Tighten up a street driven HEMI (long?)

The questions in this post are aimed at the engine builders on here that KNOW the answers!
I developed the desire for a 426 HEMI when I was 10 or 11. Richard Petty was having one of the best seasons in history in a square body, 426 HEMI stock car. I decided then to own one of these cars.
Finally in the spring of 2012, I was driving a square body convertible with a 426 HEMI. Everything about the car was designed to be DRIVEN. First it was a convertible, next was power steering and brakes. I also mounted a Gear Vendor overdrive ahead of the Dana with 3.54 gears. The 727 shifts AUTOMATICALLY with the help of A&A components and a Turbo Action valve body. The converter is as tight as PTC could make an 11", 250K+.
I've enjoyed driving it over 7,200 miles now, It is just what I wanted with just one problem, it uses WAY too much oil. I have won all the "Best of Show" trophies I want, won at Pigeon Forge 8 times in a row, now I want to DRIVE the car, a lot!
I have an extensive collection of original car magazines with many HEMI cars tested new. I know that a lot of them complained that they had to add a quart of oil for every tank of gas, but I am not satisfied with that. I have decided to pull the engine apart over the winter and "tighten it up".
I have chased the oil consumption through intake gaskets, Superformance cured that, leak down, compression checks, catch valve in line to the PVC, all to no avail. I suspect valve guides/seals, but conversations with the BEST HEMI engine builders (you know who I'm talking about), have convinced me that it is a combination of cylinder sealing and guides/seals.
So, who makes the best piston that has the lowest expansion rate? How tight can I run them? I currently have "Diamond" with 4.35" bore. If I need to, I am prepared to bore the block and buy new pistons. What ring size is readily available after 4.350? Richard Nedbal's book suggests a Napier second ring with a "gapless" top ring. I have a GOOD shop that will get the bore straight and put the proper finish on the cylinder walls. What brand ring do you guys suggest? What wall finish? What ring gap? What type of rings?
Next, the heads. I might as well step up to a new, better head. I am currently running MP but am looking at the Edelbrock or Stage V. How tight can I run the valve to guide? What type of seals?
I have lost track of the engines that I have built over the years. The last one was a Gen I HEMI with a 6-71 blower for a 32' roadster that has never had a valve cover off since I put it together in 2009! I want my HEMI to be like the LS-7 that I built and installed in a 70' Chevelle with air, PS, PB, tilt etc. in 1995. I drove that car ANYWHERE I wanted and NEVER had to add oil! It is still running strong and dependable.
Any and all info would be appreciated. What I want is real, tested solutions by real engine builders.
Thanks

Funny posting.

Could of summed it up just saying, "Hey I need to build my hemi to use less oil".

From your posting it sounds like you might be a under qualified hemi owner but a over qualified chevy guy.

I am no expert but I run low tension napier second, low tension oil and top rings, the fresh short block (410 SB) would turn over like an old worn out 273 with glazed over walls that burns a ton of oil but this thing never uses oil. This is basically the ring recipe that GM used on the LS motors to fix the oil consumption issues they had. I am running diamond pistons, dont remember the number but we set them to the tightest diamond recomended.

I would also run the bearings all on the tight end of acceptible with a high quality shop doing the work to make sure they are in all the specs like taper, roundness, diameter... everything, not just a quick check of diameter in one place. This will lower oil volume through the engine and a good oil pan and windage tray set up. Then you can run a standard volume pump and keep everything lubed while reducing excess oil on the cylinder walls.

No reason a hemi has to use a bunch of oil.

Just use modern parts and your engine will work like a modern one. I have a Toyota 4Runner with 200,000 miles on it and it barely uses any oil.

EFI is one of the best things you can do for engine life since it keeps the cylinder walls from being washed down. Do you have a wide band on your Hemi? If not you should install one and see what is going on. More likely than not you're running 11:1 AFR while cruising down the road and washing the cylinder walls.

Hone with a torque plate, use metric rings, use o-rings or modern gaskets everywhere, etc. It can be done, just takes a careful machine shop. Lots of Hemi guys build drag race engines and they don't really care about oil consumption so you have to find someone who is more familiar with modern stuff and the newest parts that are available.

