Hello everyone new here i just have some ?'s concerning a 383 block that has a 0 deck.I plan on using trick flow heads flat top pistons.What head gasket and push rods would you recommend on this engine ? wanting to see if i will have any piston to valve issues . Any help would greatly be appreciated.
mak567
Nobody can tell you whether or not you will have piston to valve interference. There are many variables involved and each engine build must be measured. Here are some articles to help you....
http://www.racingheadservice.com/Information/Technical/PistonToValveClearance.asp
http://www.popularhotrodding.com/en...articles/hardcore/0607em_high_performance_engine_building/piston_clearance.html
http://www.iskycams.com/camshaft.php
Normally, if you are seeking a good, tight squish to ensure that the motor will run on pump gas without pinging, you will want to set up any small block Chevy with 0.035" to 0.045" squish. With a zero deck, the thickness of the head gasket is the squish. Use caution when using aluminum heads, use only the head gasket recommended by the head manufacturer to prevent brinelling of the head. No such caution is necessary with iron heads.
If you would like help with choosing the right cam the first time, call up your favorite grinder and ask for a recommendation. You must know some things about your motor before the call, such as the REAL AND ACTUAL static compression ratio, not what the piston manufacturer calls the piston. In other words, if you buy a piston that is advertised as a "9 to 1" piston, then all of the other components of your engine must match those used on their "9 to 1" engine. You have to use the same bore and stroke, the same piston deck height as they did, the same chamber size in the heads and the same head gasket thickness as they did. Pistons alone do not determine the static compression ratio.
The 5 values which need to be determined in order to calculate the SCR...
1. cylinder volume in cc's
2. actual combustion chamber size in cc's (determined by pouring the heads)
3. piston crown configuration and subsequent (-) or (+)
4. piston deck height volume in cc's
5. head gasket volume in cc's
If there is any of this stuff that you don't understand, just ask. I'm a pretty good teacher.
Richard
http://www.racingheadservice.com/Information/Technical/PistonToValveClearance.asp
http://www.popularhotrodding.com/en...articles/hardcore/0607em_high_performance_engine_building/piston_clearance.html
http://www.iskycams.com/camshaft.php
Normally, if you are seeking a good, tight squish to ensure that the motor will run on pump gas without pinging, you will want to set up any small block Chevy with 0.035" to 0.045" squish. With a zero deck, the thickness of the head gasket is the squish. Use caution when using aluminum heads, use only the head gasket recommended by the head manufacturer to prevent brinelling of the head. No such caution is necessary with iron heads.
If you would like help with choosing the right cam the first time, call up your favorite grinder and ask for a recommendation. You must know some things about your motor before the call, such as the REAL AND ACTUAL static compression ratio, not what the piston manufacturer calls the piston. In other words, if you buy a piston that is advertised as a "9 to 1" piston, then all of the other components of your engine must match those used on their "9 to 1" engine. You have to use the same bore and stroke, the same piston deck height as they did, the same chamber size in the heads and the same head gasket thickness as they did. Pistons alone do not determine the static compression ratio.
The 5 values which need to be determined in order to calculate the SCR...
1. cylinder volume in cc's
2. actual combustion chamber size in cc's (determined by pouring the heads)
3. piston crown configuration and subsequent (-) or (+)
4. piston deck height volume in cc's
5. head gasket volume in cc's
If there is any of this stuff that you don't understand, just ask. I'm a pretty good teacher.
Richard
Go buy yourself a few simple tools that EVERY engine builder should have.mak567 said:
Checking springs
Adjustable pushrod checker
Dial indicator
Total of $50
p-to-v issues usually arise when running big camshafts that have tight LSA's. You can run fairly aggressive camshafts and not have p-to-v issues if the LSA is wide, such as on a 114 or so. Running a thicker head gasket to get a little more p-to-v clearance is never the way to go. You simply have to check it by yourself to be sure. Most aftermarket flat-top pistons will have at least 2 valve reliefs.
The motor I just built had flat-top pistons with 6cc's worth of valve reliefs. The heads were AFR 227's with 65cc chambers. My cam was pretty big but it was ground on a 105 lsa which made the clearances too tight. I advanced the cam 4 degrees and the exhaust was easily in spec, but the intake was too close. Retarding the cam 4 degrees brought the intake within spec too, but then the exhaust was too tight. In my case I had to cut notches in the pistons to get the p-to-v clearance I needed, but had I ordered the cam on a 113 LSA it would have went in without a problem.
