skongolf

I am planning on putting a stock '05 LM7 5.3 in my Chevelle wagon and I am thinking about putting 799 heads and a new cam in the motor before i put the engine in the car. I thought I read everything I needed, then I read that you have to mill the heads to keep the compression the same or you sacrifice performance in the low end. My goals are to make it a daily driver and do some autocross and want to keep the MPG reasonable. I also know the car has 2.43 gears which are not the greatest, but it will keep it cruising down the road. I found a good deal on the heads, but I am wondering if just getting new heads(used stock 799 heads) and throwing in a cam is only half the battle. I dont want to buy the heads then throw another $500 at it to get it where it needs to be. Thoughts.

Darth_V8r

iTrader: (4)

799 heads on a 5.3 will make for a good running engine. You should mill them down to 62cc for stock compression. You could also install .041" MLS head gaskets, which will tighten up quench, slightly improve compression, and help control spark knock. There were a few years where the 4.8 and 5.3 shipped with 243 heads, and they ran awesome. I want to say 07-08 for sure. So, you could just use the 799 heads with the stock cam and stock everything else and have a decent running engine.

If you want more, but don't want to get into springs, etc, you could get a drop in cam from cammotion, which would basically get you much better than stock, allow you to install your used 799 heads as they are right now with stock springs, rockers, pushrods.

So, let's say you do everything I just described up above... You'll still probably want a LS6 intake at least, and you'll want long tube headers to make it shine, and you'll want to get a tune. Bottom line, you'll end up with an additional $500 in it no matter what. The head gaskets and bolts alone will potentially get you into $300 territory.

skongolf

So mill and do the head gasket you mentioned or just one or the other. Thanks for the great info.

Darth_V8r

iTrader: (4)

if you are going to cam it with >220 duration, do both. if not, then pick one. good luck

skongolf

I am getting the heads for sure. Any cam recommendations? I read an article in super chevy where a stock LS6 cam worked really well with a head swap. Not sure how much milling the heads would run, but probably not in the budget at this point.

Darth_V8r

iTrader: (4)

LS6 cam is a poor match for a 5.3. I have one in my suburban, and I have been unhappy with it. it gives up too much low end without gaining much on the top end. Gives decent dyno numbers on the high end, but not much fun to drive. Only reason it's still in there is I'd rather dump the money into the 'hawk.

I would look into cam motion drop in cams. They have a "LS 5.3-10 stage 2" cam that would be a great upgrade over stock and work with the stock springs in your 799 heads:

210/215 duration on a 114+4 LSA with lift at .518/.510

Since you aren't going to mill, use the .041" MLS head gaskets with that cam, should be a good running engine for a DD and some street fun. If you decide later on that you want to rev it up a bunch, there are better options than the LS6 cam

skongolf

Cool. Thats the info i needed. Do you think it would be worth changing the timing chain or anything else when I do the cam and heads? Pretty sure I am going to go with the head gasket you suggested and new head bolts.

Darth_V8r

iTrader: (4)

Personally, I would. I tend to think an old timing set with a new cam is asking for trouble, but I can't really give a good scientific reason why. I just think it is good practice. Would you be OK if you didn't? probably