So I had a thought today. I wanted to check piston to valve clearance before I sent my heads off to be ported. That way I would know how much could be milled off and not worry about it. So there are several different ways to do this. I prefer the Play-dough method. This requires me to steal my daughters Play-dough and put it on the piston. Bolt the head on with an old head gasket. Then put on two rocker arms with push rods and then turn the motor over a few times. Then measure how far it dented the Play-dough. The issue with this is that sometimes the lifter will collapse. They sell "test" springs and solid lifters bla bla bla. I'm not spending money on more tools so I made my own solid lifter today.




So I dug through my bin of random lifters and found two promising candidates. They didn't look collapsed and not too rusted.



So these will serve two purposes. I can use them to find the piston to valve clearance with the old factory springs that are on the head. And I can use them when I get the heads back and need to check push rod length. Or maybe I'll just weld 14 more and have a solid roller cam.

 

So today in the mail I got a new set of LS7 lifters and a Summit Racing rocker trunion upgrade kit. I know I said that I was going to put in old lifters. But the LS7 lifter from Summit were cheap and the old ones I had were pretty rough. Most of them had over 250k miles on them. So I pulled the old lifters out and put the new ones in. I had pulled a set of rockers off of an Impala SS last year. They only had about 50k miles on them. So I ran them through my super high end Cascade Mineral Spirits parts washer.



I had already pressed the old bearings out the other day. So this is what I have to work with.



The Summit kit was really well packaged. I felt like I was opening a case full of jewels.

So 30 minuets later I had them all done.






The Summit install tool works well and I feel it was worth the $15. But you could do this without it if you have a collection of sockets.

 

I used the same lifters in my build. They work fine and nice and quiet. I used a pushrod length checker and bought a new set of pushrods.

 

I like playdough. And that kit from summit is nice. May be doing a cam swap in the escalade so I'm going to tab that.

 

Well my son and daughter are a little upset with me. I owe them some Play dough.


I bolted one of those greasy 799 heads with an old head gasket to my motor. I threw in my two solid lifters and a couple old push rods.

Best I can tell I have .200" clearance on the exhaust valve and about .230" on the intake with the stock 799 heads. At least that's what the blue calibrated Playdough has told me. From what I have read if I have at least .100" I'm good to go. So this should mean that I have lots of room with my cam and pistons to have these heads milled anyway I want.

So if I send the set of 799 heads that I pulled last weekend off to be ported they will finish with a 69cc chamber. I think I'll have them mill that down to a 65cc. That will give me a 10.8:1 static compression ratio and a 8.46:1 dynamic. I think that will run on 93 octane and be an awesome street car. I'm not sure how much nitrous I can get away with having that much compression. I'll start with a 150 shot and see what happens. If it blows up then I guess I went too far. Then I'll have to swap the LS6 back in. I guess if that's my worst case scenario then I'm in a good spot.

I do want to mention that I haven't 100% made up my mind that I'm going to have the heads ported. It's a lot of money for 30-40 hp. And I do HATE parts being in machine shop hell. So I'm toying with the idea. But these heads very well may just get bolted on as it. Well I might clean them first.

 

I was a little nervous about the Summit bushing kit at first after reading some of the reviews. But the tolerances on my kit were really good. The bushings all fit really well. Everything was perfect. The price was good too. I wanted to go with the bronze bushings instead of the roller bearing kit. I never understood the logic of swapping out one roller bearing for another. Seems silly to me. But the bronze bushings I get. Worst case they might wear out and make some noise. But they won't put metal in the motor.

 

grabbing the lq9....hysterical

 

Ok so I have a problem. I need some advice. After I made my last post I was cleaning up and I noticed that both of my welded lifters had broken the tack welds that I put on. The stock spring pressure was too much and broke the weld. This collapsed the lifter. So my readings were way off. No big deal. I made a trip to Tractor Supply and got a two pack of springs that fit in the place of the stock valve springs. Then I plopped my Play-dough back on and turned it over. This is what I saw.






