What more harm does the bigger fap cause other than lower compression. Not trolling just an honest question as i am learning here. Sorry for the delayed response i was sick and busy over the weekend
Glad your back, recover quickly, and here ya go. If i type it out (and i can) it will make me sound like a KNOWITALL. So instead of that i'll give you a GQQD read link...--> This one is Short and to the point.---> http://www.hotrod.com/articles/ideal-quench-height/ There are better reads but there LONGER and more complex. Like this one---> http://garage.grumpysperformance.com/index.php?threads/tumble-and-swirl-quench-squish.4081/
I understand quench, understand compression detonation etc... Just the way he worded it sounded like there was more damaging things that could wind up happening like martians invading the planet lol. I read the first one and will continue to read the second one when i get up as im a 3rd shifter and almost out of work. My question is this...i have dished pistons... And even with the measurement of the top land I still continue to have to calculate for the dished area of the piston. The magazine article using the same engine also used a really thin head gasket, am i wrong in guessing that they used it to compensate for the dished piston where as the head manufacturer recommended a thicker head gasket for a flat top piston?
Also i messaged the guy above about the harland sharp rockers as im willing to pay that for a quality product as long as there are no issues with it
I as well never had good luck with Comp hardware period...I have had everything from ****ty lifters to , ill manufactured guide plates to just down right ****py cam grinding and dowel pin indexing on their catalog cams. They grind nice custom cams if you know what you want... their catalog cams pretty much **** c**** water just from the stand point many are straight lifts and duration's on ex and int lobes.. I agree that Harland Sharp is great bang for the buck as far as rockers go in a moderately used mill. If you need custom pushrods you can get what you need once length and dia. are determined from Trend .......If you are really serious about a cam shaft.. I recommend Bullet cams. A lot of the old Cam Dynamics people still run the show there and I have found them invaluable.
Your post 94 is correct , (you are not wrong) you want to be in the least or tightest or lowest quench , but still FALL in the recommended / suggested, areas. TRY AND GET THE DISTANCE BETWEEN the heads and pistons at TDC, to fall between, .038 and .046 on most engines. When a head gasket thickness is listed its supposed to be the compressed gasket thickness ,this can be important in determining quench distance. Full dish pistons (what you have) eliminates most of the quench effect. On one of our engines, with Aluminum rods,the piston hit the head, the stamping on the flat(quench)area was so close that 2 of 8 pistons left a reverse IMPRESSION of that over bore number .
They don't come any SHARPER than 31 the Man Knows his ****, he should jump in and explain this too... His explanation may be more understandable than mine.
It's not Martians, but picture non linear graphs and bell curves. Picture things that the dynamics are greater than the sum of their parts. Picture things that have diminishing returns. You can drop compression slightly by using a thicker head gasket. The math works to do that. However that has the unintended consequence of increasing the quench distance. Follow that ? The increase in quench distance and loosing its effects is more damaging than the drop in compression is helpful. The Drop helps $0.20 worth and the increase hurts $2.00 worth- you're $1.80 in the hole. It costs you more to get to work and back home than you made for the day. Jump over a dollar to grap a penny. Dished Pistons have a top land close to the head and the Pistons dissipate heat thru that area quite evenly. That's one thing. Another thing is with tight quench there is little chance for carbon deposits to develop there. Carbon build up gets hot, causes hot spots and will cause you detonation problems. Even worse on a hot piston that doesn't get its quench. Another thing is The quench distance also forces the mixture to the center of the dish - better flame in the cylinder. Together those things equal much more than they add up to.
I already have the cam so im going to go with what i already have. If i didnt already have it i would look into ordering something from another manufacturer. I had someone tell me to run trick flow chromolly pushrods as they are quality... Any experience with them?
Im in flint, any chance you might be free on a weekend to come give me a hand? I have all the tools we need just wouldnt mind an experienced hand to help teach me a thing or 2.
I'd go with this, after you find the length for your engine---> http://www.compe***ionproducts.com/...-Length/productinfo/ELGPR-15790/#.WIgL7dQrKt8 You want seamless and wall thickness. They're on sale usually 6.99/111.84 a set, now 5.82 / 93.12 a set.
Ok i was reading it as you were talking physical damage not just loss of power although i understand detonation equals a loss of power and potential physical damage. So bring piston to tdc measure distance from top of piston to top of block then subtract that from the total distance you want which was stated to be min of .040. Then the remaining number is the head gasket thickness you want correct? I can use the depth rod on a vernier caliper for this correct? Or is there another way? Does it have to be cylinder #1 or any cylinder at tdc? Thank you for the help! Ps dont be offended by the martian comment was the only thing that popped into my head with the way i was understanding things
Does the thicker .110 wall have the same internal oiling flow as the .080? Just read somewhere for street use the .080 was used because of the larger oiling p***age. Im asking because im trying to learn why to use one over the other.
