505 stroker fresh off the dyno - Power seems low? Thoughs?

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Minnesota Muscle

Minnesota Muscle

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So there's the question. This is the first stroker build for me. After comparing notes with very similar builds it seems to be missing 50-75 horse easy. Even the owner of the engine shop/dyno felt it was lacking greatly. It fired right up and break-in was flawless, runs smooth after ten pulls this dyno sheet below was the best we could do, and that's with their 1000cfm carb and a 2" spacer. 574hp and 605tq is all it had. Changing from the 950 quickfuel to their 1000 holley gained it only a couple HP difference, hardly noticeable. Engine liked 30deg of timing the best. At 32deg, it lost 4hp and 2tq and kept loosing power with any increase in timing. This is a very reputable shop that does many big HP engines, so I trust their equipment. The shop owner could only speculate that I was somehow given the wrong pistons and have something like 9:0.1 compression, which is a piston 440 source offers as an option. I will be calling 440 source on Monday to see if there was any chance this could be the case.


-1978 440 block bored .30 over
Lined honed and deck just cleaned up. Bearing clearance at .00275-.003
-440 source 512 stroker kit with 78cc pistons for a com ratio of 10.6:1
- 440 source stud girdle
- ARP studs on mains and everywhere else in engine
-Untouched Trickflow 240 heads
- .040 MLS head gasket
-Cam is a custom grind Howards Solid FT
Lift .599in .620ex 110 lobe sep
Duration @ .50 254/262
Lash set to .016 cold as it calls for .018 hot
-Rocker arms are PRW 1.5 ratio steel roller with B3 racing spacers for correct geometry which caused me to loose about .025 lift which puts me closer to .574in / .595ex
-Smith Bros 3/8" dia push rods
-Headers 2"
-Victor intake
-Carb Quickfuel 950
-All MSD ignition
-6qt pam
-Melling high volume pump
-Brad Pen 30weight break in oil

IMG_20210819_101756.jpg


512.png


512 dyno sheet.png
 
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30 degrees of timing seems a bit low.
AF ratio is not bad. I will ask like above- what’s your cam dialed in at? It also may be a small cam with narrow lobe separation.
 
Did you guys do a compression test with a warm motor? What did it crank out?

I am running 10.2 to 1 pistons in my 493" RB and it cranks within a few pounds either side of 200 psi in all 8.

Same compression ratio pistons in my 408 magnum and nearly the identical cranking compression.
 
It should be easy enough to tell if you got the wrong pistons. What's the cranking compression? Did you take any photos of the pistons? What did they look like? I would think both pistons would look totally different.
 
Howard's dual timing chain and timing gears were installed dot to dot. Here's a picture of the pistons. I'll make sure I send it to 440 source too, maybe they can tell the difference.

Also forgot to mention 91 octane fuel, (best we had in the area).

IMG_20210609_212408.jpg
 
Along with above on cam degree. Most of the 440 blocks I’ve dealt with the deck height is more than factory spec, and usually not square front to back. I believe the 512 kit calls for .015” below deck for pistons. Also your lash may be tight. My 440 with eddy heads is .004” - .005” difference between hot and cold. The lash may not make much difference. But something to check. Just a couple of my thoughts.
 
After the tenth run they kinda throw their hand up and said, "I guess that's what is it", and ushered me out the door. Never did a cranking pressure test.
 
Dubob said:
Along with above on cam degree. Most of the 440 blocks I’ve dealt with the deck height is more than factory spec, and usually not square front to back. I believe the 512 kit calls for .015” below deck for pistons. Also your lash may be tight. My 440 with eddy heads is .004” - .005” difference between hot and cold. The lash may not make much difference. But something to check. Just a couple of my thoughts.
Click to expand...

You are correct -.015 deck. When the machinist asked where to cut the deck, I called 440 source, the guy said, "ahhh just clean it up should be fine". I'm guessing there was a miscommunication and he wasn't aware exactly what I was working with. As down the road, long too late did I see the 15 thou below deck requirement. One thing I screwed up on was not measuring how far down in the hole the pistons were. Would this taller deck hight be my culprit?

And why is the timing so low?
 
Minnesota Muscle said:
You are correct -.015 deck. When the machinist asked where to cut the deck, I called 440 source, the guy said, "ahhh just clean it up should be fine". I'm guessing there was a miscommunication and he wasn't aware exactly what I was working with. As down the road, long too late did I see the 15 thou below deck requirement. One thing I screwed up on was not measuring how far down in the hole the pistons were. Would this taller deck hight be my culprit?

And why is the timing so low?
Click to expand...

How do you know what the compression ratio is if you never measured where the tops of the pistons are relative to the deck height???

