About to cam swap, Should I also port heads?

[Dylan1214]

Like the title says i'm getting ready to swap my stock L99 cam out with a GPI VVT SS3. Retaining VVT and deleting dod/afm. I'm concerned about valve train/cam longevity so i'm also going with a full set of Johnson slow leak lifters and a CHE trunion upgrade. Since I have to pull the heads for the DOD delete anyway would be worth it to send in my heads and get them ported? I've read several conflicting threads regarding gains/what to expect. I've seen posts saying its a complete waste of money and to only expect gains of 5-10HP to threads/posts saying best money ever spent gains of 30-45+.

[QUICRNU]

I was in the exact same spot, wish i had before and after #s. My tuner, who does not sell or install heads said it was well worth it and gave a few examples of 15 to 40rwhp depending on the build, 3 other shops on here agreed. If you have the funds, do it. I have no regret. Research options though, as some gmpp cnc heads are pretty cheap.

You will enjoy the cam for sure either way!!!

[QUICRNU]

Also, stay away from 3.91s if you ever intend to go Boosted, especially PD Blower.

[go_go_gadget88]

I am in the midst of this same thing. Granted, I have LS3 so I didn't NEED to take heads off. But I wanted inspect lifters before new cam went in. I him-hawed around on it for a bit but finally decided that while I am doing all this work, it made sense to do them now instead of tearing into it again later just for the heads. Heads are not worth as much HP as cam, so it would have been a lot of work for less gain. But, between heads and cam +tune (didn't get tune after LTs) I am expecting it to feel like a whole new car!

My tuner was the one that finally convinced me. I was originally going to go with cam and gears, but he said if I planned to do heads anytime remotely soon, just do them now and be done with it. Plus it'll save a bit of $$ on a retune later just for heads

[christianchevell]

Heads matter more with serious cam and other high cost mods that need flow like a stroker, consider this I run a 11;1 stroker 428 with a cammotion old stage three like .613/.578 220s 230s with 114 +4, I just use gmpp CNC heads and figure they are 5 hp really...... Someday I will do ls7 small bore stroker cam and $$$$$$$, for you; costs $1400 gmpp heads, no cleaning up old heads and you can sell them off and gain some better flow numbers but without the need for the flow with the most radical cam on a stock cube LS you wont gain much...serious that's what porting is increasing flow and no need...... The whole deal for a l99 is you will get hollow stem intakes and you can raise more comfortably the RPM limit on the engine and be able to sell your used heads for some make up $$$$ that why you should do it, don't expect miracles from flow......

And you can dump a lot on just porting your stock heads with flow numbers even worse from some monkey with a dremel...Look INTO Dickey Scoggins GMPP freshened Ported heads.....they are the best deal I found out there........Good Luck, and on the internet the ability to type means your also capable to lie easily also...and I work in Law enforcement at a penitentiary so BS is everywhere and bravado with macho and EGO just go with common sense and you should be fine......and Opinions are like.............

Here a little article I used to post on here I use their oil and well parts over the years from about everyone who recommends their oil, and their site has tech bulletins and articles etc and same damn fine testimonials.........
GM LS Hydraulic Roller Cam Bulletin
Attn: GM LS Engine Owners
Re: Hydraulic Roller Cam & Lifter Failures Due To Improper Lubrication
As the marketplace stretches the power levels of the popular GM LS platform (especially in power adder applications), a marked increase is being seen in hydraulic roller cam lobe deterioration, along with lifter wheel and needle bearing failures. The root issue of this problem is a general lack of understanding about the lubrication needs of this engine platform.
Customers often do not consider the need for either a break-in oil or application specific formula due to the fact that their application utilizes a hydraulic roller cam. Since these LS engines are primarily for street/strip use, a typical customer may use a conventional 20W-50 “Racing Oil” or a similar off-the-shelf lubricant. The engines are thus not broken in with specialized break-in oil, meaning that the proper foundation for valve train durability is never established.
As street applications featuring the LS engine are not typically warmed up before driving, the heavy weight oil (such as 20W-50) is slower in flowing to the hydraulic roller lifters. The result is a lack of adequate lubrication. The LS platform pump and oiling system is designed for 5W-30 viscosity grade oil, so using heavier weight oil actually reduces lubrication and often leads to rapid valve train failure.
Driven Racing Oil™ recommends using BR30 Break-In Oil and LS30 Synthetic Street Performance Oil as a two-part solution to this growing problem.
By utilizing the BR30 Break-In Oil, the proper additive foundation will be introduced into the engine. This is accomplished first by breaking in the LS engine for 30 minutes to one hour much like a customer with a flat tappet valve train would. The customer should then drain the oil and change the filter, install a fresh fill of BR30 and continue to break-in the engine for the next 500 miles.
Due to the use of hydraulic lifters in these engines, it is critical that the oil be changed after break-in to remove the metal particulate created during the process. If these small particles are allowed to stay in the oil system for thousands of miles serious damage will occur.
After the break-in steps are complete, it is time to install the LS30 Synthetic Street Performance Oil, which is a properly formulated 5W-30 motor oil designed specifically for GM LS-based engines. The LS30 oil features mPAO synthetic base oil technology that increases High Temperature High Shear (HTHS) bearing oil film thickness, so the oil flows like a 5W-30 but protects like a 15W-40.
This innovative technology enables LS30 to provide the required viscosity for the LS oiling system and deliver the added protection required for higher lift cams and hydraulic roller lifters.
This two-step lubrication process provides the proper viscosity and additive chemistry for the unique requirements of modified GM LS engines with hydraulic roller valve trains. Properly completing this sequence of steps utilizing both the Driven BR30 Break-In Oil and LS30 Synthetic Street Performance Oil will establish the proper anti-wear film in the engine, remove harmful break-in particles and provide excellent ring sealing.

