318 LA rebuild after losing a valve seat

[Righty Tighty]

Yes sir. The only thing I’m concerned about now is the piston to valve clearance, since I went with a slightly bigger cam. My machine shop guy thinks I should be fine, since “those pistons tend to sit pretty low.” I’m gonna check anyway, just because it makes me nervous.

 

[Righty Tighty]

Those are the heads I ended up buying. Came rebuilt from Rock Auto in great shape. Had to change out the springs and cut the guides down to fit the cam, but all should be good now.

 

[RustyRatRod]

Those are the heads I ended up buying. Came rebuilt from Rock Auto in great shape. Had to change out the springs and cut the guides down to fit the cam, but all should be good now.

What's the .050 duration on that cam?

 

[George Jets]

Those are the heads I ended up buying. Came rebuilt from Rock Auto in great shape. Had to change out the springs and cut the guides down to fit the cam, but all should be good now.

You want to use the light original single coil valve springs at first for breaking in the camshaft, you don't want burn the lobes off your new cam with the higher pressure valve springs as your cam is breaking in mating up to the new lifters.

Then you change out the valve springs after the cam is broke in, with air pressure in the cylinders to keep the valves up and shut while you are changing out the springs.

 

[Righty Tighty]

What's the .050 duration on that cam?

.213/.220

You want to use the light original single coil valve springs at first for breaking in the camshaft, you don't want burn the lobes off your new cam with the higher pressure valve springs as your cam is breaking in mating up to the new lifters.

Then you change out the valve springs after the cam is broke in, with air pressure in the cylinders to keep the valves up and shut while you are changing out the springs.

Well ****. Let’s pretend I tossed the old springs. What now?

 

[RustyRatRod]

.213/.220



Well ****. Let’s pretend I tossed the old springs. What now?

I think I said it before....there's no way in heck that's ever going to have piston to valve contact. No way, no how. It will be a good practice to check though, but it'll never happen.

 

[George Jets]

.213/.220



Well ****. Let’s pretend I tossed the old springs. What now?

Put on a set of stock single coil used 318 valve springs. Your machine shop guys probably have a used set around. Otherwise I am sure someone on here has a used set they can ship you.

318 springs, not 360 springs they look the same.

Burn that cam down and you will be going through the whole engine again.

 

[George Jets]

Rods are back from the shop and all is well. Pistons, cam, and timing set installed. Measured bore and depth of the cylinders to calculate compression ratio while I wait for the timing cover gasket to arrive. Also drilled out one of the cam thrust plate bolts to give it the oiling hole it needed.View attachment 1715478651 View attachment 1715478652 View attachment 1715478653 View attachment 1715478658 Gonna hit up some engine shops tomorrow to see if they have any junk solid lifters I can have to check piston to valve clearance, since I’ll be using hydraulic lifters.

I see you are Dot to Dot on your timing gear line up at 6:00 o'clock on the cam gear and 12:00 o" clock on the crank gear.

You are going to want to roll it over until your cam gear is at 12:00 o'clock and your crank gear is at 12:00 o'clock so when you drop in your distributor it will fire at top dead center on compression stroke on #1. You line up the 2 dots with a 12" ruler straight edge.

Right now at dot to dot, 6 cam to 12 crank . . You are 180° off for dropping in the distributor, it will be firing TDC on cylinder #6.

That is just the way it works on the mopar small blocks.

 

[Righty Tighty]

I see you are Dot to Dot on your timing gear line up at 6:00 o'clock on the cam gear and 12:00 o" clock on the crank gear.

You are going to want to roll it over until your cam gear is at 12:00 o'clock and your crank gear is at 12:00 o'clock so when you drop in your distributor it will fire at top dead center on compression stroke on #1. You line up the 2 dots with a 12" ruler straight edge.

Right now at dot to dot, 6 cam to 12 crank . . You are 180° off for dropping in the distributor, it will be firing TDC on cylinder #6.

That is just the way it works on the mopar small blocks.

Thanks for catching that! Maybe dot to dot is a chevy thing?

And touching back on the springs, I'm concerned that stock springs would bind. The cam I have has .454/.475 lift, and when I tried the Comp 901 springs, they were binding at the machine shop when he was checking for installed height. I had to go with taller springs.

 

[George Jets]

Thanks for catching that! Maybe dot to dot is a chevy thing?

And touching back on the springs, I'm concerned that stock springs would bind. The cam I have has .454/.475 lift, and when I tried the Comp 901 springs, they were binding at the machine shop when he was checking for installed height. I had to go with taller springs.

Ask @RustyRatRod about this ^^^^^.

 

[RustyRatRod]

Thanks for catching that! Maybe dot to dot is a chevy thing?

