Jason99T/A

iTrader: (21)

We finally had some time to check the piston-to-valve clearance with the Thunder 230 cam. With stock heads, the cam had 155 thousandths of clearance on the intake side. With a set of GTP stage 2 5.3l truck heads (my old solid roller heads), the intake valve had 80 thousandths clearance. These had a 2.02 intake valve and were milled 15 thousandths.

You should regularly shoot for a minimum of ~80 thousandths clearance on the intake valve.

The cam is on a 111 lsa, with 0 degrees of advance ground into it.

Jason

<small>[ June 07, 2002, 11:10 PM: Message edited by: Jason99T/A ]</small>

DravenMyers

Thanks Jason, so there shouldn't be any piston to valve clearance problem with my 5.7 GTP Stage 2 heads, right? <img border="0" alt="[devil]" title="" src="graemlins/gr_devil.gif" />

VINCE

iTrader: (1)

I think Jason's old heads were milled 15 thousandths... The 5.3L ones..

DravenMyers

So which pushrods will I need, 7.350 or 7.400 <img border="0" title="" alt="[Confused]" src="images/icons/confused.gif" />

Jantzer98SS

iTrader: (54)

I have a few questions:

1) How much is milled of the 5.3 heads?

2) How much advance is ground in the TR224?

And just out of curiosity, if you advance a cam, doesn't the clearance diminish even more? Is that why you Thunder chose not to grind any advance in the cam?

Jason99T/A

iTrader: (21)

DravenMyers: Do you know how much your heads have been milled? Normally, the 5.7l GTPs are milled 30 thousandths. This will be cutting it very close in terms of piston to valve clearance. Have your heads been finished yet? If not, just tell Craig to mill them 15 thousandths if you want to be on the safe side.

Jantzer: The 5.3l heads were milled 15 thousandths.

Retarding the cam opens the exhaust valve earlier and the intake valve later. This give you more clearance on the intake side, and less on the exhaust side. Advancing the cam will bring the intake closer and the exhaust slightly further from the piston during the overlap period (where piston to valve clearance becomes an issue).

The TR 224/224 has 4 degrees of advance ground into it. The TR 230/224 has 0 degrees advance ground in. This was done to help top-end power, since retarding the cam moves the powerband upward.

<small>[ June 07, 2002, 11:48 PM: Message edited by: Jason99T/A ]</small>

AlonzoVersion 1.0

Time to pay up fellas I told you it would clear.Thanks for the info. <img border="0" alt="[Firebird]" title="" src="graemlins/formula.gif" />

DravenMyers

</font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by Jason99T/A:
<strong>DravenMyers: Do you know how much your heads have been milled? Normally, the 5.7l GTPs are milled 30 thousandths. This will be cutting it very close in terms of piston to valve clearance. Have your heads been finished yet? If not, just tell Craig to mill them 15 thousandths if you want to be on the safe side.

Jantzer: The 5.3l heads were milled 15 thousandths.

Retarding the cam opens the exhaust valve earlier and the intake valve later. This give you more clearance on the intake side, and less on the exhaust side. Advancing the cam will bring the intake closer and the exhaust slightly further from the piston during the overlap period (where piston to valve clearance becomes an issue).

The TR 224/224 has 4 degrees of advance ground into it. The TR 230/224 has 0 degrees advance ground in. This was done to help top-end power, since retarding the cam moves the powerband upward.</strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">Jason, I bought my heads from Thunder and I already recieved them. So, I guess they are milled 30 thousandths <img border="0" title="" alt="[Confused]" src="images/icons/confused.gif" /> <img border="0" title="" alt="[Embarrassed]" src="gr_emb.gif" /> Should I just stick with the TR224 then?

VINCE

iTrader: (1)

Draven you could see if you can find someone to cut valve reliefs in your pistons for you to be on the safe side. I would not take any chances with our engines. Downtime sucks..

The Emperor Of Darkness

so, how big cam can you go til yu get into valve clearence problem for those heads?? either solid or hydraulic! with stock pistons that is! <img border="0" alt="[Firebird]" title="" src="graemlins/formula.gif" />
Thanks,
Ahmad

<small>[ June 08, 2002, 04:57 PM: Message edited by: The Emperor Of Darkness ]</small>

Jason99T/A

iTrader: (21)

Draven, you will need 7.350" pushrods.

As Vince said, you can either have someone notch your pistons or just use the TR224 cam. Using the 230 with that setup is going to very risky, IMHO.

The 230 cam is about the biggest I would use with the GTP stg 2 5.3l heads (milled 15 thous.)

