Ptv questions
Ptv questions Hey gents. Im about to pull the trigger on a set of heads. (Tfs 245cc heads.) Was lookinging to mill to bring compression up. Motor is a lq9 block with a gen 4 rotating assembly. (Flat tops) cam is a 230/238 .626 .626 113+4 i want to mill the heads to 61cc. But i dont wanna have any ptv clearance. (I dont wanna flycut the pistons) the motor is not together and i have no way of putting the heads on before they are milled to check what my clearance is. Can anyone shed light on if you van calculate ptv without having parts in hand? Thanks for the help gents.
Not sure anyone can answer based on just the information provided. The opening/closing valve events, opening/closing ramps, advance/retard of the cam, etc. all play into this. I think the only thing you can do is get the heads unmilled and make a bunch of measurements to figure out if they can be milled and by how much. Also, with that high compression you probably want to minimize the quench to keep detonation in check.
The TFS heads should have more valve drop than the stock heads, so if the short block were together you might be able to use the stock heads to make some initial measurements and then make estimates from there if you know the valve drop differences.
The TFS heads should have more valve drop than the stock heads, so if the short block were together you might be able to use the stock heads to make some initial measurements and then make estimates from there if you know the valve drop differences.
Not sure anyone can answer based on just the information provided. The opening/closing valve events, opening/closing ramps, advance/retard of the cam, etc. all play into this. I think the only thing you can do is get the heads unmilled and make a bunch of measurements to figure out if they can be milled and by how much. Also, with that high compression you probably want to minimize the quench to keep detonation in check.
The TFS heads should have more valve drop than the stock heads, so if the short block were together you might be able to use the stock heads to make some initial measurements and then make estimates from there if you know the valve drop differences.
The TFS heads should have more valve drop than the stock heads, so if the short block were together you might be able to use the stock heads to make some initial measurements and then make estimates from there if you know the valve drop differences.
Thanks for the info. I was affraid of that answer. I figured it to be the case but wasnt sure. Good info on the quench as well. That was something i had also planned on keeping low as possible to help with detonation to be able to run the compression i wanted. But i also plan on running e85 so im not to worried about detonation. Although i would have a 91 tune as well. Looka like what ill do is get them at 65cc. (I know that will clear) and then measure and see if its worth going down to 61cc. Thanks for the help. Hopefully ordering the heads tomorrow. 🖒 by the way i think the valve drop difference is 50 thousands difference. If i remember correctly. But dont quote me on that because valve drop is new to me so i could very much be wrong haha.
Idk if this helps but i read a post where a guy had an ls2. With trickflow tfs 225 heads. An eps 230/238 604/600 112+2 cam. And milled to 61cc. I know mine has quite a bit more lift. but duration is the same and hes on a 112 not 113. Which from my understanding gives me more room? Thanks again.
Staging Lane
Joined: May 2013
Posts: 67
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I recently finished assembling and breaking in my new engine for this pulling season. Engine Specs:
- LQ9 Stock Short Block, Floater Piston and Rods (Gen 4 Style)
- Tick SNS Stage 2 (231/235, .625"/.605", 111+2)
- 799 Heads Milled .030", 60cc Chambers, Manley Race Valves (Stock Size)
After final assembly, I have more then .110" Exhaust, .095" Intake Clearance, which Martin @ Tick informed me was enough to feel comfortable. I'm thinking it's worth checking but should be very close, hopefully will be enough
- LQ9 Stock Short Block, Floater Piston and Rods (Gen 4 Style)
- Tick SNS Stage 2 (231/235, .625"/.605", 111+2)
- 799 Heads Milled .030", 60cc Chambers, Manley Race Valves (Stock Size)
After final assembly, I have more then .110" Exhaust, .095" Intake Clearance, which Martin @ Tick informed me was enough to feel comfortable. I'm thinking it's worth checking but should be very close, hopefully will be enough
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I recently finished assembling and breaking in my new engine for this pulling season. Engine Specs:
- LQ9 Stock Short Block, Floater Piston and Rods (Gen 4 Style)
- Tick SNS Stage 2 (231/235, .625"/.605", 111+2)
- 799 Heads Milled .030", 60cc Chambers, Manley Race Valves (Stock Size)
After final assembly, I have more then .110" Exhaust, .095" Intake Clearance, which Martin @ Tick informed me was enough to feel comfortable. I'm thinking it's worth checking but should be very close, hopefully will be enough
- LQ9 Stock Short Block, Floater Piston and Rods (Gen 4 Style)
- Tick SNS Stage 2 (231/235, .625"/.605", 111+2)
- 799 Heads Milled .030", 60cc Chambers, Manley Race Valves (Stock Size)
After final assembly, I have more then .110" Exhaust, .095" Intake Clearance, which Martin @ Tick informed me was enough to feel comfortable. I'm thinking it's worth checking but should be very close, hopefully will be enough
Thats awesome. With the 13.5* valves my heads have i should be able to clear the bigger cam no problem. I think im gonna have him to the 61cc. And i guess if i have to flycut ill flycut but i dont think ill have to.
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