I have a unknown mileage (guy said he bought it from a yard as a replacement which said motor had around 90k) he got rid of it because he had a 58x motor and this was a 24x motor. I picked it up for $250. Ive been through the whole motor, cleaned and had the heads resurfaced, bottom end looked ok, not much hatching on the cylinder walls if any. I had to pull the heads bc of water sitting in one of the heads intake or exhaust tracks causing a lot of rust buildup. I pulled and cleaned the heads, swapped the oil pan to a fbody and put it back together to test it on a stand before investing further. Engine ran no problem but made alittle less vacuum than what I expect for stock.

Engine is now going into a car so I pulled the cam for a summit stage 1 truck cam, new chain and gears. Started pulling the heads to replace the lifters with morel 5315s I picked up for cheap. I decided to pull the valves and do another lapping as I remember some putting on them last time (over a year ago since I have been in this motor). Got the pass side off and apart and this is what I have found.

what do you guys think? The worst one is an intake valve with a large pit (darker area). Not sure if I need to purchase new valves and when they come do I just Lap them and verify a nice contact patch?

do you think they are bad enough to warrant change? Wondering if the lower vacuum around 14-15” with stock 5.3 cam if I remember was because of this? I was looking at the melting V1935 and V2000 valves as replacements. I haven’t gotten to the other side yet but wanted to get your thoughts. Getting the higher mileage lifters out of the bores has been a PITA!


Intake

Exhaust

Exhaust

Exhaust

Intake

 

I would spend the few minutes to lap them and see if they pass the water test, if so send it.

 

What do the seats looks like? Are the valves bent?
I bought some junkyard 799s a while back. The valves looked like that, the seats looked worse. Also several of them were bent. Spun them in a drill and it was very obvious. Ended up getting all new valves and valve job.

 

That was after lapping... lol. I did it by hand tho vs the drill method.

 

Seats look better on the head honestly... They are not bent. Like I said this motor was run after I got it on a stand before tearing it apart a 2nd time to do the cam/lifters which is where I am at now. They are straight as an arrow just pitted, not sure why but my brain thinks the driver side is going to be worse for some reason and that could be my memory of that side being worse coming through. Won't know till I yank the head and remove of course.

 

Do they seal up?

 

Didn't test yet. The heads are disassembled. I haven't ever had to test sealing so I assume the water method is just to put water in the chamber or intake tract/exhaust track and see if it leaks?

 

Yep. I put them upside down with water in the chamber and let it sit. See if you get bubbles or a slow drain.

 

seems technical! How does that compare to 150psi of cylinder pressure trying to get out?

 

Not a darn thing Its a sanity check.

 

That pressure is against face of the valve as well, so it can actually help sealing. Kinda like like when its not totally sealed sometimes and then you put the valve spring in and its fine.

 

There aren't many other ways to check for a leak with the head off that I'm aware of, so that's kinda what you get. But so far every valve I've had pass the water test held compression, the ones that didn't, didn't.


And there's a hell off a lot more than 150 psi in there lol, that helps seal the valve like said above.

 

Can the machine shop recut the valves? You can recut the seats and the valves with stones, but it may be cheaper to get new ones if they are that bad. Personally I'd lap em in and vacuum test the heads. I usually do vacuum testing with no springs in. If you do it this way rotate the valves in different positions on the seats.

I feel like what I'm saying is confusing. So if you lap the valves in, mark their seat with a marker on the valve and the head (so you know the starting position), vacuum check it. If it works, rotate the valve a bit and do it again. If it seals then you're good.

This is how I learned to do it.

 

machine shop would cost more to cut and drive and pick them up. I can get new valves for like $100 on summit. If I buy the new ones and just need to lap them to get them to seat right I would be fine with that so I know I don’t have to pull the heads again. But do I really need to invest more into these heads? The whole motor only cost $250 lol. Might be worth it for piece of mind and give me some time to do alittle porting. What I don’t want to do is invest in new valves and they plus the heads will need to be recut and add to the cost. If I buy them and drop them in I’m good with that.

I had a valve seals spring break and they are new on the heads. I pulled a spring off an old SBC valve spring and swapped it over. This motor was suppose to be on the cheap $400 dorman LS6 intske bc LS1 and LS6 intakes are $$ all of a sudden. Got my summit cam for $200 new from summit, morel 5315s for $175 shipped cheap LS2 style timing chain set, $99 eBay fbody pan.

anyways... how do you vacuum test the chamber? Figure you clay around the chamber and use plexi or something and use a vacuum pump and verify it holds vacuum?

