Considerations on pistons in a 360 engine.

Posted By: Moparbil

Considerations on pistons in a 360 engine. - 07/30/09 08:25 PM

I have a 1976 360 engine. I am planing to prepair it for a swap with the damaged 340 in my Cuda.
I have striped down the engine to check the condition. It looks quiet OK. Chrank and bearings is very fine. Cylinders shown very little wear.
I would like to increase the performance so it will produce around 400HP.
Shall I keep the the original pistons and just change the rings and do a honing of the cylinders ? Or should I change pistons to obtain higher compression. Is it at all, vice to install new pistons without reboring the cylinders ?
What is the compression rate of the original pistons ? Will they work well with the 340 or edelbrock alu heads ?
What cam shall I choose ?
Have checked the internet for engine rebuild kit
Any recommendations ?

Many questions, Thanks to all answers

Posted By: RapidRobert

Re: Considerations on pistons in a 360 engine. - 07/30/09 08:35 PM

You're down to the bare block so definitely bore/hone it for plasma moly file fit rings, KB pistons to get the CR in the 10's w .040" quench

Posted By: Rug_Trucker

Re: Considerations on pistons in a 360 engine. - 07/30/09 08:39 PM

Quote:

You're down to the bare block so definitely bore/hone it for plasma moly file fit rings, KB pistons to get the CR in the 10's w .040" quench

That much compression in a streeter?

Posted By: therocks

Re: Considerations on pistons in a 360 engine. - 07/30/09 08:54 PM

We have the KBs in my kids 360.They work well with 10.2 compression.Rocky

Posted By: Crizila

Re: Considerations on pistons in a 360 engine. - 07/30/09 10:08 PM

Steel heads = 9.5, aluminum heads = 10.5. Thats rule of thumb, as cam choice can have a big effect. Good rule for street cam / operation though.

Posted By: 440newport

Re: Considerations on pistons in a 360 engine. - 07/30/09 10:59 PM

Is there a ridge at the top of cylinders? If not, I wouldn't be afraid to run new pistons without boring the block, just give it a light hone and go. I did my 360 this way. I prefer SpeedPro/TRW H116CP pistons over the KB's.
At spec they're about 0.016 in the hole and give about 9.25 compression with stock heads. I had my heads decked about 0.020 to get 69cc chambers and about 9.66 compression.

If there is a big ridge though, I would go ahead and bore the motor.

Posted By: Rug_Trucker

Re: Considerations on pistons in a 360 engine. - 07/30/09 11:14 PM

Quote:

Is there a ridge at the top of cylinders? If not, I wouldn't be afraid to run new pistons without boring the block, just give it a light hone and go. I did my 360 this way. I prefer SpeedPro/TRW H116CP pistons over the KB's.
At spec they're about 0.016 in the hole and give about 9.25 compression with stock heads. I had my heads decked about 0.020 to get 69cc chambers and about 9.66 compression.

If there is a big ridge though, I would go ahead and bore the motor.

Sometimes a ridge is nothing more than a ring of carbon. I've cleaned them with a brass wire wheel on a drill.

I would mike the bores and check for taper before making piston decisions.

And on a home/hone and build? Cast iron rings.

Posted By: 69L78Nova

Re: Considerations on pistons in a 360 engine. - 07/31/09 12:17 AM

Quote:

Steel heads = 9.5, aluminum heads = 10.5. Thats rule of thumb, as cam choice can have a big effect. Good rule for street cam / operation though.

I would also factor in quench distance as well. Im running over 11 to 1 in my 360 with aluminum heads and pump gas. Granted I am running the MP509 cam (unfortunately), and that is probably bleeding off a lot of it. As Im sure you know, with todays head and piston designs, along with modern cam profiles, the old rule of compression ratio limits on the street should go out the window

Posted By: Noblewk

Re: Considerations on pistons in a 360 engine. - 07/31/09 12:58 AM

As said before, check the bores with a mic looking a taper and Bore. If your within .002" of spec get a good set of speed pro hyper pistons, if your .004" in spec get a set of KB forged pistons and run them. Hyper and forged pistons grow with heat. Not only that .004 with forged pistons will take a 200 shot of NoS with no problems.

If your over .005 get it bored. Else you will end up with piston slap that will drive you crazy.

