Hi again all,

One often overlooked process (by me at least, until now) is measuring the deck for quench/squish. Once I get my short block re-assembled, I want to check it. The issue is that deck bridges are expensive - I'm consistently pricing them at ~$100 or more, and for something I likely won't use again for years, it just drives me bananas that a dial gauge connected to a piece of upside down 'u' shaped aluminum is so expensive. All the youtube videos I've watched use these overpriced gadgets, and I'm wondering if anyone else has a solution that works as well and is accurate, even if home-made.

I was thinking a straight edge and feeler gauges could do the trick. I know it's low tech, but so is an overpriced piece of painted aluminum with a dial gauge attached. Spending hard earned moolah on an expensive tool that is versatile (even if only occasionally used), I get.

Conversely....spending $100 or more on an extremely simple and specialized tool that gets thrown into the tool bin after a single use until (if ever) needed again in some distant future - I have an issue with that.

I've checked the forum before posting and didn't see anything relevant regarding a more reasonably priced tool to do the job, but if this has already been discussed in another thread, just let me know, and as usual, thanks everyone for your guidance!

 

Quench is a bit harder to check. Your deck bridge can easily be checked low-tech style with a straight edge and feelers. Usually this isn't as accurate as dial indicators, but will certainly work for determining piston height at max stroke. Rock your piston down on the thrust side, and measure. Rock it up on the thrust side and average the two readings. Now measure depth right at the pin. Average these and you will find your piston to deck clearance. Now, when looking for quench, we need to know your actual measured compressed gasket thickness and gasket bore size. The gasket should fit your combustion chamber, not the bore, and no smaller than the bore. Quench will include the space outside your bore line. Quench includes final combustion chamber volume, using the final chamber valves, springs, and plug, measured from where the chamber tapers to gasket/head deck. I would focus on an accurate static compression ratio by measuring the chamber, gasket, and piston depth/volume (or protrusion). You will gain a lot more knowing these, than studying numbers that aren't easily changed, like chamber re-designs and such. Don't ever take "published" data as gospel. Measure everything!

Brandon Unklesbay
All-In Performance

 

Straight edge and feelers over the center of the piston. If you are over the pin that is as good as it needs to be. Use a degree wheel if you have it. Don't over think it.

 

You might spurge and buy a digital caliper. It can be used for this job and a thousand others.

 

Use a dial gauge on a magnetic base. You're going to need that later in the build anyway.

 

harbor freight has a vise grip type mount base with indicator for 35 bucks. .and amazon has 20 buck magnetic base. they work for flywheel and brake rotor runout, valve lifter travel, all kinds of stuff. but the straight edge with feeler gauges plus gasket thickness will give you your quench height.

 

This is all you need.....and is pretty damn accurate.
I want to take a moment though and talk about quench. Although it is beneficial to have a proper .030-.040 quench on a build....don't get to hung up on it. Today's fast burn chambers are much better at resisting detonation than the old stuff and pulling back .5 on the compression ration is an easy way to get resistance as well. Now I bet I will get flamed by many here that, as an experienced engine builder, that I should be much more precise about what and what not to do and to a point, I agree......but after building a few full dish piston engines with NO quench and doing top end upgrades on L-48 crap dish pistons that make 400 horsepower on **** 87 fuel at 9.5 to 1....I think the whole quench thing is overwrought. If you are hell bent on it....great, but don't get hung up on something that is but a small part of the overall process. When I build an engine from scratch...I design the quench in as part of the parts selection and what to tell the machinist....and yeah, I can get away with a little more compression with a .040 quench on a build.....but the balance between power, effort and expense has to be considered as well....and on a stock short block....it is out the window.
If you have all of your parts already.....what are you going to do if the quench is .060? Are you going to mill the already machined block again or send the new pistons or heads back? Believe it or not.....the deck height can be checked on a bare block with the right equipment.....if you do not have the right equipment.....then you are checking it after the short block is assembled....and what if you cannot get the quench you want. My point is that you can get a good number before it is assembled by ordering the correct parts and having the machinist shave the right amount.
The 350 I built for my Dad 23 years ago in his 32' Three Window is a good example.....old chamber design 64cc heads on a Goodwrench 350 **** full round dish piston for a measured 9.3 to 1....Comp 292H Magnum cam, RPM intake.....that is still pulling like a raped ape 23 years later running high 12 second 1/4 miles.....
My morning rant is due to all of the fuss lately on here about quench......yes, it is good....but no, your engine is not going to knock or blow up if you do not do it right. A good portion of people can't assemble an engine properly yet spend hours pining over stuff they read on Grumpy's website.
This is not a stab at anyone....just some points to ponder.
Just my thoughts and have a good day

