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engine pros please help
after bout 1000 miles on new motor, i had my 428 dialed in near perfect. dist set up good as well as carb. it idled nice, and had really good power band..
i had my valves adjusted after the 1000 miles break in. we believed that some might have been a little loose. i had them adjusted and i was to expect to have a bit more cam due to tightning them slightly. now, they seem a bit noisier(hmmm can hear them a bit more) and my idle dropped a few hundred rpm's. idles a bit more rough. and i think a slight power loss through all pedal(but not much). do i have to re jet, re time, or anything else to compensate from "more cam"? or is it all in my mind?????? thanks for help...... |
Maybe the shop didn't adjust them correctly?? Too tight a valve could possibly cause those symptoms. I would have them checked again before going in a different direction.
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If the valve "lash" is not set correctly, it will act the way you are describing. Then again, there are several factors that can cause what you have written about.
All things being as you say, the last change was the valvetrain. May I suggest a revisit to the valvetrain? :D |
Valve lash will vary with the temp of the engine. Be sure your valves were set on a warm engine. I am sure your engine guy knows all this but it is real easy to miss a valve or two when you are adjusting them. There are some prior post that have been made as to the sequence to adjusting your valves. You can check his work without doing any more than removing the valve covers and using a feeler gauge to confirm your gaps. I like to use a $5 remote starter to bump the engine over from one valve to the other.
Once you check a valve for it's gap use a little lacquer thinner to clean off a space and use a Silver sharpe' to write the gap on the side of the rocker arm. I am not sure what cam you have in your car but I bet your clearances (gap) will be between .020 and .025. Clois |
What type of cam do you have?
What type of cam and rocker assemblies do you have? I recently had trouble with my rocker adjusters getting bored out by the push rods after only 1500 miles. Turns out the adjusters had been incorrectly heat-treated. I didn't find this out until I called the company that produced the rocker arm components. I had trouble keeping the valve lash correct.- Tom
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If your engine ran well befor, and after the valves were adjusted it doesn't run so well now, well there you go. Your valves arn't adjusted correctly. You arn't going to get more cam by adjusting your valves, your cam is what it is. Also, after adjusting your valves, you will never need to adjust timing or rejet your carb or do anything. But, we would need to know what type of cam and lifter setup you have in order to help you more. There are two types, solid and roller. Solid will require lash(gap) and roller has none.
Tim |
Quote:
Dan |
I like to set mine cold...
Coolest under the hood setup I've seen was on an older REALLY nice Contemporary, with Webers no less! But what was SO cool? It had a tach built in to the fire wall on the ENGINE side with a remote starter button next to it. Now THATS what I call 'mechanic friendly'. You could adjust your valves and dial in the carbs without ever leaving the engine bay. :D :D |
I'm not sure I would want a bump switch permanently connected to my engine. I can see a problem when the switch fails.
:D |
I like the idea of having a tach in engine comartment. Hummmmm, a great addition as I build this car.
With my solid cam, I have used some old stock valve covers with the tops cut off to adjust valves warm, this also helps to view oil flow to rockers. Even though I have a mini-starter with solenoid, I still also use the standard Ford starter relay. This allows easy connection of a hand held remote starter switch. |
thanks for the help.. my cam is a crower solid roller, with crower hippo solid roller lifters, erson rocker assemblies..... engine was a little warm. he did one side at a time. i was talking to him and might have distracted him.
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Quote:
Tom, what was the manufacturer of the rocker arms? I had that problem with precision arms several years ago. What a pain in the arse that was. |
Valve setting
You might want to check the way the valves were set. Where they set by the firing order or did he set the intakes when the exhaust opened and the exhaust when the intakes were closing. Sometimes when you set by the firing order the lifter is not all the way on the base of the camshaft. Some guys set 1/2 of the valves and then set the other half. This is old Chevy trick but I do not like it at all. Good luck, Keith
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I agree with Kieth on disliking the procedure some people use setting half the valves, then the other half--it leaves too many variables for a mistake.
I always use the firing order, but I am very careful to be exactly on the mark--I have set valves this way for 40 years an everything from farm tractors , dump trucks to top fuelers, funny cars and pro stockers---I have never ,NEVER seen a cam grind so radical that the lifter wasn't on the base circle at top center--- A trick for hydraulic lifters in the early days was to adjust while engine running and back off the adjusters until the valves clicked and then just tighten enough for the clicking to stop--this extended the rpm range before lifter pump-up prior to the modern lifter era. Jerry |
he set them by doing the passenger side then the drivers side. is this the good way to do it? or by fireing order?
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I always set by firing order. On a race motor where I expect to be doing all the maintanance on in the future I set the clearances hot once [ This is usually done on a test stand- If I have to do this in the car I run thru the first 4 cyls of the firing order then restart to run up temp before setting the remaining 4cyls] Then when the engine has cooled down overnight I check and note the cold clearance. This is the setting I use from then onwards so that valve lash can be done in a relaxed fashion knowing that any variations in settings means a problem somewhere without all the what-if scenario's.
Jac Mac |
I also use the firing order method and therefore, alternate from one side to the other as required. I can see where Kieth is coming from in being concerned about this method, it could leave room for a mistake. But hey, no matter WHAT method you use, you could still make a mistake. Thats the nature of the job.
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is the mistake in missing a cylinder due to moving around the car??
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just asking because it seems fairly easy, and i should learn to do it myself...
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As Kieth said, the problem is not making SURE the lifter is on the very bottom of the cam lobe. Your working in thousands of an inch and you can't SEE the cam lobes. Cam lobes have a 'ramp' that begins REALLY close to the 'base circle' (bottom of the lobe). There is an 'accelleration ramp' on one side a 'decelleration ramp' on the other side of the lobe itself. If your even SLIGHTLY on this ramp, one side or the other, you cannot accuratly set the clearance.
So how do you know FOR SURE where you are on the lobe? Tricky, that... |
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