Jason

<small>[ June 08, 2002, 11:49 PM: Message edited by: Jason99T/A ]</small>

Elite_Hot_Rod

Jason,

I have a set of the TR/GTP Stage II heads, they are the single spring type are they the 5.3L or 5.7L ones? TIA,

Mark

GS WS6

Mark,

Your car has the 5.7 heads on it <img border="0" title="" alt="[Smile]" src="gr_stretch.gif" />

I am still surprised that everyone is not bringing up the MTI X1 cam.......It is a 230/227 .591/.571 on a 112. That is ALOT more lift than the thunder cam and it is still not having P/V clearance issues.......

Jason99T/A

iTrader: (21)

Matt, lift is not really that important when it comes to piston to valve clearance. Max lift usually occurs when the piston is the furthest away from the valve (i.e. traveling downward). Duration, ramp rates, lope seperation angle, valve size, head gasket thickness, advance/retard, amount milled off the heads, etc. play much more important roles in determining if a cam will have sufficient clearance.

Also, as far as I know, I haven't seen anyone post the X1 cam's clearance with a set of stock/ported heads. Until we do so, you will never know how much clearance there really is. <img border="0" title="" alt="[Smile]" src="gr_stretch.gif" />

<small>[ June 09, 2002, 03:43 PM: Message edited by: Jason99T/A ]</small>

Elite_Hot_Rod

Jason/Matt,

I'm getting ready to put a bottle on it(NX GM EFI)no more than 100LB shot and was thinking about doing a cam swap from the TR 224/224 112LSA to the TR 230/224 111LSA cam. Am I going to run into any P to V clearance issues? I was also thinking while ordering the cam to have TR grind in 4 degrees of advance. Will I have any problems other than a choppey idle? TIA,

Mark

GS WS6

Jason,

The reason I ask, is that my car is currently down and I am going to be running a custom cam that is very similar to the X1. I know that it is going to be very close P/V clearance wise.....

Comp Cam 230/226 .592/.570 on a 112 w/ 2 degrees advance ground in......

The intake lobe will be on the Comp XER lobe, and the exhaust on a slightly less agressive lobe.

My heads have been milled .030 and I am also running 2.055/1.60 valves. I would imagine that it SHOULD clear, but I am gonna have to play with it during assembly <img border="0" title="" alt="[Smile]" src="gr_stretch.gif" />

Mark,

You should not have any P/V clearance issues to speak of with the Thunder 230/224 cam, but the extra 4 degrees of advance you speak of has not been tested........If you can wait about 3 weeks or so we shold have some results back on that F1 cam that I am gonna be trying out <img border="0" title="" alt="[Big Grin]" src="gr_grin.gif" />

<small>[ June 09, 2002, 04:52 PM: Message edited by: GS WS6 ]</small>

Elite_Hot_Rod

Matt,

I may have to put it all off for a while now.This evening I went up to see if the Denton 1/8 mile was finished and on the way home I think my rear end went **** up. Actaully I think it broke a bearing or the ring gear, hopefully not one of those new Moser axles I've got in there. I'm gonna have to call your Hurst shop and see If I can get it in there tomorrow and have them take a look at it. Whats the name of the gear guy over there? TIA,

Mark

AlonzoVersion 1.0

I knew it would fit without out even measuring just by looking at Terry Burgers set-up 229/229 dur .570/.570 lift with 5.3 heads milled 15 thous.

Speed Demon

iTrader: (14)

</font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif"> We finally had some time to check the piston-to-valve clearance with the Thunder 230 cam. With stock heads, the cam had 155 thousandths of clearance on the intake side. With a set of GTP stage 2 5.3l truck heads (my old solid roller heads), the intake valve had 80 thousandths clearance. These had a 2.02 intake valve and were milled 15 thousandths.

You should regularly shoot for a minimum of ~80 thousandths clearance on the intake valve.
</font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">Would stock (unmilled) 5.7L heads have the same P to V clearance as stock, unmilled, with same size valves, 5.3L heads?

If so how did the clearance go from 155 thou to 80 thou by only cutting off 15 thou?

Is the height (or depth) of the chamber shorter stock on the 5.3 heads than the 5.7?

I am curious because I am running 6.0L heads that have been decked 0.030 and want to know if mine would clear or need reliefs for this cam.

Jason99T/A

iTrader: (21)

Booker Man: There is a big difference between fitting and actually having adequate clearance. <img border="0" title="" alt="[Smile]" src="gr_stretch.gif" /> We all knew the cam would physically clear the pistons, but we did not know what that clearance would be until we actually measured it.

Speed Demon: Yes, the clearance would be the same if you put 2.00/1.55 valves in an unmilled 5.3l head.

Taking 15 thousandths off the deck of the head does not mean you loose exactly 15 thousandths clearance. Everything is at an angle, so you would have to use some trigonometry (set up a triangle, etc). Also, going to larger valves reduced the clearance as well.

<small>[ June 10, 2002, 10:50 AM: Message edited by: Jason99T/A ]</small>