440 piston to valve clearance

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Thenwhat85

Thenwhat85

built not bought
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north royalton, Ohio
Hello all. I'm building a 440 with stock stroke, rods(upgraded bolts). And trw dome pistons (2295f .030 over). I purchased a solid roller cam from Hughes. With 1.6 rockers. Total lift is .618 on the intake. I have promaxx heads milled to 75cc (.030 I believe) and the piston are in the hole .050. To get my cam cl correct I need to advance it 4 degrees. Awesome... but intake p2v clearance is only .040 at 10' abdc. I'm running a .020 head gasket and want to keep it for compression (will go to .040 if need be. Question is should the p2v clearance be so close? I've read p2v isn't a huge problem with these motors. And I was talking to another guy with a 440 bigger cam and .000 decked pistons with no problems. Thanks any help is appreciated and sorry about the long post

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While .040" is a little close for me, but I like to be on the safe side.

I like a minimum of .080" on the intake and .100" on the exhaust.

Get a couple valves that are a little larger and glue some 80 grit sand paper on them.

Grind the notches deeper and use a shop vacuum to remove the dust. Done it many times with no issues.

Tom
 
I think U meen 10* atdc, is the least amount of clearance at that point, or did U only check at that point? in other words did U check at 9* and 11* atdc? is this with the .022'' lash? what is minimum exh v to p? to gain intake clearance put the cam in at 107* cuz .040 is not enough
 
Marcohotrod said:
I think U meen 10* atdc, is the least amount of clearance at that point, or did U only check at that point? in other words did U check at 9* and 11* atdc? is this with the .022'' lash? what is minimum exh v to p? to gain intake clearance put the cam in at 107* cuz .040 is not enough
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call dave.
 
Yes I meant atdc. At 4 deg. Advanced. I'm at 106.5, 2 Deg. Advanced puts me at 107.25 I believe. The cam degreeing is a whole nother story. I have no problem removing the piston to notch them. And I didn't check exhaust yet. Hughes recommends .060 in an .110 ex.
 
Did you check it with clay and the spring load you are going to use, or did you soft spring it?

If you use soft springs, they lie and cause you to waste P to V.

In reality, the clearance between the intake valve and piston can be as little as piston to head clearance. That means if you have .040 piston to head, that's all the P/V you need. The exhaust needs a bit more. I don't like to go below .070 keeping in mind that is with the head gasket in place, valves lashed and the spring load you are going to run.
 
I used soft spring and adjustable pushrod. Did use clay but didn't like it. It did show that my valve relieves are not flat, so I smoothed them out and gained a little more. I set the valve at zero lash.have not checked piston to head clearance. And did have my head torqued with gasket
 
Thenwhat85 said:
I used soft spring and adjustable pushrod. Did use clay but didn't like it. It did show that my valve relieves are not flat, so I smoothed them out and gained a little more. I set the valve at zero lash.have not checked piston to head clearance. And did have my head torqued with gasket
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You will GAIN clearance when you use the spring you are going to use. So I understand what you are saying, you used clay and soft springs? Or you used clay and the spring you are going to run?
The amount of clearance you gain will be based on what brand rocker you run. Quality rocker arms have an engineered amount of flex built into the design. I don't like doing a mock up and using parts for th mock up that you aren't going to run.
 
I did both ways (clay and dial)with soft springs. Hughes adjustable pushrod. And Hughes 1.6 rockers arms. With clay it seem I have enough radial clearance and p2v. But when checked with dial p2v is less
 
Thenwhat85 said:
I did both ways (clay and dial)with soft springs. Hughes adjustable pushrod. And Hughes 1.6 rockers arms. With clay it seem I have enough radial clearance and p2v. But when checked with dial p2v is less
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That's what I thought you meant.
Clay with a checker spring won't work. It will just compress the spring and not the clay. It will be less with the dial indicator. Go with the DI numbers.
 
Why roll the dice? I've always stuck to .080/.100 clearance. Either cut the pistons more or thicker head gaskets. Also if your checking at zero valve lash, you will gain the valve setting clearance in distance.
 
I'm going to get my p2v .060in and .110ex. I was really asking if it is common to have p2v issues like this. I mean it's not crazy big lift and I'm not at zero deck. The heads were cut but only to go from 84cc to 75cc (.030 I think) again thanks for all your input I appreciate it and at this point should I check every cylinder?(really don't want to but I will)
 
I agree with yellow rose that using the springs you will actually run will result in more clearance, BUT like Roy said, why take chances? There's too much money involved not to make SURE you have enough clearance.
 
