analyte

iTrader: (5)

I installed the cam and heads this today on the engine stand, and I spent a lot of time measuring and checking as i went so I didn't screw up. That said, I got some PTV numbers that are much better than expected, but I'm not sure of the norm since this is my first LS build so I'm throwing it out here for comment.

Stock LQ9 shortblock
SNS Stg2 227/235 110+3 installed dot to dot
.051 GM MLS gasket
243 heads with AI 232cc CNC finished with 63cc chambers and lightweight Z06 valves. BTR platinum spring kit.

Absolute TDC was found and after the cam install, I did use the degree wheel to check it in sync and I was only .5 degrees off what was on the cam card. I installed checker springs and am using an adjustable pushrod to set zero lash in the valve train.

Once partly assembled with gasket and head, here are my measured PTV's off the retainer.

Intake: 20 BTDC to 20 ATDC
20 - .315
15 - .280
10 - .245
5 - .218
0 - .196
5 - .185
10 - .195
15 - .215
20 - .260

Exhaust: 20 BTDC to 20 ATDC
20 - .350
15 - .280
10 - .250
5 - .230
0 - .220
5 - .245
10 - .280
15 - .330
20 - .440

So does this sound too good to be true, or in line considering my heads aren't heavily milled and the cam isn't overly large? As stated before, this is my first LS build so I'm learning as I go.

Thanks,
Kerry

JakeFusion

iTrader: (7)

Those numbers are way too high. You won't even have that much clearance with a stock cam - the valve drop on a stock head is .160" so you'll never exceed that.

You must be compressing the lifter.

Aston Tibs

iTrader: (3)

I agree with Jake. Did you use a solid lifter? If you don't have any, disassemble two of your lifters and shim them up to make them solid and try again.

analyte

iTrader: (5)

I wasn't using a solid lifter. I was using a new LS7 lifter as I had read it was OK if used with checker springs. I spoke with Martin this morning and he told me the same thing.

I don't understand why the lifter is compressing with just checked springs. That doesn't make sense.

Thanks for the feedback,
Kerry

maxpower_454

iTrader: (7)

I tried it both ways when doing my build. My lifter didn't compress with the checker springs. But I agree. That's really the only way to get that much PTV. Before removing your heads again, measure your lift on the valve side of the rocker. If you're getting the specified lift, you must have lash or something else screwed up.

analyte

iTrader: (5)

I think my problem may be that I didn't set the PR length on the base circle. I'll try that tonight since I would rather fix it with my current setup than disassemble a new lifter if not required.

Thanks for the help!!

Russ K

iTrader: (1)

You can fill the lifter with oil by installing the pushrod & using an oil can to pump oil into the pushrod.

Russ Kemp

studderin

iTrader: (28)

sounds way to big, and that ext maps looks funny too

Aston Tibs

iTrader: (3)

I am using the Cadillac racing lifters and the checking springs compressed them. Luckily I had the old lifters still and temproarily modified two of them.

analyte

iTrader: (5)

As a follow up, I got the PTV checked again with the use of a solid lifter. I was able to determine that the comp checking springs were compressing the hyd lifter unlike what I had read.

In the end, I got .087 for the intake and .103 for the exhaust at the minimum. Not sure how this compares to others, but I'm good to go on my engine.

Thanks for the help!!

Kerry

Aston Tibs

iTrader: (3)

I think that will be good. That is more than I have on intake and Texas Speed told me they like at least .060 on the intake. My LS rebuild book say .125" on the exhaust but then says .100" at a minimum, so again I think you are fine. If you can get KCS to reply though I would take his word over mine.

analyte

iTrader: (5)

Are you running the SNS stg2 along with a similar head/gasket setup as mine?

I saw/read .080 and .100 for int/exh which is what I used. Maybe KCS will drop in to confirm.

Thanks!!

poltergeist 02

iTrader: (65)

.080 intake / .100 exhaust is what a lot of people recommend as a minimum and many people have run less without problems (not suggesting to do that). I am running .100" intake and .100" exhaust and have had zero issues with it. Your good to go!

analyte

iTrader: (5)

Thanks!!

Rise of the Phoenix

iTrader: (27)

My intake clearance was right at .070 and exhaust clearance was .100 with the heads in my signature.

analyte

iTrader: (5)

What gasket thickness did you use? Either way, not far from you on the plus side so I'm good to go.

Thanks!!

Rise of the Phoenix

iTrader: (27)

Stock thickness gaskets. Can't remember exact size.