And where is the intake centerline???
 
Intake centerline on the card is 106. I should clarify, when I mean it was spot on, I checked the lift and duration, I don't recall off memory what the actual lobe centerline measurement was, will have to look in the shop tomorrow.

Screenshot_20210909-102943~2.png
 
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The piston to deck clearance is crucial to knowing the compression ratio. The dish in those pistons are huge. I suspect that the compression is well below 9.5 to 1.
 
Minnesota Muscle said:
So there's the question. This is the first stroker build for me. After comparing notes with very similar builds it seems to be missing 50-75 horse easy. Even the owner of the engine shop/dyno felt it was lacking greatly. It fired right up and break-in was flawless, runs smooth after ten pulls this dyno sheet below was the best we could do, and that's with their 1000cfm carb and a 2" spacer. 574hp and 605tq is all it had. Changing from the 950 quickfuel to their 1000 holley gained it only a couple HP difference, hardly noticeable. Engine liked 30deg of timing the best. At 32deg, it lost 4hp and 2tq and kept loosing power with any increase in timing. This is a very reputable shop that does many big HP engines, so I trust their equipment. The shop owner could only speculate that I was somehow given the wrong pistons and have something like 9:0.1 compression, which is a piston 440 source offers as an option. I will be calling 440 source on Monday to see if there was any chance this could be the case.


-1978 440 block bored .30 over
Lined honed and deck just cleaned up. Bearing clearance at .00275-.003
-440 source 512 stroker kit with 78cc pistons for a com ratio of 10.6:1
- 440 source stud girdle
- ARP studs on mains and everywhere else in engine
-Untouched Trickflow 240 heads
- .040 MLS head gasket
-Cam is a custom grind Howards Solid FT
Lift .599in .620ex 110 lobe sep
Duration @ .50 254/262
Lash set to .016 cold as it calls for .018 hot
-Rocker arms are PRW 1.5 ratio steel roller with B3 racing spacers for correct geometry which caused me to loose about .025 lift which puts me closer to .574in / .595ex
-Smith Bros 3/8" dia push rods
-Headers 2"
-Victor intake
-Carb Quickfuel 950
-All MSD ignition
-6qt pam
-Melling high volume pump
-Brad Pen 30weight break in oil

View attachment 1715788967

View attachment 1715788968

View attachment 1715788978
Click to expand...

not going to make a whole bunch of diff. , buy ur running the valves a hair loose , .018 cold setting should be .012 for alum. heads , and should run best about 34 degrees , ------jmo
 
Kern Dog said:
The piston to deck clearance is crucial to knowing the compression ratio. The dish in those pistons are huge. I suspect that the compression is well below 9.5 to 1.
Click to expand...

I understand. Things were being worked on in small stages, and I overlooked it. Been beating myself up for it. It obviously creates a huge unknown. That's what I'm hoping to narrow it down too with this thread.
 
Ok, let's ask some FLAT OUT CLOSED ENDED questions.

Did you use a DEGREE WHEEL and DIAL INDICATOR and PISTON STOP to install tha camshaft? Yes or no?

What is the measured cranking compression pressure on a compression gauge?

You came here for help. Stop doing a Mexican hat dance around questions and answer them. We can help you, but we need answers.
 
Kern Dog said:
The piston to deck clearance is crucial to knowing the compression ratio. The dish in those pistons are huge. I suspect that the compression is well below 9.5 to 1.
Click to expand...
They do have a large dish, but look closely. Those are step dish pistons. See the flat on the intake side? It's taller then the rest of the top of the piston, so he may have a little more than you think. We won't know without some solid answers.
 
RustyRatRod said:
Ok, let's ask some FLAT OUT CLOSED ENDED questions.

Did you use a DEGREE WHEEL and DIAL INDICATOR and PISTON STOP to install tha camshaft? Yes or no?

What is the measured cranking compression pressure on a compression gauge?

You came here for help. Stop doing a Mexican hat dance around questions and answer them. We can help you, but we need answers.
Click to expand...

Pretty sure I'm answering every question I can at this hour. I've already answered your questions. Yes it was degreed with a wheel, stop and indicator.
The Dyno operator never measured the cranking pressure.
 
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Minnesota Muscle said:
I understand. Things were being worked on in small stages, and I overlooked it. Been beating myself up for it. It obviously creates a huge unknown. That's what I'm hoping to narrow it down too with this thread.
Click to expand...
No big deal ! just trying to help you like you ask us to ! looking at those pictures of your pistons, looks like you may have 27cc pistons instead of the 17cc dish your suppose to have ! really hard to be for sure looking at a picture though
 
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