Ok guys, I am about to buy a rust free 79 c3 with a new 400ci motor...these are the mods:

Mods: {drivetrain has approx. 3,000 miles on it since new}

-400ci small block
-780 Holley carb
-Brodax aluminum heads
-Manley Thunderstick cam
-Roads pump up lifters
-1.5 + 1.6 ratio Rockers
-Ceramic coated long tube headers (possibly custom)
-3 speed auto (will have to double check with my uncle exactly what it was)
-2500rpm stall converter
-shift kit
-3;90 gears (LSD)
-Wheels are original 15's w/ 225-60's

i saw the car...the only problem mechanically it has is that when you start it up it takes a while for it to heat up to stay running on idle....but once it does, this thing is a beast!

i spoke to a friend who had a 383 swap in his 79 and had the same problem and he said he fixed it with a tune and something about fixing the fuel regulators to lean or rich(dont know wat that means because im kinda new to this stuff). Also he said the engine gets real hot because the hood is sealed and lets no air in to the engine...he recomended a electric fan to have running at all times to keep the big 400ci cool.

please guys, i have read up on here and you guys know your stuff. let me know if this is what i stated or a major problem? I need to know asap. thnx

 

Sounds like you have cooling problems right off the bat. That should have been taken care of before anyone decided to sell it. Lots of mods there for an inexperienced guy like yourself sorry to say but maybe it might save you some grief. Lots of C3's around that you can start with and learn and add parts to get more power later.

My opinion, you are over your head with this one and I would pass, you are going to be spending allot of money trying to find someone to fix it for you. Sorry for being so blunt

 

my deisel mechanic had a 79 just like this and pulled apart and restored everything on his engine...i got a trusted guy i nthat department. all i need to know is how to fix the cooling problem if it is a problem in local traffic area....the car will be driven short distance so well see....just curious more about the start up situation than anything else...thnx but dont think im in over my head

 

New water pump, dual electric fan, new rad, indy style chin spoiler to get more air up into the engine bay....

 

now that is the info i wanna hear...thanks! keep it comin

 

I am happy you are confident you will be able to fix everything and enjoy your Vette.

 

i appreciate your honest opinion thanks for the help....and still keep it coming lol

 

Do you know if the heads
had the steam holes drilled, they help
the cooling

 

Maybe I'm missing something here, but I didn't see where you said YOUR CAR overheated, just that it won't idle until it's warmed up. If that's the case, your choke (assuming you have a choke on that Holley) isn't adjusted correctly. The choke fast idle cam should keep the throttle slightly open for a fast idle until the engine is warm enough to idle without help from you foot or the choke. If I'm misunderstood your problem is overheating, then what the others said is what you need to do.

 

yep your right on....the guy told me that sometimes it gets a bit hot because of the hood being closed and not having enough air going to the engine besides whern the ac is on .... my friend told me it could be the choke.

he recomended an electronic fan to permantly have running to help cool the engine.

 

I had the same problem with my 75 and the new motor. I had an electric water pump, but it didn't do the trick. I installed dual electric fans/mechanical water pump and have the fans running all the time when the motor is going. Not idling is probably the carb. The choke probably needs adjusting or you need the adjust the carb. Let out the idle mixture screws until it stays running once you get it started. May have to play with how much, but it may keep it from dying. Worth a try. It sounds like the car will be a lot of fun.

 

You seem to be having difficulty understanding a cold idle problem which is most likely a simple choke adjustment. I think you would discover an overheating problem is much more complex issue especially on a modified 400 small block. Read some of the post on this forum for more insight into what some members go through to find the problem. If you think this is a simple solution, why not say to the current owner: "fix the overheating issue and we can complete the sale". Let him install electric fans and prove there is nothing else wrong. If you buy this car with an overheating problem I hope you get lucky and find a simple solution.

 

First off, welcome.....most hoods on cars are sealed, and lots of guys on the forum have bigger and more powerful engines without cooling problems. The trick is to find out whats wrong with that car.

Here is my top ten list

1. Open the hood and look down in front of the rad. Vacuum/blow out any lint or trash that has accumulated.
2. Make sure rad is topped off and some kind of green/red/yellow color.....not a rusty color. If it's rusty a rad flush is in order.
3. As mentioned previously, the lower spoiler is extremely important for directing airflow up into the rad....if its not there get one. They are easily broken by parking curbs.
4. Test your thermostat in a pot of water with a thermometer. It should start to open at the posted temperature on the thermostat. If it doesn't replace it. I'd recommend a 195*
5. Look at the rad hoses and make sure they are good. Any bulging at the clamps is a sign of a worn out hose. Replace them.
6. Corvettes come with foam pieces that surround the rad on the sides and top. They seal airflow leaks. Make sure they are there.
7. Make sure the fan shroud is in place, and in good shape....if its not fix it up.....this is the "ductwork" so to speak that connects the fan to the rad. No ductwork no cooling.
8. Drop in an ounce or two of Downy fabric softener. This will reduce the surface tension of the water and allow the coolant to flow through the rad with fewer bubbles in the mix. Makes for better cooling. Works the same as 40 below or waterwetter.
9. If your still having troubles pull the rad and have a rad shop look at it, some of the passages may have become plugged, by who knows what's been poured in there in the last 30 years. They can fix that.
10. Time for a new high effency aluminum rad.....The kind where each individual louver has louvers. Your problems should now be cured.


Having to ride the pedal for a few minutes until the engine gets some heat in it isn't unusual for a larger cam engine.

Hope this helps.....happy wrenching

 

thanks...i think the spoiler and the fan would help a ton....so that will be first on my list. besides a tune of course.

 

An electric fan does not need to run all the time. Mine only comes on in town and then only enough to cool the engine down. then it shuts off. On the highway (above 40mph), it never comes on. The key is having all the seals and spoilers installed so you get air through the radiator. These cars are "bottom breathers". Air comes in the bottom of the front bumper and exits under the engine. The hood has very little effect.

 

I run a fairly stout 406 and went through quite a learning curve myself. The more power, the more heat. Period. If you can drive it for short distances, watch the temps. If the temp climbs and never seems to go back down, the radiator isn't efficiant enough. I went with a 31x19 Griffen and an a single 16" electric fan to keep mine cool.

The idle circuit on the Holley is most likely calibrated for a 350. The IFR's are .031 stock. I went to .035's which are a bit rich, but I can start this stone cold and drive it with zero warm up. I don't even have a choke.

 

you are the man! thanks for all the help. so you can program an electric fan to come on and off at certain times?

 

Good luck with your new about to buy or did buy 79.

 

I don't think you are over your head. As for as Motor Head's comment about your being over your head wasn't too encouraging. I'm sure at one point in his car enthusiast life and like us all..... were over his/our heads about working on vehicles. The only way you can know about these things is to learn then do. If you want this car then buy it. You sound confident enough to tackle these potential problem(s) associated with this vehicle. There are plenty of folks on this forum to help you along. Motor Head included.

 

thermo fan switches cost about 20 bucks. they turn on the electric fan at a specified temp. they usually have an option of like 160/170/180 degrees. Since you don't have an ECM and arn't worried about getting into closed loop, you should probably just get the coolest one you can find.

My uncle installed an electric fan on his 52 pickup and just mounted a switch in the dash so he could control it himself... of course he can leave it on an drain the battery or he can forget to turn it on when the car is hot.... I always liked the thermo switches better.

be carefull with adjusting your carb, you can blow/burn up the motor if you run it too lean. make sure you have someone who knows that they are doing at least watch you to make sure you don't kill it.