DrJones

LQ4 with 1.8 rockers

This is my build and the BIG question is around the rockers, can anyone give their thoughts on 1.7 /w upgraded trunnions vs 1.8 CompCam roller tip rockers with this combination?
Are there any valve train components I should add change remove?
thanks in advance to anyone giving their thoughts....

LQ4 block

Eagle rotating assembly (pistons rods crank) 408cid

4”stroke

H-rods

CP-carrillo pistons 4.030

Heads ls3 0821 new bronze guides & valves

CompCam Ultra Pro Magnum adjustable 1.8 roller tip rockers (1676)

CompCams short travel lifters (875)

CompCams Valve springs up to .700 lift (26527)

head gaskets Cometic MLS .051 Compressed

Heads cut .003 and block .005

lethal racing night fury cam 233/242 629/629 113+

1.78 long tubes

Edelbrock dual plane 4150 intake

Holly Terminator with stealth fuel injection 4x100lbs injectors

ARP bolts through out

G Atsma

Will the spring rates support the heavier rocker weight? And are you set for .666 lift with 1.8 RR? I know the springs are. But setup is different.

DrJones

Atsma thx for replying
not exactly sure what you mean by “setup”
Are you referring to PTV clearance? If so, what I have done with my BTR .660 springs still installed, removed all rockers & plugs installed the 1.8s on cyl #1 and very carefully rotated the assembly being hyper sensitive to any changes in rotating efforts and I did not feel anything at all other than the springs.
And to my surprise I didn’t get any coil bind either. Also the roller to valve tip wipe looked pretty good with the 7.40 push rods.

thoughts??

showdog75

iTrader: (8)

Do yourself a favor and put some clay(play dough) on the piston and measure exactly how much clearance you have Clarence.

showdog75

iTrader: (8)

Btw I like all your specs. Should prove a runner.

Che70velle

iTrader: (6)

DrJ, are you going back with new LS3 hollow intake valves, or a new solid intake valve? Your setup should turn some rpm, so valve weight will matter here, especially with a larger (and potentially heavier) LS3 intake valve selection.

KCS

iTrader: (20)

Thats not how you check PTV. You should still be fine as far as PTV is concerned since you have forged pistons which almost certainly have pretty generous valve reliefs, but you should check it the correct way to be sure.

SCJW

I agree. Sounds like a nice combo.

Check PTV clearance with clay for sure!

DrJones

Update
slight change in my rocker choice
while discussing the spring upgrade with my machine shop today they discovered the .700 CompCam spring install height is 1.90 and the 0821 heads allow for 1.80-1.85, now the cost to accommodate the springs quickly out weighted the benefits for this build.
So I opted to ditch the 1.8 rollers for BTR LS3 Shaft Rocker kit (BTRSRKR3KIT) with 1.7 rocker
I’m hoping this might yield better results due to a considerable weight difference in the valve train components. Also I have to ditch the short travel lifters because I’m losing the adjustable rockers.
In place I’m using Howard’s Cam lifters 91174
this should still work fairly well.

DrJones

Agreed that is not how to check PTV and these pistons do have good sized reliefs.
But since the latest turn of events I’ll be going with 1.7 rockers so this concern no longer exist.

DrJones

I’m shopping around as I type for lighter valves
any recommendations???

Che70velle

iTrader: (6)

Nothing wrong with LS3 OEM valves. They are hollow stem, relatively light for their size, and very affordable through GM. I wouldn’t simply throw them in and go however. Have a shop do a competition valve job and set the heights the same on both heads. And for what it’s worth, you can still run the limited travel lifters with the BTR shaft setup. It’s a lot of work setting up for pushrod lengths, but you can do it. Just takes a little time and a lot of patience.

DrJones

im really interested in using short travel lifters, can you share your method?
The preload with the CompCam lifters is .003-.005 and I’m not sure how I’d accomplish this with out adjustable RAs

Thx

DualQuadDave

iTrader: (6)

Some advice, go w/ Johnson lifters, not the Howards. Best lifter on the market, by far. Howards are rebranded Morels, Comp's may be, as well. Not surestock rockers w/ trunnion kit should be plenty for your application, but if you want shafts, they are better. Shoot for 11.5:1 static compression, also. Also, what intake are you planning to run?