I have honed and reringed many engines with success with clean bores. You have to mic them out to be sure, your eyes will have a hard time detecting a taper or .005"

Posted By: joedust451

Re: Considerations on pistons in a 360 engine. - 07/31/09 05:02 AM

Quote:

We have the KBs in my kids 360.They work well with 10.2 compression.Rocky

+2, if these are the KBs i'm thinking they are, its been awhile sence i built my .060" 360, i think they were KB192s if my memory serves me, they were a quench dome pistom, my compression was 10.35.1, ran great on pump gas with the XE284H cam, RPM air-gap, 750dp, stock J heads, this was by far the best street SB i owned, it was a screamer, at 3700ft. alt., it ran 13.2s @ 104 in a full bodied 73 Swinger & 4.56 gears, that was on the limiter in all gears too (6000 chip), car was low 12s @ sea level easy, so these pistons will work on pump gas & iron heads.

Posted By: Moparbil

Re: Considerations on pistons in a 360 engine. - 07/31/09 07:27 AM

The motor has the original dish type pistons and have never been touched.
A quick check on taper, using the ring gab metode, shows a taper of 0,002 max. No edge is felt in the top of the cylinder using the nail test. Original honing marks are clearly seen in the lower part of the cylinder.
Do not have correct tools to meassure cylinders on hand right now.
If I can get away with only honing the cylinders and install new standard size pistons, I will do that. On e-bay I have found rebuild kits from Falcon performance that include pistons and cam. Is it OK ? Or should I go for TWR or KB.
I am not building a race engine, more a street preformer.

Posted By: RapidRobert

Re: Considerations on pistons in a 360 engine. - 07/31/09 08:14 AM

Quote:

On e-bay I have found rebuild kits from Falcon performance that include pistons and cam. Is it OK ? Or should I go for TWR or KB.
I am not building a race engine, more a street preformer.

With .040 quench you will be able to run pump gas with a CR in the 10's and CR is the most important parameter(imo)in an engines power producing potential. The pistons in those kits will not have enough CH. You want your short block parts selection to be spot on w nothing left on the table that way any future additions(or changes) will only compliment your foundation.

Posted By: 2boltmain

Re: Considerations on pistons in a 360 engine. - 07/31/09 05:03 PM

Stock replacement pistons will all be smogger compression. If on a budget go with the KB107. they are under $200 a set from Scummit.

Posted By: joedust451

Re: Considerations on pistons in a 360 engine. - 07/31/09 06:12 PM

Quote:

Quote:

On e-bay I have found rebuild kits from Falcon performance that include pistons and cam. Is it OK ? Or should I go for TWR or KB.
I am not building a race engine, more a street preformer.

With .040 quench you will be able to run pump gas with a CR in the 10's and CR is the most important parameter(imo)in an engines power producing potential. The pistons in those kits will not have enough CH. You want your short block parts selection to be spot on w nothing left on the table that way any future additions(or changes) will only compliment your foundation.

These would be the pistons i'd get, the KB190s that i ran in mine, it has a .040 quench dome, they are 219.00, they come in standard, .020", .030", .040", .060", .070".

http://www.summitracing.com/parts/UEM-KB190-030/?image=large

Posted By: Noblewk

Re: Considerations on pistons in a 360 engine. - 08/01/09 12:09 AM

Get some Speed Pro ZH116CP's they have the "sexy" DurOshield� coated piston skirt and CNC machined.

Great pistons for the prices, they are not as heavy as forged and will not require you to hone the extra .001 for the growth factor.

Posted By: 76dart

Re: Considerations on pistons in a 360 engine. - 08/02/09 02:33 PM

KB190s

Posted By: Moparbil

Re: Considerations on pistons in a 360 engine. - 08/03/09 07:40 AM

Ok.Thanks for all replies so far

.
I have been recommened TRW speed-pro, KB 107 and KB 190.
Trw speed pro seems a litle low in compression and KB 190 a litle high, they also require machining of heads.
KB 107 seems to me to be the compromise, that can used with both the iron 340 heads and alu aftermarket heads, am I right?

The low wear of my cylinders in mind, I judge from your replies that boring the cylindes is not necessary and use of moly rings are best when doing a home honing.

What cam will the right match? (Again good street preformer, not race)
I have a offenhauser inlet + 650cmf cab and headers.

Posted By: MoparforLife

Re: Considerations on pistons in a 360 engine. - 08/03/09 10:23 AM

IMO - unless you are planning on the engine running 100,000+ miles standard cast rings will more than suffice and save a few bucks at the same time. It was not uncommon for the OEM type rings to run 100,000.

