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1977 Silverado Crew Cab.

Sounds like you have a vacuum leak and the PO instead of fixing it, compensated by use of the idle mixture screws.
 
I'll throw this up real quick then I'm off to work....I'll check in later.

DSCN1407 (1280x720).jpg
 
y5mgisi said:
Here is the spot,



And here is the carb number,


Click to expand...


looks like a 4MV...stamped number says 1969, 49 state, Chevy application, most likely manual trans....the date code says its a service replacement and not installed on a production vehicle as they are 3 years apart.
 
As luck would have it, a friend had a 350 choke stove sitting around. I plopped it on and it looks like it will be perfect! One odd thing that I'll have to figure out is that when that arm rotates, all it does is close the choke flap. It doesn't rotate the high idle cam and so on. So something is going on with that as well.

 
Got my parts in the mail yesterday. I'll get it registered this week. Hopefully be on the road by next weekend!
 
Something like, get it on the road as cheap and effortlessly as possible and have that be that until probably August. At that point, go all in, balls out on getting it painted and the interior done by January. Probably drive it like that until about April when I will do the 4x4 swap and then likely do a motor swap another the following winter.

That's the plan anyway...
 
Oh Yea, also I pressure washed the crap out if it today! And got the choke hooked up and working! And in other news, Picked up a can of carb clean today. Had a hard time telling fir certain if I was getting the rpm to raise or not. I sprayed a quick burst right down the carb and it only affected it slightly. I then took a piece of vacuum line and put it to my ear like a stethoscope and found noise in the area where I thought maybe I was getting a response from the carb clean. I pulled the carb to see if the base gasket would tell any tails and it doesn't. So I'm just going to get a new gasket and put it back on.*

Two other things I noticed is the carb bolts do go through into the intake runners and didn't have any sealant on them. Unlikely that they would leak, but who knows. Also, the two rear carb bolts don't go through and seemed pretty long to me. Possible that they were bottoming out before the carb was tightened down all the way. The area I suspect of leaking is at the rear of the carb at the base gasket. So we'll see.
 
So today I pulled the valve covers to check over the valves since it had a lifter tick. This thing is perfectly clean inside! And it has 3964290 heads which I gather are pretty decent. Went around and adjusted the valves. Also I had the wife crank it over while I watched the rockers to make sure I didn't have a flat lobe. They lift alright! A lot! Maybe this does have a bit of a cam in it like the po said.

 
I think the coolest part about this truck is the big block. That 396 is just flat out the whole character of this truck. I think you would be surprised the mileage you would get with EFI and an overdrive.

I would just use EFI kit like smokin said. Would be much easier if you do have a cam, or if you choose to mod something later. I am biased though as I went through the tbi tuning hell when I was younger, when you had to get custom burnt chips, before mega, yada,yada,yada....

I have been driving a fat block daily for 10+ years. Get about 13mpg. 15 on the highway.

Not great but not that bad compared to a tbi350 in the same truck....and I know your all about the LS stuff and they are not even comparable. I get that.

BUT COME ON IT'S A 396! How cool is that!
 
Tomorrow my day shall be spent getting the truck road worthy! I'll get it registered Monday and start cruising it around!
 
I wouldn't mess with a TBI on that motor. Waste of time and frustration you don't need. I would go with a aftermarket self tuning fuel injection. With a manifold swap, good set of headers and exhaust, the fuel injection you could pull good power from that old rat motor.
 
We'll see. Time will tell which direction I ultimately end up going. I have a tough time putting too much time and money into an old style motor, but the flip side is, the old style motor is just so cool! I can say for certain that the motor and doing anything to it as absolutely last on the list at this point.
 
if it is in good running condition and meets your needs for power/mileage, I'd keep it in there. That is one reason why I haven't taken out my 454...it still hauls my 10K around good, but mileage sucks...but as long as its a working truck I'll keep the 454 in there until I'm ready to make the 6BT install.
Your engine looks like it was well maintained as far as oil changes are concerned!
 
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