Che70velle

iTrader: (6)

Sure. It’s going to require you to individually measure all 16 separately. Use an adjustable pushrod, and once set in the lifter cup and rocker arm, carefully turn the pushrod adjuster outward until the pushrod is snug in both cups. The entire pushrod will spin at this point, but firmly. Too much turning here will result in you pushing lifter cup down, and numbers will be wrong. Tear the setup down, being careful not to turn the adjustable pushrod, as this will alter length and mess up your numbers. Once out, measure the pr with a caliper and record the measurement. Repeat the process. Because of the very small preload window, it’s crazy important that you measure each valve separately. You’ll likely end up with several different pushrod lengths after your done. Take good notes, so you’ll know which pr goes where when you receive them after you order. I use a 12” caliper to measure the adjustable pr, and I always make sure to tell my pr maker that I measured with a caliper, so they understand how I achieved the numbers.

DrJones

Thanks to DualQuadDave for making want to get “the rest of the story”
After days of research I ordered a set of Jonhson 2110R lifters. This decision came to fruition due to the leak down test performed by GM Performance division. this is a snip from the article I found on corvettefourm.com
(• In late 2013 GM Performance went to Johnson Lifters to ask them what they had for their COPO LS engines.
o GM tested the Johnson 2110 lifters, GM LS7 lifters, Cadillac Racing lifters, and others to include those from Morel
o GM took the lifters and put them through months of testing, and the Johnson lifters were the only ones that they had no issues with axle retention.
o Johnsons were repeatedly tested past 8,500 rpm

• Slow bleed-down lifter describes the ability to maintain lift without collapsing, or the repeatability in common rotation on the cam:
o If you had a .630” lift camshaft but your lifters bled down .030” as the lobe of the cam rotates, you essentially would only be getting .600” of lift from your cam
o GM found that
• Johnson lifters maintained their lift 95% of the time
• LS7 lifters only maintained their lift 50% of time)

While Johnson’s come at a considerably higher cost As do BTR rails and springs BUT the piece of mind is priceless.
Not mention when you blow the doors off your smack talking brother’s 7.0 at the track.

should get the johnsons on Tuesday, so after work I’ll get the heads on and start sizing for my pushrods. I intend on checking each valve individually and fingers crossed they all come in within the preload window of .040" +/- .010". If the BTR springs can keep the valves in check this combo should allow for consistent 7500 rpm passes.
Thoughts?

omc8

iTrader: (7)

You don't want to use Play-Doh it rebounds too much and give a false reading . You want to use modeling clay .

tblentrprz

Or... use checker springs and measure especially if you'll be playing with cam timing. Actual springs with pushrod deflection will increase PTV ~.020"

DrJones

BTR rails and Johnson lifters showed up last Monday. got the heads on and measured preload on each lifter. Johnson says the 2110R (R being “reduced travel”) preload is .035 +/-.010. Using 7.40.800 pushrods all fell well within their specs. Assembled the rest and dropped it in over the weekend
used a pressurized “priming”oil tank to pre-prime the complete engine. With 45 lbs of air on the tank oil pressure gauge showed 20-25 lbs Pushed 5 qts into it. Twisted the key it fired off in 3 rotations and had oil pressure instantly, 80lbs at 2500.
after a little break in time everything sounds great and spins up effortlessly. Unfortunately the transmission is a worn out 700r used for mock up purposes so I really can’t put any power to it (I don’t want to kill it)
I have a Lingenfelter 4l60e (early one piece case) being built for this. And will be using a TCI 3500-3800 9inch converter. This trans build will easily handle 800-1000 HP.
The question has already been asked. Why not a bigger/stronger (th400 or 4l80,etc)
This is because of 3 reasons
1) it’s rotating mass lighter therefore spin up is faster
2) 1st gear is the lowest ratio of all GM 4 speeds (maybe of all GM autos)
3) 5 pinion planetaries front and rear from a 4l70-75 will provide that “extra”
those reasons (IMO) make it good choice for 60ft times

grinder11

iTrader: (1)

Do NOT use Play-Doh!!!! EVER!!! It can, and does, spring back/bounce back when valve lifts off of it. Use modeling clay. Modeling clay does not change. NEVER use Play-Doh.........