Need help figuring compression ratio..

[TruckManiaMike]

The heads came out of the factory really close to 1.000. Your heads have NOT been cut! How far down from the deck are the pistons when
they are at TDC?

I measured .145”

 

[1 Wild R/T]

Your compression tester is "optimistic"...
"new" doesn't mean "accurate"

 

[TruckManiaMike]

Currently running a compression test on my compression tester

 

[zyzzyx]

 

[TruckManiaMike]

Compression tester checks out

 

[1 Wild R/T]

Your cam timing events have to be "interesting"... Zero overlap & short Exhaust duration..

 

[TruckManiaMike]

No clue what cam is in it but I need a new one one of the lobes is wiped

 

[BSB67]

To the OP, are you sure you are reading the gauge correctly. And did you do all eight cylinders? Maybe take a picture of the gauge after you've done a test and post it. If you actually have 170 psi, you would have audible detonation any time you leaned on the throttle going down the road.

The intake closing point will determine the cranking pressure. Assuming the guage is correct, bleed down lifters will give a false high reading, as will a wiped cam lobe or a bad lifter. Have you messed with the timing chain recently?

Finally, based on the evidance so far, I think you'd be fine using the smallest combustion chamber head you could find and run a 0.020" steel shim gasket.

 

[1 Wild R/T]

That wouldn't be the cylinder reading 170 would it? Exhaust Lobe?

 

[BSB67]

You've posted before I put my post out there.

Wiped lobe - okay. New cam? If so, was it installed correctly?

 

[TruckManiaMike]

I didn’t know anything about the motor buying it, my grandfather bought it from some guy selling it on the side of the road.never drove it in the road, did run the motor with truck stationary but wasn’t firing on cyl 6 due to intake pushrod fell out likely due to wiped cam and a bunch of sunken exhaust valves.

 

[TruckManiaMike]

To the OP, are you sure you are reading the gauge correctly. And did you do all eight cylinders? Maybe take a picture of the gauge after you've done a test and post it. If you actually have 170 psi, you would have audible detonation any time you leaned on the throttle going down the road.

The intake closing point will determine the cranking pressure. Assuming the guage is correct, bleed down lifters will give a false high reading, as will a wiped cam lobe or a bad lifter. Have you messed with the timing chain recently?

Finally, based on the evidance so far, I think you'd be fine using the smallest combustion chamber head you could find and run a 0.020" steel shim gasket.

I have the motor completely disassembled in my garage right now. I did a compression test on all cylinders and these are the results…
8-160
6-40
4-120
2-120
1-150
3-90
5-150
7-170
Cyl6 had missing pushrod
Cyl3 had very sunken exhaust valve

 

[1 Wild R/T]

I think if you take a good look at that cam your gonna find more than one suspect lobe...

 

[BSB67]

Well, it's obvious/simple - new cam, new heads w/ 75 cc chambers.

The next thing you'll need to decide is whether to pull the whole engine down, and what to do with it.

 

[33 IMP]

Making a BUNCH of assumptions here, like the short block (except for cam) is serviceable, and pistons won't be replaced. So, here we go....
Assuming .030 over 440, 75cc rpms (or equivalent) standard.035 head gasket, and .145 deck height..... calculator says 8.42. Steel shim hg might get a little more.
I'd bet that motor was less than 7.5 to 1, as it was.
Err on the mild side for camshaft, just my opinion.
(I use Wallace racing calculators, he has one for just about everything).

 

[TruckManiaMike]

Okay, wanted to put a decent cam in it to utilize the aluminum heads but it sounds like these pistons are really hindering me. How much would I benefit from getting new pistons? Any recommendations?

 

[hunt2elk]

Okay, wanted to put a decent cam in it to utilize the aluminum heads but it sounds like these pistons are really hindering me. How much would I benefit from getting new pistons? Any recommendations?

At that point, maybe you should consider a stroker kit from 440 Source?

 

[TruckManiaMike]

Pheww I don’t have another 2800 to put out! But could my block be decked? Is there a door way to tell if it’s been decked like how we checked with the heads?

 

[RemCharger]

Like I said earlier, you will still make power with what you got.
My bone stock 77 440 bottom end with ported 906s went 12.10s in 2 different full body stock 64 Dodges.
If you go to Moparts tech archives , I started a thread about 440 smoggers years ago

 

[RemCharger]

Fastest STOCK smogger 440 bottom end times??