February 23, 2025, 06:27 PM
Mike FrizieConverter spacing ?
Whats the thinnest spacer you’ve have to run on your converter? I can pin mine freely and it’s not touching the flex plate . Is it possible to not need one to your 1/8 gap? I know this a stupid question but pretty sure this is the first time I’ve run this ‘verter.
February 23, 2025, 08:18 PM
Big SteveWith the converter push all the way back Spec is .125-.180 inch with or without any spacers if thats what your asking
February 24, 2025, 04:42 AM
Mike FrizieCorrect. And thanks. But I was asking was is it possible to achieve the 1/8 I want with no spacer? Dad put the ‘verter in a swears it went down all the way. like is said , spins free and is not contacting flex plate.
February 24, 2025, 04:50 AM
rustyif the convertor was built for your midplate by one of the major companys you shoudnt need a shim.if the convertor will turn it is in the pump gear properly.push all the way way in and measure.i like to be close to the 180 but steves numbers are good.
February 24, 2025, 05:12 AM
Mike Frizie10-4 guys. Thanks for the reassurance .
February 24, 2025, 07:07 AM
Larry WoodfinRusty is correct in that it would not spin if it were not all the way engaged. It is also correct that if you have between 1/8" - 3/16" clearance, no shim is needed. An easy way to measure is insert drill bit between flex plate and converter pad.
February 24, 2025, 08:10 AM
RPROGASquote:
is it possible to achieve the 1/8 I want with no spacer?
Yes
Bob
February 24, 2025, 08:41 AM
Lenny5160quote:
Originally posted by Larry Woodfin:
Rusty is correct in that it would not spin if it were not all the way engaged. It is also correct that if you have between 1/8" - 3/16" clearance, no shim is needed. An easy way to measure is insert drill bit between flex plate and converter pad.
Yep, I always bring 1/8" and 3/16" drill bits under the car with me. The 1/8" bit must fit between the converter and flexplate, but the 3/16" bit must not fit.
February 24, 2025, 10:21 AM
wideopen231If reading correctly Issue is too little gap. If so you have to pace transmission or remove little material from converter mounting pads. Guess can send to have cut back or carefully grind them. If later I would mic pad slowly remove material to get gap needed and make sure to remove exact amount for all three. ALTHOUGH goes against my religion I would get close and finish with flat file. Any decent machinist could spin it up in lathe. That would be my choice.
February 24, 2025, 06:08 PM
rustyif not enough gap,when the flexplate flexes it will go in too far and wear the pump
February 25, 2025, 11:23 AM
Mike FrizieUpdate: I measured the gap by installing washers I couldn’t get in any more in, then mic ing the thickness and came up with .220 . So Plan is to install a.075 spacer onto each bolt , which should pull the ‘verter out .145, which should be inside the 1/8-3/16 spec?
February 25, 2025, 12:39 PM
Big Steve.145 is perfect. Send it
February 25, 2025, 02:33 PM
Mike FrizieThanks just hard to believe the bbc is that odd ball of a piece to cause a variation with a major manufacturer .
February 25, 2025, 04:28 PM
FootbrakeJimMichael, it sounds like a lot of slop, but it is definitely not limited to BBC applications. When you really think about it, that .120-.180" range (1/8-3/16") is a standard rule of thumb for any of our common racing platforms, GM, Ford, Mopar, and whatever converter & automatic trans you put behind it.
Think about the number of different parts that all get connected together, and the different possibilities for variations in the many manufacturing processes that feed into that total allowable range of variance, which is 1/16th of an inch. (.062"). That range is due to what they call "tolerance stacking" in manufacturing. There are a lot of different potential culprits in that chain. Engine blocks have allowable tolerance variations for the dimension from thrust bearing to the rear (bellhousing) surface. Thrust bearings have allowable tolerances for thickness of thrust flange. Crankshafts have multiple +/- dimensional tolerances, one of them being for the distance from thrust bearing fillets to the flex plate mounting flange, and also an operating / assembly clearance (allowable fore/aft movement) of the crank within the block. Flex plates have multiple tolerances, from disk material thickness, distance from converter pads to the plane of the base disk, etc. Torque converters have dimensional tolerances for various dimensions that would result in allowable variations of the total distance from the pump drive end to the flex plate mounting bosses. Trans Pumps have manufacturing tolerances. Transmission cases have casting and machining tolerances. If you had 2 complete assemblies, (Engine/Converter/Trans), and one of them had every dimension of every component at the allowable "maximum material condition" for all components, and the other unit had the opposite - all tolerances for every part were on the short end of all allowable variations, it is remarkable that a powertrain assembly plant could build hundreds, even thousands of completed assemblies per day. With each of the components coming from a separate manufacturing plant. So that converter snout, which can move a reasonable distance in or out of the trans pump, gives the automotive engineers a place to accommodate all the manufacturing variables of all the other components. Think of it like an expansion joint on a sidewalk.
Yes, you could specify much tighter precision tolerances on every component, but your manufacturing costs would go up exponentially, and your production volume per day would go way down.
February 26, 2025, 04:36 AM
rustyquote:
posted February 25, 2025 04:28 PM Hide Post
Michael, it sounds like a lot of slop, but it is definitely not limited to BBC applications. When you really think about it, that .120-.180" range (1/8-3/16") is a standard rule of thumb for any of our common racing platforms, GM, Ford, Mopar, and whatever converter & automatic trans you put behind it.
Think about the number of different parts that all get connected together, and the different possibilities for variations in the many manufacturing processes that feed into that total allowable range of variance, which is 1/16th of an inch. (.062"). That range is due to what they call "tolerance stacking" in manufacturing. There are a lot of different potential culprits in that chain. Engine blocks have allowable tolerance variations for the dimension from thrust bearing to the rear (bellhousing) surface. Thrust bearings have allowable tolerances for thickness of thrust flange. Crankshafts have multiple +/- dimensional tolerances, one of them being for the distance from thrust bearing fillets to the flex plate mounting flange, and also an operating / assembly clearance (allowable fore/aft movement) of the crank within the block. Flex plates have multiple tolerances, from disk material thickness, distance from converter pads to the plane of the base disk, etc. Torque converters have dimensional tolerances for various dimensions that would result in allowable variations of the total distance from the pump drive end to the flex plate mounting bosses. Trans Pumps have manufacturing tolerances. Transmission cases have casting and machining tolerances. If you had 2 complete assemblies, (Engine/Converter/Trans), and one of them had every dimension of every component at the allowable "maximum material condition" for all components, and the other unit had the opposite - all tolerances for every part were on the short end of all allowable variations, it is remarkable that a powertrain assembly plant could build hundreds, even thousands of completed assemblies per day. With each of the components coming from a separate manufacturing plant. So that converter snout, which can move a reasonable distance in or out of the trans pump, gives the automotive engineers a place to accommodate all the manufacturing variables of all the other components. Think of it like an expansion joint on a sidewalk.
Yes, you could specify much tighter precision tolerances on every component, but your manufacturing costs would go up exponentially, and your production volume per day would go way down.
Dan "Jim" Moore
Much too young to feel this damn old!!
and lol the pump gear is .375 thihick if the distance is not near center it will rise out and get on top of the gear or too deep and wear the pump.
when everthing was all factory used parts things were different for sure