This entry was posted in Tech Bulletins on April 5, 2010 by admin.

And you should know the correct math for setting the preload and the amount of preload recommended for the Johnson lifters versus stock .040-.060 range for ls7/3........ and yes ratio 1.7 x .047 thread pitch at zero lash = .077 movement at one turn on the threads due to the ratio for the rocker....something a lot of guys screwed up...... and one turn equals too tight for even the ls7 with .070 preload and higher rpms...don't bottom out.... Good Luck.

[Punisher_ATX]

IMHO id spend the money elsewere and come back to the heads when youve done all the other things and want more. Ryan can chime in also but typically youll gain more from milling the heads some if you have the room than porting would for the money. Food for thought.

[Bo White]

Heads would be off so.....port em.....

[Clarkstar]

Port em... as Bo stated...

[Russell James]

Compression is power. Port flow matching the cam lift improves power.

So, the big question is really related to what the cam was designed for. Is the PTV already super close? First of all if it is, I wouldn't use it. But... if it is not, find out from the cam designer if it will work good at 11to1, mill heads to that.
At the same time, ask about the lift...will it support more port flow? If it will, port those suckers.

When you hear about very little gains from ported heads, I think that is mainly comparing with a stock cam. A stock cam will not benefit from increased port flow. The LS3 heads stock are an excellent match to the stock cam.

When you go with a cam with overlap, you are losing actual compression/cylinder pressure. Most cams above a stage 1 type of grind, will benefit from a bump in compression. Again...I wouldn't bump compression on the stock cam. That 10.7 is ideal for the stock cam. Get up in the stage 2/3/4 cams... get that compression up 11ish and maybe a couple tenths more. If 93 is available.

So for head work, talk to someone that really knows the details and PTV clearance of that cam. If the ptv is already uber close, and you can't bump compression....just my opinion but I would pick a cam with generous ptr and room to deck the heads. Assuming 93.

[frankwjr]

....just curious...your sig says dynoSteve tune...so did you have a chat with him?

also..since as we know mods are seriously addicting! do you ever plan to go F/I? I ALWAYS try to take the long view...can save a sh!t load of $$$$...either CNC LS3 or better CNC LS9 heads with LS9 head gaskets and ARP head bolt/studs makes for a motor that can take a lot more without worrying the heads will lift....food for though..then just sell your heads as is to offset the cost...

2nd will the slow leak lifters work for the VVT? just askin 'cuss I don't know...

and yes the CHE trunnion kit is awesome but here you could also save a couple of $$ going with either Straub or Powell(off of ebay) trunnion kit...been runnin the Powells for about 1.5 years and whew like 15k miles...along with the 3/8 push rods(lol it's funny how NOBODY ever remarks that I run 3/8 P/R's lulz) and the PAC springs the motor is quiet and I can/do run her to 7k regularly...

so yes compression is king...for N/A...not so much for F/I if you plan on running 93...and our motors benefit from a forged piston/rod upgrade...

good luck OP and report back! peace out...

[Dylan1214]

Thanks for all the input guys, definitely got the answers I was looking for. Going to call a couple shops come Monday. I'm planning on creating a Cam swap/build progress thread in the near future so standby for updates.

[GPI Aaron]

We spend a fair amount of time on the dyno making sure our products are a good value for our customers. We also test competitive products to find out where our strengths and weaknesses are. The post earlier pointing out the importance of compression ratio and components being designed to complement one another is spot on. Here is a link for some research we did you may find informative.
https://gwatneyperformance.com/cam-testing/

[Russell James]

Originally Posted by GPI Aaron

We spend a fair amount of time on the dyno making sure our products are a good value for our customers. We also test competitive products to find out where our strengths and weaknesses are. The post earlier pointing out the importance of compression ratio and components being designed to complement one another is spot on. Here is a link for some research we did you may find informative.
https://gwatneyperformance.com/cam-testing/

Great article! One question... if one were to leave the LS3 bottom end completely stock, flat top LS3 pistons. Can we use your 66cc heads with the SS2 or SS3 cam? Do you know what the exh valve PTV will be?

[GPI Aaron]

The SS2 clears fine, the SS3 however depending on the actual measured intake valve free drop of the heads we build for you it usually ends up about .030 before block expansion and valve train deflection. It's pretty tight and we have it running on several L99s with great success. That said, I don't mind being that close on auto cars where a mechanical over rev isnt a factor but I get a little concerned on stick cars. It kinda figures like this: start out with .030 lose .020 in deflection and pick up .012 in block expansion you really have about .062. Let's say you do a accidental 5-2 downshift, and spin it to 9500 monentarily, the valves will loft, the lifter plunger will take up all the preload and then we have a potential clearence problem. So long as we pay close attention to intake lifter preload and keep it at or under .050 I would sleep just fine. The other option is our new Max package where we use a 12 degree head, there by freeing up some clearence, while providing better intake manifold options. https://gwatneyperformance.com/spotlight/