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The chevy 400 (NOT 427 but Four Hundred even cid) engine has a std 4.125 bore. BUT, that puts us right back to connecting rod issues.

I didn't check to see if comp height of a 400 piston = 350 comp-ht or not so at this point i'm not sure if "one CUSTOM rod fits all" between 352 and 374 Pack V8 while using Chevy pistons.

However, there are at least 2K 400 pistons on eBay.

jepistons.com/Catalogs/SRP/Chevy_SB/400_flat.aspx

Specs for chevy pistons (and custom Chevy pistons) including compression height (pin to top of piston) and rod lengths for which they apparently offer various ros lengths.

I guess I'm still not understanding why we'd choose to go with $2000 custom rods/$400 SBC pistons instead of $1000 Packard forged pistons.

jack vines

I was going to hold off saying anything until things were a bit further along, but I can never keep a secret plus a blending of the minds and experience is key.

I have been playing for a while on the possibility of piston work for Packard. With the many different and really old Pre-War's we have been working on many of the Studebaker Pistons are not available and we turned a set for our Big Six and Special Six.

In light of the recent issues with Egge and the 374, we started looking at this. Egge will consider a run of 374 pistons for us at 200 sets bare minimum. Of course at repair rate, size variation, and taking up space on a shelve, as Fred has pointed out from the Business aspect, it really is not cost effective to peruse.

I recalled having a used set of Jahn pistons that I removed from a 374 two years ago. I compared the two pistons in measurements and the differences were in Jahn having a High Dome and Egge has an extended skirt.

Moving forward, For Packard, we have cast what I am calling a semi-universal blank. In its design for flexibility, one blank was given Extra stock. It can be machined to a bore ranging from 4.000 inches to 4.312 inches. This will allow flexibility to cover both 352 and 374 and a nice oversize range for each.

Plenty of meat on the dome for different options. The pin height is set 2 5/16 from bottom as cast and will machine 374 2.070 pin Hight. In addition the mold can adjust to allow the cast to adjust machine pin bore higher or lower by 5/16 inches making it versatile in applications.

We are "Playing" with turning a set to put into a 374 on the floor. This will be a low priority in the shop trying to get cars ready for the spring shows but will keep updates coming. We really need to look at total costs and if it makes sense.

Feedback is welcome, don't beat me up too bad 

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Hi, Troy,

Is the flat top piston on the left with the L1956 stenciled on it an Egge 374"? That's their part number, but it looks completely different than a set I picked up recently. Those I found have a barrel skirt similar to the pop-up you show on the right.

jack vines

The piston on the left looks like an EGGE piston, to tell for sure there will be the EGGE name cast on the inside.

The barrel skirt piston you think is an EGGE may be a very old EGGE or a Jahns. Look at what's cast inside

Sorry guys..... Yes the one of the Left L1956 is the Egge 374. They cast it last year for me at .060. The pop top on the Right is a Jahns .030.

Interesting however, is late last night, I got them out and measured the cam grind. Jahns has a .012 grind between A-A and B-B as expected with Aluminum. On the Egge, I measured no grind. I will check again today on the measuring stand at the shop to verify.

Place BOTH pistons in oven at about 300 degrees F.
Then measure how much they EXPAND due to heat.

The lack of a cam grind usualy (tho not necessarily) indicates a relatively low quality piston for low speed or lite duty operation engine. i.e. an "economy grade" piston.

Does the piston with NO cam grind have a VERTICLE (or mostly verticle) slot or T-slot on the side of the piston OPPOSITE the thrust side???

Quote:

Hi, Fred,

Thanks for the reply. The Egge barrel skirt 374" pistons I picked up must be VOOS (Very Old Old Stock) as all the 374" pistons from them I've ever used are the slipper skirt style similar to OEM.

Do you have any memories or recommendations as to how the barrel skirts are better or worse? Any difference in bore clearance? Any idea why they changed?

I'd forgotten Jahns was big in the cast repop piston business back in the day. I'd remember them as a performance piston and thought forgings. They changed the name to Jahns Engineering and eventually became JE, where one can still buy forged pistons today.

Back to the barrel skirt; since Egge bought many molds as other piston companies went out of production, wonder if these were from a Jahns mold?

The later production slipper skirt pistons appear similar to a Badger design.

jack vines