So now I'm left with a dilemma. The only reason I went with this cam is because the tech at Summit told me it would work. I thought about advancing or retarding the timing. But if I understand that right it will act like a see saw. It will give less clearance to one valve and more to the other. The only option I'm seeing is to get a different cam. What do you guys think?

 

So let me just say Summit Racing is awesome. I just got off the phone with there customer service. One of the reasons I went with this cam was because of the Summit tech on the LS1tech.com. So I told customer service that. He had me show him the link to the post over there. He read it and said "I'll send you a return label now". So I guess I'm getting a new cam. I'm not sure what to get though. I kind of had my heart set on this one.

 

Summit used to do custom grinds about the same price as a normal cam cost. Maybe see if they'd be willing to do a custom of that exact cam specs just with a little less lift? Then you'll have the cam you knew was going to work well and the piston to valve clearance you need? Just a thought....

 

I feel like something was off on your 2nd attempt at checking PTV...
I've ran much larger cams than that one and didn't have anywhere close to issues with PTV.
Are you sure that the stock length pushrods were the correct length for you?
Why not just use stock lifters and calculate preload to rule out possible issues with lifters/pushrods?

 

I'm not sure that the pushrod is right. This is what I'm going to check when I get home. To be honest I'm not sure how to calculate preload on an LS7 lifter. I know they have .200" total "squish" but in this situation I don't know how that translates into PTVC. So what I'm going to try is to use my welded lifters and then a push rod length checker. Put the cam on base circle and set the checker to zero lash. Then try again. Hopefully everything will be fine. But like I said I have low expectations. I didn't see that valve move at all with the factory pushrod. But who knows, I may have just missed it.

 

How much did you mill the heads?
I would use less clay too. Put it on pretty thin, like .150".

From the pic of your welded lifter it looks like the tack welds might be interfering with the pushrod and not letting it sit all the way in the cup. Can you use another lifter and lock the plunger some other way? Like with small washers or something?

 

As far as I know the heads are stock. I pulled them off a wreaked truck. The pushrods seem to fit all the way into the lifter when I hold the lifter and a pushrod in my hand. But there could be something I'm not seeing. Either way if I'm understanding it right, I should be able to find zero lash with these lifters and a push rod length checker and try it again. If that doesn't work I can try taking a lifter apart. I have a bucket full of them. Also I plan on filling the chamber of the heads with water to get a rough idea on CC size. It won't be exact but it should tell me if there is anything crazy going on.

 

Ok so I have at least a little figured out. The stock length push rods are in fact too long. So to check this I threw out my welded lifters. Then I took a lifter apart and flipped the internal plunger around backwards. This basically makes a solid lifter. I found a video showing how this works. I put my length checker in there with my new solid lifter and set zero lash. My checker says that I need a pushrod that is 7.324" long. The factory rods are 7.380. I did the clay test again but so far only on the exhaust side and got .180" PTVC. So my piston to valve clearance is good. But this raises a question. Were these heads decked or do Summit cams require shorter pushrods? I pulled the heads off a truck in a junk yard. So anything is possible. I need to figure this out because with stock heads it would put me at 10.9:1 compression. I don't want to go any higher.

 

Might not hurt to try and measure the chamber volume in the head if you have a piece of scrap plexiglass and a graduated syringe. I think Jegs/Summit sells a kit for $20 as well. I'd highly doubt heads from a completely stock junkyard truck would have had work done to them, but better safe than sorry I suppose.

There's a more in depth way to measure valve clearance with checking springs and a dial indicator if you have the time. Although the playdough method is probably fine as long as you get consistent measurements if you repeat it.

 

Yeah my next step is to check out these heads. In my experience anyway most cam makers make cams to run with either factory or longer pushrods not usually shorter. Shorter usually means the heads are decked. So Now I need to find out by how much. If I'm right I'll be selling these heads on ebay and looking for another set.

 

Ok so after annoying the **** out of everyone over on the LS1tech forum and a very long night of tinkering, I think I have this all sorted out. So I was under the impression that when you check piston to valve clearance that you need to use the pushrod that you intend to run in the engine. This is NOT the case. With a solid lifter in the engine and clay on the piston and a light test spring in the head. Use a pushrod length checker set zero lash on the base circle of the cam. Then turn the motor over. Pull the head off and measure your clay. You are NOT taking lifter preload into account when you are checking for PTVC with a solid lifter.