If you have to go in and tell your builder how to build the engine, you need a different builder. I don't know a single engine builder (myself included) who will let the customer come in and tell them what rings to run, how to finish the bores, what guide clearance to use and all that.

The engine doesn't know it's a Hemi. It has no idea what it is. If your rings don't deal, it's not because it's a Hemi. If the guides are loose it's not because it's a Hemi.

A Hemi is no different that any other internal combustion engine.

One big reason, the exhaust valve is usually submerged in oil. Get the best valve seals and go over the drain backs in the corners of the head, there's a lot of oil leaks in the rocker assembly up there. At speed I wouldn't be afraid to say 50% or more of the oil capacity is up in the heads. Get a piece of welding wire 1/16 , bend and attach so the end sticks down a little in the center of the hole, this helps promote flow since oil can't swirl in. Can't remember who told me that but it was way back before the turn of the century.

Beware of one major Hemi-problem, that the rockers sometimes do not line up well and try to push the valvestems away. (Too short, and wrong geometry) This, along with coarse finish on the valvestems can eat the guides after a short while. And the MP alu heads have valvestem clearances same as iron heads, way more than needed on alu heads. When building a Hemi you need special attention to the heads, or you will get an oilburner....

Thanks for the replies. I didn't mention bearings, what is the tightest clearance that you run? I use Brad Penn 10-30 and have 80lb. cold and 25lb at 850 rpm idle. When hot, I have 60-65lb at 5,000 rpm.

What guide clearance, bearing clearance and tightest piston to wall clearance do you use for a 6,000 rpm street engine?

So could the problem be isolated to the heads? Leak down, compression tests all look good. No blow by that I can see. The glass catch can between the PVC and intake never collected oil?

Yes it could quite easily be a guide/seal problem. My last two Hemi's had Stage V heads prepped by Tim Banning and after running Hemi's since 1980 I was very impressed these two didn't use any oil. They both ran CP pistons speced by Tim as well. I can't remember the clearances though.

All the good hemi engine builders and hemi machine shops I dealt with when I ran 426 Hemi motors in NHRA stock class set the intake valve stem to guide clearances at .0000 to maybe .0002 cold on the stock iron heads, around .0015 to .0019 on the exhaust side cold
On the Stage V aluminum heads I would use similar clearances for a street motor, make sure the motor has some heat in it, warmed up to at least 100F + before revving it above 3500 RPM
I would do a quick check of the clearances by moving the valves up and down in the guides with no springs, keeper or retainers on them first, if they slid up and down easily and no rocking side to side or forward to backwards clean I would use them and oil them up and install the seals and go racing
No oil consumption in any of those motors
We where using stock type TRW or Speed pro 5/64 file to fit rings back then also

So Cab, do you think that the guides could pass a quart of oil in one tank of gas? 200-250 miles?
Do you suggest I just pull the heads in the car and replace them and see what happens?

My Street Hemi had an oil consumption issue when fresh even though it had been rebuilt by a reputable Hemi SS racer. Turned out to be 2 problems: it was way rich, washing down the bores (you could literally smell gas on the dipstick), and oil was getting past the guides. Correcting the carbs fixed the 1st issue. Installing oil seals on the guides that were high-heat silicone (got them from Silver Seal) cured the 2nd. After that the car ran cleanly even with a fairly big cam, and quit drinking oil.
I agree on the geometry thing; you can see how the springs that kind-of locate the rockers allow side movement; Landy came up with a collar arrangement back in the day that fixed that.

Yes: I always run the collars too.

I might as well step up to a new, better head. I am currently running MP but am looking at the Edelbrock or Stage V. How tight can I run the valve to guide? What type of seals?


If the MP heads have the original guides, I would start looking there. They were over-sized and soft from the factory. I had a new Hemi build, with new alum. MP heads that was smoking. It was the guides!
I sent the heads to Modern Cylinder heads, and the problem was solved.



Mark

Thanks for the info guys, This is what I needed!

It don't matter what head you use, just need good guides and seals

Hemi Ragtop...it sounds like you have a ring seal issue to me.

