Not to exciting as this build turned mostly stock / NOS. I would like to thank those that provided feedback during build Doc, Tom, Russ, TA performance, CAR's and others I'm forgeting. I have to send a big shout out to my friend that allowed me to use his heated shop during another cold winter in Michigan. Machine work: -chem dipped and derusted. -.030 bore (yes EGGE piston measured and weighed good no issue) just cleaned up with minor rust pits left top of one cyl. - .010/.010 crank, balanced etc. -rods reconditioned -crank bore and deck checked and good. -rebuilt oil pump Heads: -new valve "Russ Martin" -new seats and yes some exhaust seats replaced. -machined for valve seals on intake side only. -milled surfaces. -rebuilt rocker shafts (with help from a friend with some mad skills). -spring pressure checked -match ported along with DOC MOD intake. -cam and lifter NOS stock. -steal cam gears -"Best" gasket All threads tapped, oil passages brushed, bolts cleaned ( most originl hardware) and orginized, sheet metal cleaned and minor dents removed, measured, inspected, all checks made on and on. Now assembled! Back to getting engine compartment finished so it looks as good as the engine. Can't wait to build the 364 next!
Valve stem seals are NOT on exhaust only, but intake ONLY. Hope this was a mis-print??? As a guess-timate will end up with about 9.0-1 compression. The squish/quench area will NOT be anywhere near what it should be & will be MORE prone to detonation. Pistons in hole .050"-.065" plus compressed head gasket thickness of .035" = .085"-.100" squish/quench area of the ideal of .025"-.050". If it doesn't end up running as good as you thought this could end up being the problem. Just my thoughts. Good luck.
Thanks Tom yes intake side. Doing this on phone and was thinking about the seats "edited"I measure the pistons at TDC avg. .045 with .035 gasket this would be .080 but with .010 removed from heads back down to .070? I noted the machined ring around the top of EGGE piston tops, I don't believe this is there on the stock Pistons. You would think this would add to this measurement and maybe not as bad as expected. Do you believe detonation occurred because the piston dome is to far down from head lacking is squish at a lower compression? the cam is a stock NOS 401 like 431 lift with 114 deg separation. Decided Riviera with Dyno flow didn't need a larger cam. Oh cam was free too!
it will still be .080 in the hole no matter how much you mill the ends. nice find on a nos stock cam.
Pistons 0.045" down from the deck surface is about average for a stock engine from Buick. Milling 0.010" off the heads isn't significant. Was the block deck surface milled too? Squish occurs around that outside edge that is machined on your pistons, the flat portions on piston top (but not the dome), and where the sides of the dome fit into the chamber. As piston approaches TDC, the fuel/air mixture in those areas is 'squished' out towards the center of the chamber near the spark plug where is more likely to be burned quickly. The mixture in outlying areas is less likely to be burned quickly/efficiently, resulting in lost power. If you are concerned about it, replace the thick composition gaskets with stock steel shim gaskets to return it to stock configuration. I'd probably run it as is. You can change later, but it'll be more work after engine is installed.
Milling the heads has NOTHING to do with the squish/quench area. If you use the composite gaskets the block needs to be decked .035" minimum. If using steel gaskets .020" minimum. This will also raise your compression to a more favorable level. Will DEFINITELY make for a better running engine, weather it be stock or otherwise. Again, just my thoughts. Tom T.
No decking of block. I see regarding buick domed piston combustion. I understand this may reduce compression slightly. I also understand how detonation could lead to the edge of the Payton's. I can't believe this will affect the power or drivability all that much. Will have to see how she runs but have had thought about steel head gaskets. Thanks again
It's foolish to underestimate the effect of quench. You might not be able to utilize a full timing curve. Then simply blame today's crappy gas. The "quench" takes some of the residual temperature out of the dead areas of the chamber and helps keep the remaining end-gasses from lighting the mix apart from the plug. One of the downfalls of a chamber that "likes" less total timing is that as the piston rises, the compression raises the temps up to a critical point, along with the hot end-gasses... promoting the likelihood of an abnormal combustion event. This temp and the ignition point of the various fuels is always considered by engineers. The effects of mixture-motion to enhance vaporization and increase energy potential prior to combustion are long and well documented. Formulas are used at the design stage with OEM's, as well as students of ICE engineering. This tremendous effect is one of the single most overlooked factors by hobbyists and hot-rodders. It is rarely accounted for in hp or cfm estimators, as very few facilities outside a lab environment can actually measure that effect. There is an actual predictable effect up to that point of diminishing returns. Quench is but only one factor of many. The very little spent getting an engine machined to ideal specs is the difference between the "it runs ok" and the one's that match and exceed the most technologically utilized engines. This old iron is better than you think when you can idealize the specs, and understand what's happening inside.
i agree that quench is very important, but with the dome piston on the nailhead and the shape of the head not sure how much it really matters.
