Keith Atlanta

What Go-Pro attachment are you using for this that stands up to 800+ degree EGT?

30ftpanther

iTrader: (1)

What do the OSO experts think about a lifter problem or cam timing? The motor does not sound right to me.

phragle

iTrader: (3)

Im not an engine expert nor well versed on cams, but that looks like a smaller cam than a 500 efi and with a 114 lsa should not in my feeble brain not revert with decent exhaust,

Like I said, my name is not Bob Straub, I am not a cam guru, but I think you have a problem other than the problem you think you have.

Unlimited jd

iTrader: (5)

Need to fix that loose rocker or collapsed lifter before going any further

compedgemarine

I am no expert but the odd bank looks like it has a miss to it. if you watch the mist it is erratic unlike the even side that stays pretty steady. also yes you can hear a lifter or rocker rattle in it for sure. another problem, it was pointed out that any leak in the system will cause it to revert, there is water coming out from the joint between the manifold and riser so there is a leak. you then said that you tested everything and there is no leak but point out that the water is coming out the leak at the joint. what they are trying to tell you is that leak in the joint to the outside air causes it to revert more, not that there is a leak in the manifold. before you worry about some really complicated H pipe that will probably cause more problems than it helps you need to fix the lifter noise, flat running and the leaks in the exhaust stream. also you dont need to worry about the mist being drawn into the ends of the pipes as they will always do that no matter the length. as was pointed out, if it does not pool in the bottom of the manifold it is not a problem.

Crude Intentions

iTrader: (1)

As already mentioned the leak at the riser/manifold joint can and will cause reversion. Don't think it's leaking because of reverting. That leak will cause it.

Scott Danforth

Thanks for all the responses

I will be re-taking videos this weekend

since this video was taken almost a month ago: the following has been done

the leak at the flange has been taken care of. - this helped a bit, however did not resolve the issue
the angle has been addressed - changed from 5 degrees forward to 10 degrees back - helped a bit, however did not resolve the issue
the types of elbows used has changed - standard height in the video to the +6 in the pictures - helped the most, however did not resolve the issue
compression test taken - range is 7 psi between low and high value, nominal 153psi with the throttle plates closed
leak down test of each cylinder - no leaks to intake or exhaust except when tapping the valves with the deadblow. I used my compression testing whip so I do not have a percentage, however I know pressure took about 20 seconds per cylinder to decay thru the gap in the rings.
spark plug review - all plugs show burning slightly rich, however motor only run at idle, and only rough adjustment of carb has been done.
and what you guys are saying is a rattle is actually the exhaust noise echoing in the garage off the tin garage door directly above the motor and not being picked up properly by my crappy phone.

I will post the go-pro videos this weekend along with the pictures of the pools of water at the bottom of the manifolds

MILD THUNDER

iTrader: (3)

that is not true, nor is it the issue. Plenty of carbed marine engines came with 114lsa or wider cams. The only issue i see with the camshaft, is if you installed it incorrectly, and your cam timing is jacked.

your valvetrain is rattling, i would solve that first.

any reason you chose to use a vacuum secondary carburetor?

Scott Danforth

Had the vac secondary carb on the shelf

mcollinstn

I have a question.
You mentioned that you installed the cam "straight up", which on a 114 LSA cam, means a 114 ICL..
But your cam specs are based on a +4 installation (114 LSA, 110 ICL).
Not trying to stir up trouble, but WHICH is it?

114/114 will keep the exhaust valve open longer as the piston is moving down creating vacuum that encourages reversion.
If you look at your figures, the exhaust valve does not fully close until your crank has pulled the piston down for 30 degrees of rotation.

At 114/110, you are 4 degrees BETTER in that respect.
While this number doesnt seem to mean much, let's look at it in a way that's easier to visualize.

With a 4" stroke and a 6.135" rod length, at 26 degrees past TDC, the piston has moved down 0.227".
At 30 degrees past TDC, the piston has moved down 0.351".

That's a difference of 0.124", which is 54.6% FARTHER than the initial baseline of .227.
Putting it another way - at .227. the piston has opened up a volume equivalent to 3.31 cubic inches, pulling inwards.
at .351 the piston has opened up a volume equivalent to 5.11 cubic inches, pulling inwards.

Now, you also have the intake valve open at the same time, which you might want to say reduces the amount of "stuff" the downward-moving piston pulls in from the exhaust. This would be true, if the exhaust port and the intake port were both at atmospheric pressure. BUT they are not. The exhaust is operating at a slightly POSITIVE pressure, although at idle it is admittedly not "much" positive pressure. The intake, however, is operating at a significant VACUUM. For this reason, at low rpm (idle or slightly above), when the intake valve opens, any positive pressure remaining in the cylinder tries to rush INTO the intake port, which then turns the cylinder into a negative pressure area as well, sucking exhaust back up towards the cylinder until the exhaust valve closes.

This phenomenon is exaggerated in a multi cylinder motor that uses a shared intake plenum AND/OR a shared exhaust plenum. Your motor shares both.

The actual POSITION of the cam (straight up, +4 advanced) doesn't make as much difference as the seat-to-seat overlap, but it DOES still matter a bit.

Things you can do to make it better.
1) Longer exhaust tailpipes - the farther from the port you can get before you introduce water into the exhaust, the better off you are.
2) Additional cooling water "dump". Put restrictors in to reduce the amount of water that DOES get injected into the tailpipes. Depending on the number and location of water bungs in your tailpipes, you can sometimes still run LOTS of water into the manifolds, into the risers and tailpipes, yet tee off at the rear of the tailpipe to a separate thru hull dump fitting. This reduces the amount of water introduced into the tailpipes. You can even use a spring-ball type arrangement to limit the amount injected at idle, yet at speed, the springs are pushed out of the way and additional volume is injected.
3) Lower your engine's vacuum at idle. While this sounds weird, engine vacuum is a driving force in water reversion. You can pull timing out under 1500 rpm, and your idle vacuum will drop accordingly (mainly because you will be opening up your throttle plates a little more to achieve the same idle rpm - and if you have to open them very much, you should open up the hole in the throttle plates instead).. Can't recall what ignition you are running, but any sort of low-rpm retard module will do the trick OR if you run a mechanical advance, the old staggered spring thing will also work. Use a spring that locks timing at baseline until 1500 rpm, yet allows full advance wherever you currently desire it. You would have to modify the travel stops on your centrifugal weights to end up with your current total advance though.
MC