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Bellhousing Allignment mismatch dowel


40desoto

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Im using a 250 25inch block bellhousing in order to mount  a T5 5 speed transmission into a 218 23in block. The bellhousing matched up just right allowing me to use the starter and flywheel that came from the 250 block a buddy of mine recommended that I dial in the bellhousing in order to make sure the transmission is perfectly alligned with the crank/flywheel etc..  He also mentioned to look into using offset dowels in order to get it all perfectly dialed in.....    dowel pins?!!  I didnt even think about those when I put my flywheel, clutch, and bellhousing on the motor but I do see the need for them.

The problem Im having is that the holes for the dowels are different between the bellhousing and the 218 block?  The 218 block has much larger diameter where the dowels go in.

 

I hope this is not a stupid question..  Are the dowels really necesary?  If so do they make dowels with different sizes on each end? Is it necessary to dial in the bellhousing if the transmission shaft slides in smoothly?

 

 I know they make offset dowels to allow you to finely adjust any offset.

Edited by 40desoto
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Id certainly be interested in why he(your friend) recommended the flywheel/bell housing/starter combo from a 250 on a 218. Is that what he happened to have?.

The dowel pins are a necessity to align the parts and keep them aligned.

??

DJ

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218/230/237/250 and 265 flatheads all use the same size .750" long X .500" Diameter block to bell housing dowels.

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The reason I decided to keep the bellhousing from the original 250 car is that I didnt have a bellhousing for the 218 and I liked the way the starter sat higher than other bellhousings thus allowing me to keep the original foot starter switch. 

Don the 250 bellhousing is not from a fluid drive car and yes everything with the transmission, adapter and related parts fit well. 

 

Also, when I use the lighter flywheel from the 218 engine I cannot keep the starter from grinding when I use the much much heavier flywheel from the 250 engine I get no grinding issue from the starter.  This issue was what had me thinking about getting the bellhousing alligned perfectly. 

Is there any drawback from using such a heavier flywheel?  I mean its about twice as heavy as the other.

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I compared the 250 Engine dowel pin hole to the 218 dowel pin hole and Im thinking that the 218 dowel pin hole might of been honed out at some time.

Note the rusty block is that of the 250 block.  The silver block is the 218.  Note the last picture is the 218 with the dowel much smaller than the hole.

 

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Edited by 40desoto
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The reason your starter grinds when using a 218 flywheel is due to the mounting flange on the flywheel. Did you measure the starter gear relationship to both flywheels? I had to modify the starter mounting flange in order to use a 218 flywheel on a 251 engine. Using the heavier flywheel should not be an issue.

 

On the dowel pin issue I do not have a clue as to why the holes are not the same size unless a prior owner drilled them out as opposed to using a drift punch to remove/install them. I did dial in the transmission pilot hole in my bell housing prior to enlarging the hole. But I also used the dowel pins and I did not use an adaptor plate that already has the correct sized hole. I suggest you contact the vendor who sold you the adaptor plate and follow there recommendations.

 

Bell-starter_1.jpg

 

MVC-001F_1.jpg

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As mentioned, the pin should be the same size, and YES, alignment dowels are required.  If the holes in the block have been drilled out then you need to be concerned about how straight the hole is and also how round the new hole is.

Any competent machinist can make an off-set dowel with what ever od and offset you want.

 

A big heavy flywheel on a smallish engine will function but the engine will not spin up as quickly as with the wheel Mopar originally supplied. That said, once up to operational speed, the engine will not bog down as quickly when you approach a slight grade. Quite often, the weight of the wheel is a function of the vehicle weight with many compromises thrown into the equation.

 

As to using a non-218 wheel, there is a difference of 0.185" in the amount that the flywheel face of the flange is from the block; 1.0" +/- for the 208-218 and 1.1875" +/- for all others. This will account for starter to ring gear mis-match and the reason Don had to cut his bellhousing. Using a 250 wheel on a 218 will place the ring gear 0.185" closer to the block/deeper into the starter. You can shim the starter to move it back to where it should be.

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Thank you Don and Wayfarer!  Always a great wealth of knowledge.  Thank for the information on the difference in flywheels.  When I measured them from mounting area to teeth they where pretty much the same distance measuring from the farthest area of the teeth (farthest from the starter)  The difference I see is that the flywheel from the 218/230 has more narrower teeth than that of the 250 flywheel.  I think Im going to stick with the 250 flywheel and avoid modifying the starter mounting flange etc.

 

The original Dowel pin hole is .500" and the enlarger hole on the block is .615"  Im wondering if I dial the bellhousing to allign it and I use a .210 offset dowel pin I can use that offset pin to hold the bellhousing allingned?  or should I drill out the hole on the bellhousing in order to match that of the block and purchase a correct size dowel pin?   My concern,  like Wayfarer mentioned is if the enlarged hole was done correctly by a machine shop and alligned. 

 

To to add a bit more details to my situation....  I purchased the engine with a Torqueflight adapter kit and Im wondering if this hole was enlarged to match the adapter kit..?  The adapter kit did not have a dowel so Im not sure of the previous owner was planning on using one.  I have since sold the adapter kit.

 

post-4811-0-15852100-1402589745_thumb.jpgpost-4811-0-97614700-1402589876_thumb.jpg

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You might have a later than 56 flywheel with a different tooth count on the ring gear. If thats the case you might be able to swap ring gears between the two flywheels.

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The only 'proper' way to rectify the big hole would be to overbore it and press in a sleeve/plug and then re-bore in the correct position...will not be cheap or easy as only medium size or larger vertical mills have enough depth to accommodate the length of the block. A horizontal mill would be best but can be harder to find a shop with one.

The other option, not often used, would be to mount the bellhousing, dial it in, and then 'match drill' the bell and block in a new location. This would also need to be accurately done to insure that the pin was square to the block face.

 

Can you provide a few more pics of the alum adapter?  It looks to be 'old-timey'; perhaps from one of the airport tuggers?

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When I get home from work this afternoon I will send some pics of the adapter.  Its not aluminum its cast and also has the PDCD logo on it.  Its factory..

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