Then we politely disagree. What I wrote was not my personal opinions, people can use it for benefit or not. I put this stuff here so the hobbyist may consider that clearances and specs may greatly benefit the engine, and often cost very little to arrive at with some forethought. Why start off with obstacles? There still are end-gasses to deal with.
same here, what I wrote was not my personal opinions. to bad the nail head has a dome which hurts the flame travel, so maybe with the piston higher in the block might even make it worse. don't know if you can rid of the dome with the big cylinder head volume. of course you still need to keep your compression up.
I disagree!:grin: In my case, it was 1977, I was 16 years old, and barely anyone knew what quench was! I plead 'didn't know any better'.ou: Anyway, I built the 425 in my Blue '66 back then with TRW pistons 0.040"+ down in the hole and stuck the thick head gaskets on, notched the pistons for the big Isky cam I put in and it's been a great running engine. It's run 13.40's at 102 mph with the over-cammed, low compression, and too-much quench setup. (now I know, bad combo) I've been wondering for years just how much better it could run with the proper quench distance and compression ratio... any guess? Now that we're older and wiser, quench should certainly be a build consideration for best performance.
Walt, doing some rough math, you had about 9.6 compression. with that big cam 10-10.25 compression would have been nice. you still ran some great times for the day. the video you made of that track run was really great. could you repost the video please, thanks. I tried but it would not play.
I figure I'm in the low-low 9's compression wise. I'd like to address those issues, but I have too many other projects right now to mess with a good running car!
I hate for this thread to run away, and the points on the dome were not ignored. I'm referring to something completely different, what happens before combustion and it's impact on the threshold of octane tolerance and tune-ability. A .060" higher dome is still relatively low and a long way from the plug location. That dome isn't blocking anything as viewed from the plug. It's a good 1" below the plug, unlike a BBC which may have a dome completely blocking the plug from the rest of the combustion area. That's where flame travel would be an issue. Regardless of where the plug is, EVERY engine needs all the help it can get mitigating temps near the end-gas regions and far away places of the chamber. When quench is ignored or worse, clearances in "the danger zone"... this factor IS the limitation to the combustion event. It's somewhat irrefutable. One would be correct to think the impact of a particular design IS debatable. Abnormal combustion from end-gas presence and the temps of the far away places may well happen before load related detonation. Every engine design has a balance of trade-offs...good and bad. A huge benefit to the Nail chamber design is the high swirl and plug location, leading to it's total timing requirement being less. A large detriment to the Nail is lack of quench area and the later spark timing increases the likelihood of abnormal combustion via the natural temp increase during compression. Basically the further up the piston gets before the flame travel reaches those areas the hotter the mix is, esp. with end-gasses present. The temp increase from compression is easily calculated, and with stock cammed engines having a cylinder pressure curve very high at low rpms, may actually exceed the ignition point of pump fuel. The engine doesn't care how "mixture motion" happens, as long as it happens. In this case it's swirl. Swirl is very effective at low rpms as the rising piston accelerates the swirl. One would want to reduce the swirl (and use more raw port flow) when raising the rpm level of the engine past it's design range. The swirl itself would eventually be an rpm wall, hurting the combustion event regardless of the airflow, by exceeding the point of diminishing returns of energy release and likely tossing fuel back out of suspension. Having command of these factors is the difference between a 9:1 knocker and a 12:1 pump gas beast. In the late 80's early 90's MIT was publishing test papers showing the static compression limit for 87 octane being 17:1 (?...memory), obviously under lab conditions, using quench and mixture-motion. I never got as far as to find an equivalent load/rpm metric from those tests that could relate to a real world combination to find where the line was. I was happy where I got, for my purposes. Not to swing Johnson's, but at that time I was building 12:1 pump gas iron-headed engines and starting to get into 7-8 liter displacements getting 28-30 mpg's using my new found, not fully understood information. Basically I got lucky with a few well planned builds and it took quite a while before I really understood it...if ever.
:gp: just wondering if there was really a quench for a nailhead between the dome and the penthouse roof of the head . now make it a nailhead stroker with the piston dome staying on top dead center longer, getting in the way even longer. maybe not so good?
I would like to see more quench area...it would never hurt, and always help. To the degree of benefit??o No: A stroker could reduce the need for dome, but there's not much dome along the sides of the chamber anyways. I would think the orientation of the Nail's dome could assist the quench area in maintaining the swirl's existing direction, without disrupting it. Again... these have 2 completely different functions, and... None of us have sensor's, so....? All I'm saying is instead of questioning a known benefactor, implement it. It will never hurt, likely cost almost nothing, and begin paying for itself immediately anyways. [the Nail's quench area as I picture it in my head is seen where the squarish portion of the chamber overhangs the bore outline, I bet if one adds up the area there's more than what first appears. There's quench on 4 sides. The dome is blocking very little of it. This geometric arrangement is used to great benefit in both true hemi chambers as well as 2 stroke designs. The angled sides of the dome are used to help direct motion up into the chamber, not block it]