And touching back on the springs, I'm concerned that stock springs would bind. The cam I have has .454/.475 lift, and when I tried the Comp 901 springs, they were binding at the machine shop when he was checking for installed height. I had to go with taller springs.

It wasn't the springs. The 901 is good to right at .500 lift. I bet the retainers were hitting the guides or "something else" was wrong. It was not the springs. Was he trying to set them up using the thick exhaust valve rotators?

 

[krazykuda]

I see you are Dot to Dot on your timing gear line up at 6:00 o'clock on the cam gear and 12:00 o" clock on the crank gear.

You are going to want to roll it over until your cam gear is at 12:00 o'clock and your crank gear is at 12:00 o'clock so when you drop in your distributor it will fire at top dead center on compression stroke on #1. You line up the 2 dots with a 12" ruler straight edge.

Right now at dot to dot, 6 cam to 12 crank . . You are 180° off for dropping in the distributor, it will be firing TDC on cylinder #6.

That is just the way it works on the mopar small blocks.

Thanks for catching that! Maybe dot to dot is a chevy thing?

And touching back on the springs, I'm concerned that stock springs would bind. The cam I have has .454/.475 lift, and when I tried the Comp 901 springs, they were binding at the machine shop when he was checking for installed height. I had to go with taller springs.

No, 6 and 12 dot to dot is the easiest way to set the cam and gears with the chain...


Just keep building and when it comes time to put the distributor in, take out #1 spark plug and put your finger over the spark plug hole, then rotate the engine until you feel pressure - that will be the compression stroke where you set the distributor to TDC and the distributor to the #1 cylinder when installed...

 

[Righty Tighty]

No, I tossed those rotators. You’re right about the guides, he did have to cut them down. Can stock 318 springs handle the lift at .475?

 

[nm9stheham]

• You put the dots at 6 and 12 and just put the distributor in to fire #6. No need to do anything else, unless you want to waste time.
  
• I don't fully agree on the need to change valve springs for break-in. It depends on the cam and the actual springs. If the open valve pressures are under 300 lbs, I don't bother. Having the proper level of ZDDP in the oil is far more important if your springs are not too stiff. What springs and cam is this? Or is that info back on the thread?
  
• RRR is right on the likelihood of piston to valve contact. But always check. You can buy some light hardware store springs for that task.

 

[RustyRatRod]

No, I tossed those rotators. You’re right about the guides, he did have to cut them down. Can stock 318 springs handle the lift at .475?

No. You need to always use the matched springs for the cam. The 901 would be perfect.

 

[George Jets]

Stock 318, 302 Head single valve springs and retainers and posi-seals. Can't imagine someone throwing these new replacement springs away from the reman build that Rock Auto did.

They are either brand new or have been tested to be with in new specs.

The valve rotators Righty is talking about probably came on his 318, open chambered heads, the ones that dropped the valve seats.

 

[nm9stheham]

Rather than putting time and focus on changing springs for break-in for something like a 901 spring, the OP's time and focus is far better spent on:

• When the engine is assembled but before the intake is on, prime the engine
• Then put marks on the pushrods and lifters, and rotate the engine it several times by hand to make sure each lifter rotates, at least a little bit. Lack of lifter rotation will kill a cam lobe even with stock springs!
• Make sure that a good moly cam lobe paste (like Isky cam lube) has been used between lifters and cam lobes, not a runny cam break-in fluid

 

[Righty Tighty]

• You put the dots at 6 and 12 and just put the distributor in to fire #6. No need to do anything else, unless you want to waste time.
  
• I don't fully agree on the need to change valve springs for break-in. It depends on the cam and the actual springs. If the open valve pressures are under 300 lbs, I don't bother. Having the proper level of ZDDP in the oil is far more important if your springs are not too stiff. What springs and cam is this? Or is that info back on the thread?
  
• RRR is right on the likelihood of piston to valve contact. But always check. You can buy some light hardware store springs for that task.

Open spring pressure is 274. The cam is the Lunati 10200701LK, .454/.475 lift, 213/220 duration. The springs are the Lunati 73262 with 346 spring rate and 274 open pressure @ .454.

No. You need to always use the matched springs for the cam. The 901 would be perfect.

So, the Lunati springs I have installed are the springs the manufacturer recommends. I'm not understanding something here.

Stock 318, 302 Head single valve springs and retainers and posi-seals. Can't imagine someone throwing these new replacement springs away from the reman build that Rock Auto did.

They are either brand new or have been tested to be with in new specs.

The valve rotators Righty is talking about probably came on his 318, open chambered heads, the ones that dropped the valve seats.

Yeah, I do feel foolish for tossing the springs that came with the heads, but I really didn't think I'd have a use for them. I ended up selling the 901s on eBay, also for the same reason.