My 572" hemi is more of a race build that's streetable, but it doesn't use oil. I've never had to add any to it. Been running it since 2006. I don't drive it as much as I used to. Having kids put a damper on that, lol, but it used to see a lot of street time. Not to mention track time.

The first 2 freshen ups, the valve guides and valve stems were worn. First freshen up in fall 2008 I just put in new valves, tightened it up so I ran it for 4 more years like that.
This last time I had bronze liners installed along w/ new valves...that was over the winter of 2012/2013.
I still use the factory style springs to locate the rockers...may contribute to the guide wear problem?
I have MP aluminum heads from the 2005 production range.
I use the teflon valve seals on the intakes and NO SEALS ON THE EXHAUSTS.

My main clearances are .0035" and rods are at .0023-.0024 w/ coated bearings.
Piston to wall is .0075".

I'll be freshening it up here soon. Hoping to get it on the stand and apart in the next month or so.

I forgot to mention that those clearances are for the stock type 5/16 stem valves

Forgot to mention, but I'm pretty sure mine were set up w/ .0015" intake and close to .002" exhaust stem clearances w/ the std. 5/16" valves.

Thanks Chip, This is what I am looking for, clearances and advice on parts as well as real world experience.

Before the thread dies, Please share with me what piston rings/piston brands and types are the best for sealing up the bore. For instance, what is the tightest piston to bore and what piston do you use? Also, what ring size is available?
Thanks

The piston alloy(4032 for street motors, not 2618 ) will determine what clearances are needed, any GOOD brand of forged pistons and a good set, not a cheap rebuilder set of 1/16,1/16 3/16 (standard tension oil rings) size file to fit moly rings should work real well, I shoot for .0045 per inch of bore size(.0045 X 4.310= .01935 end gap, round it up to .020) tight and .0050 per inch on the second ring and go have some tire smoking fun , not oil smoking fun
I do have the machine shop hone all my blocks with a torque plate and the type of head gasket the motor will run and add .0005 additional piston to wall clearances for all my street and strip or bracket race only motors

Thanks Cab, I notice you don't run "gapless" rings. The 4032 alloy is JE is it not? I don't remember other manufacturers mentioning it.

Some of the after market company don't offer that tight clearance 4032 alloy Ross being one of them
JE,SRP and Diamond as well as probably several other do offer any of their custom piston in either alloy
JE doesn't own that alloy, the foundries make the piston blanks and the piston makers finish them

My pistons are Diamonds using the typical 1/16", 1/16", 3/16" ring pack. Have been using Total Seal plasma moly rings, not gapless.
I'll be switching to whatever ring Diamond recommends me to run for nitrous.

I like tighter piston clearance for noise reduction but once the negine is warmed the higher expansion alloys are supposed to be just as tight as the low expansion ones. Unless you have a really loose piston to wall clearance I dont think it would make it use a bunch of oil unless you had an insuficent ring and bore finish combo.

I plan on doing whatever it takes to make the bores straight and true. If it has to be bored to do this, what is the next available ring/piston size above 4.350?

4.360 That is .040 above the stock 440 4.320 bore size
Make sure that you get the ring size correct for your application and that those rings are in stock

What block are you using? If that is a stock Hemi block then 4.35 is already too big and could be part of your problem.

This is a timely post for me. I have been running my 528 Hemi on the street for about 7 years now, and after finally solving recurring intake gasket sealing issues by going to Superformance gaskets, oil consumption went down, but it still is excessive. I am getting ready to pull the Hemi out to put it in my wifes 'Cuda, and I think I will pull the heads and have them freshned up with emphasis on the guides/seals as I believe this is where the problem lies. I like to see these subjects come up in the race section as most of the Hemi guru's here have a lot of knowledge and talent that really helps those of us who don't know all of the idiosyncrasies and tricks that make a hemi great. When I bought Rich Nedbals book on Hemi's, there was a lot of info missing and I called him. Rich told me that the publishers edited tons of really good info out for cost reasons. Thank God we can come on here and get great advice from guys with the "Been there' Done that" T shirt. Thanks to all!

It is a siamease bore Mega block