Thread: Am I going to kill my 460?

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I have a 71 Lincoln with a rebuilt 460 in it that has been making some clatter noise when going up hills, or putting my foot into it. The car seems to run great at highway speed. The block is a donor from 1972, bored 60 0ver, with the original 71 heads I had with the car. The carb is a brand new Edelbrock 600cfm, and I put a Pertronix II electronic ignition on the car. The heads were ported while we did the rebuild, and we added a set of full roller-rockers, and Keith Black pistons. I have no faith in the goofus who rebuilt the motor because of some other car-related issues, so now I have brought it to a different guy who seems to know his stuff.

Today he adjusted the new carb for me, and then did a compression test on one of the cylinders. He said that it came out at 175 psi. He said that the reason why the car was clattering under load was probably pre-detonation because the compression ratio is so high. When the original guy built my car, he had a cam ground to his specs, but because of the issues I had with him, he never gave me a cam card so we are flying blind. The new guy said that he would not be surprised if my compression ration wasn't 10:2.

He said that there is a good chance of damaging the motor because of the pre-detonation problem. He recommends yanking the motor very soon, pulling the heads ofrf and seeing exactly what we have to work with, and staring over with a good foundation to work from. Does any of this sound out of line to the more learned folks here on the board?

(edited to add that the car has a new tranny, dual exhaust, and a Weiand Stealth intake manifold. He considers the intake manifold to a component of the problem, and recommends a different one when we pull the motor.)

Michael

Detonation will kill the pistons, better be looking for some higher octane fuel. If you're allready running premium, try some octane booster. Could also take some of the timing out of it, though that will lower the performance....

Thanks Dave.

If you do decide to let him work on it, suggest to pull the heads off with the motor IN the car. There's no reason to pull it completely out of the car to pull the heads off. That's a waste of labor and ends up costing you extra money. That being said, I agree with Dave about trying higher octane first. It's easier to go put 20 dollars worth of high octane fuel in it than to pay someone 20 hours worth of labor for no reason.

definately better to try some higher octane fuel first.... try gapping the plugs a hair wider too, the pertronix should be able to do it if you have a flamethrower coil to go along with it..... might clean up your driving a bit.... other than that you can try to back off the timing just a degree or two, that much wont hurt performance much... i'd try a few of the cheap things before putting a ton of labor into the car.... i dont know about your mechanic but with me... 20 hours of labor would cost you about $1600

Sounds stupid....but,

If detonation is the problem, get a water injector kit and it will go away.

I used water injection on a 11:1 comp. 429 from a '72 t'bird to stop pinging and still was able to use regular-low octane fuel. It was in a '56 FORD pickup and pulled a trailer too. Just check the water level everytime you fuel. Worked well.

I used a Stealth intake on a 10:1 454 in a 68 Caprice and had no detonation problems when running premium. I'd get a second opinion and make sure the timing is set right. You should be able to make it work.

Originally Posted by mizlplix

Sounds stupid....but,

If detonation is the problem, get a water injector kit and it will go away.

I used water injection on a 11:1 comp. 429 from a '72 t'bird to stop pinging and still was able to use regular-low octane fuel. It was in a '56 FORD pickup and pulled a trailer too. Just check the water level everytime you fuel. Worked well.

What is a water injection kit? How does it work?

Thanks.

Water injection is a process in which you can inject a small spray of water in to the carb/manifold. It should be a last resort. First it is more important to me and other builders here to find the problem, repair or redo it right and then tune. Yes water injection does work for cooling the intake charge and has a few other tiny improvements (key word; tiny). It just a band-aid for your problem. I still stick by getting this problem resolved the right way. It'll definitely help you understand this problem for futures set ups.

Since there are differing views here, I will probably print out this whole thread and show it to the guy to see what he says.

I'm assuming that it isn't loose, because the double-roller timing chain was new when the motor was rebuilt, and that was only a couple thousand miles ago.

I run a 429 in a 57 Ranchero. The early heads and a Stealth with cam
and headers. I don,t see why the manifold would be a problem. I did take
mine down to 10.1 comp.ratio when rebuilt. My car isn't as heavy as yours.
Maybe take out some timing and run 92 oct.
good lick, Ron

you mentioned that it pings on wide open throttle. I could be way off so someone correct me if i am, since it's such a big motor I would think a bigger carb would help. a 750 cfm should be good, you should also check out your fuel system, what's your fuel pressure? make sure its getting plenty of fuel and air and not too little of either one.

You could also retard the cam timing 2 to 4 degrees to delay the intake closing point, thus trapping less fuel/air mixture and lowering the dynamic compression ratio of the motor. It would be a lot cheaper than changing the things in the motor that would fix the detonation problem. Count me among those who can't make a connection between the intake manifold and detonation.

Fuel pressure was looked at initially, and it was 4.5, and I am using a new filter. As for carburetion, the 460 previously had an Edelbrock 800cfm that was a boat anchor when it came to power and fuel mileage. We went with a new, smaller Edelbrock 600cfm w/ electric choke and noticed an immediate improvement. I picked up 2-1/2 mpg fuel economy, and the car was much more responsive.

The general recommendation here locally is that the most important thing is lowering the compression ratio to make to car run better on pump gas, without the expensive juice, or additives. One of the ideas is using thicker head gaskets, and another is getting the KB pistons milled down a bit. The engine was originally punched 60 over and that isn't helping things I'm told.

My current motor guy thinks that my past motor guy didn't have much engine building experience and just slapped some good parts together without trying to get the best performance out of them. He thinks that his reasoning was, the more horsepower the better, when I am actually wanting more bottom-end grunt because this is such a heavy vehicle.

I am leery about the extra expense of pulling the motor though, I would prefer to do the work in the car, but he said that it will be easier to work on out of the vehicle, and that it will save time & money. My head hurts, and I think I need an aspirin and a beer .