New 440 rebuild - looking for quench

Hi all,

I recently had a 440 engine built for my '71 Satellite, and am not entirely satisfied with the way it turned out. Long story short, I think there is too much clearance above the pistons, and I'm not getting good quench. Here are the build details:

late-70's 440 motorhome block, bored .030 over (4.350)
Cast crank, stock stroke 3.75
Stock "LY" connecting rods
Edelbrock Performer RPM heads 60929, 84 cc chambers
SRP 213455 pistons, 6 cc valve reliefs
Mr. Six-Pack cam & lifters
tti headers, full-length, 2" primaries
six pack induction

The block was decked and trued, and pistons are .010 down in the hole
Head gaskets are Victor Reinz, which my builder says are .050 thick (presumably, this is compressed thickness).
This means I have .060 clearance from top of piston to head surface.
Combustion chambers have 84 cc, and piston valve reliefs are 6 cc. This calculates to a c/r of 9.73:1.

My understanding is that I should have about .040 clearance between piston and head for good quench/squish.
If I switch to a head gasket that's .030 compressed thickness, this would give me good quench, and raise my c/r to 10.17
I live in California and the highest octane gas available here is 91.
My question is: does anyone see a problem with changing to a thinner head gasket? That is, no danger of pistons hitting the head? Any other concerns?

I'd appreciate any opinions or suggestions, thanks.

Roger

Trade ya ?!?!? I have .035 and I'd rather have .060 !! Sure .045 or.050 would be nice BUT I'd leave it alone at .060.

.040" quench is ideal & reportedly it goes away fast above .045". I cant say if the ping reduction bennie of quench would negate the ping increase from the additional SCR (not my area) but I'd be doubtful of pump 91 but a person could always proportion in some race gas as needed. Any other potentials for why it ain't performing? (not enough advance/wrong cam/carb tuning needed). Sumpin ain't right tho.

What’s the soecs on the cam - lift, duration at .050”, etc. ?

It's actually performing pretty well, but not as well as I think it should be. I did a lot of research and planning before this build started. I designed it to have .040 quench, and my builder was not comfortable putting the pistons that close to the head. Unfortunately, I didn't find out the thickness of the head gaskets until after everything was together.

Unfortunately, I don't know. Mr. Six-Pack does not divulge his cam specs, but I told him this was a street car, and I didn't want anything too radical. All I know for sure is the LSA is 114, and the intake is much less than .236, sorry.

Some thing you need to know about piston to head clearances are that the piston to cylinder wall clearances can add to the deck height of the piston when it rocks over after firing and reaching TDC My message is the center of the piston may be .010 down from the deck but what are the outer edge doing when it is running
I've seen from .003 to .012 height differences due to the piston to wall clearances on the outer edge of the pistons
.042 has worked well for me, .035 piston to head clearances was hitting on both sides of the pistons in my old pump gas six pack stroker motor .042 didn't
that motor ended up with 10.78 to 1 compression and had no issues on Oregon 91 octane pump swill with 10% ethanol in it
My cam was much bigger than yours though, 260 degrees at .050 intake side with 266 @ .050 on the exhaust with 108 LSA installed at 106 intake lobe centers

i think there's a lot of misunderstanding about quench distance. .040" is considered the minimum. anything beyond .060" is considered to begin to diminish the positive effects of quench. I don't consider your quench distance a major drawback; especially if you take in the effect of eventual carbon build-up. john erb of united engine & machine has a good write up about this. don't believe all the internet jockeys.

your quench is fine. why do you think the engine is under performing.

couple of things to look at...
1. ignition timing, where is it set?
2. headers too large
3. air fuel ratio? have you had this checked?
4. what springs in the secondaries?
5. what advance springs in the distributor

I have never heard anybody at the dragstrip worry about quench. Jerry above here has some great points.

This!

provide the answers to these questions, and start doing some tuning. If you have the timing set at the factory specs, the motor won't run at it's potential.

Never heard the OP mention a dragstrip. In fact, when replying to the cam specs he said street car.

fuel delivery has always been the biggest performance related issue on a street/pump gas 440 six-pak for me. springs in the secondaries were next in line. get that solved and then go after the timing. closing the intake valve too soon can create a headache.

