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#1
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Gasketmatching 906 milling.
Im in the hunt for some CC´s !!
Not that I know if I need them, but to be doubble safe, I hate taking the engine apart once its ready. Right now I have 10.35 static and approx 8.35 dynamic. Its with my milled down 906`s. I have a perfect quench of 0.040. I have heatblocked intake pangasket. I have 1" phenolicspacer. It will proberbly work well,, I dont know,, do YOU?? To be 100% sure I can lower the value one or two tenth by polishing/grinding the combushionchambers. I always heard that gasketmatching the chambers is a sin! WHY?? Becorse you loose compression by adding cc? Well thats just my goal!! It cant be becourse of turbulence? The thin "ring" of gasket between the head and block right now must be a worse interferer,,, or? If I gasketmatch the heads I will easely get the cc that I perhaps dont need!! It all for my 383 with 4.28 bore. So the Q´s. 1. Will i do with 10.35 and all the above mention. 2. Can I gasketmatch the heads? Best R Olle |
#2
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that 10.35 would be hard for a professional to make it work on the street, and that's with a guaranteed source of quality fuel. one slip and you detonate it. if you had a big enough camshaft you could bleed some of that compression off at lower rpms but it would come back in the higher rpms anyways. with enough messing around you can probably do it but your timing and fuel curves will be the difference between life and death.
gasket matching the chambers? why would you want to do such a thing? yes you would lose performance, if you could somehow figure out how to do this. gasket matching the ports is a more common practice but its a bad idea as well because if you open up the ports to the gasket size you basically make a bottleneck area for the air to lose velocity in. not a good idea. maybe port match the tops of the intake ports with the intake manifold and make sure the gasket isn't protruding but there isn't much else you could do. either way i would be running some kind of race fuel/premium mixture until you have the jetting worked out. but if you get it all working right, between your port job and the bump in compression that chally is gonna haul ass like you wouldn't believe. i hope your changing the cam as well? |
#3
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Hi
Thanks for reply. 10.35 or 10.25,, does it matter? I can easely get one cc from grinding the chambers. I can get two with a 0.027" gasket,, Shall I go for 10.1 or test this 10.35?? So many Q´s and still not sure on how to do!! Thanks for support. An additive will be simple to use. Best R Olle |
#4
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well 10.35 or 10.25 isn't a big difference, really for a more mild engine (450hp or less) you would want around 9.5
the more gasket thickness you add the more quench you add, you are perfect at .040 right now so adding to that number might offset how much compression you lose with the slightly larger volume. if you can polish a couple more cc's out of the chambers that would be a much more effective way of getting the job done. an additive is easy to add but octane additives don't do squat, you will need a 20 percent mix of 108 octane race fuel from sunoco or something, that's the only way to see a real improvement. |
#5
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Thanks again.
Those answers help me a lot. I know in what direction to move, and Isure wanna run that engine fat at start. I have a .496 lifting camshaft and a Holley streetDominator intake. TTI 1 7/8 and mandrel bent 2,5" tube all the way back. I have a 3.91 8 3/4" rear and I hope it will work out well. I also have the KB siverolite pistons who is told to run cooler than standards. I guess If I can gain that single CC from grinding/polishing,, I will end up close to 10.25. It cant be a catastrof,, can it? I hope the car will move. I have also a forged crank with weigh in rods, redone with ARP´s. All new bearings, windagetray and MP Chrome box. I run 0.080 Compcams custom made pushrods correct lenght to this new "closed Chamber combo",, OOOOHHHHH I wish it will work!! And burn some rubber!! Best R Olle |
#6
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Hi Olle try to stay under 10.0:1.... i know.... and i hate pinging engines and remember that you lost allot off power if you cant adjust your timing up to 36-38 degree of timing...so dont go to high its to easy to loose more than you winn.
Stefan |
#7
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Well this is a subject for additional Q´s.
