Water injection on C8 302

I use water injection on my supercharged '89 LX. It will help to control detonation but I wouldn't think you would have a severe problem at a 10:1 CR. If you haven't done so you might try and back off the timing and make sure there isn't a buildup of carbon in the combustion chambers and double check the overall tune of the engine.

When used on a N/A water injection lowers combustion temperature which in turn stabilizes the burn process and controls detonation. This doesn't occur without paying a price in reduced performance. Lower combustion temperatures reduces horsepower. Also, the water takes up space in the cylinders which decreases the amount of air and fuel burned further lowering horsepower. To help get back lost power you can increase timing but the major benefit is you can run the engine on lower octane fuel. A side benefit is the water will remove carbon from the combustion chambers.

First thing, dump the Edelbrock Carb (good for the plug and play guys, terrrible for just about everything else), replace it with a Holley

650dp. Second, part of your problem is the .060 overbore of the cylinders, as the walls on the 302 block are thin enough as it is.....As for the water injection, sure a slight water injection spray will help just a bit, but not to the point that your going to see added HP......Your still going to have to use the super unleaded gasoline to keep your motor happy, even with backing your distributor advance down just a bit...........................

Bill S.

Scott Williams wrote:

He's complaining about the high cost of gas and you tell him to get a double pumper? Maybe I'm missing something here. ;)

If you back off your timing and put 89 octane in the car will it diesel? If it diesels that means you _need_ at least a high enough octane gas to stop it from dieseling. If it pings on lower octane, but never diesels then you can work with it.

Start by retarding your base timing and unplugging the vacuum advance (remember to plug the line). Go for a couple quick drive and blast down the street at WOT. You want to keep backing down on the timing until you no longer ping at high revs at WOT. You will likely need to adjust your carb after that to get your idle back where you want it, so do that. Then plug in your vacuum advance. Go for a drive and listen for pinging, namely at part throttle. Turn the screw in the vacuum port with the allen wrench 1 turn counter-clockwise, and go for another drive. Repeat until the pinging is gone. Performance will suffer from this, but you may be able to run on 89 octane, 87 if your really lucky.

I know what it's like. My first car was a '67 Galaxie 289, which ran on 87 octane and would rev out the wazoo. My second car was a '68 Galaxie 302 (great grandma's car) which needed 89 or it would diesel and ping. I didn't like paying more for the same amount of gas with the '68 so I tried to make it run on 87 but couldn't. I got it running pretty good, but it would still diesel sometimes. Finally I said screw it and put 89 in and tuned my advance to get the most from it. The kicker is that the 289 was faster on '87 than the 302 on 89! The 289 also has 200,000 miles on the original engine and transmission, whereas the 302 has 97,000.

I couldn't justify paying for 93, or especially 94 octane, especially in a

10:1 compression daily driver. 93 is a 4 point jump from 89, and you probably don't need that much for 10:1. If it were me I might get all ghetto and fill it with 10 gallons of 89 and 10 gallons of 93. LOL

Anyway, if you haven't tried already go ahead and do the timing procedure I mentioned on a tank of low octane gas. You can try 87 if it doesn't diesel on it, but if it does move up to 89. You may have already tried that, and that's why your looking at water injection, but I just wanted to make sure before you go through the hassle of water, which I've heard more bad stories than good.

Cory

Hey Cory,

Believe it or not, a properly tuned holley 650dp will actually get better gas mileage than that 650cfm Edelbrock unit sitting on his car

Bill S.

Cory Dunkle wrote:

I was just using the mist as an example. How do you inject the water though? I've seen electronic controlled setups for Turbo EFI motor's, but not for my more vintage setup. Is it like a nitrous plate?

Scott Williams

Yikes! That does suck. Give the lower octane a try anyway, if it doesn't diesel when you turn it off there is hope of getting it to run well on it, though it won't be as peppy as on 89.

Cory

Bill, I respect your experience and knowledge, but I've heard umpteen #'s of complaints regarding Holley carbs, and (I'm being honest) I've never heard anything negative about Edelbrock's. Please educate me. Seriously. Why Holley over Edelbrock?

Scott Williams

I had a conversation today with a member of the Early Mustang Club here in Colorado. He said that he's running 10.5:1 compression and is running 85 octane without a whimper from the motor. He said it was due to the altitude. Basically saying that, yes, the motor may be 10.5:1 @ sea level, but... take it up a mile high dropping the air pressure, and having less O2 in the air also, drops the equivalent compression to 9.5:1. Thus the ability to use regular pump gas. Truth or BS? Judges??

Scott Williams '66 High Country Special

compression

Ok Scott,

Yes, the older versions of the Holley (Pre-2000) did indeed have their problems, but the newer items are far more superior as they have gone to a better manufacturing process. Why Holley vs Edelbrock....For years, we used the Edelbrock carb on most of our customers cars, then we went out and got a chassis dyno and found out that while the Edelbrock is indeed a great plug and play carb (meaning out of the box it required less tweaking to get the car to idle, and run well), it was not the greatest carb for performance and fuel mileage. Sure the new Holley

04777C 650dp will require a rejetting, and the addition of the Moroso 1:1 linkage kit, but after it is tweaked properly (I do suggest finding a shop with a dyno equipped with an air/fuel ratio device), we found that the Holley made 10-20% more HP over the Edelbrock, and was able to hold a better, more consistent air/fuel ratio. By being a more stable carb across the rpm range of the engines we had, this meant better fuel economy, better acceleration, and better performance with the Holley over the Edelbrock unit...................

Hope you find this helpful...............

Bill S.

Scott Williams wrote:

Scott,

You just found another nech racer without a clue............You really want the answers, I'll hook you up offline with a person who uses nothing but 428's and 427's in your area in the cars he produces....He'll give you the real information.................

Bill S.

Scott Williams wrote:

Bill S.: I can verify what you're saying about the Holley carbs. On most applications, about the most you have to do is a jet change and a air fuel mixture adjustment. On the more radical engines, there is more you can do to get optimum results, like change the pumps, squirters, pump cams, power valve, and air bleeds, if equipped with screw in air bleeds. Some people even remove the choke and mill off the choke horn to get better air flow to the primaries. I just installed a 750 dp with 4 corner air/fuel adjustment on mine and all we did was a jet change and was good to go, and was averaging 1 gallon of fuel per run. That was from the time we started the motor to go make the run till we shut it off when we got back to the pits. I'll take a Holley over an EDL carb any day!