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I might be aquiring a 401 to swap into my YJ that will replace a 304. I have a rebuilt 727. Will I be able to just drop it in utilizing the 304 exhaust manifolds and 304 flex plate???????What about internal/external balance that I have seen mentioned before.
You will need a tf727 to 401 flexplate and a 401 balancer. the only current 727 flexplates are available on ebay and are SFI thick plates right around $125 ea. The rest will work.
Are your refering to a harmonic balancer and what is SFI.
bor-
Mat is referring to a 401 TF flexplate (listed on ebay thru Mad Dog and ?) that happens to be SFI approved (extra thick material that will not explode). You will also need a 401 Harmonic Balancer (damper). Everything else will interchange.
Larry
SFI = used to stand for Sema foundation incorporated but not its "standards for specialty/performance automotive and racing equipment". To race you need special SFI ratings that are sactioned by tracks/event companies. Basically on a flexplate it means the flexplate retains a certain thickness and a harmonic balancer has a couple of #'s associated with it and one says the balancer outer ring must not be able to fly apart if it cracks.
For a 401 swap you will need the OEM or aftermarket specific balancer and flywheel. The 304 isnt balanced right and all AMC V8's have specific balances for each cubic displacement. So even if it fits you will get major vibration.
YEs---My reference to the balancer was to clarify if it was the harmonic balancer or the crank/flywheel. Thanks to all for the replies. I have been logging on to this site every day for a year now. I have read just about every article on the site. I am ready to go big with a 401 and have been waiting patiently for the ooportunity to aquire one. I have a YJ on 1-1/4 ton axles and 42", rebuilt 727 (heavier clutches, shift kit) rebuilt D-300 (will be go w/4-1, or a Klune V) The information on the site is priceless due to the specific nature (AMC) of the product. I want to stay w/AMC because everyone else in the world is going to Chebbie--- and with this site, the necessary quality parts are now available. I plan on decking my engine out with alot of the Bullltear stuff---
Good luck with that build Bor! I may do another open jeep this fall. For now I am building up my ZJ with some unimogs and possibly a AMC powertrain.