robertsjm711

I just purchased a 5.3 and now am thinking I have a 4.8. The question I have is the injectors that are on the engine are 25326903, which I have been led to believe are for the 5.3 flex fuel. There is a tab on the head gasket that is stamped "4,8" and from what I can see it has flat top pistons.

Did they put those injectors on the 4.8?

Any help, guidance or resources would be greatly appreciated.

-Jon

G Atsma

What year is it? The later (07-on, I believe) 5.3's do have flat top pistons. Before that, they are dished. The main difference between 4.8 and 5.3 engines is the stroke. For that reason (same bore size), they might use the same head gasket.

robertsjm711

I was told it was a 2001. I havent dug into how to tell year but it is a drive by cable so 2001 seemed possible.

G Atsma

Sounds right. Trucks went to drive by wire around 2003. So IF it does indeed have flat tops, it should be a 4.8. 5.3's of that time all had slightly dished pistons to keep the compression down.
If the seller claimed it is a 5.3 I would try to get your money back if that is a problem, as converting to a 5.3 involves a crank, rods, and of course new bearings.

robertsjm711

Would it be conceivable for a 5.3 to have 4.8 head gaskets? I just found a sensor that is only for flex fuel (some fuel comp/temp) and with the flex fuel fuel injectors it leans 5.3. I am not confident on the dish or no dish pistons, I'll take another look soon.

G Atsma

Since the bore on the 5.3 and 4.8 are the same, the head gaskets could easily be the same also. You could then easily have a 5.3 if unsure on the piston configuration. If you could check the stroke with a wire down the spark plug hole, you would know for sure.

tech@WS6store

iTrader: (2)

4.8 and 5.3 use same head gasket.
If you are looking to build it, or reassemble, we have the parts you need at the best prices PLUS if you have 862 heads and they have a notch on the deck, we are one of the only places that offer mls gaskets that will work with them.

You other question...its def a 4.8l. l59 5.3 was a flat top but didnt come out til later. it used 243 heads also.
They did have flex fuel back then also. so its possible you have truck flex fuel inj. also all 4.8/5.3/6.0 reg inj are the same, and flex fuel same way. those are good inj and can come in handy.

G Atsma

He wasn't sure of the dish/no dish situation, so maybe still either way.

tech@WS6store

iTrader: (2)

Id say nearly 100% its a 4.8. check casting no on crank.

JoeNova

The 3' borescope I bought for my cell phone was less than $5 shipped to my house.

I take it and a spark plug socket with me now when I buy engines. Plug it into the USB port, stick it in the hole. Helps spot the guys that are trying to sell a 4.8 as a 5.3 pretty easily.

G Atsma

Wow, did not know that existed! Cool idea, Joe!

robertsjm711

I didn't know they offered a 4.8 flex fuel. I'm going to look into that phone scope and make sure, I think I see dished pistons but it is hard for me to tell.

robertsjm711

I guess I should add that I thought they didn't make them back in the cable throttle body days, only in the newer 2010+ drive by wire.

robertsjm711

http://www.e85vehicles.com/