Hey everyone,

A little history on the car. I bought her with two engines, the original #s on a stand b/c it was giving the previous owner (PO) "troubles". The PO put in another 350, supposedly balanced and blueprinted, and put in a performance cam, edelbrock intake, huge carb, and was setting the car up for racing.

I've been driving the car for several months with this engine that hasn't lived up to my expectations of a "Drag Car" (it's SLOW).

The oil pressure gauge has been funky for the past couple of weeks, and I haven't had time to fix it. And of COURSE, during this time, the oil pump decides to go bad and I don't know until the engine starts making weird noises.

So now I have two engines that need rebuilding. I want to put the original motor back in. However, I want certain things out of it and this is where all of you knowledgeable people come in.

1. What to do with the engine that's in it now?
2. How do I go about getting these things out of my original engine:
a. Reliability, the car will be a daily driver
b. Best MPG as possible, ie 20+
c. Run on lower octane gas
d. Still have decent power.

Here's a list of parts from the "beefed up" engine that's in her now that I'd like to re-use:

New Holley 600cfm carb
Edelbrock Performer Intake
MSD 6A box
Upgraded to HEI Ignition

I know you guys love using your brains thinking these things up, so help me out!

Should I buy all the parts myself or just turn her loose to a shop?
What do I need?
What part of the rebuilding can I do myself (I've never done an engine rebuild, but I've done 99% of the restoration of the car myself, I'm very good at learning)?



Thanks for everything you guys have done!

There are a number of ways you can go with rebuilding an engine as you are aware. The "built" motor that the PO did grenaded prematurely. Even before it did, you experienced poor performance. In 74 the General was no longer interested in performance as fuel economy became king. So, the original engine can be one of two small blocks. The L-48 and L-82. If it is the L-82 you may have something to build on, but the L-48 is a waste of time as it is. Primarily what makes HP and torque is the heads, intake, cam, carb, and compression ratio. Entire volumes have been written on the subject.

My suggestion; price the rebuild out, and compare it to GM's Hi-Po Crate motors like the ZZ4. You will probaly find the General to be competitive.

MPG is a factor of gear ratio. You probably have 3.08 rear gears, but thats a guess. 20+ mpg is really not very likely if you have a ratio numerically higher than that.

Alex

Rebuilding a motor can be fun but it can end up costing more than buying one ready to go. By the time you take it to a shop to have it bored out, buy new pistons and rings, turn the crankshaft, replace cam bearings, cam, lifters, rod bearings, timing chain set, and gaskets you will have close to $1500 into it. Rebuilding the heads will cast you about another $600 if they have to machine in new valve guides just to bring it back to original. Add some more if you want to improve the performance. Add in the cost of gaskets, water pump, fuel pump, and anything else you might want to change out.
If it is a L-48 you will need flat top pistons instead of the dished pistons that it came with. I wouldn’t spend the money on the heads. Get a good set of after market heads like the Edelbrocks or AFR. Then when it is all done, you don’t have any type of warrantee. So you hope everything stays together.
The assembly is time consuming but can be done with help and a good auto rebuild book. The trickiest part is checking for the right clearances for the bearings and proper torque specks for the bolts. Have fun and good luck

If you lost your oil pump, you probably lost the crank. I have been there, with my '79 L48. I put a reman'd crank, bearings, push rods, oil pump, water pump, Performer EPS intake with an edelbrock 750 carb. I have great performance, but no mileage. My crime is that mileage is no concern, as I look at more ways to beef her up. If you own a vette, you didn't buy it to save on gas, so don't let it be the reason for not getting the performance it deserves.
Let it be a Vette. And most of all, enjoy it. Life is too short not to.

|UPDATED|12/17/2002 11:47:43 PM|/UPDATED|

Hi All!
I've got a L-48 in my '76, & a Edelbrock manifold & Carb. She's quick, but the mileage is DEFINATELY lousy! I look at the mileage as the cost for the privledge of getting out & enjoying my Vette!
Laters!

I've found myself in a similar spot my vette came with two motors. The matching one was out of the car in tuff shape the other was in the car in not much better cond. Doing most of the work myself its starting to get a little tight in the corvette budget file. I'm letting the stock engine wait while I finish the other. That mouse will have a couple of teeth. the others going to be bone stock original. Some parts off one belong on the other so I need a map of sorts. It would have been cheaper to buy a crate motor. The problem I never had all the money at once. So as the drips and drabs came in I built.

Well, here is my .02 (and you are going to love it).

BIG BLOCK!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

Here is how you do it. First check all the availalbe sources for crate/ready to go engines. Then, check you local paper/trading post, etc. No doubt you will find somebody with a 454 out of a truck for $500 or less.

Since the 74 could have come with a big block from the factory, it won't be all that unusual to drop it in.

Here is what you get. You can build a very mild engine using stock heads, good pistons and good cam. A sweet set of headers, aluminum intake, and carb, and you are off and running. You will re-use your exact same distributor, trans, starter, motor mounts, power steering hoses, alternator, etc.

You will have to get a different flywheel, and accessory pulleys. With a low profile intake and air cleaner, it will still fit under your hood. NOTHING, has to be cut or chopped on the car for it to fit.

It will pack a whale of a punch, get decent mpg if you are not in it at every stop, and ...well, size really does matter.

You can then sell the engine that is in the car, or maybe even trade it to a machine shop for a big block they may already have sitting around.

Plus, when you pop the hood at a car show or local cruise in event, everybody will have to come take a look, and they will whisper over their shoulders (Hey dude, come check this out, it has a freakin Rat motor tucked away in here).

Oh, did I mention the sound of a big block? That is the deep throbbing heart pounding punch you get out the pipes like a pack of angry hells angels roaring through the country side on demon possesed harleys?

A good crate motor ( large or small ) may be a good way to go. As mentioned above, big blocks are definatly a "show stopper" and they will fit ( my '74 had a 454 in it ). If fuel economy is a necessity, put in a set of 308 gears and get yourself a good "over-drive" transmission. My '93 has almost exactly the same rear wheel HP that my '69 427 has but it gets about 7-8 mpg better around town and over 10 better on the highway.
If you have the money and plan to keep the car for long enough to recoup the cost, get a big block crate engine with fuel injection, an over-drive trans and 308 rear and get 'almost' the best of all worlds.

69MYWAY... I'm drooling. STOP PUTTING EVIL THOUGHTS IN MY HEAD... you have no idea how huge of a fan I am of your car... whenever any friends start talking about my car and what I'm doing to it... I open up your pictures and say... one day, when I grow up, I'm gonna make one of those

I don't want to put a big-block in this Vette, because I'm saving that for the chrome-bumpered one that'll be next one day (after medical school finishes and loans go bye bye).


Glenn,

Crate motors are great, but I already have two engines sitting at home for the Vette, and my garage is SEVERELY limited. And I want to put the original numbered engine back in so I can get that load off my mind that I'll lose it, it'll rust and seize up, or Gnomes coming in at night and stealing it...

Imran - 74 Convt

If you plan on rebuilding it yourself it can be done for as little or as much as you are willing to spend. I had about $1100 in to my motor when I got it back from the machine shop. That included: boring .030 over, new pistons and rings, cam bearings installed, crank ground and matching bearings, cam and lifters with new vale springs from Crane, heads cleaned an checked, freeze plugs installed, oil pump, timing chain and gears, and gaskets. Then the fun part started. New intake and carb came later, now I am putting on new Performer RPM heads. So as I said; as little or as much as you are willing to do.
Good luck