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Hi guys, looking for any insite or advise on building a lm7/4l0e for a truck application. Right now my plan is to tear down a higher mileage lm7 and replace bearings, oil pump, timing chain, and rings. I'll be running a tbss intake and I'm looking for cam/head suggestions. This isn't a off-roader, It will be a 4wd street truck to advertise for my shop. it's easy to get 91 octane fuel around here so I have no problem with milling heads for a bit more compression, and I'm looking for a decent lope at idle. truck will very rarely tow anything. I've done some searching and couldn't come up with much solid info. If anyone has experience with a good mil/cam combo the help would be greatly appeciated.
For a "Budget" I would just run this cam or https://www.summitracing.com/parts/sum-8701/overview/, a set of Ls6 blue springs, longtubes, a I6 trail blazer stall converter and let it eat.
ive seen several people mill .030 not sure how much that will raise the compression.
You can also check the classified as there are 4.8/L33 piston/rods in there from time to time, witch would be flat top and another cheap way to bump the compression up.
Also your going to need the correct transfer case for the passenger side drop front axle.
212/218 is a great cam for the 5.3. Go over to performancetrucks.net and you will see all the 5.3 with a 212/218 cam. For heads just get your 5.3 heads milled and/or ported depending on how much you want to spend. If you want to buy heads the TFS 205 heads are probably the best aftermarket heads for a 5.3. The TBSS intake is the best bang for the buck so you are set there.
Flat tops won't interfere with a higher lift cam then? Also would the stock lm7 heads (off a 07 suburban) flow well enough or should I hunt for something else? Not trying to buy anything new, but if I can pick up a used set of another engine that would flow better I could snag some pretty easily
Flat tops won't interfere with a higher lift cam then? Also would the stock lm7 heads (off a 07 suburban) flow well enough or should I hunt for something else? Not trying to buy anything new, but if I can pick up a used set of another engine that would flow better I could snag some pretty easily
Those will be 243/799 heads from a 07 suburban and it would not have a Lm7 engine it will be a Gen4 5.3
Witch engine do you have?
and yes the I6 trail blazer converter is just a cheap way to get a higher stall speed
Flat tops wont interfere with a cam as much as shaving .030 off the heads will
You have a very good plan of action for your build. Smart to tear the high mileage engine down and go through it right up front. The TBSS intake is a great budget upgrade for these LM7 engines for better flow and increased HP. The LM7 should have some 706 heads on it and while not the best for max effort high rpm builds they are good for building more of a daily driver naturally aspirated high compression engine. We would recommend sending the heads out to a good reputable machine shop to at least have them milled .030" which would bring the 61.5cc chambers to around 57cc and boost compression to around 10.1:1. If the budget allows for added flow, performance and efficiency it would be a good idea to have the shop do bowl work and a competition valve job.
For a camshaft to work well with the weight of your K5 and have that noticeable lope your looking for we would recommend our Stage 1 Truck Hi-Lift cam kit SUM-8719-1(209/217 112+1 .550/.550 lift). This kit includes the cam, LS6 valve springs (work with stock retainers), valve locks and valve seals. This will provide exceptional torque down low and through the mid-range while with the use of the included LS6 valve springs provide good reliable power up through the 6500 rpm range if there is a need to ring the engine up to those rpm's. This will work well with a stock torque converter so no need to buy a stall converter.
Being that it is a high mileage engine it would also be a good idea to get new lifters and we have the SUM-HTLSKIT LS7 lifter and LS2 tray kit. Also being high mileage would be a good idea to change out the old needle bearing trunnions to bushing trunnions with our SUM-141560kit. To do so you will need a installation tool and we offer two types depending on what shop equipment you have available. You can use theSME-906011tool if you have a vice or with the use of a press you can use theSUM-141560-IKtool.
Flat tops won't interfere with a higher lift cam then? Also would the stock lm7 heads (off a 07 suburban) flow well enough or should I hunt for something else? Not trying to buy anything new, but if I can pick up a used set of another engine that would flow better I could snag some pretty easily
Interference is not related to lift, but duration/overlap. Max lift is achieved with the piston way down the cylinder.
Thanks summit, good info. Would that be the most aggressive cam you would suggest? Also would I need shorter push rods for the milled heads?
If you wanted more of an aggressive cam you could go with the camshaft kit SUM-8701-1(218/227 112+2 523/524)that Ls7colorado previously recommended. This stage 2 cam will have that low range torque like the stage 1 Hi-Lift with a little more grunt packed behind it and carry good power throughout the rpm range. Another step above that would be the Hi-Lift version of the stage 2 which is camshaft kit SUM-8720-1(218/227 112+2 600/600). This stage 2 Hi-Lift will have some of that low range torque but will really come to life in the middle and upper rpm range. Both of these are cam and spring kits like the stage 1 Hi-Lift. The only difference is both of the Stage 2 camshaft kits come with upgraded Pac beehive springs instead of the GM LS6 beehive springs.The Hi-Lift stage 2 would be the max we would recommend for you with the use of a stock torque converter.
As far as recommending pushrods the best and safest way in our opinion to make sure valvetrain geometry is correct is to measure for the pushrod length for your particular application once the heads and cam are installed. To do so you could use the TFS-9501pushrod length checking tool.
The .600 lift version will have better valvetrain stability anyway
Interesting! To further my valvetrain education (IOW, NOT being a smartass..) how is a .600 lift more stable than .550?
It goes against my ignorant logic, but not for the first time! LOL
Basically adding lift for a given duration results in less negative acceleration as the valve approaches peak lift. You might think of it as trying to avoid squaring off a Sine wave. .550 with Ls6 springs or .600 with Tfs-16918-16 Beehives are nice combinations that put the coils near bind for better dampening. The coils aren’t allowed to go crazy and this reduces stress.
09-24-2019, 09:02 PM
K5 Blazer lm7 budget build 