So then I wanted to see what my pushrod length would need to be. So on base circle I set the checker for zero lash. Pulled it out and saw 7.29. LS7 lifter preload is .075 to .100. A factory LS pushrod is 7.385. So 7.29 + .100 = 7.39. So that means that I can use stock pushrods. What I wasn't understanding is why I can't check PTVC with a stock pushrod. I thought the lifter "pumped up" and added to lift. I didn't realize that it doesn't gain that preload distance on the valve when oil pressure filled the lifter

So on to the heads. I was wondering if these old heads had been milled at some point. I found out that the deck thickness from the deck to the bolt face on any of the front facing head bolts should be about 1.625". Mine measure ranging from 1.618 to 1.626. So I am going to guess they have never been milled.

Sorry to annoy the crap out of everyone here with my rambling. But I'm just glad I have it figured out (I think). Now I just have to make up my mind as to if I'm going to have the heads ported, port them myself, or just bolt them on as is.

 

This is not annoying, it's how people like me learn from your research. If we understand the thought process you use, then we can apply similar logic to our own issues when they surface. Which happens a lot by the way.

If the lifter pumped up with oil hydraulic pressure to its max extension, then there would be no way it could adjust for wear in the rockers / springs / pushrods and get longer to compensate. So I think the way it's supposed to work is; the valve spring backpressure is stronger than the combined hydraulic and lifter spring pressure in the lifters when they fill with oil. Then when the rockers and rods wear, the oil pressure helps extend the lifter a little bit more over time to take up the lash. But never so much that it floats the valve off the seat - at least that's the intent.

Right?

 

So I had a very long discussion with a tech from Texas Speed yesterday. Now before I explain what was talked about let me say that I know they are a highly reputable company and they stand behind there products. This is in no way me "bashing" them or anything like that.

So I finally got around to calling Texas Speed to ask a few final questions about sending off these 799 heads for port work. I was interested in there stage 1 service. Mainly because I don't really have any interest in larger valves being installed being that it's a street car. There flow numbers looked promising and so was the price. What I wanted to know was what would the finished combustion chamber volume be after porting. That way I could figure out an accurate dynamic compression ratio with my cam. Also I wanted to know if the price on the site included seals and other small parts.

So I waited on hold for about 15 minuets. When the tech answered he seemed nice enough. I asked him what the chamber volume would be after the port work was done. He said "I'll have to check with the machinist". So in my mind already off to a bad start. He came back on a few minuets later and said that it would be the same as stock. Then I asked "Ok how much are you milling off to get it back to the stock cc size?" He answered "Let me ask the machinist". A few minuets later he came back and said "none". So I asked if they do any bowl work at all on the heads. He said no. They only enlarge the intake and exhaust runners, and also do a valve job. He then said that it was worth around 20 hp on my type of build. I thanked him for his time and hung up.

So a few issues with this. This service is $800 + shipping. He also informed me that there stage 2.5 service ($1200) is basically the same as the stage one but with bigger valves. So either way, if they port heads they are doing no bowl work at all. Again I'm not trashing them at all. I'm just comparing services and trying to find the best value. But in my mind to only gain 20 hp for $800 just isn't worth it. Not unless there was another benefit.

So it would seem there are 3 major players in the head porting world for LS engines anyway. Advanced Induction (AI) , Total Engine Airflow (TEA), and Lingenfelter. I know lots of the LT1 guys here have sent heads off to AI and had amazing results. But the cost is much higher. By the time it would be done I would have $1300 into having AI port the heads. I would probably gain 40 hp or so.

So for now I have decided to do none of the above. I'm not going to have the heads ported. It just doesn't seem to have enough gain for the money. So I'm going to clean up the 799's and bolt them on as is. I may de-burr them and clean up the exhaust side a little. But no machine work. I might send them off down the road, but not right now. I think I can still make a lot of power with the stock 799 heads and a lot of nitrous.

So coming soon, redneck head work with pictures.