Got a 4.8LS swapped 95 step side Chevrolet Silvy that we use as a shop truck. It's hunting for idle and will stall out when putting it into gear. Snap-On scanner shows both banks really lean +25 on both banks.. So.. We potentially got a vacuum leak.. I started by checking the PCV hoses, brake booster hose, and all other locations. I could not find any leaks.. I was then running the engine and spraying everything down with brake cleaner watching/listening for a change in engine idle. Nothing. I then broke out the smoke machine. Removing the cold air intake and taped off the opening of the throttle body. Put the smoke machine on where the PCV hose on the passenger side hooks up and turned it on.. Within seconds I could see smoke coming from around the fuel injectors where they plug into the plastic intake manifold. I thought maybe the intake gaskets but with a bright flash light and putting my face right down there-it still looked like it was coming from the injector O-rings.. I wanted to be really sure so I took some axle grease and slathered it around the ports where the intake meets the head and continued to smoke it.. ALL 8 injectors are leaking at the O-ring's.. Just wondering if anyone else has seen this before?

I pulled the fuel rails out to replace the O-rings.. The rings are hard as rocks.. Brittle.. Breaking into pieces when trying to remove them. Also, the fuel rails literally lifted right out of the intake with very minimal pressure. I think I found the problem. Going back together with it now. Will re-set all the fuel trims and drive it to see what is going on with the STFT and LTFT's after this. Just one more thing I've never experienced before but it may help others. Based on the way the truck was running I would have sworn the IAC was bad.. But the fuel trims gave it away. The idle would hunt up and down, and up and down, and then eventually stall out even in park. I would stall intermittently as well just putting it into gear, but not every time. It was very confusing. But... I think I found my huckleberry.

I hope this post helps anyone who is chasing engine problems. Injector o-rings.. Just one more thing to check.

 

Kawwabugga My name is Gabe. I am new to this site and found this post, which is very helpful btw, by searching your posts. I read a post you had a few years ago about your sons truck with the 5.3 and a mild Cam. I also read that you used westside machine here in Houston.
i am hoping to be able to get some advice from you since i am close to taking my used 5.3 block to them. I also am considering a mild cam. And wanted to see how you liked the one you put in your sons truck and any advice you had for my trip to the machine shop. I have a good idea of what i want them to do with the block but like most people i have a budget. My goal is to bring the engine back to stick condition, but use a mild cam. Any advice would be helpful.

 

If I may, how will the truck in question be used?
Do you want the powerband higher in the rev range?
Do you mind losing some low end power?
If the answer to either or both the above is "no", you might not want too much of a cam, likely a cam like the BTR "Truck Torque" cam. 202/202, .511/.511, 111 + 1.
One area where there is power to be had throughout the range is a good multiangle valve job and bowl blend, aka pocket port.

 

Well, Jeff, or Cleet, are both really good guys at West side. You can't go wrong with them. They do really good work, and surprisingly they are pretty fast on getting stuff completed and back to you. My sons truck has the GM Hot cam in it.. 219/228 duration, and .525" lift on both intake and exhaust. It's not a bad cam... but there are certainly better choices. His truck is a wee bit soggy on the bottom end-most likely due to the weight of the truck. A little bit higher stall converter may make a huge difference there, and or a gear swap. That's the one thing to consider.. When you make a change like swapping the cam, it typically leads to more changes as you go. Its best to have a complete picture of exactly what you want when you are done, and then work towards that goal. I know FEW people that after doing a cam swap, just leave it alone.. Most people I know will swap the cam out multiple times until they find one they really like, that really works with their combination. For example.. If you have stock exhaust the cam you choose may need more duration on the exhaust side to help push the spent gasses out of the factory manifolds. If you buy/install a cam that is meant to work with factory exhaust, and then later swap to long tube headers.. That cam will no longer be optimal, and you will most likely need to swap the cam again to get the most out of your combination. Like G says above... really think about what it is you want in the end.. There are many people who choose the wrong cam-typically too big in lift/duration-and then regret having swapped the cam. I won't make any cam recommendations.. I'll simply say that doing your research will help you figure out what you want in the end. I know you said you want to rebuild the engine to "stock".. But.. you did not mention what year 5.3 you have.. If you have an early motor-you can't go wrong swapping to flat top pistons and bumping the compression up a bit. Also, if you already have flat tops-you can go with thinner (compressed) head gaskets and gain a little compression that way. Think of compression as free horsepower. It's only bad if you have too much-and that would be something approaching 12:1 which you most likely could not do without domed pistons, and/or a head swap.. So, if you don't have flat tops-get them! You can use the 4.8L pistons that are flat tops and they have a slightly higher compression height on the piston which will add a little bit more compression. Also, you have not mentioned what type of heads you have...There is compression to be found with smaller combustion chamber heads.. Look up Richard Holdener on Youtube and his videos on the 706 casting heads... I think a flat topped 5.3L, with 706 heads, and a mild cam will give you a smile for years to come.. Just keep your cam selection on the tamer end. Also, get new cam bearings installed in the block by Westside.. It's a must.
If you have any more specific questions, please feel free to ask! Lots of good folk here.. It just sometimes takes a minute for some posts to catch wind before they sail!

