Help me pick pistons for my 360.

I am currently running KB hyperutectic piston with a -1.20cc domed piston head and a 1.675" compression distance. I'm running the basic fel pro blue head gasket I believe it's .039"compressed thickness with at a 4.180" bore. My engine currently has a 4.030" bore with stock open chamber iron heads. I have a bad wrist pin in cylinder 6 with a little scorning on the wall but the compression is still good so I might have to go 4.040" bore. I want to go to a forged piston this time around. I'm figuring I'm at 10.5-11ish compression wise with my current set up and want to stay as close to that as possible. What forehead piston/ head gasket combo will keep me close to my desired compression? I have some ideas but would like others input as I am no pro at this.

Has anyone heard of DSS racing Pistons? I'm interested in their -5.00cc pistons. I'm also interested in the SRP & Icon flat tops.

What heads and how many cc-s are they?

The heads I will be running are aerohead iron 974 castings with a 2.02 intake valve,a homebrew port job, and open chamber. I'm not sure on the cc of the camber as they don't list that and I haven't checked them. They should be in the 68-70cc I would assume.

If you are running under 6300-6500 rpms go with a KB piston and opt for the higher compression( I think they are the 190). The KB's are closely matched for stock balancing. You probably won't find that with a forged piston. You'll need to pay for the rebalancing. I don't think you will be making any power beyond 6000 rpms with those heads.

I wish you were in need of a set of .060 over high compression pistons as I have 2 sets sitting here. Guys want them but have no money

How high of compression are they? Are they the Wiscos you have listened here? I did remember seeing you had some listed. I still have stock 3.58 stroke too.

Hoping to take some parts to monster mopar. I will check my Stash tomorrow

My 8553PT's compressed from .059" to .051". 4 & 3/16 bore (didn't have my calipers nearby for the bore dia measurement but does correlate with your 4.180 dimention).

I'm running the KB190 currently and I believe the wrist pin hole is the point of failure. That's what I'm replacing them. They have roughly 25k mi and hundreds of passes on them. The majority of use for the engine is at the track nowadays, so I need toughness and reliability.

I had a .040 360 block that was rebuilt and had a wrist pin failure, too.
Just yesterday it left on the scrap truck, it had a deep groove in #5 and would not clean at .060. It was a 1977 block and might have been savable if it were an early block. I bought a set of 273 rods that have been bushed for floating pins from a Moparts member. I plan to use those in my 1990 roller block when I get around to machining it, it had standard bore pistons in it and almost no ridge. I will need some very light pistons to go with this build and would like to see 9 to 1 compression and maybe a 4" crank.

Here's a link for the pistons I'm wondering if anyone has used or herd of, because this is the first I've heard of this company.

https://m.summitracing.com/parts/dms-6350x-4030

that X deal looks like snake oil.

I thought that looked pretty hokey too. I'm sure a good Teflon coating would be far superior to that.

The best "deal" is probably some wiseco/pro true pistons..... They come with rings.

I'd go for these myself--SBM670040F05 Mahle Motorports, they come with rings as well. J.Rob

Thanks guys this is exactly why I asked! These look like both fit the bill perfectly. I like the price on the Wiescos but the thin rings on the Mahle is pretty attractive too.

Here is the reason I need new pistons. I really don't think that they should fail like this after 25k mi. Even with a few hundred passes.

That would be detonation that blew the ring land off that part. What timing are you running and octane fuel?

I was running 34* total all in by 2000rpm with 93 octane on the street,I mix a few gallons of 110 in at the track.

Agreed, be sure to solve that (more octane, maybe slightly stiffer springs) before you fire up the rebuild.

Racetec can build anything you need at a good price... I like dealing with the guys that build the parts not just resellers like Summit/ Jegs, etc. Give em a call.

What top ring gap were you running?
Ive pulled ring lands off like that when i have messed up the ring gap and had it too tight

racetec pistons use a smaller metric ring stack..

KB hypereutectic required larger top ring gap...

I honestly can't remember as I built this 10 years ago. I do know I ground them to KB spec but can't remember the exact gap.

Would a stiffer spring really help? I've never heard of that coming into play but I don't claim to know everything. I am replacing the springs, and heads for that matter. I've got a pair of aerohead reman heads with 2.02s and .509 lift springs that will be going on this time around. I've also got a MP 292 .508 purple shaft that's going in too.

You butted the rings which blew the ring land off. Your end gap must have been correct or close to run 25,000 miles though. You were running hot with borderline fuel or just didn't lift when it was rattling. Was your top ring @ .026-.028"?

You won't beat the Mahle's with their tighter than normal clearances for a forging. J.Rob

.


You hit the nail on the head, on the way to the track we got off the e-way and the truck was HOT I got on the throttle to blow the carbon out after the extended cruise, it rattled and I didn't lift as quick as I normally do. I'm sure that's when the I poped that chunk loose. I should have known it would rattle after the hour or so of 70 mph at 34-3700rpm. Live and learn I guess.

My experience with those pistons is they can be a great budget piston but need a pretty big ring gap. And if you set the gap for street it aint gonna be suitable for towing or nitrous at a later date. If you set them big for extra load like drag then when your street driving the gap is a bit big and blow by goes up. Compared to normal pistons the extra load gives far greater ring growth than other piston designs.

Well, the DSS pistons are forged and machined in St. Charles, IL. It's an interesting little company from the website.
Looks like they've been more in the road racing arena.

$329 per set for an entry level forged piston is a smokin' deal. Probably mainly ford and SBC applications at that price point. 4032 alloy is the lower expansion alloy.

R.