A Turbo 400 will bolt right up to an LT1. All late LT1s are 1-piece rear seal engines as are all small blocks since '86. I don't know about the flexplate you have. I have used a '95 Surbuban flexplate with a TH400 so I know it should be no problem to find one that works, and inexpensively. The original harness and computer can be used, Howell or Street and Performance can rework them I understand. Unless you are planning to make a lot of power-adding changes to the engine, I would have it converted to Speed Density to eliminate the MAF sensor. My understanding is that only C4 accessories work out in a C3 because of the location of the a/c compressor on an LT1 in B or F body. The low and right compressor mounting also messes with the rh motor mount, they use further back holes in the block in B-body and F-body mountings (but "standard" location Chevy motor mount holes are present in all LT1 blocks). Hope that helps.

 

It does! Thanks for the additional info! J

 

I have brand new factory LT4 heads, 1.5 roller rockers, hot cam, and manifold for sale in the C4 section. The top ribs on the manifold are polished and clearcoated. I sold my 94 LT1 and am now putting a LS2 in my 73. You can have the whole setup for $2000.00 shipped.

Carl

 

The 4.3L block casting # is 10168588 and casting number for the heads is 10208890. The 5.7L block casting # is 10125327 with #10125320 cast on the iron heads.

Either route (it sounds like) will require electric fans for the radiator unless u can make the "B" body water pump bypass to a centrifical fan clutch work in a C3.
Unless u have an electronics background the FI conversion u will have a very steep learning curve. Its not real complicated but things like logic pulses may really frustrate u if you need to verify or troubleshoot all the sensors/devices.
For the carb conversion all u need is that GMPP dual plane intake and install electric fans for cooling the radiator. U can use your old carb, distributor and set up the ignition just like the original C3.


Be careful here. The LT1's were externally balanced and had a zero balanced dampner on the shaft nose. That means all the external balance was done by the flywheel - flex-plate in your case. Your gonn'a need a one piece shaft flex-plate balanced for an LT1 that has the correct number of starter teeth for your starter/trans position.

FYI the iron head LT1's (5.7L or 4.3L) all used the same cam. It was more of a truck cam made for torque and low rpm. The duration was pretty short at 0.050" with only 191* on intake and 196* on exhaust (but had a tight 111* LSA). While u will have good low end it will stop breathing before 5000rpm and fall way short of 300hp. I would upgrade the cam for a C3 application but maybe u can find a good used LT1 cam for cheap. Don't worry as most stock roller cams that year were made of billet steel and last forever with roller lifters. BTW i still have my old stock cam in my aluminum head '94 LT1 that i will remove soon. 202* intk / 207* exh @ 0.050" with 116* LSA - only 170K miles on it. Would u like to trade for something? I need another LT1 FI intake for porting with my old heads as the original is still in use on the car.

cardo0

 

The crankshaft in an LT1 is the same part as any 5.7L 1-piece rear seal motor-nothing special as far as I know. I am not aware that they require any special LT1 flexplate, but could be wrong.

 

U need too read the post again. What makes a LT1 damper unique is the zero balance where other external balance once piece rear seal dampners have a balance weight that's not neutral. Also the LT1 s don't have the key slot for the dampner. The dampner (bracket) is fiction fit only.

Another problem is the turbo 400 has no output signal for his PCM. The PCM controls shift points and will need a response from the trans. It also calculates vehicle speed from the trans vehicle speed sensor. I don't know how u can bypass or "dummy" those PCM inputs. Maybe marktn can explain how he did it.

cardo0

 

An LT1 crankshaft does have the slot for the crank key (at least most do) it is just not used. The hub does not have a keyway, but it seems to be a popular mod to add it. I have a friend with a blown then turbo'd LT1 Camaro that has gone through several cranks. A "standard" 1-pc seal 350 crank is the same as an LT1 crank.

You can buy a VSS generator from many sources; Howell, Street and Performance, Painless, etc. It screws inline with the speedometer cable where it screws to the transmission. Use manual transmission PCM programming and all you need is a VSS input. I would personally use the 4L60E from the donor car, but a TH400 is not hard to set up the computer for. Same friend with now Turbo LT1 Camaro has a TH400 in it.

By the way. Why are we ? I am trying to give facts and not personal attacks.

 

Mark...I picked up a 168 tooth flywheel off the bay item #280391408353 for a 1 piece rear seal. Then this should work, correct? It has no weights on it.

 

Anyone else know if this flywheel will do the trick?

 

Ok then read this : Rebuilding the Chevrolet LT1 Engine: By Doug Anderson @ http://www.enginebuildermag.com/Arti...t1_engine.aspx

CRANK KEYS
There is no keyway in the hub for the harmonic balancer, so GM used a special cutback key that was flush with the front of the timing gear on the 1992-’95 engines. It’s p/n 10128303.

When the crank position sensor was added in 1996 for OBD II, the cutback area on the key was shortened so it stuck out far enough (about 0.100") beyond the face of the timing gear to index the notched disc that was used for the crank position sensor.


No personal attacks implied and i do like what u say about the VSS generator. I don't know it the PCM programming will work. But w/o it read like u were leading the way to a dead end here. And what i can't seem to get through is that the LT1 crnk balance is different from other one piece seal crnks (externaly balanced).


I can see my advice/information is not understood nor appreciated here. So good luck to u and your LT1 conversion.

cardo0

 

So which Gen II 1 piece rear seal small blocks are internally balanced? Truck engines? SUV engines? Which?

 

OK. According to Mortec, there is no distinction of LT1 or "regular" 5.7 1-piece-seal crankshsfts.

http://www.mortec.com/cranks.htm

GM Performance also seems to confirm this.

https://store.gmperformanceparts.com/store/SelectProd.do?prodId=7896&redir=true&man ufacturer=GM&category=Cylinder%20Block%2 0&%20Components&name="Crankshaft,%20Cast %20Iron"&model=<!--14088526-->

According to another site I found, all 1-piece seal 350s are internally balanced with the right damper and flexplate/flywheel. If you look at the F-body go-fast pages, a very common mod on an LT1 is to key the crank hub. Even though it is not keyed, it is put in at a specific place. For example:

http://www.golenengineservice.com/ht...ml#crankhubmod

As far as I know all 1-piece seal 350s can use the same flexplate.

http://www.enginebuildermag.com/Arti...balancing.aspx

Jegs lists no differences in flexplates for LT1 and standard 1-pc seal applications.

GM Performance Parts, same thing.

https://store.gmperformanceparts.com...umber=14088761

Finally, see this page on LT1 with TH400 swap.

http://www.ls1tech.com/forums/automa...questions.html