Hello Peterbuilt,
I really appreciate your advice; I will get a compression test done on the engine first. I bought the car in September 2021 with 87,000 miles listed on the milage odometer, but the miles are unknown, and the odometer no longer works. The engine still runs strong, but I need to get it checked. I purchase a 210-piece mixed Stanley home mechanic tool set so that I could do some of the basic engine repair work myself. I also invest in a Haynes C3 Corvette repair manual. I am still trying to decide on maintain the original distributor and getting the timing set properly or investing in an electronic setup. Peterbuilt, I take you again for your help!

 

Hello rmrtrex,

Your red C3 in the photo looks great, have you had it long. Getting 375 hp or more out of your L48 seems like a fun ride when you hit the throtte,
if I can get into the 300 hp or more hp, that would be all that I need. I just feel that a C3 deserves to atleast have 300 hp! I will follow the great
advice for upgrades provided!

 

The Haynes manual is very basic, order a Passenger Car 1973 Corvette Service Manual it will give you a background on how systems work.

The Assembly instruction Manual (AIM) has illustration to show you how things go together.

Do you have any service records on your car?

 

I agree with what Peterbuilt says!
I have both manuals and found that I get the most use out of the Corvette parts and accessories manual.
It has great illustrations and supplies all the GM part numbers and the number of parts required.

 

True, depending on your set up.
Just stabbing an electronic distributor into a car that isn’t computer controlled does nothing for you.
You can easily set up a points distributor to almost any ignition curve the OP will need for his set up without spending hundreds of dollars.

 

Hello OldCarBum,

Thank you for providing information for 73 passenger car service shop manual and 73 Corvette Factory Assembly Instruction manual.
I found both for sale on Ebay and saved to my favorites list to buy. They provide so much more information compared to the Haynes
Repair manual that I currently have. I realize how inexperience I am with not knowing that all of these great resources exist.
I have a good investment in home mechanic tools and these additional manuals will be a big help. Corvette Forum is such a great
community with so many C3 owners with a wealth of knowledge and experience like yourself. Thank you again for helping me!

 

I have had it for about close to 2 years.
The L48 has the following:
1. XR276hr roller camshaft plus 1.6 roller rockers, retrofit roller lifters
2. New 64cc E Street Cylinder heads with 2.02 valves.
3. New double roller timing chain
4. Flowtech long tube headers with straight 2.5" pipes feeding into Flowmaster Delta 40's, with H-Pipe
5. 2101 Eddy Performer intake
6. Have both the 1906 Edelbrock and original Quadrajet. Using the 1906 right now though.
7. New A/C Delco Fuel Pump. Hard to find. NOS
8. 4 speed BW Super T 10 Tranny
9. Hi rise Valve covers
10. New A/c Pump and everything with it. Blower fan, Dryer, filter, hoses etc:
11. New dual electric 11" fans
12. New Carpet, Seats, Battery, Alternator, Digital Gauges
13. All new u-joints plus new rotors and brake pads.
All smog devices plus cat gone.
Probably other things I am forgetting.

 

If 300hp is all you seek, I believe changing your exhaust to straight 2.5" with headers and possibly adding a mild cam (Don't over cam your car) that will work with your original cylinder heads should get you pretty close. As stated before, fine tune what you have first: start with carb, spark plugs, wires, Dist. cap, rotor and see how you like that first before you start throwing a lot of money into it. (Check your engine compression also)
You will learn a lot here from this forum, I know I have.

 

As I said before with your mild cam upgrade all of your stock parts should work well. Timing initial maybe 14 to 16 degrees, 36 total mechanical and keep the factory vacuum advance. Should idle around 650 steady as stock.
I did a dozen junk yard builds like that when I was a kid and money was tight. Boiled the tires with them all.

