440 compression ratio?

[70gtx]

hi,took my heads off and found flat top pistons with a dimple in the middle ,they are .030 & have a parts #L2266 .does any one know what type these are.
also my deck hieght to piston is .091 & have stock 346 heads with the tulip valves.
i think stock heads are around 90cc . can any one tell me about what the com. ratio is.
and what i can do to get it to 9.5 ;1 if possible with out changing piston because these are new. i did a compression check it is at 160 right know.

[DartGT66]

The 2266 pistons are TRW forged 'magnum' pistons, often called 10:1 pistons. Depending on your head gasket thickness and .030" over bore, you should be around 8.5-8.8 at the moment. Milling the heads .060" should bring you to about 9.5:1 with the steel shim gaskets. Before you do anything, measure your heads.

[70gtx]

thanks dart,i also have 906 closed chamber, how much c/r would i gain with these.i have to send either 346 or 906 to be ported and new valves &seats. anyway which one is better for my application, i would like to get it max c/r and run on 93 oct. maybe i can get 10 to 1 out of 906.

[DartGT66]

The chambers are roughly the same size in both heads, so the choice is yours.

[440 Jim]

It would be more expensive, but if you go with aluminum heads such as MP stage 6, or Indy SR, they have 75 cc chambers and that would bring the CR to 9.6!

Porting, all new valves, seats, and milling iron heads gets expensive maybe $1000 or more depending on porting. For $1800 the Indy's would bolt right on.

[This message has been edited by 440 Jim (edited November 23, 2000).]

[Sport]

70gtx It seems that you want max comp. for pump gas so that you can avoid that bad word detonation. What you want to watch is your cylinder psi. Regardless of your cam or your comp. ratio cylinder psi will vary. You can have a 8.8/1 motor small cam with 160psi. or 12.5/1 big cam motor with 160psi. The late closing on the intake valve on the big cam will bleed off cylinder psi. Hughes engines says that the 440 will get into the danger zone of detonatoin at about 170psi. Bill Shurmen of Shurmen Race engines says that180psi is the limit that pump gas will support. I like you would want to build my engine as close to thepump gas limit as possible. You are already at 160psi. whitch is close to the suggested limit. You do have room about 20 psi. if you go by Bill Shurmens limit. If do not change anything else you could shave your heads to get close to the 180psi. But like any other mopar guy I know your looking for more power also. If I were you and since the heads were off I would have them shaved for max 180 psi and also get a slighty bigger cam for more bleed off . Witch means you can shave the heads even more for more static comp. It will take some figuring on your part but if you put it together and your sitting to hi on your cyl.psi you could always pick a different gasket to adjust final cyl.psi Also the 906 or the 346 both respond very well to pocket porting If your looking for cheap extra perfomance and you can do it your self I would not put them back on without doing it . If your not changing the cam Iwould not go more than .030 If you go with abigger cam you could up to .060 Make sure you get the intake side of the head shaved also or you will have intake sealing/fit problems. If you want to play it safe don,t go more than .040 Iv;e personily have taken a906 head to .100 off the bottem .050 onthe intake but with that much off adds a whole lot of other things to consider. And actually the the ratio for shaving the heads is .010 off the bottem .0123 off the intake side of the head. Witch Idid not follow on my 906 but I had my own mad reasoning for that .And to this day I love my 906,s but Ialso liked the looks of the 346,s intake ports If I would have put as much work into the 346 as I did the906 they would be just as good or better. Sport

[70gtx]

yes i'm at 160 know but ithink ineed to get ratio up where i need it than a cam to correct psi & keep at 170.i quess im going to port the 346 heads my self with the template, the valves in that head are brand new but ill go stainless since i hear they are good insurance. illhave them shaved .060 &the intake surface shaved also.ill put them on and see what my cranking psi is at .
i know i should go with indy heads but just dont have $$$$$ to do that .
would like to see at least the 509 cam

[Sport]

