289 Main Caps

[Silver Bullitt]

https://www.ebay.com/itm/HI-PO-289-K-Main-Caps/143109125546

Title: "HI PO 289 K Main Caps"
Description: "For sale are five original 289 HiPo main caps. When installed on a stock 'plain-Jane' 289 these make a HiPo. There is NO difference between A, C or K blocks OTHER than these caps. Installation will require align bore/honing by a competent machine shop. Offered at no reserve. Buyer to pay shipping, $16 USPS flat rate, or local pick up ok. Cash or pay pal only. Good luck bidding."

Heads up, there is some funny business going on here. 5th cap pictured is a C2OE-B instead of correct C3OE-A

[s2ms]

I emailed the seller about that yesterday, he replied that's the way they were on the block he removed them from and that the HiPo rear cap is the same as A and C code. Told him they were indeed different, and mentioned the casting number difference.

At least he had a reasonable opening bid considering the wrong rear cap.

[6s1640]

I emailed the seller about that yesterday, he replied that's the way they were on the block he removed them from and that the HiPo rear cap is the same as A and C code. Told him they were indeed different, and mentioned the casting number difference.

At least he had a reasonable opening bid considering the wrong rear cap.

Hi Dave,  Educate me.  I realize the rear HiPo and LoPo caps do have different casting numbers.  Are they geometrically identical, but cast with different alloys for strength?  Other than cast number, what makes the HiPo casting HiPo?

Thanks

Cory

[camp upshur]

Very very similar unlike the front four. The 271HP cap is nominally thicker as you can see on its' forward face.

[s2ms]

^^Nice comparison photo. As far as strength I doubt running a standard rear cap would be an issue at all.

[camp upshur]

Concur. In theory a crank is under it's greatest stress between the ends. Which is why some blocks, like a real Boss 302, were designed as they were. I say 'in theory' because the 289 has its own pointless design deficiencies. 289 cranks snap at the first throw which is one of the reasons why they changed the firing order (ask me how I know). The other is the cheapness of external balancing. EL STUPIDO.