1975 Chevy Silverado 7.4L 454 (Suggestions one what to do)?

[Schmutz]

Hello,

First post here. My brother and I just bought our late grandfather's 1975 Chevy Silverado, Camper Special, C20, 7.4L 454, 8,200lb GVW Truck (66,000 miles). We both have a little experience working on cars, but, we also have a lot to learn.

We have some questions, but, first, some facts:

A-  The truck is running pretty well, but, our mechanic told us that the carburator could use some work. He suggested a rebuild.

B-  Our mechanic changed the spark plugs and told us that he looked at the spark plugs, and based off what he saw, the engine seems to be burning a little oil.

C-  We can see where the truck is leaking a little oil from the valve covers and the oil is dripping onto the exhaust manifold.

D-  We had a compression test done and our mechanic said the numbers looked pretty good (all cylinders were between 125 and 145).


QUESTIONS:

1-  Our father told us that the truck takes "premium" fuel. Is that true?

2-  We know that we want to fix the truck up and make it as close to new as possible. We plan on redoing the worn parts of the interior and getting a paint job. We're trying to debate how much to do under the hood. A complete engine rebuild, or an extensive tune up and parts replacement.

3-  We are struggling with deciding on taking the original carb off and having it rebuilt or simply buying a new Edelbrock carb? What are the advantages/disadvantages to both courses of action?

4-  We are struggling with deciding to keep the original intake manifold (w/out EGR) or to get a replacement Edelbrock one? What are the advantages/disadvantages to both courses of action?

5-  Should we upgrade our distributor to an HEI distributor?

6-  We need to replace most of the gaskets on the top half of the engine, what else should we focus on besides replacing, rebuilding, or upgrading the Dist, Intake Mani, and Carb?  We are open to suggestions.

7-  What would you do if you were in the same situation? Where would you start? What would you spend your money and time on?

FYI:  We want to maintain the integrity of our late grandpa's truck. we don't want to upgrade it to the point where it is no longer the truck that our grandfather drove (for sentimental reasons). Although, we wouldn't mind giving it a few performance updgrades here and there as long as we maintain the integrity of the original truck. Ideally, I\ff my grandpa were to somehow come back to life, I would want him to recognize the truck, and be proud of us for how great it's running and maybe even notice some improvements (he liked tinkering around with mechanical things).

Thanks in advance!

Shane

[Engineer]

Those 454s had 7.9:1 compression so premium fuel is not needed.

Rebuild the factory Q-jet.

And yes, you want to convert to the HEI.

[Schmutz]

Thanks Engineer!

[rich weyand]

Those 454s had 7.9:1 compression so premium fuel is not needed.

Rebuild the factory Q-jet.

And yes, you want to convert to the HEI.

Agreed.  I have the Edelbrock, it was on it when I bought it, but the Qjet is preferable.  Rebuild it.

With 66,000 miles on that engine, you probably don't need to do anything.  Put new gaskets on the valve covers to kill the oil leak there, but that's about it.  You should be good for 50-75 thousand more miles before anything major.

The HEI distributor is a great, easy upgrade.  Definitely do that.

You could put a dual-plane intake manifold and headers on it, which would improve the breathing quite a bit, but why?  It's not like you don't have enough torque or horsepower.

Mostly I would just enjoy it and the great memories of your gramps.

[454Man]

Oil on the plugs indicates valve seal leaks. Not hard to change. And not a horrible thing. Rebuild that qjet as suggested maybe throw in some smaller primary rods. hei here aswell.

What's under the hood??? If you have to ask maybe we shouldn't race...

[Schmutz]

Thanks Rich and 454 Man!

[454Man]

Nooooo prob :-) keep us updated.

What's under the hood??? If you have to ask maybe we shouldn't race...

[Schmutz]

Dropped off the carb for rebuild today and ordered the Edelbrock intake manifold. I believe we already have an HEI Distributor; a mechanic told us that since it's a 1975 it's alredy HEI (first year the did it).

Shane

[Schmutz]

Update and Question:

- Got the Carburetor back and it looks great. Our Edelbrock intake manifold came in. I've test fit the carb to the intake manifold. All seems well. FYI: Our stock intake manifold does not have an EGR as originally thought.

QUESTION: I found my engine block number. Although, I also have a list of all of the RPO (Regular Production Options) in my glove box. The engine code does not match up with my RPO code.

My VIN # is: CCZ245F439243 (what does the "Z" mean - I know what everything else means and I know that the "Z" should be the "engine" but, nowhere on the internet can I find a "Z")?

My engine code is: T0625TSD
This means that my engine was built in Tonawanda on June 25th. By googling TSD, I've found that my engine is a 215 HP LS-4. The discrepancy is that my RPO Code shows an LF8 code listed for my V-8 454. Also, the "Z" in my Vin # doesn't seem to match any type of specific engine as far as I can find on the internet.

Bottom line: How much horsepower do I have and is the engine an LS-4 or is it an LF-8 like my RPO List states that came with the truck and has my VIN# on it?

[rich weyand]

http://www.ehow.com/info_10034601_1978-chevrolet-454-engine-identification.html
http://www.73-87chevytrucks.com/techinfo/73-91VIN/1975truck.pdf

[Edemich]

From the above link:
Your engine decoding is as follows:
C-Chevrolet
C- 96 or 106" chassis
Z- 454 engine
2- 3/4 ton
4-Panel
5- 1975
F- produced in Flint, MI

Rest are production sequence.

[Edemich]

Try and find the casting number on your engine.  It will be the only way to determine if this is the engine that came with your truck.  Check this site out when you have found it

http://www.nastyz28.com/chevy-engine-code-stampings.php

I would check the internals of your HEI distributor and look at putting a new one in like an MSD or similar.  If it looks good inside then leave it.  My magnetic pickup went out and left me stranded and for less than 200 you can put a serious upgrade in.