 

Hello rmrtrex,

I hope that you family and you had a great Christmas, I keep writing down all of the great advice and parts information into my build notebook.
I went through your list and copied down parts that you listed. I can see why you have a hot engine. It seems like you have really gone through
your car well. I wanted to ask since I am staying between the 300-350 hp range, how do you feel about Edelbrock Top End Kit to help keep things
simple for just a top end build and 2.5" exhaust set up.
Edelbrock part #2038 E-Street EFI Top End Kit is designed for 1957-86 Small-Block Chevy V-8 engines. This Top End Kit produced 338 HP & 389 TQ on a 350 c.i.d. Small-Block Chevy with 9.0:1 compression
Edelbrock part #2038 E-Street EFI Top End Kit is designed for 1957-86 Small-Block Chevy V-8 engines. This Top End Kit produced 338 HP & 389 TQ on a 350 c.i.d. Small-Block Chevy with 9.0:1 compression. The kit delivers entry-level affordable street performance and great drivability from idle to 5,500 rpm. This kit includes a Performer EPS intake manifold, E-Street cylinder heads, Performer hydraulic flat tappet camshaft, pushrods, timing chain, complete bolt kit and an Edelbrock gasket set. To get great performance out of any engine, all of the components must work together.

I really appreciate your advice on this.

 

Top end kit is a good Idea, but it all depends on the health of the short block. Wouldn't you rather go with a retrofit roller cam set up instead of dishing out for an EFI? You might spend the same amount of money but you wouldn't have to worry about breaking in the cam as you would with a flat tappet cam. You also wouldn't have to worry about the oil additives you would be needing to put in it every oil change. I know some oils have the zinc additive already, but I didn't want to worry about that every time.. I went the Hydraulic Flat tapped cam the first time and it wasn't broken in properly so I had to dish out again. There is a technique to breaking in a flat tappet cam.
Also, a roller cam is going to give you a little more hp than a hydraulic flat tappet cam. Granted a roller cam is probably 2 to 3 times more than a flat tappet cam. Put it to you this way if I had to do it all again, I would order the top end kit from Edelbrock for the Retro Roller cam set up. Look up the Dynosheets at CompCams web site, I think you would be happy with an XR270 cam.
After speaking to Edelbrock and Comp Cams, they told me the most cam I could put in my car was the XR276 because of my cylinder heads, so I did so. Keep in mind my car is a 4 speed, so I really didn't have to worry about a torque converter. If your car is automatic that is something else you might have to change.
Going the top end kit is probably a good idea since they give you all the right items that you would need. If you go either the roller or the flat tappet cam way, I would advice you to look at the dynosheets on the CompCam web site. That way you see the specs of everything and hopefully it will help guide you to your goal.

Good luck!

 

Hello rmrtrex,

My head is spinning, I really appreciate you taking the time again to help me, and after reading your reply, you have given me alot to think about.
I like the fact the Edelbrock makes it easy for you with parts that match but you are right, the flat tappet cam is not my first choice. Every thread that
I read always puts the roller cam first even if it cost more. My first choice for aluminum heads from my research would be:
-AFR 180 cc 64 cc Eliminator heads
-A comp cam or Lunati Voodoo roller cam and lifter kit? (I dont know how much cam I need?)
-Do I need a new performance timing chain?

If my engine is up to it after a compression test. How do you much cam do you think I need for my set up below?
-stock quadrajet carb installed, Edelbrock performer intake installed, (purchased but waiting to be installed - Doug's D350 ceramic coated long tube headers, Pypes universal stainless stell 2.5" x-pipe with cutouts and a pair of 2.5" Flowmaster 40 series 409 stainless mufflers
-I already have a Champion 3 row Aluminum Radiator and 150 Amp Powermaster Alternator, do you feel everything that I described above would be all I need for 300-350 hp. I am not very experienced when it comes to engine builds other that reading, but I am hoping to simplify the performance process as much as possible.
Thank you again rmrtrex for all of your advice!

 

 

Dear discoshark,
You received lots of good advice on how to increase the HP on your '73 just bare in mind that changing to a top end kit and installing a better cam is a little harder than changing a light bulb in a table lamp.