Jebby

 

Thanks for the input, Jebby, and all who have responded, for that matter. Yeah, I'd like to avoid that kind of hassle if at all possible, and really don't want to put too much energy into this quench deal (I guess I got a bit concerned with folks telling me that quench is the end all be all in the process) - running back and forth between home and the machine shop is not my idea of a fun day out.

So how do you plan/blueprint for quench when you already have the entire rotational assembly and heads, yet don't have the equipment to measure deck height? - I don't have access to the block now anyway. It's at the machine shop.

I've posted most of this information on another thread I started pertaining to cam and piston selection (thanks for the guidance there too, btw), but to put it all together based on guidance I got there, here is what I have

Top end:
DL-5089 E street heads (64CC chamber, 185cc intake runners, 2.02 intake/1.6 exhaust valves)
EDL-2020 intake and carb assembly (Airgap intake and 650 CFM AVS2 carb)
Cam/lifters - Comp Cams 284H cam and lifter kit (haven't purchased yet, but this is what I'm going to get)
Rockers - 1.52 roller rockers
Push rods - Haven't picked out yet. Existing ones are not completely true, so will likely purchase new ones recommended for this setup


Bottom end:
Pistons/Crank -Balanced Eagle B15405E040 385 (6.3l) stroker rotating assembly with .040 over KB hyper pistons

Engine block:
350 '3970010' casting 4-bolt main block bored .030 over. Not 100% sure, but assume deck height 9.015-9.020 (the engine builder I bought the long block from years ago typically decks .005-.010" for deck 'cleanup'). Currently at the machine shop, waiting for them to get to it. Plan to have them bore to .040 over in order to use the .040 KB Hyper pistons included with the aforementioned Eagle rotational assembly - assuming that they can do a .010 cleanup of the bores, and don't have to jump to .060.

 

I guess a feeler gauge will get you where you need to go, but the quick and easy way to measure the depth of something is to use the depth measuring blade on a slide caliper. (I'm not going to insult your intelligence by telling you how to do it.) It's something you're definitely going to have to do, too. I looked around, and nobody seems to know what the compression height is on the pistons that come with that kit, so god only knows how far down in the bore they are going to be. If you don't own a slide caliper, you can borrow one from somebody who has enough sense to own one. Or, you could dig some change out of the sofa cushions and go buy one. You can get one at Home Depot for 12 bucks.

WEN 6.1 in. Electronic Digital Caliper with LCD Readout and Storage Case 10761 (homedepot.com)

I use mine all the time.

Scotty

 

At home.....you mock up the crank in the block and simulate TDC of the rod journal at each corner.....from there measure up to the deck.....then you add 1.050 (1/2 of small block rod journal), subtract the 1/2 the stroke, the rod length, piston C/D...and what is left is how far the piston is in the hole.
You do the four corners to see if one end is higher than the other......a lot of blocks are tapered from one end to the other from the factory.

Jebby

 

a simple method is install 4 pistons and measure. has the block been decked yet? or are you not decking it? because in those cases, just go with what you have. if you want to see how much to deck the block, best bet is to put the rot assy in and see. you already own new pistons? ask manufacturer what exact pin height is. they used to add .010 to make the deck height lower. then they started lowering the piston .010 to make it as-stock after decking. they also sometimes make the piston with orig deck height...