Originally posted by Sport:
70gtx It seems that you want max comp. for pump gas so that you can avoid that bad word detonation. What you want to watch is your cylinder psi. Regardless of your cam or your comp. ratio cylinder psi will vary. You can have a 8.8/1 motor small cam with 160psi. or 12.5/1 big cam motor with 160psi. The late closing on the intake valve on the big cam will bleed off cylinder psi. Hughes engines says that the 440 will get into the danger zone of detonatoin at about 170psi. Bill Shurmen of Shurmen Race engines says that180psi is the limit that pump gas will support. I like you would want to build my engine as close to thepump gas limit as possible. You are already at 160psi. whitch is close to the suggested limit. You do have room about 20 psi. if you go by Bill Shurmens limit. If do not change anything else you could shave your heads to get close to the 180psi. But like any other mopar guy I know your looking for more power also. If I were you and since the heads were off I would have them shaved for max 180 psi and also get a slighty bigger cam for more bleed off . Witch means you can shave the heads even more for more static comp. It will take some figuring on your part but if you put it together and your sitting to hi on your cyl.psi you could always pick a different gasket to adjust final cyl.psi Also the 906 or the 346 both respond very well to pocket porting If your looking for cheap extra perfomance and you can do it your self I would not put them back on without doing it . If your not changing the cam Iwould not go more than .030 If you go with abigger cam you could up to .060 Make sure you get the intake side of the head shaved also or you will have intake sealing/fit problems. If you want to play it safe don,t go more than .040 Iv;e personily have taken a906 head to .100 off the bottem .050 onthe intake but with that much off adds a whole lot of other things to consider. And actually the the ratio for shaving the heads is .010 off the bottem .0123 off the intake side of the head. Witch Idid not follow on my 906 but I had my own mad reasoning for that .And to this day I love my 906,s but Ialso liked the looks of the 346,s intake ports If I would have put as much work into the 346 as I did the906 they would be just as good or better. Sport

I forgot to add something very important , when you shave your heads you are messing with your piston to valve clearance. I had about .100 clearance with the stock pistons /heads .75inthe hole withthe 509 cam after Ishaved my heads .100 that gave me .ooo Ihad to have valve pockets put in the pistons .100 deep That may be my engines weak spot I never measured the stock pistons thickness, I did read That Hughes engines said it was safe to go to .070 on the pockets on stock pistons ,so Iguess Iam walking on thin ice on the piston deal.But my Sport runs 7.12@100 mph 1/8mile 440 509cam 1800 stall 170psi. 3.91gear pump gas if Iget any detonation I know were its going to blow through, I should have just got new pistons to start with but Iwanted to build cheap,, so far so good. I will build my next engine the right way Sport

[70gtx]

boy, you guys really got me going know. so if i shave .060 i will only end up with .040 valve clearance?
SPORT ; what deck hieght do you have?
does anybody else have flat top pistons without releifs[.092 deck hieght] with a 509 cam. if so how much clearance do you have.

[Rob Voyles CA]

[/QUOTE].But my Sport runs 7.12@100 mph 1/8mile 440 509cam 1800 stall 170psi. 3.91gear pump gas if Iget any detonation I know were its going to blow through, I should have just got new pistons to start with but Iwanted to build cheap,, so far so good. I will build my next engine the right way Sport
[/B][/QUOTE]

Man Sport...sounds like its running good. Did you say 1800 stall? How does that work with that 509 cam? I had always heard that cam was a dog without a 3500 stall converter. Also, what else do you have done to your heads? It sounds like they're flowing nice too.

[DartGT66]

As far as aluminum heads go, the Stage VI's are nowhere near 75cc, the last set I heard of was 88cc, mine were 84-86. When milling the heads, you also have to consider the lifter preload thing ; .060" shave will change the preload accordingly. I would propably just shim the shafts to get it right, although in two latest budget engines I have built, I just shortened the stock pushrods. It seemed to work.

[72Challenger]

You can't rely on anyone else's clearance numbers unless you know that the two engines are *exactly* alike. And you'll never know that without measuring. The best thing to do is get a dial indicator, use springs meant for measuring, and check your existing clearance and lift. Then you know how much you can shave off the heads using your existing cam, and you have an idea what to expect with a new cam. Keep in mind that a higher lift cam will most likely open sooner as well, so you need even more clearance than this method would indicate. That means you need to measure again after you install a new cam.

Yes, this is a lot of work. But how much work will you need to do if you bend a valve, or ruin a cam lobe, or worse? It's cheap insurance.

