MandMcustomperformance
Member
I know it is supposed to be set @ 10°btdc but just would not start
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I know it is supposed to be set @ 10°btdc but just would not start
So, the timing gear set was installed without any advance?
With advance it would not start
Okay guys I have a few minutes here are the recorded measurements for Jay's engine.
Camshaft Style:Hydraulic flat tappet
RPM Range:1,000-5,000
Intake Duration at 050 inch Lift:212
Exhaust Duration at 050 inch Lift:218
Duration at 050 inch Lift:212 int./218 exh.
Valve Lift with Factory Rocker Arm Ratio:0.447 int./0.462 exh.
Lobe Separation (degrees):112
How were the hydraulic cam followers adjusted?
Did the mechanic use the 2 or 3 stop static procedure..... or did he use the much more accurate 8 stop static procedure?
Crankshaft
Journal Diameter
No. 1 2.4484
No. 2, 3, 4 2.4481
No. 5 2.4479
Taper .0002
Out of Round .0002
Main Bearing Clearance
No. 1 .0007
No. 2, 3, 4 .0022
No. 5 .00250
Crankshaft End Play .002
Connecting Rod Journals
Diameter 2.0978
Taper .0003
Out of Round.0003
Rod Bearing Clearance .0006
Rod Side Clearance .006
Deck height 6.358
The GM SBC 5.7L deck height should be 9.025"
Bore 4.00
Stroke 3.480
Dish pistons
Dished Pistons as in the GM Full Dished?
If so, the GM Full Dished piston should NEVER be used in the Marine version.
Clearance. 0020
Volume +7.00cc
Ring clearance
Top .014
2nd.014
Oil .011
Valves 1.94 int/1.50exh.
Cylindar Head combustion chamber volume 64cc
Average compression 9.4:1
RPM curve is 346hp / 360ft,lbs @ 4800
Ingnition is GM (OEM) coil distributor and module.
Has anyone actually looked at the spark lead?
In other words, and with a properly marked off harmonic balancer, and with a known to be true #1 TDC......, has the progressive and TA been verified?
fuel pressure is 23.5 @ 3000 rpm.
Fuel system is stock dual pump w/separator
So as you can see this was a refresh build and rotating kit is OEM direct replacement
If this is an MPI engine with the HVS (distributor with flat cap) Timing is not adjustable.
HVS = high voltage switching.
Chris, correct me if I am wrong..... this HVS is a form of EST (electronic spark timing).
You index the HVS and the ecm takes over.
Yes, I think that we all understand this.
Since the timing chain is new and tight, the timing (distributor indexing) should not need to be fine tuned.
Agreed!
You can move the HVS slightly to improve the running condition with a slightly loose (Worn) timing chain.
All Ignition Advance timing is controlled by the ECM.
Agreed!
In order to comprehend this, we must first understand that the Non-Mechanically Advancing distributor housing (such as EST) is initially indexed as to offer full advance.
Since the laws of physics do not allow a spark event (at the spark plugs) to occur any sooner than it is initiated by the triggering mechanism, the ECM creates an electrical event delay.
This delay is then varied by the ECM as per engine RPM.
Example: at let's say 1,200 RPM, the delay brings the actual spark event to 2* BTDC.
Now when we add the BASE of 10* BTDC, each cylinder now sees an actual spark event at 12* BTDC.
This delay continues to be varied (reduced) as RPM increase.
Example: at let's say 3,200 RPM, the reduced delay now brings the actual spark event to 22* BTDC.
Now when we add the BASE of 10*, each cylinder now sees 32* BTDC.
I think we have established that the timing is not the problem.
I have yet to see the actually ignition advance curve as per any testing.
Why not map it out in graph form so that we can look at it?
I have had numerous mechanics suggest a prop change to increase rpm under load.
Should this freshly rebuilt engine perform as well or better than the previous engine?
I would say yes.
If so, why would you want to change to a lower pitch prop ?
In other words, if the old engine pushed this hull along just fine with the existing propeller, why doesn't this fresh engine?
Problem there is we could essentially get rpm up but speed might still be shallow on plane.
Yes, anytime we prop down, we may gain WOT RPM, but the speed will be sacrificed.
Dyno says the performance is there without any power loss and have spoken with several other companies and have been told that people buying 383 stroker have similar experience.
With that said, the issue was resolved by changing prop pitch.
If I was to pull out my two Q/E built 5.7L 280 HP SBC engines, and was to replace them with two identical Q/E built 5.7L 280 HP SBC engines, I would NOT need to change the prop pitch.
Can someone please explain to me why replacing one engine with a similar but more powerful engine, would require dropping down in prop pitch?
I fail to see the logic in that!
My points:
Engine fires up emediatly
Engine idles smooth
Engine exccelerates nicely without lag or miss.
Engine does not get hot
Engine does not backfire
Engine goes from idle to wot emediatly no delay
Engine under load is at full rpm wot
Under load still no delay miss or lag from idle to wot and back
No change in engine sound or performance getting up on plane but dies (I assume that you meant "does") take a while to get up on plane.
If it had anything to do with it timing would the results not be different?
Are you comparing actual previous engine to new engine "dead-stop-to-planing-attitude" elapsed times?
In other words engine is screaming to get boat up on plane
First off guys sorry for the multiple messages service is spotty where I live
Anyway I see Rick might be leaning towards the ecu not functioning correctly
However my question is this; If ecu is not functioning properly wouldn't it be affecting the engine's ability to run no matter what the rpm is, even causing pre detination @ idle?
All due respect, I know of no such thing as Pre-Detonation. However, I am very familiar with Pre-Ignition and Detonation.
Each of these are two entirely different phenomena.