 

So, something like this? It's for zero-decking, but concept is the same


....Or for the more security-minded folks, just do a search on youtube for "336 SBC 305 4 corner mock up for zero decking" (Part 4 4)

 

more involved version of feeler gauge and straight edge.

 

If you want to get really, REALLY **** about things, and you're a REAL HARDCORE CHEAPSKATE, what ya do is, install all 8 pistons in the #1 cylinder and measure the piston-to-deck height of all 8 to make sure they are all the same. If there is any difference, make a note of it. Now, install your lowest piston in the #7 cylinder and measure the piston-to-deck height again. If the piston-to-deck height is more, then you know that the back of the deck is higher than the front. If it's less, then you know the front of the deck is higher than the back. Using the same piston, do the same thing on the #2 and the #8 cylinder. Make a note of the different piston-to-deck heights. If all of your pistons were the same height when you installed them all in the #1 cylinder, now you know how much to shave the decks to make all of the piston-to-deck heights the same.

Now, let's say your pistons were machined by a guy who drank his lunch that day, and they are all different heights, within, say, .005" from the highest to the lowest. And, it turns out that your decks are both the same height, but they're both .005" higher in the back. (If this turns out to be the case, go buy a lottery ticket, because today's your lucky day!) Well, in that case, you don't even need to have the decks shaved. You can just install the shortest pistons in the front of the block, and the tallest pistons in the back, and your piston-to-deck heights will be pretty darn close all the way around!

Things like this can happen because of mass production tolerances, even if nobody involved is drinking their lunch. Chances are good that your pistons will have a much tighter tolerance than the deck height of the block, but this method is still really good for determining how much the decks need to be machined. (the variables here are the compression height of the piston and the center-to-center distance of the connecting rod. that's why you use the same piston on all 8 cylinders) It's tedious and time consuming, but it doesn't cost any money. My dad was a big DIY'er and he used to say, "The difference between an amateur and a professional is, an amateur will spend time to save money, while a professional will spend money to save time." There is a cheap and effective way to do just about anything, and the trade-off is usually that the cheap and effective way is time-consuming. Professionals buy expensive special tools to save time, allowing them to perform more tasks in a given time, and thereby increasing their profit margin, especially when those costs are passed on to the customer, as it customarily is.

Scotty

 

your eagle rotating assy uses Keith Black pistons. several different KB 383 pistons say 1.433 compression height. plus half of 3.75 stroke plus 5.7 rod comes out to 9.008. they say the stock deck height of a small block is 9.025. your shop said they usually deck .005 to .010. it could have been decked twice. it could have been decked 15 or 20. i prefer if the shop knew and wrote down how much they took off. but if yours was decked .005 you are in the hole around .012 if decked 10 you are at .007 in the hole. so i realyl doubt you have the room to cut the block any farther. zero decks are for racing. a .028 composition head gasket will put you at .035 or .040 assuming your block is 9.015-20. not a horrible place to be for a quench height. aluminum heads? cuz i recall you talking 10.5 or so CR.

 

Get some modeling clay.....lay it on the pistons, bolt a head on without a gasket. Turn it over a few times, remove head...measure thickness of clay.


JIM

 

ok, why without head gasket? cuz that changes apparent height by .015 to .041.

 

Just make sure it isn’t 95 degrees in the shade! LOL!

Jebby

 

You bolt the head down and remove it. I guess if you have a money tree out in the back yard you can afford to ruin a brand new head gasket just to avoid doing some easy, simple math . I don't have a money tree, so I guess I'll just have to add the compressed thickness of the head gasket to the measured thickness of the clay.

Scotty

 

It's a great idea, but if the clay is too thin, good luck getting an accurate measurement. Maybe there's a better material to use than modeling clay?

Scotty