[DartGT66]

As far as the valve to piston clearance goes, I have never figured out how to measure that with a hydraulic cam and unadjustable rocker gear? I built a low buck 440 using those 2266 pistons and the .509 cam in the spring, 906's milled .060" with steel shims. Didn't check the clearnaces though; maybe that's why it run like a shit and clattered a bit?

[72Challenger]

Two ways to check with hydraulic lifters I know of. Since the checking springs are really light, try filling the lifters with oil. They shouldn't bleed down during the test. Or find a spring that fits inside the lifter and that's stiff enough to overcome the valve measuring spring.

I'm sure there must be other solutions as well. Anyone?

[70gtx]

i still have one head on so ill check clearance with the stock cam &measure the lift on cam.let you know what i find.

[70gtx]

what is the proper way to check piston to vale clearance. i got a solid lifter & 0 clearance. shuold it be measured on the exhuast stroke and than on intake stroke at tdc or 10 before &10 after tdc.
i measured at tdc and came up with .182 intake &.336 exhaust .cam seems to have 435 lift &038 head gasket , .092 deck hieght.
something seems wrong.

[72Challenger]

Actually, that sounds like it could be right. At tdc, the exhaust is well on its way to being closed, any problems with it will likely come btdc. As for the intake, you'll likely hit the piston a little after tdc, so you could be closer than you think. BUT, you really should measure in 1 degree increments between 10 btdc and 10 atdc. Intake clearance shouldn't get less than .100, exhaust no less than .120. Yes, it's tedious, but a lot better than the consequences if it's wrong!

[DartGT66]

When ordering ROSS pistons you have to measure the valvelift at 6 degrees before and 6 degrees after TDC to get proper depth valve reliefs.

[Cameron's Racing]

70gtx, I put clay on top of piston, use old head gasket and install head, set valve adjustment and rotate engine one rev. Pull head and measure clay where valve has hit it.

Regards,

------------------
66 Belv 440 auto 10.76 @125
69 RR 426 wedge auto 9.74 @ 138

[70gtx]

well im not sure where to go from here ,maybe you can help . 440 +.030,.092 deck hieght,flat top trw with out relief. have .192 intake &.340 exhaust clearance with a cam with .435 lift . new stock heads about 94cc7.040 gasket, gives me 8.2to 1 .160 psi comp.
know if i shave heads .060 & use 020. shim gasket brings my clearance to .112 ,9.5to1, plus i want to puta mechanical cam in something close to the 509 hydr.which will give me more lift and duration,
question#1 is how much do you clearance will i loose.more than .012 . and
question#2 do they have a piston that i can use to get comp. to 10 to 1 with out shaving 346's with 94cc ? which is better

[Sport]

Gtx. Where do I go from here? Ive asked that guestion myself many times. Isee where your at, you want a bigger cam, more comp.but you have piston to valve clearances limiting you and I can tell you dont like it.Its all up to you as what you want to do.You can put new pistons in with big valve pockets and go with big big cam if you want.But it sounds like you already have a very good short block thats .030 over . I think the guestion is ,what are your intentions for the car this is going in? If you plan on driving this on the street stay away from the 509 and the 484 you can do it ,I did but Ihated those cams on the street, And I am a gear head! Besides redoing a short block that already sounds decent, 1 option is to build this short block closer to itscloser limitations because from what your telling me you still have room Go with a bigger cam like a comp extreme or a Hughes engine fast lift stay under 240@.050 and dont worry about P toV. Cl. Those cams will probably allow you to shave your heads .030 also for more comp. But always check If after you put this combo together you end up with 180 cyl.psi. .100 P.to V.Cl you will have maxed out your short block as it is currently built I know this is easier to say than do. For reference the 509 is 248@.050 and the484.is 241@.050 If you use the 509 you probably wont be able to shave anything and your cylinnder psi will plumet piston to valve clearence will be at their min. If you have a heavy car that wont help matters nuch . I know my car runs pretty good with the 509 but I have the valve pockets and extra comp to go along And a big thing I left out was is my sport only weights 2900# with me in it .And who cant make a car that light go fast SPORT

[Streetwize]

Okay...

I read this string as long as I could without chiming in but now is the time.