RustyRatRod said:
I agree with yellow rose that using the springs you will actually run will result in more clearance, BUT like Roy said, why take chances? There's too much money involved not to make SURE you have enough clearance.
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why don`t u sell your 1/6 rockers, and put 1.5`s on it / that would give u about .040 more clearance. easest way out !
 
Yeah that's not going to happen. I want the lift. And the compression. I'm either going to notch the pistons or go with a thicker gasket.
 
Thenwhat85 said:
Yeah that's not going to happen. I want the lift. And the compression. I'm either going to notch the pistons or go with a thicker gasket.
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The thicker gasket will cut the compression you said you want.
 
Yeah I know. With the .020 shim gasket I'm at 12.3 if I go to .040 it puts it at 11.8 so half a point. Not sure how much I'll lose notching the pistons. Probably not to much
 
Thenwhat85 said:
Yeah I know. With the .020 shim gasket I'm at 12.3 if I go to .040 it puts it at 11.8 so half a point. Not sure how much I'll lose notching the pistons. Probably not to much
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I wouldn't think it would be as much as the gasket.

I would put the proper springs on first and see how much more space that gives you. You may find that you need nothing but that.
 
Thenwhat85 said:
Why does putting the springs I'm going to use different from soft springs? Pushrod flex?
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Using the valve springs you will actually run will take up any extra slack out of the locks and retainers and give you a little more room. That's the down side of using soft springs to check clearance. You don't always get the truth.
 
RustyRatRod said:
Using the valve springs you will actually run will take up any extra slack out of the locks and retainers and give you a little more room. That's the down side of using soft springs to check clearance. You don't always get the truth.
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It's not about locks and retainers and installed spring height, if it were...that would help gain some notable installed spring height.
The actual installed spring pressure will set the valve in the seat a hair, close a .001 gap in the roller tip rocker and bore ... but its not gonna be an earth shattering amount and fix his P/V clearance problem. I myself pay more attention to the exhaust valve to piston clearance...in this case i would check that and then make my decision to tear into it or not, but...based on 12 something compression ratios and assuming he is going to to wing ding it...i , for his sake, will also recommend staying with industry standard V/P clearance. For the record....im fine with a min .060 on the intake V/P.
 
Yeah it's going to be a drag only bracket motor. But I want it to be reliable and not have to mess with it. Do it right the first time kinda thing. I'll check everything again this weekend.
 
MOPAROFFICIAL said:
It's not about locks and retainers and installed spring height, if it were...that would help gain some notable installed spring height.
The actual installed spring pressure will set the valve in the seat a hair, close a .001 gap in the roller tip rocker and bore ... but its not gonna be an earth shattering amount and fix his P/V clearance problem. I myself pay more attention to the exhaust valve to piston clearance...in this case i would check that and then make my decision to tear into it or not, but...based on 12 something compression ratios and assuming he is going to to wing ding it...i , for his sake, will also recommend staying with industry standard V/P clearance. For the record....im fine with a min .060 on the intake V/P.
Click to expand...

I was citing my own personal experience using the soft checking springs. Thanks for your opinion.
 
Thenwhat85 said:
Yeah I know. With the .020 shim gasket I'm at 12.3 if I go to .040 it puts it at 11.8 so half a point. Not sure how much I'll lose notching the pistons. Probably not to much
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If you have the ability and the tools, or someone to do it, the best fix is notch the piston. The problem is guys want a mile of radial clearance, or they don't have th correct tooling so they just make a big cut. Then you just pissed away all the compression you tried to save and it would have been easier to use a thicker gasket. That very thing caused me to buy my own piston vice.

The reason to use the springs you will run is because ALL rocker arm shave flex engineered into them. Or they should. I'd bet a substantial pile of cash that if you measured your lift at the retainer with checker springs, you will see more lift than you should. And the rocker ratio will be greater than advertised. As an example with a 1.6 rocker and a .400 lobe you should have .640 lift with zero lash. With checker springs you may see .656-.660 lift. That's because the springs won't flex the rocker. Put your valve springs on and it will b nuts on.

I learned this because I bought some Norris 1.6 rockers one time. Nice stuff. I was mocking stuff up for p/v and all that and I had way more lift than I should. So I put my indicator on the lobe. It was dead nuts on. Called Norris and they said that's they way they are made. I hung up and called Wayne Jesel. He verified what Norris said.

To this day, I never check anything valve train related without the actual spring fitted.
 
Well if that's the case then I need to order my pushrods first. Because I'm using an pushrod length checker and soft spot springs. I'm sure if I used the solid roller springs it's going to flex/bend the pushrod tool a little too much. And how are you compressing the valve spring at 10 atdc with 400+ lbs of pressure. Or are you measuring valve drop first and then just subtracting lift.
 
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