I know a lot of people talking about 36-38 and even 40 degrees! Ive been there myself! Lately I read somewhere that 34* and a high compression is the ultimate goal! I havent tryed it yet,, I will in a short while. I also bought a set of Cometic gaskets, together with a little fine tuning,polishing/grinding of the heads I will put my figures down to 10.0-10.1. But Im still not sure of where I read about the timing! ANYONE?? Best R Olle |
#8
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cc's
Hey Olle
Long time no hear. What exactly is your goal? If you are looking to drop your compresstion and or power, Then go ahead and increase the cc's drop the comp:. My question would be WHY ? I recall all you went through to biuld your 383. Am I mistaken or are you trying to lose some of the horse power you worked so hard to put together? Or is good fuel that hard to get at your location? |
#9
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Hi Dan
Its always fun to get your opinions. Ive done several since last input. Lets make a short update for you and everyone: I milled down my 906 to "closed Chambers". I recived a total of 70cc. I got an perfect quench of 0.040. I will run heat blocked intakepan gasket. I will run phenolic 1" spacer. I will run 3.91. I can get whats called 98 octan fuel in Sweden, but Ill guess its comparable to yours 94!?. The figures together whit my new camshaft will give me 10.35static and 8.35 Dynamic. I started to get "cold feets" since everyone was talking about my values are on top of or above the upper limit,,, WHO KNOWS? I then desided to lower the compression by some tenth to make people happy,, including myself. Every CC is equal to one tenth drop in both static and dynamic. I can gain some CC´s hard by grinding/polishing the chambers. I can get nearly 2CC´s by changing from MP steelshimgasket to a Cometic 0.027. I will still have a desent 0.047" quench. The new Cometic gasket with only one additional CC from the heads will give me 10.1 and 8.1 ! I think I will go for it! Better be safe and happy. Ill guess the Challenger will fullfill my goals anyway with the new set up combo written in a reply some rows above this. What do you think?? Best R Olle |
#10
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hi olle,
i think the 8.35 dynamic (if true) should work. i would give it a try. keep water jacket temp. reasonable. feed it with cold air, but beware of "ram air" without proberly modified carb, cause this could lean out the a.f. a good description of mod. carb for "ram air" is in david vizard´s "how to build h.p. pt.2" dont make the af richer than neccessary... you surely have radiused the sharp edges of the piston valve reliefs. you probably want to unshroud the intake valve a little bit. but you surely dont want to inrease the diameter of the chamber, because that would increase timing requirements also. would be very counterproductive. mik |
#11
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I started to get "cold feets"
Hey Olle Step a little closer to the fire and warm your feet. (70cc) on 906 heads is impressive. I run the 452's milled down to (74cc) chamber volume. Your combonation sounds like a good one as far as you went. I wouldn't back off the compression . It sounds as if fuel octain will not be a problem for you. Compression is a lot harder to get,then it is to get rid of. You didn't mention the cam grind you selected . Judgeing from your post I assume it to have plenty of duration. I would like to know what deck height you will have and what type of piston you plan to use. (Just as a guess) It sounds like flat tops with a low deck height. The next question I would like to ask is how much did you mill off the intake mounting surface of the head? Also you didn't mention what intake you would use. If I recall you were running a 727. If so what convertor are you useing? |
#12
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Thanks Dan,,
OK here we go. Ill guess you could smash my fingers at some point,, but I have a limited budget and have to continue on the track I chosen from start. I will use a Street Dominator intake. 1" phenolic 4-holespacer. I have KB flat pistons with valve relief. The pistons are 0.020 from deck,, that is BELOW deck. The cam is the weak point according to the "Swede guru" , but the figures are.. .486/.495 and 222/234@.050" I must admit this one,, I wasent brave enough,, I just ordered the 0.027" Cometic gasket. Gives me 0.047 in quench. I milled close to 0.100" I havent milled the intake at all!! According to my Swede Pro, I shouldent! The goal is to keep the intake "High" as he told me,, since the intake ports normally have a "knee". You can get free from it by letting the intake rest in the "original" position. By grinding the upper edge of the head intake port and grinding the mounting hole in the intake the problem is solved and the flow is improved a lot!!?? I will run with 3.91. And 727. I will keep my 2500stall converter, a sacrify for getting most streetable function out of the combo. Ive added a big transoilcooler. I run TTI headers and TTI mandrelbent 2.5" tailpipes. I cant find out what Ive missed,, can you?? Did I tell you the 906 was ported to maximum flow, not by MP-templates, but be the advices from a bunch of streetracers. The most important spot have been to add sharp edges at the roof of the intake to let the mixture free from the portsurface and prevent the flow to "stick" against a smooth curvature! The valves have been height matched and in addition to the seatmatching carefully backcutted. I have new matching valvesprings all shimmed down to equal force. The combushion chambers are milled equal with a laboratorium volume measurement glass with 0.1cc scale ( 2 feet long = 50cc!!) The Q have been if I should go for 10.3 or 10.1,, Ive desided 10.1 and thats it!! The pro says 12.8-12.5sec with original Challenger weight,, I say,, lets hope it works!! Ohhh I added some extra, like 275 tires, new governor spring, MSD, a safety loop, new joints and on and on!! Please tell me!! Best R Olle B |
#13
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are you sure with the 8.35:1 with that cam?