Thanks for the input so far, everyone, but I think this post is getting off track. There are several benefits to proper quench/squish other than simply making more horsepower. Obviously, not everyone agrees with these benefits, or on the amount of piston-to-head clearance that's required to attain them. I'm not trying to be a wise guy, but it wasn't my intent to debate this or to defend my position on quench. I do have some timing issues in my engine, and I am working on addressing those separately. My objective in this post was to get opinions on whether or not .040 clearance from piston to head is too close in my application. I respectfully ask that we try to stay on that subject.

.040 might be too close, we don't know how much your piston to bore clearance is and how much your piston rocks in the bore. also if your burning some oil eventually you will have carbon buildup on top of the piston and you'll have even less clearance. I wouldn't go less than .040 on the quench, in fact I would just keep what you have. are you having detonation problems now?

I was getting some detonation at higher rpm's, when the secondaries come in. I am using a distributor I got from Rick Ehrenberg on eBay. However, it's giving me more total mechanical advance than I want. We had to retard initial timing to 10 degrees, and fatten up the jetting, to stop the pinging. Unfortunately, now it doesn't run as well in the lower ranges. Tomorrow, I am taking the distributor to a local guy to put on his machine, and measure exactly how much mechanical advance it's giving, and at what rpm's (I want to see how closely it matches Ehrenberg's published specs). Depending on what I learn, I'm thinking maybe I can use an FBO distributor limiter plate to restrict the total, which would allow me to bump the initial timing back up.

As far as piston rocking, my bore size is .030 over (4.350) and my pistons are also .030 oversize (SRP 213455), on stock "LY" rods. I didn't ask my builder if he measured this, but I'll check with him.

I bought 2 of those limiter plates last week. they are waaaaayyy off! I'm betting your distributor has a 13 degree plate and that with 10 degrees initial is 36 total and no pinging. if you want more initial timing change the plate, or weld it up to get the degrees you want. pinging isn't always timing or cylinder pressure. any contaminates in the chamber will cause pinging. I went thru the .040" quench thing the first time I did this 20 something yrs ago. I was real anal about it! a few engines later with .050"-.055" quench and no difference. just try to avoid .060"+. change whatever you want but I doubt the head gasket thing is worth the time or money.

Well,that's disappointing. Actually, you're the first person I've read about who's had bad luck with it.

According to Ehrenberg, my distributor should give about 26 degrees total, all in by 2500 rpm. I'll talk to the distributor guy tomorrow about restricting it to something closer to 18 total - or maybe I'll try to get a 9 degree plate. That way, i could set initial to 14-18, and still stay under 34-36 total.

I don't know that I'm going to go to the trouble of switching out my head gaskets. It depends on what I can achieve by playing with the timing.

I would suggest: (1) setting the initial with "the vac gauge method" (2) get 34-36 total (initial+slots) useing the right slot pair on the FBO plates (I was not aware there is a prob with em). (3) mix/match spring combo so you are just under the pinging point at WOT up thru the gears on your hottest/driest(most likely to ping) day then (4) plug in the can (if used) & adj it with a 3/32 allen so you are just under the ping point under varying RPM/load conditions in everyday driving on your hottest/driest day & there are differenct cans available that the curve starts at different in hg levels (do your homework there) & you can shorten the total as needed (strips of epoxied feeler gauge) & increase it slightly (file notch wider) as needed. Peoples' hearing varies & there is silent ping so give it a slight cushion & you want to be "reasonably" close to that "pinging" line but never over it. & check that it will crank over when hot & if balky use an ign cutout to get it cranking then switch on the ign or retard the initial (1) deg & retry. Those guys who mod dists can get em in the ballpark or even close but every eng is different & dead on needs alot of adjusting/tweaking.

My opinion: 0.040" will work fine with your motor from a clearance stand point. I would definitely prefer that over 0.060". It may, or may not have detonation problem, but I believe that I could work through that based on the fact that you seem close now. Knowing the cam ICL could have a bearing on the detonation outcome along with several other items. All that said, now that its all together, I don't know if I would go chasing after this.

