First a little backstory. 3 years ago I rebuilt the TBI 350 in my Suburban. No real changes other than a cam swap to the Summit 1102 which I have been pleased with as it is significantly more torquey than before.

During this engines life span it has been overheated a few times due to a coolant leak, but it doesn't knock. It does however have a mysterious loss of coolant however. So much so in fact that if I were to drive it every day I would have to put a gallon of coolant or more in it every week. I have had it pressure checked and the mechanic was not able to find any leaks. This leads me to believe I have a cracked head as the only thing he hasn't done is a bore inspection.

At the least, sometime in a month or so I am going to pull the heads and check the cylinders to see if any of them are devoid of carbon, which the water would prevent from building up to my knowledge. At this point i'll probably have the heads checked by my machinist.

There is no water in the oil, so I am not thinking the block is cracked, and as I said it doesn't knock.

My question is this. If the heads are cracked, would it be a decent upgrade to have a set of junkyard Vortec heads machined and upgrade the intake to a carbureted vortec with an adapter plate?

I am thinking this could be achieved for around $300 with machining and valve spring upgrade. The truck is on a stock chip with shorty headers and true dual exhaust (no h/x pipe) plus the cam (204/214 .421/.444).

Basically, would this be too radical of an upgrade for the stock computer?

 

I dont know about the cam/stock com. I do know that if you are loosing fluid and a pressure test showed no leak, that that is impossible. Or am I not understanding correctly. You Had a pressure test done and there was no leak or you couldn't find the leak? If you are loosing fluid it will show on the pressure test gauge. Now, weather its in the head or block is the question.. most shops can stick a sniffer in your exhaust and tell you if it is burning coolant. other than that, you have to isolate block or head and pressure test them individually to know what/where the leak is. Pretty sure those vortec heads are very common. Biggest thing there is, you are rolling the dice on junk yard stuff. You would be surprised at the percentage of ALL the heads out there that have cracks and/leaks. Im talking about EVERY head made.

 

When pressure was applied there was not a leak that was visible or significant pressure loss to my knowledge. What I am thinking is it could be a small crack in the chamber and when the engine is warm it could be burning the coolant then. As I said, he didn't do a bore inspection so it would be impossible to know whether or not it is leaking in there. In addition, if the crack is small enough it wouldn't have a huge loss in pressure, but could still result in the loss of coolant. In terms of the junkyard heads I would have them checked/machined before install with a valve spring swap. If they are cracked on inspection then obviously I would return them and try my luck again.

Basically, this isn't definite, but I'm thinking if I have a cracked head I might as well upgrade and I could avoid some overhead cost by picking up the heads at the yard then having them machined instead of paying someone way too much for a used set, having no warranty, and losing money. Just want to know how everyone thinks the stock chip will handle it.

 

HOW are you going to handle the EGR?

Vortec heads don't have an exhaust crossover provision. You'd have to pipe in exhaust from--perhaps--an AIR fitting on the header tube.

GM sold parts to do all this, but I think they've been discontinued. At least, I haven't seen the kit advertised for years. Maybe the stuff is available individually.



Why not just pull the plugs out and look for the ones that show steam cleaning?

 

truck is already running with EGR disconnected. Not worried about that. Obviously if I pull the heads I'll see the plugs. Again, this is if one of th heads is cracked. Not to be a dick, but please read the whole post.

 

If you pull the plugs and none of them show steam-cleaning, you can kind of guess that the coolant isn't going into the combustion chambers and you won't need to pull the heads off.

Yes, I made the assumption that you'd want to use EGR with the Vortec heads. I DID read the whole post, nowhere did you say you had disabled, or wanted the EGR disabled.

 

While you are correct about the EGR, and that is something to consider. I said in the first post I was going to check for steam cleaning in the cylinders when I pulled the heads. That's what I was saying I wasn't trying to be a dick about. Regardless, I am just looking for the question I asked to be answered. Can the stock computer handle cam AND the head/intake swap? Does anyone have experience with this setup on a stock chip, etc.

I feel like pulling the heads would be the most accurate thing to do because there will be no doubt then and when you pull the plugs its less obvious to me anyway. As cheap as a set of head gaskets is it's worth the money to me to be sure they're good.