Do I Need a Bushing for the TC for a 273/318 Swap?

-
Z

zephyr

Well-Known Member
Joined
Oct 31, 2017
Messages
356
Reaction score
163
Location
San Bernardino
I will be having my 273 replaced with a 318 in my 65 Dart. It has the original 904. I've been told I'll need a bushing for the 318 crank to reduce to the OD of the little 273 torque converter. Is this true? Where can I get one?
Thanks
 
Depends on what year the 318 is. The "big cranks" started in 68 or 69, don't remember. You may need to find someone with a small lathe, they would be easy to make
 
Look up member Charlie S, I believe he makes them.

54EA5935-6AA4-4F65-B900-C23326B3629F.png
 
Best thing would be to replace the TC when replacing the engine. Probably be better for the balance and maybe stall speed... Just a guess. Correct pilot bushing...
 
67Dart273 said:
Depends on what year the 318 is. The "big cranks" started in 68 or 69, don't remember. You may need to find someone with a small lathe, they would be easy to make
Click to expand...
All 318's I've ever seen have the large register for the torque converter. As far as I know, only the car '64-7 273's, and the '60-67 slant 6's were the only engines with a crank with the small register.
 
=Max Wedge= said:
Best thing would be to replace the TC when replacing the engine. Probably be better for the balance and maybe stall speed... Just a guess. Correct pilot bushing...
Click to expand...
That's something that would have to be made. There weren't any factory torque converters with a large button that fit the early ('67 and older) 904's. I understand that you can also change the pump and input section of the transmission to do the conversion too, but, I've never done it that way myself.
 
cudamark said:
All 318's I've ever seen have the large register for the torque converter. As far as I know, only the car '64-7 273's, and the '60-67 slant 6's were the only engines with a crank with the small register.
Click to expand...


I’ve actually physically seen two 340 cranks with the small register. I’d never seen one before about a year ago.
 
I just verified that there are 2 of them. Both 340 cranks and both have the small register. One had to be machined and one hasn’t been machined yet.
 
what @yellow rose says is 100% true, @Scody21 was there putting the transmission in. Our buddy that owned the car found he had a second 340 crank that had the small register as well, both were early production 67 340 cranks. He had both machined by his engine builder to the larger register.
 
@yellow rose Perhaps they were forged 273 or 318 poly cranks (2128278 2128869 2205700) balance drilled to 340 specs? PAW used to sell them that way. Is there a stamped number evident on those small register 340 cranks? 68 production year transmissions were also built from june 67 production dates and they all had larger registers for 68 model years. a 1 year only 67 LA 318 would have the small register too, it may even have a forged crank.
 
I'd still like to see a photo of one. If true, they must have been in a manual transmission car, as all the automatic versions used a 727....which all used a big button converter. I have seen a few 340's with 273 cranks in them. Not from the factory though. They were put in because they couldn't find a good 340 or 318 forged crank at the time of the rebuild. One guy I know running a class drag car did it on purpose to lighten up the 340 reciprocating assembly. He also ran 273 rods, a 904, and a 7 1/4 rear for weigh savings!
 
pishta said:
@yellow rose Perhaps they were forged 273 or 318 poly cranks (2128278 2128869 2205700) balance drilled to 340 specs? PAW used to sell them that way. Is there a stamped number evident on those small register 340 cranks? 68 production year transmissions were also built from june 67 production dates and they all had larger registers for 68 model years. a 1 year only 67 LA 318 would have the small register too, it may even have a forged crank.
Click to expand...
I've never seen a 318 with a small register either. I'd sure like to see one if they exist. Even the 273 in an A100 van didn't have a small register crank. They used a 318 crank in them.....or maybe machine the register to the bigger diameter for use with the 727. Without weighing them, a 273 machined to the bigger diameter and a stock 318 forged look the same. They may have different stampings on them though. Never got that deep into it.
 
cudamark said:
I'd still like to see a photo of one. If true, they must have been in a manual transmission car, as all the automatic versions used a 727....which all used a big button converter. I have seen a few 340's with 273 cranks in them. Not from the factory though. They were put in because they couldn't find a good 340 or 318 forged crank at the time of the rebuild. One guy I know running a class drag car did it on purpose to lighten up the 340 reciprocating assembly. He also ran 273 rods, a 904, and a 7 1/4 rear for weigh savings!
Click to expand...
Do a search, there are posts about this on this very forum, do you really think three different guys are going to make this up lol.

No question they were/are 340 cranks, definitely not 273/318. Our buddy buys and sell mopar parts and knows a fair amount but this was his first encounter with this as well. One was removed, machined and reinstalled and is now in his car. I will ask to see where the other is and maybe get a pic of the freshly machined register
 
lead69 said:
Do a search, there are posts about this on this very forum, do you really think three different guys are going to make this up lol.

Not deliberately, but, they could be mistaken by repairs/replacements done in the past. I don't know how many people have told me that their first generation Barracuda came stock with a 318, but, there's no way I could count the number on my two hands........or even by adding my toes.
Click to expand...
 
You must log in or register to reply here.
-

Back
Top