 

G Atsma & Kawabuggy,
I am swapping a 2000 5.3 with 862 heads into an 88 OBS. I plan on installing 2.5 -3 in exhaust true dual, x or h pipe. Id say I am just as interested in torque as I am hp, so street truck for sure.
As far as the cam goes I want to go as far as I can without having to buy a torque converter (not in the budget, yet) but I think my 862 heads wont let me, they may not be able to go with the flow. I have budget for either a head job, or I could find a used set of better flowing heads. I still need to do some research on the 862's, maybe a do what G said and do the valve and port job. I hoping that this will be a one shot deal, i dont want to be swapping cams in the future. Having said that I would consider swapping heads if the cam and the 862s dont work out.

I appreciate the insight on westside machine, I spoke with them yesterday and today I spoke with Houston Engine and Balancing. I might go with them, he's the first shop I spoke with that made sure to mention that he uses a torque plate when boring. Although, he charges about 100 more to use the torque plate than does westside. and btw i do plan on using the flats tops. But ill have to wait and see if i need a bore over, ive had two shops tell me getting pistons has been difficult these days, so getting an odd size flat top may not be easy.
G Atsma do you know a shop that does the "pocket porting?

 

Any good head shop that does any porting can do a bowl blend, aka pocket porting. It removes the ridge right below the valve seat. It is said to be 70>% of a good port job. That and a good multi angle valve job will add a nice bit of power without any downsides.
As far as pistons, if flat tops are in the plan, just use stock 4.8L pistons in stock or whatever oversize you need. These should be easy to find, but w/ the COVID B/S maybe not so much
Where are you located?

 

Westside DOES use the torque plate on boring/honing work! You should go to their shop and ask them to look around. They have no problems showing you around the shop! I would also say that your 862 heads are EXACTLY the heads that you want for a "mild" build! You can have West side put in the larger intake valves, and then pocket port/bowl blend them for you when done-they do all that stuff in-house for relatively cheap! They can also do 5 angle valve jobs which will get you the better flow. Lastly, don't forget valve springs! Your old ones are probably sacked at this point, and most cams will require a little stronger spring than factory anyway. Find some PAC 1218's on Amazon, or Ebay and take those with the heads and have them installed along with the valve job. Be careful buying Pac springs on Amazon or Ebay though as there are fake china knock-offs floating around.. I should know, I got a set recently... Read the ads carefully before buying.. Or, use one of the sponsors from this web site so that you know you are getting the REAL deal.

Westside can source your pistons for you-they can get everything, or anything you need, right now.. Or, you can look here;
https://www.ebay.com/itm/27384474127...Cclp%3A2334524

 

*most* 5.3l's I've torn down have not needed to be bored.. Lightly honed-YES.. But bored? NO. I only bored my son's truck because we were searching for more power.. If you still have the cross-hatch pattern in your cylinders, and when measured the taper is still within spec, have them just hone it and save money, and then you can use standard pistons like I linked above.

 

I will say the only downside to using aftermarket pistons is that *sometimes* the compression height is lower than a factory piston will be. This is to take into account the possibility that the block will be, or has been, decked, and they don't want the piston sitting too far OUT of the hole. So... If possible.. Use A/C Delco, or GM, 4.8L pistons... You can always measure whatever piston you buy anyway and then have the block decked accordingly to have those pistons sitting right where you want them to be. Keep in mind factory pistons, in a factory un-decked (non-decked?) block will stick OUT of the hole! Yes, you can learn that right here on this web site. It's where I learned it. After market pistons with shorter compression heights may not stick out of the hole, and will cost you compression.. Remember that free horsepower we talked about?

 

Afternoon,
For some reason i havent been able to send this post, i sent it once a few days back and it didnt go through, weird. I took my block to Westside this last friday. Phil, measured the bores and anticipated having to go .020 over. Hopefully they can get me some flat tops.

I finally buckled down and did research on cam selection, i appreciate the suggestions here, but the youtube video that really helped was from MyvintageIron, he had cam selection video, it really learned me allot. I learned the most important things to me are drivability, It will live in low rpms as I will be in using the truck in the city as well as highway and I want good idle quality. I think you are right about the 862 heads, even though they are the "best" flow numbers i think with a little help and the right cam they will do just fine. The first choice im leaning to is a Howard cam with 114 LSA, here are the choices in order.
Howard 216 int./224 exh. .551 int./0.551 exh 114
Trikflow 216 int./220 exh 0.560 int./0.560 exh. 114
Howard 218 int./218 exh. 0.604 int./0.604 exh. 113

You guys have any thoughts on these choices? They are very similar I know.