Typically you want at least .100" of p-to-v clearance on the exhaust side, but you can run it way tighter on the intake side. You run into issues when you don't get all of the proper supporting valvetrain components in place. Having the proper springs to do the job is the most important thing. Then you want to lighten the valvetrain wherever you can. This makes the springs job easier to do. Titanium retainers and locks, some chromoly thinwall pushrods, etc, etc.
When a piston hits a valve it is almost always the exhaust valve. On the exhaust stroke the exhaust valve is slowly closing, but the piston is coming up very fast, chasing it. If the springs aren't up to snuff, they can lag behind just a tiny bit, and if the clearance was tight to begin with, contact can be made. As the piston is chasing the exhaust valve upward, the intake valve is slowly opening. For a brief moment, the intake valve is opening downward, while the piston is still coming upward finishing the exhaust stroke. Once the piston hits tdc at the end of the exhaust stroke/beginning of the intake stroke, it will head back down and pull away from the intake valve very fast. But for a brief moment they will be very close. The clearance doesn't need to be much to be safe, 050" is fine. Just make sure your timing chain is tight. As they wear out and get slack they can vary a few degrees on hard acceleration and deceleration, lol.
Just to complicate things a little, lol, not all pistons will be notched in a way that lines up with the cylinder heads you are running. Here's a picture of the pistons I just notched. Notice how much lower the exhaust valve (notch on the left) actually opens relative to where the notch is on the piston:
What cc TF heads? What static cr are you aiming for? What cam?mak567 said:
I am using TF 23* 64cc heads on my '0' decked block. I built it to run on pump gas. Using 12cc dish pistons and 0.041 Felpro head gaskets. Static CR is 10.30 and it runs on 89 octane. Cam is a CC XE274H. Intake closing is +/- 60* ABDC. Late closing of the intake valve helps with high static CR.
I have no P/V issues. You have to check, yourself, as to what pushrod length to use.
Once you know the head cc and the piston cc, there are many online CR calculators. Ideal quench is +/- 0.040. With '0' deck block the quench will be the head gasket thickness.
Run a 3.48" stroke is one way to get close to 10.5:1.mak567 said:
If you're "hoping for 10.5", and considering where you are now, you're gonna need a ~6cc larger chamber (combined w/a 6cc valve relief FT piston) or a 12cc inverted dome dish, or some combination of the two to get it done, while maintaining a tight quench. BTW there are quite a few gaskets w/a 4.090"-4.1" bore diameter.
The different calculators do not agree on this point. The one I use HERE uses a negative number for a dished piston. The one found at Wallace uses a positive number for a dish.383elky said:
This same discrepancy can be seen between the various piston makers in the catalogs, etc. Some use a negative for dish, and vice versa- so be sure of what the calculator "wants" in that regard.
If you'd like, we can input your numbers and give you your correct CR. I'd say judging by the CR you got that the number for the piston volume should have its sign reversed, if the parts and specs you used are similar to those above.
Trick flow heads
I used a felpro .039 gasket with mine and the pistons were .006 in the hole and had no issues but i had KB135 pistons. Setup had very little knock counts/pinging issues. I used a Comp Cam 12-365-4. Ran great until the cam went flat. Don't think I will ever use a flat tappet again. Listen to Tech.
I used a felpro .039 gasket with mine and the pistons were .006 in the hole and had no issues but i had KB135 pistons. Setup had very little knock counts/pinging issues. I used a Comp Cam 12-365-4. Ran great until the cam went flat. Don't think I will ever use a flat tappet again. Listen to Tech.
cobalt327 said:Gregg, IIRC it is a Comp 292H.
Welcome aboard. So you w/TFS, huh?
Thank you and yes I am with TFS.
I would like you to stick with our heads,from what I see from the thread and what I have calculated I would suggest you return the heads you have to go with our 72cc heads.
If I calcuated correctly the 72cc heads with a .039" gasket you will have 10.17:1 compression if the block is zero decked.
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