Hipo Block Question

<font face='Comic Sans MS'>I've been told that is basically an old wives tail. Except for those blocks modified by private parties, there never were screw in galley plugs on any Hipo block from the factory. </font id='Comic Sans MS'>

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I've been told it was a Shelby only thing.

I put the answer in my book (Mustang & Ford Small Block V8) on page 3-3. Carroll Shelby installed front screw-in plugs for the oil galleries when he reworked the 289 HiPo for competition versions of the Mustang GT-350 (rated at 350 hp), and for the Cobra Daytona coupes and Ford GT prototype race cars (380 hp). All other used the ½" freeze plugs. Of course, anyone could modify the engine, but from the factory, production 289 HiPos used freeze plugs.

If memory serves me correctly, in Bob's book is a copy of a TSB that was to install screw in plugs for loss of oil pressure complaints. I believe the TSB was dated sometime in 1967.

Personally, they should have came with screw in plugs. I never posted it on this site, as I was to ticked off at the time. But the FIRST TIME OUT OF THE GARAGE with my K-coupe I lost oil pressure.

8 hrs later it was fixed (very nerve racking on a just completed Kar), but it was a lot of work doing it in the vehicle. On my maiden voyage all 3 front plugs popped out. I DID NOT do the block prep work, and should have installed screw in plugs prior to assembly, but the press in ones were staked and had Loc-Tite on them. So now they are all screw in plugs.

I retrieved the plugs out of the oil pan a couple weeks later when I took the pan off to check the lower end after driving it for a hundred or so miles.

Bob, thanks for the effort of your books, and for joining the site. .

The TSB called for flaring the cup end .005"-.010" more for better retention. They suggested using a ballbearing slight larger than the inner diameter and tapping it to enlarge the opening. The cup should be sealed with a Permatex No. 2 and driven with a flat-end punch until the edge of the cup is just below the chamfer hole. In thirty years of driving, I never had one I installed come out, so if done properly, freeze plugs work fine. Carroll Shelby left them in in the street Mustang GT-350. But, for the race GT-350, Cobra Coupes, and GT-40 (350 & 380 hp versions) he used threaded plugs. Can't argue with "better" and threaded plugs are definitely better.

Bob, I will never know why mine came out. My Dad installed them, and he's been building engine for 40+ years. Serious race engines too.

They were staked and sealed also. Just one of those things I guess.

Thanks for the clarification on the TSB.