i would assume it needs at least 10-12° more, but to do the math, there is a calculator on kb-silvolite.com mik |
#14
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Olle, I can't tell from your posts if you have actually run this car yet or not. Does it actually detonate or are you just afraid it's going to? If you haven't then put the best fuel available in and see what happens. Remember that aluminum heads would solve (or prevent) this problem immediately, but I realize you are on a budget (aren't we all!!), plus you have lots of time and money invested in the 906's. My point being, maybe try all the usuall tricks to run cooler, including aluminum water pump housing and pump. Keep the quench tight, this helps cooling too. Aluminum dissipates heat way faster than steel. How hot is your thermostat? Do you have alum. rad?................djs
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#15
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One more thing Olle you could go to a cam with later intake valve closing, this will reduce cylinder pressure as well, but obviously you can't get to radical or the engine won't run well. Let us know what happens..............djs
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#16
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Quote:
The only figure I could read out was the 0.050 intake value to put into the calculation-program,, I hate it since Im a figure/number freak,, but anyhow,, some US engine Pro guy told me the figures shown in the cam pattern point towards 63-63.5 degree at zero. Well,, I put 62 into the program,, but I amit,, there is a "gray zone" !! BUT,, Thats way I feeled forced to go for the cometic 0.027 gasket. In addition to ONE gained CC by polishing/grinding the combo will give me 10.1 static. Thats for sure!! The dynamic will be 8.1 ! If the value are as low as 57* Im still at the correct side of 8.5,, Ill guess/hope/sure that the values will work. If you take a look at the combo I wrote some posts ago,, What do you think,, Will It be a pleasure to drive or some boring never correct adjust son of a #¤#%¤# ?? Quote:
The reason why I started this post was to get the last inputs according the compression. Since I didnt get a bulletproof OK I ordered a set of Cometic 0.027" gaskets. I know I ruined the perfect 0.039" quench,, I know I ruined my economy,, (my wife dont know,, YET!!),, but I will still gain 0.047" and that is GOOD!! I gained 2 easely CC´s without milling my heck off, and the total volume will be desent. As for the "cool run" , I have the heatblocked pan gasket. The 1" phenolic spacer. And Im going to start the engine with 74 main jets on my 750 vacsec carb. Im really happy,, HAPPY,, for the support yopu gave me,, I need to be sure,, I have spend million of hours on the car and ordering parts. I havent spend that much money,, If I could afford it it would have been much easier with a set of Alu-heads,, but not in the same range of Challenge!! The goal was to make the engine just like the Swede well named guru told me,, not using MP-templates,, sharp edges in the port and bowl area, radical milling, and a street friendly combo that will launch my original Challenger in Show condition for high 12`s at the quarter!! Tell me more before I start bolting the parts together!! I know I can easy retard the cam some degree if It looks wrongs at the rebuild,, but I hate to split the engine during the season. Deep down I had to accept its just one of all the common Challenger R/T convertible with all matching #,, you cant ask for miracles!! Can you?? Best R Oll |
#17
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Since the timewindow for editing is so short,, I had to put the above input as a completely new one,, Im sorry I wasent born on the right side of the Atlantic sea,, sorry for my poor way to make things possible to understand for you!!
New version of above post!! Quote:
The only figure I could read out was the 0.050 intake value to put into the calculation-program,, I hate it since Im a figure/number freak,, but anyhow,, some US engine Pro guy told me the figures shown in the cam pattern point towards 63-63.5 degree at zero. Well,, I put 62 into the program,, but I admit,, there is a "gray zone" !! BUT: Thats why I feeled forced to go for the cometic 0.027 gasket! In addition to ONE gained CC by polishing/grinding the combo will give me 10.1 static.Thanks to the nearly 2cc won by going from 0.019 to 0.027" Thats for sure!! The dynamic will be 8.1 !IF THE VALUE AROUND 62-63,5 is correct! If the value are as low as 57* Im still at the correct side of 8.5,, Ill guess/hope/sure that the values will work. If you take a look at the total combo I wrote some posts ago, what do you think, will It be a pleasure to drive or some boring never correct adjustable son of a #¤#%¤# ?? Quote:
The only reason why I started this post was to get the last inputs according the compression after making the milling and recived the correct volume (70cc). Since I didnt get a bulletproof OK I ordered a set of Cometic 0.027" gaskets. I know I ruined the perfect 0.039" quench,, I know I ruined my economy,, (my wife dont know,, YET!!),, But I will still gain 0.047" and that is GOOD!! I gained 2 easely CC´s without milling my heck off, and the total volume with the one from polishing will be desent. As for the "cool run" of the engine, I have the heatblocked pan gasket, and the 1" phenolic spacer. And Im going to start the engine with 74 main jets on my 750 vacsec carb. Im really happy,, HAPPY !!,, for the support you gave me,, I need to be sure since I have spend million of hours on the car and by ordering parts. I havent spend much money,, If I could afford it it would have been much easier with a set of Alu-heads,, but not at all in the same range of Challenge trying to make a street killer with ironheads!! The goal was to make the engine just like the Swede well named guru told me,, not using MP-templates,,adding sharp edges in the port and bowl area, the radical milling, and as a result a street friendly combo that will launch my original Challenger in Show condition for high 12`s at the quarter!! Tell me more before I start bolting the parts together!! I know I can easy retard the cam some degree if It looks wrongs at the rebuild,, but I hate to split the engine during the season. Deep down I have to accept that my car is just one of all the common Challenger R/T convertible with all matching #,, so you cant ask for miracles!! Can you?? Best R Oll |
