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Engine basics => Engine set up tips => Topic started by: steven yampolsky on July 07, 2014, 05:08:34 PM

Title: 20FP: iron vs ABN cylinder
Post by: steven yampolsky on July 07, 2014, 05:08:34 PM
Is there a way to tell if a FP 20 is an iron or ABN version?
Title: Re: 20FP: iron vs ABN cylinder
Post by: Tim Wescott on July 07, 2014, 05:43:32 PM
Iron attracts magnets.  Aluminum & brass don't.

Got any rare-earth magnets around?
Title: Re: 20FP: iron vs ABN cylinder
Post by: Brett Buck on July 08, 2014, 01:38:31 AM
Is there a way to tell if a FP 20 is an iron or ABN version?

  Yes, very easily. The iron-liner motor has a case with a noticeable bump where the boost port is. The ABC is smooth.

First is iron-liner, second is ABC.

   Brett


Title: Re: 20FP: iron vs ABN cylinder
Post by: Dane Martin on July 08, 2014, 11:13:07 PM
i thought the FP series was abn, and the earlier iron models were FSR.
Title: Re: 20FP: iron vs ABN cylinder
Post by: Steve Helmick on July 09, 2014, 12:05:28 AM
The ball bearing ones (.25, .28...and I think .32) are marked as "F", but became referred to as "FSR". The FP's were iron/steel or ABN, and bushed main. Tho the pictures posted are very useful, the magnet test is the one you can rely on. The visual difference between an ABN and an iron/steel is there, but fairly subtle, especially if gunked up with burnt fuel residue.   H^^ Steve
Title: Re: 20FP: iron vs ABN cylinder
Post by: Andrew Tinsley on July 09, 2014, 04:09:20 AM
What Brett said is true, but beware of people like me, who have rebuilt the Iron FP20 with ABN cylinders! If you are looking to do a BBTU on the FP20, then Brett (I think) and certainly "Dirty Dan" Rutherford say that the BBTU always works with the ABN set up but can be hit and miss on the Iron FP20. I have tried several Iron FP20s in BBTU mode. My findings are that they all give an excellent BBTU type run, but they need far longer to run in and get there. If it isn't fully run in, is where you get the problems.

Andrew.