What seems odd to me is that you wanted a motor with 0.040" quench but you got one with 0.060". How did that happen? FWIW, whether its the motor build, or the distributor, the more ownership you take in it, the better the results will be.

the FBO plates I have are totally screwed up. near as I can figure the slots are set up for .010" movement equaling a degree. this wrong. .0154" is a degree. .010" is close for the vacuum advance degrees. I measured and checked every way from sunday and they're just plain wrong. I did do some measuring and found a way to use some of the slots , but the plate shifts position at full advance that screws up the desired total. first time I got anything with FBO on it that was wrong. waste of $50.

It's a very long story, partly my builder's fault, and partly mine. As I said earlier, he was not comfortable with the pistons being that close to the head. In fact,in our initial planning discussions, he didn't really seem to be a big fan of quench - that probably should have been my signal to find someone else. I tried to be very involved, but the build dragged on forever - nearly 3 years!! Near the end of it all, he assembled the engine without letting me know when he was going to do this, and I didn't find out the head gaskets were .050 thick until the engine was back in the car, I was working on dialing it in, and having detonation issues. This was the very first engine I've ever built from scratch and I definitely learned a lot of things that I would do differently if I ever do it again (which - knock on wood - I don't plan to - HA!).

Thanks for elaborating. I am surprised that their limiter plate has a large center hole, which seems like could allow it to flop around a bit.

I have seen this chart posted in several threads - don't know how accurate it is:

Modifying advance slots
Dist degrees / slot size
6.............. .340
7.............. .355
8.............. .375
9.............. .390
10............ .405
11.5 ......... .420
12............. .435
13............. .445
14............. .460
15............. .475
16............. .490
17............. .505
18............. .520

Have you done a cranking compression test?

If the cam has fairly short seat timing, the cranking compression might be fairly high, and/or the dynamic compression might be close to the trouble zone.

There are other items that can contribute to the pinging....... stall(if an auto), rear gearing, engine operating temp, etc.

If the cranking/dynamic compression numbers are high enough where it’s a concern, I’d probably look at slowing the mechanical advance curve down, and employ a small amount of vacuum advance to get the timing up where it should be during part throttle cruise.

I've only checked one cylinder so far. I was surpised to see it was 180, then I read that a cam can cause higher cylinder pressures so I'm assuming that's what it is.

My car is an automatic, 2300-2500 stall, with 3.23 rear gears. I'm also running vacuum advance. I know those are all factors. But the only detonation we've seen has come at high rpm, when the secondaries open - and I'm pretty convinced that it is due to too much total mechanical advance.

maybe the fuel mix is lean when the secondaries open. i would expect detonation to be a problem with the motor warm and under a low rpm load.

So, how low does the total timing have to be to keep it out of detonation?

For California 91 swill, I’d have built it with .040-.045 quench, about 9.75cr, and a cam that would put the dynamic Cr solidly under 8.0.

Which I’m sure would have broadened the tuning window with regards to the timing curve.

Edit...... plugging some numbers into the uem calculator....... it takes a cam a little longer than one might expect to get the numbers to work out.
For example, a 220@.050 cam intalled at 110, with 9.75cr has the DCR at 8.3.
Bumping the CR to 10.17 puts the DCR at over 8.6.

I haven’t tried pushing the envelope on that type of build....... when I hear “pump gas”...... I err on the conservative side.

You mention detonation at higher engine speed - does it rattle when the carbs open then subside or does it continue to rattle until you tip out of the throttle ?

I can tell you what I run. My quench came out around .046 on my 440/493 with a solid flat tappet cam and Indy EZ heads. My comp ratio is 10.6 and my cam is a custom grind from Dwayne Porter (Fast68Plymouth) that is .585 & .592 lift with 264 & 270 @ .050 on a 110 LSA. I run 36 total advance all in by 2000 rpm. I have no ping at all and have never had any ping. I have no vacuum advance as my dist is a Mallory race unit and has no vacuum advance. I use the Felpro .039 head gaskets. I understand where you are coming from since good quench helps fight ping (detonation) as when I built my eng that was one factor I wanted to be around .045 give or take a few thousandths because I run on 92 pump and did not want any detonation problems so I made sure I had decent quench. I would have thought your eng builder would have wanted to build decent quench into your eng. .060 is not the worst but I shot for .045 as that's a good quench to me and not to close to the piston to get worried with a steel rod eng. A good build in todays world is a zero deck flattop piston eng with .040 head gaskets and a closed chamber head. If you have .050 gaskets then going to the Felpro .039 would get you around .049 quench down .011 from .060. But the only .050 head gasket I know of would be a custom made Comedic head gasket. Ron

I had no idea the FBO plates had an issue. Thanks for the heads up! I will see about reducing the center hole & seeing how much adv the slots do give.

