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LT1 rotating assy into a Vortec 5.7 block opinions

29K views 43 replies 12 participants last post by  Jim Rockford 
#1 ·
Just picked up a(nother) sweet 77 impala coupe. has a decent running 305 2 brl engine in it now,but I'm looking do do a budget 350 i have a vortec 350 short block that has a bad bottom end, haven't pulled the pan yet to see if It can be saved, but I also have a very low mileage lt1 that came out of a road master with an electrical fire, few burn sensors , but that all, wondering about installing the pistons rods and crank into the vortec block and topping it with a set of l98 heads I have laying around and a used edelbrock performer .. What do you guys think...?
any thoughts on a good roller cam?
 
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#29 ·
LT1 Carb intake

I have an LT1 with a carb intake in my chevy c30. I'm actually thinking of converting it back to fuel injection using a megasquirt. I could have purchased a megasquirt for about the price I paid for the carb intake, but I didn't because of the horror stories I heard about the opti-spark distributor.


The main problem I have with the carb intake is that the truck runs the best when the outside temp is in the high 80's or higher. It's like the intake doesn't get hot enough and the fuel doesn't vaporize.

My LT1 is out of a B body also (Police car). I have a stick shift, and if I had an automatic with around 1600-1800 rpm stall it probably wouldn't be a big deal. With the stick I tend to drive around town at 1200-1500 RPM and it doesn't want to pull smoothly at that RPM unless you really ease into the throttle.

I've had 3 different carbs on the truck and they all had problems. Quadrajet would bog when opening the throttle in neutral, and a vacuum secondary Holley 750 and also a 650 double pumper. The double pumper has annular discharge boosters and is fully adjustable with air bleeds (and I've made tons of changes to try and get it right).

The carb intake pull very hard once I get past about 1800 rpms. The B body cam falls off probably around 4000 RPMs but the engine will easily rev to around 6000 doing a burnout (yes, it's a dually!).

Oh yeah, and the LT1 can be a bit picky about gas. Even with 93 octane I have to watch out for detonation. But my vehicle weighs 5500 pounds. It also seems to like a good amount of advance. I probably need to get my advance curve in sooner (I have a stock accel HEI replacment).

I had to notch the truck's frame to clear the A/C delete pully also. I bought the A/C delete pulley and the pulley was huge. I went back to autozone and then bought a smaller pulley (they sell just plain pulley's and they let me look through the boxes until I found one that would work) and mounted it onto the A/C delete bracket I bought. Then I cut the stock belt and guestimated how long a new belt needed to be with the smaller pulley and bought that from autozone. It works perfectly.

It definitely has good power. Not like a big block but decent.

Cheers,

Dan
 
#30 ·
Those LT1 carb intakes are pretty rare. GM was the only company that made them, since there is no real aftermarket for them. Lots of guys convert sbc intakes to fit. The middle 2 bolt holes on each side are different. Make sure your LT1 is actually an LT1 though. They made a "baby LT1" called an L99 that is actually a 4.3 liter V-8. It was put into some Caprices, i'm not sure on the Roadmasters though.
 
#32 ·
Yea I know about the L99's, the Caprices where the only ones that got em.. My block say 5.7 and the casting number is 327... and I've already gotten the intake. Picked up a beehive kit for the heads and the thin head gaskets.
 
#34 ·
Looking good! I don't know if you remember my build from the Impala forum, but we made 420 HP with a quadrajet, ZZ9 cam and HEI. Be sure and convert to screw in studs if you use much of a cam at all. I had a few problems there. Also, the early beehives had a problem...I'm sure they're better now. We also staggered the rockers with 1.5's and 1.6's but I really think it would have been just fine with all 1.6's. Good luck with your build and it's good to see you here. Bill.
 
#36 ·
Change of plans...

Well plans where to install a LT1 rotating assy in a extra vortec block I had laying around, but turns out the crank in the vortec was broken and spun the no.4 main and the rear main..so that idea was scrapped , then I had an extra LT1 I was gonna just slap my zz4 cam in and drop it in with a carb and regular HEI
Then I found this..









Wait...What color was that?

That right GM blue.....For the stock 70's smog motor look.

Gonna run a stock GM 4brl aluminum intake with the EGR blocked and a nice qjet. stock manifolds. I might squeeze out a good 275hp. and 300+ lb ft of torque I hope,... This will have just over 9.5 to 1 CR so its on the edge for regular gas.
 
#40 ·
I wanted to ask, what springs are those?:cool:

When I read of guys looking to build a 305, your engine is what they should be building instead IMHO. I believe one of the better things that came from the EFI 350 engines were small chamber heads again. I cannot say how many SBC 350's I've bolted together using the double hump small chamber heads (and other heads that are just as good, but w/o the fuelie markings like the 040, etc.). They all were good engines.

Now that they're available, a 350 built w/the late small chamber heads, a Q-jet, a factory aluminum Q-jet intake along with a recurved HEI, a set of headers and an RV type cam will run really well and will blow the doors off a similarly equipped engine w/smog heads.
 
#41 ·
#42 ·
Well got it running, had to wait on a new radiator. otherwise it runs like a stripped *** ape, Does need a better exhaust, , i was checking the temp and had it sitting there idling and it just died , now I have no spark. Some days you just can't win.
 
#44 ·


little update, after this I found what GM wanted the timing to be at, during this vid it was set at 0 degrees with vac advance, , after I reset it to 10 degrees advance and no vac advance its a whole different car.
 
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