512Stroker
We are all here because we are not all there.
I took a reading on No. 1 this morning just to make sure I wasn't dreaming.
I cant explain it.
I found my Cranking Cylinder Pressure (CCP) problem
- Thread starter 512Stroker
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I cant explain it.
Looking at the age of that tool, that would be my first choice.
512Stroker
We are all here because we are not all there.
Yes Sir
I was really pissed when I first put it in the car with the recommended 2200 stall converter performed very poorly, could never get the tune right.
Late last year I installed a 3000 stall converter and upped the gearing to 3.55:1
and that finally woke it up. The tune almost fell in place, the car now performs well for a small displacement engine.
my old 340 was close on specs had 190 cyl pressure , it would ping going up a steep hill in 2nd gear once the revs were up it was fine it would not run well on 91 octane . needed 94 . building a 340 now with the same specs as yours except using trickflow heads not that they will make much of a difference
TT5.9mag
Two atmospheres are better than one
At 1.22 lb/ft per cube you’re doin alright. And with 224/230 @ 050 you shouldn’t need a ton of converter or gearing. Is the car heavy? That might be some of it.
all FBO does that mean distributor as well ,? that may be part of why you are not pinging , put in a stock distributor and see what happens . i'm having a distributor done by them now hope it helps
512Stroker
We are all here because we are not all there.
Nat I did have Don @ FBO custom curve a distributor for my engine after I had issues with the tune and yes it did help.
If I remember correctly
16* initial + 18* mechanical advance = 34* total all in @ 2600rpm
Plus 10* vacuum advance
This engine was dynoed at 35* with no ping on 91 octane pump fuel.
One more thing, from the start I have run this engine with a large capacity, high flow cooling system with a 160* high flow stat.
When I pulled the plugs yesterday after 2500 miles they looked perfect, I put them right back in. Before anyone asks they are Autolite 63 plugs.
512Stroker
We are all here because we are not all there.
I weighed it at the county scales - 3150lb's half tank of fuel no driver.
Your right, I never thought of it torque/cubic inch
I have had BBM, make less than 1.22
Thanks
Man after my old school heart. 63 Autolites.
So let’s see if I got this right. Now that u got the better compression reading all is well with the motor and u. How do u know the new numbers are right? Or they are because they make u happy. Kim
512Stroker
We are all here because we are not all there.
Kim I dont think the numbers are accurate, but I can't imagine that the pressure numbers are way out of whack and no I not happy.
To start out with I think my expectations were to high for a small displacement engine that in conjunction with a tight converter it seem like the engine was under performing, which it was. Know that I got the converter and the tune straightened out and now that I know the engine does not suffer from from low cylinder pressure I have renewed faith in this combo and going to run it as is.
One change will take place the removal of the Comp retro Hyd rollers.
I hope that answers your question?
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Sort of. Kim
190 ? don't sound right for the static compression ratio and camshaft. I'd think somewhere around 150 -170. imo
512Stroker
We are all here because we are not all there.
Sorry that's all I got.
512Stroker
We are all here because we are not all there.
Someday If I can lay my hands on a quality Compression gauge I will rerun the numbers and post them.
Stay tuned
512Stroker
We are all here because we are not all there.
Well you were pretty close.
The suspense was killing me.
This a brand new compression gauge on loan from the local auto parts store.
170-180 psi across all 8 cylinders, I even went back and did No.1 twice to see if would repeat which it did.
So now we know.
Great!!! Kim
TT5.9mag
Two atmospheres are better than one
Ok now we’re in “makes sense” territory.
TT5.9mag
Two atmospheres are better than one
What we know is you can test 3 different compression gauges on the same engine with the same (hopefully) test method and get 3 different readings. Check, double check and verify.
512Stroker
We are all here because we are not all there.
I did use the same method, WOT all plugs out. I even had a battery charger on just so I would not lose any cranking rpm
That's more believable. Still high. My slant 6 spark knocked at 175 PSI until I did some tuning on it.
Ivoryk3ys78
Well-Known Member
When I put my combination together for the 408 I built using trickflow heads I used Wallace racings Dynamic compression calculator and with the 11.2 compression I was having it setup at and the solid lift cam specs showing closing at 65 ABDC it gave me a dynamic compression of right at 190.
Wallace Racing: Dynamic Compression Ratio Calculator
After the engine was built we tested then and they were all 190 to 200 so the calculator was real close and I have had no issues with detonation on 92 octane. That is initial at 16 total at 35
I guess I am just saying those calculators are pretty accurate. I was shooting for as much cylinder pressure as I could with 92 octane.
Wallace Racing: Dynamic Compression Ratio Calculator
After the engine was built we tested then and they were all 190 to 200 so the calculator was real close and I have had no issues with detonation on 92 octane. That is initial at 16 total at 35
I guess I am just saying those calculators are pretty accurate. I was shooting for as much cylinder pressure as I could with 92 octane.
Dale Davies
Well-Known Member
Yep, I do not trust any of that recycled Yak turds Chinese ****. Now days you have to read every box or label. Can not seem to be able to purchase light bulbs without Made by Xi Wunshortdong on the label.
I was looking at PAC valvesprings on ebay. PAC 1218-16 for $160, shipped out of Florida. Another at $140 out of the commie state. Then one for $109 but shipped from Zhanghunglow, China. Specs all looked the same, but I don't trust the CCP/PLA Yak turds crap and do not want to willingly support that regime.
Bret Tschacher
Well-Known Member
Which is why you should have checked your gauge against another in the first place. I have always been of the opinion that doing a comp test on any MOPAR was misleading from the day I started working on cars over 45 years ago. Engine compression during cranking is only a preliminary test just to see if there is any. MOPARs with their gear reduction slow cranking starts, I have never seen a stock engine read over 150 when another manuf. that used a faster starter would read 180. I've had my share of gauges and as I said, they are only the first gauge I go to. After that, I only rely on leak down testers ! If you read a repair manual you should see that anything over 100 is acceptable as long as they are all within 10 psi. Of course a cam that has 330 duration is going to read a lot lower than one with 240. Because it isn't spinning fast enough to initiate momentum of flow.
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