Posted By: Rug_Trucker

Re: Considerations on pistons in a 360 engine. - 08/03/09 12:23 PM

Quote:

The low wear of my cylinders in mind, I judge from your replies that boring the cylindes is not necessary and use of moly rings are best when doing a home honing.

I have a offenhauser inlet + 650cmf cab and headers.

Iron rings are best for home honing. I have a set that have gone 170K+ no oil burning. And one cylinder was pitted due to crunching up a valve and spitting it out the exhaust!

Posted By: Moparbil

Re: Considerations on pistons in a 360 engine. - 08/04/09 12:02 AM

I have checked up a litle on what "quench" is.
There is something which is still not clear to me.

How do you actually meassure the distance from the flat spot of the cyl.head to the piston flat spot with the head gasket compressed.?? (Cyl. head installed)
Is there a factor of a compressed gasket to use.

How will you be able to meassure a tolerance of 0,04, the flat spot in the head is actually not completely flat.

As I understand it, pistons are supplied with a standard quench and according to that milling of cyl.head must take place to obtain the ideal 0.04
Or is it milling of the piston.

Of course I will like to have the highest compression but absolutely without troubles on pump gas.
I would like to avoid any milling.
As I read it, it seems to me that KB 190 needs milling but KB 107 or TRW speed pro do not.

Please correct me if I am all wrong.

Posted By: patrick

Re: Considerations on pistons in a 360 engine. - 08/04/09 12:03 AM

cam: comp XE268

Posted By: hooziewhatsit

Re: Considerations on pistons in a 360 engine. - 08/04/09 04:12 AM

Quote:

I have checked up a litle on what "quench" is.
There is something which is still not clear to me.

It depends on if you're using closed chamber, or open chamber heads. Also most gaskets will say what its' compressed thickness is.

Closed chamber, the head is flat, the piston is flat, stick a 0.040 head gasket between them, boom, you're done. (the valve reliefs allow you to have a sane compression ratio)

Open chamber, put clay on the top of the piston, bolt it together, crank it around, take it apart, measure the clay, machine as necessary, check again (for each cylinder individually)

When I get around to re-doing my 318, I'm throwing away the open chamber heads I have and buying closed ones.

Posted By: joedust451

Re: Considerations on pistons in a 360 engine. - 08/04/09 07:06 AM

[quote

Of course I will like to have the highest compression but absolutely without troubles on pump gas.
I would like to avoid any milling.
As I read it, it seems to me that KB 190 needs milling but KB 107 or TRW speed pro do not.

Please correct me if I am all wrong.

If your talking about milling the pistons, you won't have to, the KB190s require no milling (as long as the block hasn't been decked), they are designed for open chamber heads like the J 915s, you say you would like the highest compression on pump gas, then these are the ones you want IMO, the Quench dome is approx. .040".042" high, you run a .039" gasket, the dome goes right up in the open area of the head, you can run a straight edge right across the gasket & the domes are right there, the outer part of the piston sits around .018" below deck. I've run both (190s & 107s), i will never use the 107s again after useing the 190s, the design of the 190 is to achieve the best quench possible, so you can get above 10.1, & still run on pump premium, the better the quench, the higher compression you can run on the same octane without detination, i ran the 268 cam in 1 360 that had the 107s, the other had the XE284H & 190s, stock J heads, RPM air gap, 750dp, it was night & day, cylinder (cranking pressure) was around 180, timing was at 36* all in at 2200, 456 gears, 2800 stall, never pinged a lick on 89.

I will have to add that this was at 3700ft. Alt, so pump high test was 89, at sea level its 93, in my area (1600 ft.), its dropped to 91.

Posted By: joedust451

Re: Considerations on pistons in a 360 engine. - 08/04/09 07:18 AM

Quote:

IMO - unless you are planning on the engine running 100,000+ miles standard cast rings will more than suffice and save a few bucks at the same time. It was not uncommon for the OEM type rings to run 100,000.

Standard cast rings do seat quick & last awhile, But they generate more drag/wear on the cylinders then a Moly plasma ring, so it robs some HP, i always run moly/plasma rings in my thrasher builds, they will seal up great with the right finish hone, & have less drag then a standard cast.

Posted By: Moparbil

Re: Considerations on pistons in a 360 engine. - 08/04/09 10:59 AM

My 360 block has the stock spec.
So if I use my old 340 heads (casting no 3418915, 2,02 inlet valve) and a .039" gasket, no milling
should be necessary anywhere, right ?
And the quench will be around the ideal ,040 ,
( will of course have to check)

Is the.039 head gasket stardard in kits or do I have to specify.

