# really stupid engine question



## 58mark (Sep 28, 2010)

I'm thinking ahead to the future, and my plan is to buy a 1970 lemans (because that's my favorite year and model)

I'm hoping to find one with the options I want already restored, but I'm not against doing a restoration myself if I can get a roller cheap.

here's the question. I have, right now, a car with a low mileage LT1 engine in it. If I end up getting a lemans that needs an engine, I'm thinking of using that engine as part of the project.

now I KNOW I don't want to use the electronics that is part of the LT1 package. I don't want to mess with computer controls, Fuel injectors, high pressure fuel pumps, and all the other dozens of things that have to be considered when retrofitting one of these modern engines into a classic car. 

But.... Is it possible to use the basic mechanics from the engines with a carb setup, without computer control at all? 

I know this sounds like a newbie question, but this is one thing I've never looked into before


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## 58mark (Sep 28, 2010)

After doing some more research on it, I'm realizing that I would need to replace the computer controlled transmission, get a new intake and carb, and install a electric fuel pump anyway.

After replacing all of that, it's not worth using the LT1, so I'm left with two options... either forgetting the idea, or wiring up the car for computer control. I really like the power and smoothness of this engine, but it would be a huge project for me. I know it's been done, so if anybody knows of any links to give me a basic idea what I'm in for, please post them here for me

thanks


Who knows... when I find the car I want, it may have a number matching engine in it that is so good that I wouldn't dream of touching it... I'm just brainstorming here...


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## Eric Animal (Oct 28, 2007)

Or have a nice 400 built mildly with around 400HP and stock looking and drive the b*lls off it!:cheers


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## 58mark (Sep 28, 2010)

see that's the thing... I'm not into speed and power. this LT1 is out of a roadmaster. it's got pep, but it's no corvette engine. I want a daily driver that looks like a 70 lemans, but gets good MPG and is smooth and quiet. The roadmaster engine is strong, quiet, will break loose the tires when I want it to, but will get 20MPG.

I've been researching crate engines, and it's hard to find anything that isn't 300HP, and probably would get 10 MPG if I'm LUCKY


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## Eric Animal (Oct 28, 2007)

Such is the nature of the beast! Build a stock 2bbl "base' 400, it will look stock, run well and get 15 mpg.....


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## ALKYGTO (Mar 29, 2010)

Do your research...that LT1 was made famous by being installed in Corvettes, as well as your Roadmaster, basically the same motor.

LT1 also has no distributor.... You will need a computer to run this engine. I would recommend talking with an LT1 engine specialist about a stand alone computer to run this engine and tranny if you are serious about it. It might not be as bad as you think. You could keep the fuel injection and everything that way. Use conventional small block Chevy mounts to put it in the car.

On the other hand... These engines were produced for a limited time, and they are not the latest iteration of the SBC, that would be the LS1, which are very popular (and plentiful) right now and there is a lot of aftermarket and factory support for these engines.

What is the best choice? 

That is your decision. Pure Pontiac, LT1 or LS1. They all have there good points and anyone of them will power your car nicely. For all out power, smoothness and fuel economy I think the LS1 wins.

Sell the LT1 and go Pontiac or LS1. :cool


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## 58mark (Sep 28, 2010)

yeah, and I know that the transmission has a ton to do with MPG. I have always loved the TH series, but if I put a 4 or 5 speed manual transmission in the car, and dropped the highest gear down to 2500 RPM on the highway, I could have a that would get even better MPG than a 3 speed TH350 or 400


but you're right, the LT1 idea is probably overkill for my plans. I should sell the car unmolested to somebody that likes that bodystyle, and then either get a crate engine, or better yet, get the original 350 from the car rebuilt so I can have numbers matching car.


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## ALKYGTO (Mar 29, 2010)

Eric Animal said:


> Such is the nature of the beast! Build a stock 2bbl "base' 400, it will look stock, run well and get 15 mpg.....


