Cyl heads.

[70bigblockdodge]

Will, for your use, I can't see worrying about CR's. Keep it so it uses regular octane gas. 9.0 would be my choice. It will be simpler to tune.

Yes, if you were to measure the chambers and down in the hole you would be lucky to get to 9:1, putting open chambers on that will put it in the 8:1 which will hurt throttle response and make the car not as pleasurable to drive. Cylinder #3 as stated above came up at 125# that's not great. He is at sea level and 9×14.7= 132.3. Add in another .020 for composition head gaskets over the steel shims in there now and will be lucky to stay in the high 8s. I think going to a ~10cc bigger open chamber With a small bore and short stroke 383 will not be great, and his is supposed to be a HP.
Just my thoughts, also the later heads do not look like the original 516 which has no end core plugs.

 

[commando1]

also the later heads do not look like the original 516 which has no end core plugs.

Well that kills it for me...

 

[twostick]

Pull the valve cover and see if the push rods on #1 are still where they belong. Not unheard of for one to go through the cup on a rocker arm and cause the valve to cease operating. If all looks good, spin the motor over to verify both rockers move as they should. If it passes that test it's pretty safe to say the cam hasn't gone flat and you have a scorched exhaust valve.

The easy button solution is 400Source Stealth heads. By the time you do 16 new guides, valves and have seats installed you will have spent most of the price of a set of Stealths and the difference will be a small price to pay for the extra horsepower plus the added bonus of it still looks stock and maybe it runs nice on regular gas with a good timing curve in it.

Kevin

 

[cantflip]

I may have more serious issues then I would wish for with my 67 Polara. I've been chasing a "miss" since I got it running and driving. I thought i'd run a compression check yesterday. Easiest access to plugs is #1, so I started there. No compression.... I thought perhaps the gage was defective but #3 had 125 lbs. I just stopped there.

I'm wondering when the first year hard seats were installed in the BB heads, 71/72?
Most likely scenario, I think, is a burnt exhaust valve. I may be fishing for a later model set of heads.

That sucks, sorry Will.

 

[bluefury361]

That sucks, sorry Will.

It's not that bad guys, just unexpected. I don't mind doing what needs to be done. I'll gain some piece of mind, and a 383 that runs like its suppost to.

 

[cantflip]

It's not that bad guys, just unexpected. I don't mind doing what needs to be done. I'll gain some piece of mind, and a 383 that runs like its suppost to.

Mostly I'm glad she didn't have a date to be somewhere right away. AFAIAC, Carlisle is still on

 

[moper]

You might be surprised. Crap in the valve seat, a broken exhaust valve spring, etc. pull the valve cover first. If you see a broken part don’t waste too much time on the rest.
As far as directions to go- depends on the issue. If it’s a head issue, I normally lean to redo what you have. But the 516s do not lend themselves to unleaded seat rings well unless you stay with the small valve. It’s a real possibility that the cut to make the relief for the west insert cuts into the water jacket and at that point I’d call it scrap. No 383 had an advertised statice compression ratio. And in order to reach that now, you have to replace the pistons and blueprint the heads and block. So if we’re me and it’s a head issue, I’d find a set of any other head casting, have that redone with the seats, and go from there.

But that’s all conjecture until you know what’s failed.

 

[70bigblockdodge]

I would not sink hardened exhaust seats into the heads. With near stock valve springs and a stock cam it will take more years than I have left to wear them back out.

 

[moper]

I wouldn’t either if it was for my own use. But he seems like he wants them and technically that’s the right way to do it.

 

[70bigblockdodge]

I'm going with your broken valve spring. Car sat a long time, that cylinder and maybe another had valve off the seat, bad sealing

 

[bluefury361]

Mostly I'm glad she didn't have a date to be somewhere right away. AFAIAC, Carlisle is still on

I just spent the past 2 days getting Connie in shape. She'll be ready no matter what happens.

 

[70bigblockdodge]

I just spent the past 2 days getting Connie in shape. She'll be ready no matter what happens.

See you there.

 

[bluefury361]

Well, I removed the valve cover and found no visible mechanical issues. Push rod/rocker arm OK. Good full stroke on the valve stem. So I shot the air to it..... silence. No audible sounds from the engine or tail pipe. All other cylinders at. 163/190
I did get an endoscope. Looks cool except I can't figure out how to add the app to my android smart phone. I found instructions and they appear to be in English, I just don't know what they are telling me to do. (I'm challenged that way). Next 8 year old that passes by, I'll grab him.

Actual cheap *** gage readings...
#2..... 163 #1..... 0
#4..... 163 #3..... 149
#6..... 185 #5..... 185
#8..... 166 #7..... 190

 

[commando1]

I did get an endoscope

Gimme the name of the scope, I'll find the app forya

 

[bluefury361]

Gimme the name of the scope, I'll find the app forya

I found the app Stan. Just have no clue how to get it on my smartphone.
WiFi endoscope HD720P

Model YPC99-5
app is inskam

 

[70bigblockdodge]

Just curious and I know you probably have one. Vacuum guage readings/needle movement.

 

[bluefury361]

Just curious and I know you probably have one. Vacuum guage readings/needle movement.

I haven't put a vacuum gage on it yet Dave. Probably would have gotten an eratic reading with the stumble it had. I made a few cursory adjustments on the carb and timing but it was obvious there was a more serious issue. First hole I checked, (#1), was zero compression.

 

[70bigblockdodge]

I haven't put a vacuum gage on it yet Dave. Probably would have gotten an eratic reading with the stumble it had. I made a few cursory adjustments on the carb and timing but it was obvious there was a more serious issue. First hole I checked, (#1), was zero compression.

Not hearing it run, I kinda wondered. Just thought that would point intake or exhaust.
#7 is quite zealous at 190 psi, I'm going to say the intake is out of #1 and the pulse back into the intake is supercharging #7 to the tune of around 13:1 compression ratio.

 

[bluefury361]

Not hearing it run, I kinda wondered. Just thought that would point intake or exhaust.
#7 is quite zealous at 190 psi, I'm going to say the intake is out of #1 and the pulse back into the intake is supercharging #7 to the tune of around 13:1 compression ratio.

I'll put the plugs back in and button it up. Then see what the vacuum gage does. Will report back tomorrow.

 

[bluefury361]

Not hearing it run, I kinda wondered. Just thought that would point intake or exhaust.
#7 is quite zealous at 190 psi, I'm going to say the intake is out of #1 and the pulse back into the intake is supercharging #7 to the tune of around 13:1 compression ratio.

Good thought Dave. I'll charge #1 again and open the throttle to see if I can hear anything.