I was one of the ones pushing for tighter squish..I prefer to call it squish because I believe that's the mechanism that benefits everything.
So when I took apart my Mom's '86 318 I was disappointed to see the pistons down in the hole something like 0.055". I used the Mr. Gasket thin gaskets which are 0.028" compressed. Do the math, the distance seems to be huge. But the results speak for themselves. The engine comes in right at 9:1 and using a stock 360 cam I am running it on 85 octane in the mountains which switches to 87 down in the flats. In other words, pump regular. Running 35 degrees total with a high perf advance curve I NEVER have detonation. Even running it down into Phoenix while still jetted for 6,000 ft in the 110 degree summer. And mileage jumped from 16 to 22!
This is the long way around the barn to say I don't think your 0.060" squish is hurting things. I have a feeling you had an idea of what your new engine would feel like and it doesn't come up to your expectations.

We have no dyno numbers or ETs or quarter mile speeds with which to judge what the engine is actually putting out. Before you jump into the deep end, maybe we should hear about the numbers it can generate.
Lord Kelvin said approximately that if you can't or don't measure it, you don't know anything about it. This may sound a little hard core but you may hear the same thing on this board, when people say until you show up with ETs don't bother.

R.

Yes, we had to bump the outboard jets all the way up to 85 (they previously were 79 & 80). I'm hoping to reduce them back down at least some when I limit the total advance.

The initial timing is currently at 10 degrees. With approximately 26 degrees total mechanical, that puts me at around 36 total.

And my original intention was to have .040 quench, and a c/r around 10.1:1

I'm not familiar with dynamic compression ratio - I'll have to study up on it. Unfortunately, I don't know the exact cam specs (Mr. Six-pack doesn't publish them).

It would rattle badly until you let off the throttle. Note, at 10 degrees initial, it is no longer detonating.

What brand and heat range, part number on the plug, plugs are you using?

i'm going to guess that you were upping the initial timing beyond the 10 degrees and were probably doing close to, or more, than 40 at WOT. those distributors have a staged centrifugal advance curve. I use the staged thing in both my cars but it's a little tricky, especially with a vacuum advance. that cam you have has a short duration intake lobe and i'm surprised the cranking compression isn't noticeably more than 180psi. could have a wide LSA. if you do a 9 degree plate it won't be simple to keep the staged centrifugal curve and vacuum advance without a short heavy spring. you'll probably have to do a full centrifugal advance without the vacuum can simply because the proper springs aren't available anymore. something I found out when I was doing the 6pak thing is that the "feel good" advance curve actually slowed my car down at the track about 2 tenths due to extra wheel spin. my last outing, some years back, was cut short simply because I forgot I had the "feel good" distributor in the engine.
I also was plagued with oil and water contamination in the chambers that limited total advance to 34 degrees. since then I've found that 37 degrees total, with clean chambers, seemed to work quit well.

finding an industrial engine pick-up plate makes setting up a full centrifugal distributor easier.

If you used the same cam you have now, the cranking pressure and DCR would be higher than what you have now....... would probably ping even more.

There’s nothing magic about 10:1 and .040 quench running on pump gas........you also have to pay attention to the DCR.
If the DCR is too high...... it’ll ping.

My experience with the metering plates that utilize replaceable jets is....... the required jet size to maintain the same a/f ratio as the OE metering plate you’re replacing is....... it will require a step up of several jet sizes.

Easily confirmed with a wide band o2 sensor and gauge in the car.

Dog-gone-it I like the way you think.