 

If it's a super budget motor I wouldn't get new valves or machine work. Just lap and see if it seals.

Where I had worked there was a vacuum testing machine that would pull vacuum on a hose. We had flat pieces of aluminum with a hole in the middle with rubber on one side and a fitting on another. You put the vacuum hose from the vacuum pump on the fitting side and the rubber side on the port(s).

They looked like this:

https://www.ebay.com/i/402340606215?...BoC2RUQAvD_BwE

I've personally never done the water method, but if you don't have the means to make your own fittings and have a vacuum pump I'd just try the water method the other people have suggested.

I love budget builds by the way. Just because you don't do something perfectly from having a top dollar motor and all work done by a machine shop doesn't mean it won't work.

Edit: Are they the factory springs? What Summit cam did you get?
And I'm by no means an expert, just asking out of curiosity.

 

Ahhh gotcha. Followed everyone’s advice and pulled the driver head. Flipped it over and installed spark plugs. Put water on it and let it sit for 10 min and no bubbles or leaks. Decided to redo the lapping on the pass head with a drill this time and gave it all she’s got. Assembled the head back together and put water on it and didn’t see any leaks but I had to leave in a hurry so I will check tmrw to see if it’s leaking etc. So far so good!






all my builds are like budget/middle of the road builds. I very rarely pay full price for anything and I try to reuse what I got or make it work. this setup was suppose to be more budget orientated but didn’t think my parts matched up well and I needed a new intake bc truck intakes don’t fit C3 corvette hoods. The intake I got $100 off which is the dorman LS6 intske which I ported alittle in the runners. The cam is a summit 8719 which was on sale for $269 and I got another $50 off it so $219 cam and it will net me 40+whp over stock. Timing chain kit is off eBay and is a LS2 style. Oil pan is a $99 fbody knockoff unit off eBay, got the new morel 5315 lifters from a forum member last Friday for $175 shipped. Heads are stock 862s that I had to get resurfaced after hot soaking in ZEP (it eats aluminum so don’t use that ****). Springs are pac 1218s which I got for cheap off eBay from speed inc when they were on sale (bulk pricing). Gona be stock rockers, valve covers and moly 5/16 pushrods that I got years ago for like $90 from a vendor here. Using a $50 eBay HV fbody style water pump to clear the vette front end, $80 db electrical 130amp truck alternator and used PS pump. $50 eBay billet accessory bracket that kicks the alt lower and out to clear the hood. $150 used deka 60lb injectors and $30 eBay fuel rails for LS1 intake. Stock everything including the balancer and oil pump (with the nut in the pressure spring mod for higher oil pressure), I did splurge on an eBay $8 oil pickup girdle of course and $30 steel motor mount adapter plates. I’m even rocking the eBay $40 head studs torquer around 60-65ftlbs if I remember correctly. Hopefully they don’t snap when I put the heads back on but it did run with them so that’s good. I also really like the $100 eBay full gasket kits and this is my 2nd motor using them with there MLS head gaskets.

like I said it’s a middle of the road build I actually put a LS9 cam in it that I had on the shelf but decided to pull it after reading about the loss in low end. The C3 has stupi 2.87 ish gears and with a 700r4 this car will
only be street driven. Decided to go with a 2000 stall 12” stock style converter and the truck cam will give me more off idle torque to get the car moving around town. Car was originally like 165-185hp and the summit cam should put me around 400hp on 87 pump.

I did decide to try out the Holley terminator EFI as I have had great luck with fitech EFi on my firebird with a turbo 5.3. Would of went with fitech again as it was $100 or so cheaper but fitech won’t drive the stock vette tach... so I off course figured out a way to get $100 off the terminator EFi and got that in the car.

the only thing new on this motor is the oil pan, intake, cam, timing set, eBay head studs alt and water pump. Everything Else I had laying around.

 

$250 motor, no water leaking....good to go, send it!

 

Facts, for $250 even if it leaks a little she still gonna get 30PSI.

 

I love the shopping list.

I'm using the 100$ ebay gasket set on my build and they seem to be of good quality. I didn't use their HG though. I wasn't brave enough to try them haha. But it was still cheaper for me to get el cheapo gasket set and then buy name brand HG than it is for me to get everything fel pro.

That thing is going to be a load of fun

 

Well ****, left the head with water in the chambers over night and all day basically 24 hours and had water come through on every exhaust and intake valve on this head....

is it because I left the water on too long? It was showing signs of rusting already. Figure I could just replace all these valves and let it eat or screw it and just clean it up and throw it back together?

they all basically looked like this and these are all different runners mixed exhaust and intake.