Why no but with that difference you lose strength. Wall thickness is usually determined by the open spring pressure, more pressure stiffer the rod. Deflection is also a horsepower robber some claim as high as 10/15 horsepower Gain from the stiffer/thicker rod. Ya know we get a bit carried away here, talkin ultimate RACE parts, when all said and done its a stock cruiser engine with just a bit of improvements, cam and head flow. This build can get by with stock wall .060 so the .080's WILL work ok, also the stock 5/16 by .060 wall rods are good for 5500-6000 RPM, much past that and they start deflecting. Then there's the what grade of material they are made out of 4130/4140... stock ones are usually made from 1018 steel tubing. The material for the tips can be 8620 bar stock case hardened, cryogenically treated and tempered, or H13 tool steel that is heat treated and salt nitrided .
Just FYI…Roller tips stop revolving when they touch the valve tip. The friction reduction is achieved by the roller in the fulcrum of the arms. Heat reduction is also an advantage of the roller instead of the gall ball. Roller tips need to be centered on the valve at mid lift to stop valve guide wear. That's one good reason the factory used flat slider tips.
The end of the rocker moves in an arc the valve stem doesn't so some sliding takes place putting a side load on the stem. When it comes to the factory which is cheaper I remember in the 60s they replaced the zerks with plugs in front end parts to save a few cents.
Keep it simple, you measure quench from the top of the piston to the face of the head. The dish in your piston will effect your compression not your quench. I don't know what article you are talking about but if they used a thin head gasket they were probably trying to keep the quench tight. A lot of us shoot for .040, if your block were truly zero decked then a head gasket with a .040 crush would be perfect, most engines have the piston slightly down the hole so a thinner gasket may have been used to compensate for the distance. Make sense?
How can a dished piston not affect quench? I just checked the depth of the dish on a 400 SBC piston and it is .156. The narrow band around the diameter of the piston, which also includes a generous 45* chamfer on the outer diameter, is the only area that can provide the suggested .040 quench. How about this scenario, deck/quench is checked on No. 1 cylinder, builder decides on .015 gasket for .040 quench. Block was decked on a slight (.007) angle at factory and let's also say No.8 rod is long .003 and compression height of that piston is .002 high also. The .040 quench height on the No.8 hole is now .028. Not likely you say? Maybe, but what if it was the case? How thorough will you be for a street engine built in your home shop? Regardless, the OP is getting way off the path of a street build. Buy quality, stock or hi-perf stuff, your heads are good, but do need a dis***embly and clean and check even though brand new. Trust no one, put eyes on things yourself. Long slot aftermarket rockers will suffice as will stock type, but .100 long pushrods, get a good street type manifold and carburetion, headers and pay attention to the advance curve. Clean all stuff, check dimensions, degree the cam, and finally, careful ***embly and torque values will pay dividends in a good running street engine. JMO.
Kinda like this? OEM Stock head gaskets are steel shim style with a compressed height of 0.015-0.018. Pistons are 0.020-0.025 down in the hole. That stacks up to 0.035- 0.043 OEM quench distance right? If you're doing a rebuild where One set of hands turned the crank One set of hands machined the block One set of hands manufactured the Pistons. One set of hands did the heads One set of hands did the rods One set of hands Pressed wrist pins and you're not checking stuff ???? I'd say that what ever happens is deserved.
Two questions, are you suggesting that the flat around the cir***ference of that piston will provide the same quench as compared to a flat top? Secondly, do you think I was talking about a hi-perf rebuild, or the OP's engine? A perfectly machined block squared to the world, indexed crank throws, rods and pistons corrected so all have the same compression height do not seem to be in the realm of the engine in this thread. Don't lose sight of the fact that the OP's build is a low-perf crate motor getting some upgrades. And who's not checking stuff? Me? I can ***ure you that has never been the case.
Wow a lot here and a lot of arguing... I LOVE IT!!! Nothing gets more information out there and new things out there like a good argument/ discussion. Thank you all. And i have checked every part i have ***embled since the start of this build including tearing the block down and inspecting everything. My new question is if 90% of the piston is a dish plus 4 valve reliefs how does that dish not effect squish? I know max rise of the outter ring of that piston must stay at the standard values of aprox .040 but doesnt the dished portion of the valve also effect both the squish and the compression not just the compression but due to the max height of the piston being the outside rim it being the only point that you can measure from. Meaning if you measured from the dish you would contact the head
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