The dyno showed:
Horsepower 448 at 5,000 rpm
Torque 507 lb ft at 4,000 rpm

Timing was set to 35 degrees total. But that was also with an old, points-type distributor - not the distributor that's currently in it.

What was the a/f ratio on the dyno?
Did the carbs have the same jet plates in them?

Unfortunately, no a/f numbers - that function wasn't working that day (a catastrophic failure on a previous test had taken them out).

No on the jets, the carbs have been completely rebuilt and re-jetted since then. The test was run with a ProMax metering plate on the center carb. Since then, I've replaced it with a stock metering block so I can run vacuum advance.

I had a very similar build...same pistons ,heads and six pack. I used a Cometic .027 gasket and milled the heads .020. Has good quench and about 10.4 compression.... I can really put some timing into it. Made 522HP on the dyno. using a Mopar .528 mechanical cam

in my opinion realistic numbers. add a better cam and a couple of degrees timing and it's 475-480hp fairly easy. I don't think upping the jetting on a 6pak is a real advantage. .093" in the metering plates, #65 in the center, .052" for both PVCR and call it a day.

I was having a conversation with one of my customers who works on a lot of these cars in his area.
He was tuning a 440-6 in a Challenger that he had just put the motor together for, and got it running.
He uses a wide band gauge in the car to get them dialed in.
The carbs he was using had the OE calibration, the motor had iron heads set up for proper quench, and a cam that would put the DCR right about 8.0. This car runs ex manifolds.
With the OE jetting(OE metering plates), the motor was in the high-10’s/low-11’s a/f ratio at WOT.
He installed some Pro Max secondary metering plates with jets equivalent to the holes in the factory plates.
WOT a/f ratio was now in the hi-14’s/low-15’s.
It required going up about 5-6 sizes to get the a/f ratio into the mid/hi-12’s at WOT.

We have encountered the same thing on the dyno here when the OE secondary metering plates get swapped for the replaceable jet type.

One of the 440-6’s I had on the dyno, which had small headers, a Comp 280 cam, 346 heads...... ended up with 65 jets in the center carb(mid-13’s a/f ratio at part throttle cruise), and 86/86 jets in the end carbs(hi-12’s/lo-13’s a/f ratio at WOT).
This was a motor that was only making 500tq@3900/424hp@5200.

With regards to the feeling that the motor isn’t as impressive feeling as maybe the OP had hoped.......
Imo, 450hp, 3.23’s, low-ish stall speed, vs carbs, full weight car....... that’s a combo I wouldn’t expect to “feel” all that impressive.

The first 440-6 I had anything to do with made about the same HP, but less TQ by a fair amount than the OP’s build.
It went in a 70 Challenger RT/SE, 3.91’s, tight TA 10”(about 3400), small tube headers.
Owner brings the car down to the shop after getting it installed so I could take it for a little test drive.
First 6bbl I’ve ever driven........ and it’s the first “hot rod” type motor the owner has ever had.
He thinks it’s an animal......... I think it’s more like “eh”.
I told him it should go 12’s based on the dyno numbers, but it didn’t really “feel” fast to me at all.
They had some old slicks mounted on rims, brought the car to the track..... put the slicks on...... went 12.30’s@113.
Way quicker than it felt.

how do you calibrate a "butt dyno"?

You just keep adding power til it feels “right”

When I first put the 383 in my car....... and having not even run the car at all for 6 years...... I figured it would feel pretty decent(knowing that it’s really hard to go backwards, and the car ran 10.70’s on it’s last outing)....... and fully expected it to run solidly in the 11’s.

First pass on the 383........ maybe 1/2 way down the track I’m thinking to myself, “what the he11 is wrong with this thing? It’s a hound!!!”...... and expected to be handed a 12.80-ish....... or maybe even slower time slip.
It ran 11.82.
Next pass..... 11.62.

Butt dyno was waaaay off.

I just had to be satisfied knowing it was running like it should........ it never did feel fast.

guy up the street from me has a big inch Oldsmobile. at the time it was a low 11 second car. he took me a ride and hammered it. my butt didn't fell anything but I thought if I did this a lot my neck would need a chiropractor. if your used to slow cars it ain't hard to be impressed. if your used to fast cars then something just has to reach out and grab you. I went to the NMCA finals in indy last fall. mopar put on a gen 3 hemi shoot out with a 10.00 index. I watched a bunch of challengers run 9.90's and these cars were drove in. makes me fell like some old guy working on flathead fords. for old muscle cars the game is over.

