the LT! motor to a restorer or something for some major coin. Its worth a lot to somebody if they want it.

 

One advantage to the LT1 block would be that its got 4 bolt mains, and if the original pistons are still there, then 11:1 slugs and the good rods (dont recall the name)

TPI and an LT1 below it are a total mismatch though... the TPI has nothing above 4500 rpm, and the LT1 has nothing below 2500.

That and the stock LT1 had solid lifters too, so theres even more extra hassle.

5-7 is right though... worth a ton to someone restoring a '70 Z/28 or a Corvette.

 

How is this thing worth so much? If it still has the suffix codes on the deck surface it would only match one car. What are the odds?

 

I did not mean to create such a discussion, but this engine is not worth a whole lot, due to the modifying that has been done to it throughout the years. the only thing on it that signifies it is an LT1 would be the serial number on the block.

 

Understood. The point remains that it has more "appeal" to the resto market than uniqueness with regard to power creation.

You said it was a factory crate. Therefore, no suffix signficance. To the resto guy, it was a "factory warrenty change-out". Just happened to lose the dealer receipts...

 

since it was in fact a crate engine it has no where near the value of an original 70' LT1 along with having been clearanced for the longer stroke crank. basicly you have an average 383 that will likely end up with oil leak issue's due to it's two piece rear main and old style valve covers. the intake will require some work to be done to get the center bolts to line up as well as the other issue's of not enough airflow through the intake. all in all, with the exception of the 33 cubes, you aren't gaining much.

 

Actually, the LT1 has some really nice aluminum valve covers... they dont leak like steel ones do.

And no one will know its a 383 from a 350 unless they open it up either.

 

old style is referring to the bolt pattern of the valve covers. a crate engine won't have an engine suffix which would halt a buyer and if you sold it as an original LT1 and they tore it down, the'd be a bit pissed. now this has has collectors value.

 

Thats not an LT1, thats a sbc with a Z/28 manifold.

The LT1 never had (stock anyway) dual carbs, or those valve covers.

 

those valve covers certainly didn't come on an LT1, that is correct. that is not a Z/28 manifold. the cross ram manifold didn't come on Z/28's from the factory. if you wanted one, it was put on later. the picture also wasn't to point out an LT1, more an engine of value that wasn't installed in the car from the factory.

 

why wouldn't he be able to run the solid lifter cam, because of the knock sensor?

 

there is a chance the noise from solid lifters will cause the knock senser to retard the timing

and i agree i'd sell the lt-1 to someone that really needs it.

 

even if the knock sensor doesn't pick up the lifter noise, the spec's on that cam will make it damn near impossible to tune.

 

I gotta agree with you on the value of that engine... I saw one sof those Z/28 cross rams on ebay (intake and 2 carbs only) a few months ago, and it went for something like $11,500... Insane price, lol.

 

yeah that goes without saying, its completely mismatched for tpi, i was just wondering about the knock sensor interference.. couldnt you just eliminate the knock sensor somehow and make it ur own problem if u have detonation like on a non computer controlled car?

 

the engine specificly in the picture is a prototyped 302 built by smokey yunick (not sure of that spelling) with canted valve heads. value of it is probably more than the cost of a Z06. as for the lifter issue, i'm not sure the lifters would be picked up since there are many LT1's and LS1's out there with solid lifter set-up's still using the knock sensor's. i'd assume it should work, but not positive. the problem more is with the specs though which could easily just be swapped out.

 

I know this post is a little late but i think you guys could be a great help to me. back in june i got an 82 trans am from a former coworker of my dad's for $1500, he said that the 305 was replaced with a 350 Lt1 from a vette, we were hesitant to believe this, but it was still a decent price. I finally got the engine serial number off it. I looked online to find out just what it really is. the last three letters that are suppose to tell what kind of engine it is. however, icouldn't find it anywhere, DDU. Could anyone help me with this?

 

You need the numbers from behind the drivers side head, on the mounting surface of the block. Shine a flashlight back there and look. It will be something like 3970010 or along those lines.

 

n/m

 

are you positive its ddu?

 

Early 70's Chevy engines had the suffix that started with C for cars and T for trucks. The D first letter might be a small block used in an Olds or Pontiac which was common. Sure not a Corvette engine.

 

But the cross-breeding didn't start till the late '70s.

D could be heavy duty (ie. dump truck) or maybe industrial?