You mentioned having a compressing test done, how handy are you?
Are you going to have a shop do that? Or are you going to get a compression tester and a spark plug socket and do this yourself? You may want to get a new set of spark plugs while you're doing that.
If you are doing that for the first time I'll bet your next question will be "How do I get to plug # (insert number here)".
Changing the plug wires is another major task if you have to go through the 'boomerangs'.

You don't have a service record and driving your Corvette for a few months will show many other areas that need attention before you consider boosting the HP.
How old are the tires, the steering parts, the rubber bushings, the U-joints ETC?

 

This made me laugh out loud!!

 

Hello Peterbuilt,

Thank you for your reply and bring many things to my attention. I love the Corvette Forum Community. Everyone has brought so much information to the table that I had not even thought about, especially with wanting to increase the horsepower but needing to make sure that my engine and suspension are in good enough condition to handle the upgrades. Unfortunately, I do not have the experience with engine testing and spark plugs and wire change out, therefore I will have to take the care to my mechanic until I can learn do these things on my own. Peterbuilt, I am going to take a step back, save up some more money and focus first on engine test and finding out what I need to upgrade with suspension and basic parts before getting some more horsepower. I appreciate the advice and also with saving me from unnecessary costly mistakes.

 

190 hp net going to over 300hp net is a lot of upgrades and $$$…
tune up what you have and spend money and gain wrenching time
see this
https://www.corvetteforum.com/forums...max-power.html
- change plug wires…oem ac delco are great..
- change plugs..ngk’s are great..
- tune your timing and vacuum advance here..
https://www.corvetteforum.com/forums...-question.html

- carb running great? Cold start to full smooth acceleration?Then great..if not? Consider a rebuild if original..like here
https://www.corvetteforum.com/forums...l82-q-jet.html
consider buying your ebay service manual as a dirty original vs reprint..see difference here
https://www.corvetteforum.com/forums...omparison.html


- if you can, remove cat ( if one is there) and put on 2.5 inch duals..
sample here
https://www.corvetteforum.com/forums...79-4speed.html
- inspects brakes
- change fluids
- download this, see post 8 to help support your manuals
https://www.corvetteforum.com/forums...ette-lonk.html

most all the above is not hard on wallet andshould really get you more response and judge from there.
please post pics of your existing engine carb etc…many can spot issues.

 

Hello Interpon,
I really appreciate you providing some good advice for engine performance upgrade. After reading through some post,
I need to have my engine tested to see if it is up to par to handle performance add ons. I need to also take your
advice and have some new plugs and wires installed. I am not sure how long my spark plugs and wires have been
on the car. My stock quadrejet carb still runs good but could probably use a good tuning. I still have the stock
exhaust manifolds and exhaust pipes. Since the car is a 1973, i did not have to worry about cats. I have purchased
a 2.5" X-pipe with cutouts and a pair of 2.5" Flowmaster 40 series mufflers with Doug's D350 ceramic coated long tube
headers. I just need to get the new exhaust setup installed. Thank you again for providing advice, it is greatly appreciated!

 

A lot of great advice already given and I totally get that your head is spinning.

Let me introduce you to Mike’s law: always do the cheapest and easiest thing first!

1). Recurve the distributor. Email Lars at v8fastcars@msn.com and ask for his recurving paper. Even if your motor is a turd, this will help. It’ll get you motivated too!
2). Before going too much further, probably worth following Gary’s advice (1999 GTR). At least then you’ll know the condition of your engine.
3). Headers and exhaust is probably your next roadblock. Not too expensive either.
4). Heads will be your next big roadblock. If you follow from 1 to 3, you’ll have seen the cheap gains, heads will get you the big chunk with both compression ratio and flow. It’ll cost you though. I’m a big Iron Eagle fan too.

 

Hello Peterbuilt,

That's funny, I wish it was that easy, that 300 hp placard is good motivation to get horsepower, but not only does my engine block need to be up to par but also my wallet,
I will have to build this engine with performance upgrades over time brick by brick.