That's the exact message Mopar is sending:
"Sell all that old garbage...we don't sell hardly any parts for them anyway, and go drop 60 grand on our
latest awesome new plastic computerized thing."

It's really not over, it's just put into perspective and now there are more choices (as long as you have a giant pile of money to spend or are willing to go into debt).
The only limit being interest of people, and available funds of whoever works on this stuff in the future.

Does a person want a fun and relatively quick old hobby vehicle with character, authentic old musclecar vibe including a few of the primitive aspects,
or does a person want a touch screen, air conditioned, much more comfortable computerized thing that looks and feels like every other
modern vehicle and admittedly runs faster in many cases?

The old Buick GS Stage 1 didn't become obsolete when Grand Nationals started showing what they can do...."9 second driven to the track" is quite common with those....
The old GS was already obsolete well before that, and the cars still have a pretty strong following. There must be a reason why.

The car hobby is wrapped up with emotions...It's not just about the ET, it's about how you got there and how the thing makes you feel.

I drove the GTX to the strip recently, raced/tested and drove back home... and the number of people who just came up to talk, was pretty amazing.
My youngest boy asked "Where do you know all these people from?". I had to explain that's just normal, but moreso when you've got something
that isn't quite a cookie cutter...

I love the modern vehicles! I drive a 5.7 hemi equipped vehicle every day, and was involved with early Drag Pak sales and development.
But Heritage still counts for something. Even though Fiat has chosen to only trot it out when they can make a profit from it (can't blame them)
it runs a little bit deeper than they know.

I guess it's all a matter of perspective. i'll be 71 in a couple of months. lived the '60's muscle car/drag racing thing. like about anything old, except grouchy old women. my friend with the olds had another engine built over the winter. 540 cubes, 670hp/670tq (bunch of $$$$ of an old guy like me). wants to run mid tens and beat up on the mustangs. I imagine those challengers I saw would run mid tens with the air on. I still ride my old dinosaurs and still get all the looks and conversations, but it's mostly people who lived the era. only thing certain is change.

It truly is a matter of perspective, I have to agree.

Myself I will always love old school the best. But that's just me. One thing about the new cars that are very fast is they all have power adders which makes a huge difference. Super and turbocharging will just about double an engines power. And not everyone can afford to spend 60k on a car. I know for 60k I can build an old car to be a lot faster then the new ones. Heck I think I have a total of about 12k in my 63 but I do all my own work also. And I agree with you Rich that its not all about et but much of it is to some people. Myself I try to look at any car for how it runs for what the combo is. You know a mild N/A 383 Roadrunner that runs 12's with 3.55 gears can impress you sometimes more then a 572 eng in a car running 10's or a turbocharged car running 10's. To me its all about getting your combo to run good for what it is. It is awesome that they are building such fast cars and that in todays world they can warranty a supercharged or turbocharged car since they make them to work so well today. Ron

Did you try disconnecting the vac can on the distributor before you rolled the timing back ?

What is the distributor you are currently running?

Me ?, I'd change the head gaskets as I believe that quench/squish works based on my limited experience... but you first need to figure out what's going on and right now it's pointing to the distributor setup.

Love this thread. I have a similar engine I built for a car I sold 4 yrs ago. Zero deck, Edlebrock heads, KB hyper pistons, etc.
Re the DCR - I found this to be very interesting: http://victorylibrary.com/mopar/cam-tech-c.htm

Not trying to be a butthead, but there is absolutely ZERO reason to use a Mr Six Pack cam in ANYTHING unless you are trying to pass Pure Stock tear down tech…the clown won’t even give specs for it and there are literally TONS of better cams out there…I don’t understand why anyone would buy one?? 🙄🤦‍♂️ He’s NOT a camshaft guru…he’s just taken ONE combination and tried a few different grinds that all have the same lift and found one that works good for that combo…by running his magic cam 😂 all anyone is doing is limiting how good their motor will run…🤦‍♂️