The rotators actually came on the 302 heads, and I swapped them out for some standards from the old heads.

Once again, I'm very grateful for all the help. Anytime I feel like I have a stupid question or screw something up, nobody has ever been condescending and always jumps in to help when they can. That certainly fosters a learning/teaching environment. This is a great forum.

 

[RustyRatRod]

Open spring pressure is 274. The cam is the Lunati 10200701LK, .454/.475 lift, 213/220 duration. The springs are the Lunati 73262 with 346 spring rate and 274 open pressure @ .454.


So, the Lunati springs I have installed are the springs the manufacturer recommends. I'm not understanding something here.


Yeah, I do feel foolish for tossing the springs that came with the heads, but I really didn't think I'd have a use for them. I ended up selling the 901s on eBay, also for the same reason.

The rotators actually came on the 302 heads, and I swapped them out for some standards from the old heads.

Once again, I'm very grateful for all the help. Anytime I feel like I have a stupid question or screw something up, nobody has ever been condescending and always jumps in to help when they can. That certainly fosters a learning/teaching environment. This is a great forum.

If you read what I replied to, you will understand.

 

[nm9stheham]

Hey... we all start out of the womb with the exact same knowledge base.... ZERO! We've all BTDT.

My personal decision on those springs would to break-in with them. Others may have a different thought, and that is all good too. I get about 255 lbs pressure over the nose, BTW, assuming a 1.650" installed height.

Now one more thought on the spring change: My stuff is always ready to fire off with a few cranks, and run and get oil to the cam immediately. So I feel confident. If you are not confident that will happen, then the softer springs may give you some grace in a startup process that is plagued by starts and stops. Are you putting in a new carb or using one that ran before? Same question on the ignition system. New engine with new carb and/or ignition is a recipe for startup difficulties.

 

[Wyrmrider]

lots of tips
how far down IS the piston and what Did you calculate the compression with the three available gasket thicknesses
ps how many cc's in the valve notchos
what did the heads cc?
how close to your estimates?

 

[George Jets]

lots of tips
how far down IS the piston and what Did you calculate the compression with the three available gasket thicknesses
ps how many cc's in the valve notchos
what did the heads cc?
how close to your estimates?

I will shoot from the hip here and take a wild guess on what his Compression Ratio will be.

By the piston height in post 118 it's looking like a stock compression height .040 over bore replacement piston sitting somewhere around .140 ths down in the hole up at TDC.

Guessing that is going to be an 8.5:1 short block. So then you figure the closed chambered 302 318 heads, and the fact that there are no valve reliefs in the pistons, and figure the. 028 ths. thin Mr. Gasket head gaskets.

Rock Auto Reman job takes a cut on the heads to clean them up, so lets say .010 there.

All things considered I am guessing he is going to end up at around 9:1 compression.

Will be fun to see what Righty comes up with when he gets all his numbers figured up.

I believe the the Reman 302 heads cc out at 65cc. New Valves in the heads makes them stand up nice, not sunken like a ground in valve job.

The stock '69 318, 9.2:1 compression 230 hp engines had their valve relief pistons sitting .040 ths. down in the hole as a comparison.

 

[nm9stheham]

IMHO, the OP has what he has and it is better to help him get it running. At least he has a smaller cam to help with a lower CR.

But since I NEVER can resist running a CR computation (damn you LOL), I compute around 8:1 SCR, but IDK the piston PN.

 

[George Jets]

IMHO, the OP has what he has and it is better to help him get it running. At least he has a smaller cam to help with a lower CR.

But since I NEVER can resist running a CR computation (damn you LOL), I compute around 8:1 SCR, but IDK the piston PN.

Will be fun to see ^^^^^ what the actual cr numbers turn out to be. Lol . . .

 

[Righty Tighty]

You know, it's funny. I really was contemplating not measuring anything and skipping calculating CR for several reasons. Primarily, it was because I'm jonesing to get this car back on the road ASAP and didn't want to take the extra time. Also, because I've never done it and was simply feeling lazy in that I didn't want one more damn thing to learn how to do. BUT....I knew you guys would be asking about numbers, and I didn't want to let you down. I did measure depth and bore yesterday, albeit not with a degree wheel installed, so BDC was definitely not 100% accurate.

I do plan on using the degree wheel later on, but here are the rough numbers I got: bore was dead nuts 3.950, depth at approximate BDC was averaging around 3.380. Again, I was eyeballing BDC, so that number isn't very reliable.

The pistons I have are the Sealed Power 814CP. Gasket I'm using is a Fel-Pro from a kit, I couldn't find definitive numbers on their website regarding crush thickness. Sent them a message and we'll see what happens.

I haven't checked the CC on the heads yet, but I will soon.