First off, With factory rocker arms (average 1.36:1 not 1.5 as Published) A .509" lift cam (for Example)is really only lifting about .460-.470" off the valve seat. You need to take this into account if you ever change to real 1.5 rockers in the future.
Also, when you go to tighter lobe seperation, overlap (exhaust closing and intake opening)increases relative to given durations. Intake centerlines should also be verified to your cam card with a degree wheel to be safe because some cheaper Aftermarket timing chain dots can be off 4 or more degrees. These are variables where piston to valve can get you into trouble. Also remember the larger the valve, the less clearance you have. For Hydraulics you can (generally) start running into trouble as early as about 230 @ .050" on a 108 separation, 235 @ 110 and about 240 on 112 on a blueprinted long block. If your block was not square decked, you better check a hole on both sides of your motor because it's not unusual to see .020-.025" difference in deck height on a factory block. As for checking piston to valve on a hydraulic, the simplist reliable way to do it is use a pair of solid lifters with checking springs.

Also, when shaving heads, you need to mill the intake side as well, but any experienced machine shop should warn you of that. If you go more than net -.060" (including head gasket)on your heads you better verify you're getting full clamping with your head bolts, you may need washers and/or re-tapping your threads with bottom taps. Rocker arm goemetry can (usually)be corrected with shims on hydraulic cam motors.

TRW 2266 are about 9.2 to 9.3:1 on a blueprinted square decked block and NHRA legal min. spec (79.5cc)heads. As most 440's are .020-.030 taller than spec and most factory heads cc at around 86-88 a non-blueprinted motor comes out to around 8.5-8.6 with a steel shim and around 8.2 with a "Blue" .037" Gasket.

Oh yeah, one other tid-bit. I would advise you to have your heads milled with the rocker shaft torqued in place, especially if you're not going to use a permatorque head gasket.

Hope this helps

Wize 1


------------------
Streetwize

[70gtx]

well thanks for all the good replies! what i should do is change the pistons but that will go to deep in the pocket right know to do it all the right way.so im going to pick a cam so far the comp cam 274/286 .507/.510 is looking good than i'll check clearance.shave heads from there. my machinist said isky makes a tool to fly cut pistons in the block.
ANYBODY HEARD OF THAT.
if i cant find one and worst comes out of all this ill make a tool out of an old head & valve and preset the depth so they all get cut the same and cross my fingers

[Streetwize]

Comp are really good cams but watch your running duration. They rate at .006 lift where as most others are at .0045. What this means is their 280 advertized is more like 290 in a Crane (for example). By the way, I think the cam you're referring to is an XE284 which is 240I/246@.050 and .507/.510.
The exhaust lobe is very close to the MoPar '509'. The Comp XE274 is about 230/236@ .050 and about .490 lift and I think would make a better choice for a 70 GTX (estimated Weight 3750lbs). Another very good choice for your car is the UltraDyne 288/290 grind which is 231I/239E .480/.507" cut on 108 and even with only 9:1 it is a SCREAMER.

Of Course if you used the mildly ported Stage V's as I've described elsewhere on this board you could use a broomstick that your dog chewed up for a cam (lol)and still make 450Hp & 500lb/ft.

Wize 1

------------------
Streetwize

[Sport]

Gtx. Its funny you considered that cam because I almost bought that at Summit because they didnt have the 509 in stock. I think thats the absolute biggest cam that you should use with your combo.For reference the mp 484/241@.050 at.075 in the hole deck hgt. had .120 clearance with heads shaved .020 on the intake . Ex. had plenty.200+ Still with 240@.050 car is abear to drive.I also tried the Eldelbrock RPM cam 480,intake 238@.050 495,Ex. 244@.050 idled better ran slightly slower than 484 but was more street freindly . Mp484 ran 7.44@92 Eld ran 7.47@91.44 Slower but much more street freindly. Icant compare the 509 because everything changed.The comp camthat you picked is similer to the Eld. but bigger,If you dont change anything I Would go the very next cam smaller, as Streetwize would suggest, and be safe .Streetwize has apost under Racing Forum about Dur@.050 for 440 street motors Good read check it out , I have heard of atool for fly cutting the pistons with the head on ,wish I would of had one when Iwas doing mine , Another story another time.Sport