So the 340 heads + KB 190 + XE284H is the way to go, I understand. Forgetting the alu heads also saves a lot of money.

Posted By: Moparbil

Re: Considerations on pistons in a 360 engine. - 08/04/09 12:53 PM

Ok with the rings

But your recommened cam xe284h seems too extreme to me. I need normal drive ability, not high rpm and rough idle.

Remember the 360 has its stock cast crank.

Other cam suggestions to match the KB190 pistons.

Posted By: joedust451

Re: Considerations on pistons in a 360 engine. - 08/04/09 03:08 PM

Quote:

Ok with the rings

But your recommened cam xe284h seems too extreme to me. I need normal drive ability, not high rpm and rough idle.

Remember the 360 has its stock cast crank.

Other cam suggestions to match the KB190 pistons.

The cam isn't as extreme as you may think, with the extra compression, it was a torque monster, even with the 2800 stall, now this was at 3700ft. in a fully loaded bench seat 73 Swinger, i'm sure i was around 3500 lbs. with me in it, plus the Alt. was killing it but you'de never know it (13.2s on the limiter in every gear), if only i took it down to Dallas & ran it & put a 6700 chip in it (had a 6000), i'm sure there was low 12s in it, not bad for a mild SB.

I'm not sure exactly what your after performance wise, but i loved the way that 360 turned out, i even had the pistons on the tight side for better sealing (1 & 1/2 thousands), top ring was at .024", second ring at .017", never used a drop of oil & absolutly no blow-by period, never ran hot. Cast cranks are stronger then may think, if your not running a Blower or Turbo or a butt load of HP, don't worry about it!

Posted By: joedust451

Re: Considerations on pistons in a 360 engine. - 08/04/09 03:20 PM

Quote:

My 360 block has the stock spec.
So if I use my old 340 heads (casting no 3418915, 2,02 inlet valve) and a .039" gasket, no milling
should be necessary anywhere, right ?
And the quench will be around the ideal ,040 ,
( will of course have to check)

Is the.039 head gasket stardard in kits or do I have to specify.

So the 340 heads + KB 190 + XE284H is the way to go, I understand. Forgetting the alu heads also saves a lot of money.

The .039" is useally the norm in head gaskets, also, if i'm not mistaken (slep'd sence then), the 915s are J 360 heads, so your good to go, i would also CC the heads & make sure they are close to stock.

Posted By: Moparbil

Re: Considerations on pistons in a 360 engine. - 08/04/09 06:46 PM

Your advice sounds convincing, as you have tried it for real. How was your idle ?

But still I am a litle scared by the high compression and particularly the wild cam.

Will the milder cam XE268H, ruin the whole set up.

???

I can�t tell if the 340 heads has been decked, I only remember it has the large valves and the condition was good.
It will of course have some influence, heads are still on the old motor. So difficult to state right now, unless there is a trick.

When you write "CC the heads" ,you mean meassure the combustion chamber volume, right. (Specs 65cc)
Is there any other specification that can state if material has been milled away.

Posted By: Retroboy

Re: Considerations on pistons in a 360 engine. - 01/09/16 07:44 AM

Originally Posted By joedust451

[quote

If your talking about milling the pistons, you won't have to, the KB190s require no milling (as long as the block hasn't been decked), they are designed for open chamber heads like the J 915s, you say you would like the highest compression on pump gas, then these are the ones you want IMO, the Quench dome is approx. .040".042" high, you run a .039" gasket, the dome goes right up in the open area of the head, you can run a straight edge right across the gasket & the domes are right there, the outer part of the piston sits around .018" below deck. I've run both (190s & 107s), i will never use the 107s again after useing the 190s, the design of the 190 is to achieve the best quench possible, so you can get above 10.1, & still run on pump premium, the better the quench, the higher compression you can run on the same octane without detination, i ran the 268 cam in 1 360 that had the 107s, the other had the XE284H & 190s, stock J heads, RPM air gap, 750dp, it was night & day, cylinder (cranking pressure) was around 180, timing was at 36* all in at 2200, 456 gears, 2800 stall, never pinged a lick on 89.

Not hijacking but Joe did you have to machine the valve reliefs with that cam and the KB190 pistons?
Cheers

Posted By: dogdays

Re: Considerations on pistons in a 360 engine. - 01/11/16 09:51 PM

Hijacking? That post is already in grade school, it's so old.

R.