a few pushrod questions
11-24-2009, 12:14 AM
#1
a few pushrod questions Ok 1st off what diameter do we need for our cars?
2nd what measurement do we use when ordering them. Now before you go and say you have to measure them to know what size, I know this already. What i am referring to is the three different types of measurement. I cant remember off the top of my head on these but if need be i will post them up. Is it the actual length from where the start of the oiling hole is, The theoretical end if the hole was not there, or where the taper starts?
And 3rd where is the best place to order the trickflow hardened chromoly pushrods?
2nd what measurement do we use when ordering them. Now before you go and say you have to measure them to know what size, I know this already. What i am referring to is the three different types of measurement. I cant remember off the top of my head on these but if need be i will post them up. Is it the actual length from where the start of the oiling hole is, The theoretical end if the hole was not there, or where the taper starts?
And 3rd where is the best place to order the trickflow hardened chromoly pushrods?
11-24-2009, 08:45 AM
#2
1.) 5/16" will be just right. I run 5/16" Trick Flows in a 7.100" length myself.
2.) Overall length.
3.) I have bought four sets of the TFS pushrods from Summit and I'm one of those people who search around for the best prices. At the time they had the best price but that was almost two years ago so...
http://www.summitracing.com/search/P...yword=pushrods
2.) Overall length.
3.) I have bought four sets of the TFS pushrods from Summit and I'm one of those people who search around for the best prices. At the time they had the best price but that was almost two years ago so...
http://www.summitracing.com/search/P...yword=pushrods
11-24-2009, 03:41 PM
#5
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CompCams method of determining how to measure pushrod length is really unnecessarily complicated. I've read it MANY times, and my eyes still glass over.
First, consider this: Without going with a custom made set of rods, you'll usually find they come in .050" increments. For the LT1 7.200 is the stock length, next longer ones are 7.250", etc. So there's some of wiggle room there.
Second, it's always better to go with a pushrod that is a little too long than a little too short, but there's a rounding point. If your measurement falls between two sizes when to round up or down.
No real harm is done using a rod that's a tad too long, but you can have a problem going the other way. That an "ole racer's" rule of thumb.
As Comp says, the correct pushrod length is the ones that give you the correct geometry. So, use an adjustable length checking tool and once the geometry is right, measure the overall/entire length of the adjustable rod that gave you the correct geometry. It's that length that made the geometry right so it's the length you need.
One thing I always do, which I don't see often mentioned, is I include the preload distance in my measurement since that's how the engine will be run. If you do a Google search you can find some very knowledgeable folks that recommend doing it that way too.
The thinking is why would you come up with a measurement that differs from the way the rods will actually run in the engine? If you make your measurement with the lifter plunger at the TOP of its travel (not depressed), then buy rods based on that measurement, when you install the new rods you effectively make them .030"-040" shorter once you set the preload.
But to address your specific question, How I do it is to measure TIP TO TIP and round UP or DOWN, depending. If my measurement comes in at, say 7.220" or a tad more, I go with 7.250". If less than 7.220" (something like 7.215/7.210"/etc) I go with 7.200". Wiggle room. That's in keepng with my preference to run ones that are a little too long, etc. A rod that's .030" or more too long is too much for me.
Of course you'd need a mic that can span more than 7" to cut it that close. Most machine shops will measure it for you should you need to cut it that close.
Hope I didn't go off topic. I'm sure others use different methods, I'm just trying to explain how I do it.
Jake
West Point ROCKS! Nation's TOP COLLEGE per Forbes Magazine!! Graduation Day Parade 20 May 2010!!!
First, consider this: Without going with a custom made set of rods, you'll usually find they come in .050" increments. For the LT1 7.200 is the stock length, next longer ones are 7.250", etc. So there's some of wiggle room there.
Second, it's always better to go with a pushrod that is a little too long than a little too short, but there's a rounding point. If your measurement falls between two sizes when to round up or down.
No real harm is done using a rod that's a tad too long, but you can have a problem going the other way. That an "ole racer's" rule of thumb.
As Comp says, the correct pushrod length is the ones that give you the correct geometry. So, use an adjustable length checking tool and once the geometry is right, measure the overall/entire length of the adjustable rod that gave you the correct geometry. It's that length that made the geometry right so it's the length you need.
One thing I always do, which I don't see often mentioned, is I include the preload distance in my measurement since that's how the engine will be run. If you do a Google search you can find some very knowledgeable folks that recommend doing it that way too.
The thinking is why would you come up with a measurement that differs from the way the rods will actually run in the engine? If you make your measurement with the lifter plunger at the TOP of its travel (not depressed), then buy rods based on that measurement, when you install the new rods you effectively make them .030"-040" shorter once you set the preload.
But to address your specific question, How I do it is to measure TIP TO TIP and round UP or DOWN, depending. If my measurement comes in at, say 7.220" or a tad more, I go with 7.250". If less than 7.220" (something like 7.215/7.210"/etc) I go with 7.200". Wiggle room. That's in keepng with my preference to run ones that are a little too long, etc. A rod that's .030" or more too long is too much for me.
Of course you'd need a mic that can span more than 7" to cut it that close. Most machine shops will measure it for you should you need to cut it that close.
Hope I didn't go off topic. I'm sure others use different methods, I'm just trying to explain how I do it.
Jake
West Point ROCKS! Nation's TOP COLLEGE per Forbes Magazine!! Graduation Day Parade 20 May 2010!!!
11-24-2009, 06:01 PM
#7
well i just went and used a Micrometer to measure out my pushrod check tool (since i finally got a hold of the person that had my 18" one) The measurement came out to 6.942. What would be the pest way to go with this? I know that they dont sell them in this size, Since i would have to get this size custom made for me.
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11-25-2009, 11:46 PM
#9