Or this^. :cheers


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## 58mark (Sep 28, 2010)

ALKYGTO said:


> Do your research...that LT1 was made famous by being installed in Corvettes, as well as your Roadmaster, basically the same motor.
> 
> LT1 also has no distributor.... You will need a computer to run this engine. I would recommend talking with an LT1 engine specialist about a stand alone computer to run this engine and tranny if you are serious about it. It might not be as bad as you think. You could keep the fuel injection and everything that way. Use conventional small block Chevy mounts to put it in the car.
> 
> :cool


Yeah, I know corvettes had the same engine, but I don't think they are tuned the same, this is a nice engine in mint condition, but it's built for cruising, not speed.

A stand alone computer? I could use the engine and tranny? my ears just perked up... interesting...


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## 58mark (Sep 28, 2010)

here's the other side of the story...

My main classic car is a 58 impala... you might be interested in reading about it in the link in my siggy.

out of respect for my father, I'm destined to keep the impala stock for the rest of my life. I wouldn't change anything on it, but the nature of a 348/powerglide combination, I don't feel like I can DRIVE it for pleasure.

I would like a car that I can experiment with, be creative, have a little fun and try things that aren't "stock nazi"

that's why I like the lemans (besides a 70 lemans was my first car) I can do any mod I can dream up and can afford, but still drive it for pleasure.


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## Thumpin455 (Feb 17, 2010)

Just because it is an old big engine doesnt mean a 400 or 455 cant get decent mileage, especially on the highway. I had an iron headed 455 in my Formula with 4.10 gears, and an 850 double pump Holley on it that got 13 mpg, similar chevies I know that didnt run in the 11s in street trim got worse mileage than that car did. I know you dont want to go fast, but that isnt my point, that car should not have gotten that kind of mileage if you believe what everyone says.

The 455 in my 70 GTO got an average of 20 on the highway, with a high of 25 on a stretch of I-40 in TN. It has 5C heads, Qjet, 280/288 UltraDyne cam, 2004R behind it and 2.93 gears. It ran [email protected] like that and had more than enough power to pass even on hills without downshifting. The idle sounds beautiful, and it runs nice and smooth making power from idle to 5500. Mind you a 70 GTO is a 4100lb car with half a tank of gas. An engine built like that is so much more enjoyable than a weak suck LT1 that has lots of requirements and changes needed to put them in our old cars.

Find a 400, stroke it to a 467 with a 4.25" crank, mild cam and whatever heads you find, stock intake, HEI, and a well built Qjet. Run a sensible gear behind it and an overdrive trans, be it manual or auto. These engines dont need lots of gear, the Formula with 4.10 gears had way too much and it was all done well before 1000ft on the track. It actually went half a second faster with 3.42 gears than it did with the 4.10s. A 455 will pull any gear you put behind it effortlessly.

Or you can follow the so called experts and stuff a chevy in it and believe that is the pinnacle of automotive worth.

Nice Impala, I have a bud who is big into 59s, he has somewhere around 20 of them.


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## 58mark (Sep 28, 2010)

thanks for a very helpful reply (and the same goes toi everybody else too)

here's where i'm coming from. the lemans I had when I was 16 only got 10 mpg, and that was when I was driving sane and conservative. To get into that situation again would bankrupt me as a daily driver. now it's possible that I just has a really bad car or carb back then, I was too young and inexperienced to do anything about it, so I had to sell the car. 

If i found a nice lemans with a really good 350, or had it professionally rebuilt and tuned, what should I expect from it in MPG?

i would do cartwheels to get over 15, but from you say I could possibly get more.

or... in insane logic, is it possible that a 400 that doesnt have to work as hard to move the car down the road can get better mpg that a 350?


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## Rukee (Feb 8, 2007)

Google is your friend, I found this in like 3 seconds, hunt around for the best product/price combo.
Painless 65105 PERFECT Engine Management System


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## 58mark (Sep 28, 2010)

it's hard to search for something that until this morning I didn't know existed. That being said, thanks for the link. That's pretty cool, even if it is prohibitively expensive, especially when I would STILL have to then go and buy a new transmission. (unless something like that exists for transmission as well, which I have now searched for and couldn't find)


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## 58mark (Sep 28, 2010)

dang! now you all have me thinking 400 or even 455....


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