#18
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Hey Olle
sounds pretty respectable. I would recomend just a few things. (1) do some home work on the KB pistons. The piston to cylinder wall clearance is critical with these even more then any other. Metal ergy is not my feild. However For some reason Kb's seem to have a larger expantion rate then most other pistons. Don't take any chances. Get in touch with the mfg and let them give you the proper specs regaurdless of any info that may be supplied with the pistons. (2)as you said your cam. Your duration seems a bit low. This would provide you with good off idle response. However it would be at the expense of higher rpm performance. I would say after about 5500 rpm you will start to see a drop in performance. So you may want to experament with differant rpm shift points. To get your best et's. (3)In the persiut of better flow. I agree with eliminateing the knee in the fastion you described. Be sure to also port match the bottom of the runners as well. But remember this will restrict you to useing only that one intake. (4)I am not so sure about adding rough edges to the ports. This doesn't sound right to me. have the heads been flowed? If so what were the results and at what vacume? Have you concidered larger valves. Such as 2.140 intake and the 1.181 exh. It sounds as if your heads are completed allready. However if not the larger valves would require you to knotch the top of each cylinder. This would add cc's for you as well as add to your flow. Perhaps you could use this as a future update at some point. I can see you have pains takeingly done your home work on your heads. (5) Tire size I don't recall the height of a 275. But I would recomend a 28" tall tire. I don't think 12's are out of the Question for your combo. But it should be close |
#19
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1.
Ive let the speed shop do the adjustment last year. They handcutted the rings to correct gap. I hope it will do,, One thing I noticed last year was a little blue smoke in the exhaust after moderate driving,, but ill guess I was to rich on the mixture! 2. I know,, I know,, Well you have to understand,, its a street cruizer who wanna be a street racer!! I still wanna have the possibility to go slow, and the cam is a sacrify to join the middle of the two goals! It could have been worse! Im sure its more agressive than the popular MP .484 and its a good starting point for adding 1.6 rockers!! I have changed governor springs for a shift point of 5200. I have also added a MSD soft revlimiter to set on 5.600 , if I wanna shift manuell! 3. I will never have the money to buy a new one,, but its like the rest of the combo,, its a little of a "hit from below",, I know the RPM is better???, but a Holley is really Close,, and a Holley is always a Holley,, ever since I was a youngster back in the middle of the 70`ths and the Big guys drove US cars with Holleys,, not Edelbrook,, LOL!! 4. Perhaps in a future, But the larger valves will slow down the flow at low to middle low rpm`s and thats the point where I need to keep the force! I have backcut the valves and done everything needed to gain max flow at low rpm`s,, but perhaps next season!! LOL The sharp edges are applied to the roof! The support for the valvestem have been grinded knifesharp all the way from beginning at port opening to behind the stem. The idea is to get the mixture away from the walls and prevent it from "sticking" and following the curvature causing turbulence! I dont know how well it works,, but the guy have a great repuation! He have been dealing with V8 for 30 years, but as mention,, I dont know myself,, Im just part of an evolution process!! 5. Yes they are 28" rear. Mounted on Rallyes 15x8. Correct Eastwood painted. In front Im still running my 14 x 235. 6. I know a lot of people will hate me for doing this to my Challenger, but the car looks bione stock!! I could never dream of ruin the exterior!! Hey I even win Throphies on smaller carshows, beeting the %%/&out of Mustangs and Corvettes!! I cant help Im adicted to power... I will never have the money to by anouther project car, and if I did,, I will always regret I didnt drive the Challenger,, I LOVE THIS CAR!! Best R Olle B |
#20
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[QUOTE]Originally posted by Olle B
[B]1. One thing I noticed last year was a little blue smoke in the exhaust after moderate driving,, but ill guess I was to rich on the mixture! Blue smoke allways means oil. 2. I still wanna have the possibility to go slow, Thats the easy part. Im just part of an evolution process!! Welcome to the dinosaur club.(ha ha) 6. my Challenger, looks bone stock!! I could never dream of ruining the exterior!! I LOVE THIS CAR!! Always keep it the way you like it! Thats what makes it your's. |
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