Hot Rod Forum : Hotrodders Bulletin Board

Hot Rod Forum : Hotrodders Bulletin Board (
-   Engine (
-   -   "Sealed Power" pistons - good or bad?! (

bbjunkie 11-26-2008 12:53 PM

"Sealed Power" pistons - good or bad?!
Hi guys!

I'm in the process of rebuilding a boat engine (Chevvy 181 L4 block) and have been offered "Sealed Power" pistons, after a quick search on google I find they are a Federal-Mogul brand, the pistons in question are 345NP (Cast)

Does anyone know if there could be issues with these? (Yes, they appear to be very cheap, but what is the quality like?)

I appreciate this is a little OT but I think you guys should know plenty about these pistons :)



junior stocker 11-26-2008 01:39 PM

The word is, Speed Pro, aka Federal Mogul pistons, are now made "off shore", like in India now. That part number is also for SBC 350 engines. I say go to E-Bay and you'll find what you need and probably very cheap. Those are also a "rebuilder" style piston, and as such, probably have .020 off the tops to compensate for block decking/head milling when rebuilding short/long blocks. I like the appearence of the Speed Pro/Federal Mogul piston more than the Silvolite/Keith Black piston and they cost less to boot. I hear Silvolite/Keith Black are also made off shore now. Time to boycot/embargo some of these defecting companies.

red65mustang 11-26-2008 02:15 PM

here's a thread about that specific piston:

techinspector1 11-26-2008 02:25 PM

Like junior stocker, I'd be concerned about the compression height of the piston. Measure your present pistons and don't settle for a reduced c.h. If you do, you'll likely render the squish inadequate to prevent detonation on the same fuel you've been using. Also check the crown of your current pistons. If they have a nice big flat area that mates up with the underside of the head at TDC, then use only the exact same type of piston crown to replace them. Some pistons use just a thin (maybe 3/8") wide ring around the perimeter of the piston, with the center of the piston at a lower elevation. The area of this ring won't allow the same squish characteristics as a nice big flat area on the crown.

Studebaker 11-26-2008 02:52 PM

I have used these pistons as replacement pistons in numerous rebuilds with no issue. Remember that if the Cylinder is bored say .030 in order to true the bore , due to the increased volume, this will also raise the compression slightly.

bbjunkie 11-28-2008 11:29 AM

Thanks guys, I really appreciate the advice..

As these are going into a boat engine, I suppose I should ask if they would be up to higher than average engine speeds, not so much higher top end, but longer operation at higher revs. The design of boat will mean the engine pulls to 4800rpm but will be used constantly between 4000 and 4800rpm.

With this in mind, what rings would you recommend?

And finally, as the only source for these I can find is in the US, I have two questions...

1) Is there a supplier for these in Europe/UK?
2) If not, is there anywhere in the US that would sell to me at a decent price?

(I'm in Northern Ireland)

Cheers again


Packard V8 11-28-2008 12:14 PM

Hi, Pete,

Talk to me off list. I'll check the shelf and if we have them, no one will make you a better deal.

thnx, jack vines

red65mustang 11-28-2008 01:47 PM

PM Mosstrooper for local sources????
he lives in Scotland, those are very common pistons

"which" rings depends on how the cylinders are finish honed ....
talk to the machine shop that will bore the block to be sure you are both on the same page for hone to rings match

Studebaker 11-28-2008 05:32 PM

I always step up and purchase speed-pro, hastings or perfect circle Moly rings. They are good quality for stock or mild performance rebuilds. I never had a problem with either of these brands. I have probably purchased over 100 engine kits from Northern automotive, they have been really good to deal with and very reasonable on their engine kits.

bbjunkie 11-30-2008 06:35 AM


Originally Posted by Studebaker
I always step up and purchase speed-pro, hastings or perfect circle Moly rings. They are good quality for stock or mild performance rebuilds. I never had a problem with either of these brands. I have probably purchased over 100 engine kits from Northern automotive, they have been really good to deal with and very reasonable on their engine kits.

What sort of questions do I need to ask the machine shop before deciding what sort of rings?

More than likely I will be going .030 oversize, won't know until I get my hands on the block from the marine engineer who is removing it (one cylinder was very low on compression, so need to see if it's a valve problem or damage in the cylinder)

red65mustang 11-30-2008 08:04 AM

one low cylinder can be just a blown head gasket!!!
or a burned single valve
or a cracked cylinder head...

your wasting your time researching and asking about pistons and rings specifics...
until the engineer confirms the cylinders do need to be bored and a total and complete $2000+ rebuild done....

"cross each bridge as you come to it" based on the facts...

wait till you get the facts from the engineer...

bbjunkie 11-30-2008 01:02 PM

I am doing the repair. The engineer is just removing the engine for me

The engine has broken the head of a valve and put it through a piston, so unless you can suggest another way of fixing it, I will need pistons!

Head gasket was fine.

red65mustang 11-30-2008 05:46 PM

order pistons and rings together as a engineered "matched parts" set/kit....

because a valve went thru the piston the whole motor needs to be torn down and inspected for damage (and wear) and cleaned

at that point it makes more sense to buy a "master rebuild" kit which includes "everything" new....
timing chain/bearings/valves/cam/pistons/rings/assembly gaskets/oil pump/etc/etc/etc

the kit will very likely be cheaper than buying each and all the parts needed by the time you are done....

buy it after the motor shop that will do the machining has determined if the crank and rods are worn and the cylinders do need to be bored to order the correct kit sizes combo

because it is used in a boat which is a constant heavy load on the motor,,,it will be wise to have the new different pistons weight and crankshaft re-balanced

Federal Mogul is truly worldwide, I would expect your local auto parts store can special order a kit in for you....

Studebaker 12-01-2008 02:22 AM

I agree, the entire engine needs to be disassembled and inspected. I would be surprised to see that the cylinder wall is not damaged (in the cylinder that dropped the valve). The block and head should be also magnafluxed, which is a magnetic way to check for cracks. You would probably be better off buying a complete engine kit if there is any wear issues. The reason most shops bore the engine .030 is not to waste time. If there is Cylinder wear, by boring and honing it 30 thousands oversize, you have perfectly round, clean, straight cylinder surfaces. Nothing wrong with cast rings for a stock rebuild, moly coated top rings seal fast and stand up to heat and pressure slightly better, but do cost more.

SSedan64 12-01-2008 04:56 AM

May check with Mahle Clevite also for engine kits, there world wide also.
They own the Clevite,Perfect Circle, victor Reinz brands etc..
Select a Continent here>$VPkontakte?ReadForm&L=EN

All times are GMT -6. The time now is 12:50 AM.

Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2017, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0 PL2
vBulletin Security provided by vBSecurity v2.2.2 (Pro) - vBulletin Mods & Addons Copyright © 2017 DragonByte Technologies Ltd.
Copyright 1999 - 2012. All Rights Reserved.