Ignition Question

[riverbound]

I got my new ignition system installed.
Msd 6al
Msd coil
Mallory dist. w/ PetronixII
My question is before the new ignition I could get 4900 RPMs and now my boat wont go over 4500. The mechanic also said he fattened up the primaries on the carb and retarded the timing a little. Befor the timing was at 34degrees total and he put it at 33 degrees total. The Boat ran really good but it didnt seem to ahve as much power as before (it was a stock dist. w/ Petronix and stock coil) The boat also does not Idle very well anymore (it seems to be loading up) I have a mildly built 460. Isky "jet boat" cam, Weiand stealth manifold, Holley d.p. Forged pistons .030 over,logs. Do I need to have the machanic put more timing in it and rejet the carb back to where it was? (I had 66 jets in there and they put 70s in now)

[moneysucker]

Check the plugs first before changing the jets. Why didn't you go with a MSD distributor? You bought a Dist anyways. Just a question. I will not run anything but all MSD magnetic pick ups are the way to go. Did you check what rev limit chip is in the box?

[Squirtin Thunder]

A bone stock 460 from Hardin Marine will turn 4850rpms with a "A" Berk impeller. There is no reson he should have changed your jets or your ignition advance. I do second Moneys' thought on the chip (rev limiter). But you would know you were hitting the chip.
BTW- is this guy you took your boat to a jet boat guy or a car guy? Sometimes we all make mistakes, but why did he do some of the things he did???? I would have him come out to your local lake and start throughing things at it ; like timing, jets, old dist advance curve.
Just a thought
Jim

[riverbound]

I didnt go with an msd dist. because i wanted to be able to bypass the box when it fails (the MSDs dont have the greatest track record). I actually wanted to keep my stock Ford dist. but they put in the mallory for the price of the rebuild of my stock. The shop I take it to is IMO one of the best around (I wont name names because I am still happy with him and continue to use him). He has done all my work and I have been very happy with him. The guy who usually works on my boat was on vacation while my boat was in there ( I didnt know until I picked it up). Everything on the boat is brand new. It is only the second time on the water since the motor was put in. I had the motor professionaly built and dyno tuned. I am going to take it back and see if they can lake test it and run it to dial it in in the water.

[riverbound]

The rev limiter is set for 6000 rpms. That was the redline the engine builder gave me.

[Squirtin Thunder]

OK sounds good just trying to help
Jim

[LVjetboy]

Changing ignition and fuel at the same time makes it harder to troubleshoot.
But dropping 400 rpms is a significant loss in both power (maybe 80 hp) and speed. Did you also lose speed? One degree in timing not likely to drop 400 rpm. Have you checked timing yourself to verify his claim? Are you sure your before and after test conditions the same?
On the holley carb, I think changing the main jets not only affects max rpm but also to some extent idle characteristics. So like Thunder suggested, a lake tune may be in order.
jer

[bp]

Changing ignition and fuel at the same time makes it harder to troubleshoot.
But dropping 400 rpms is a significant loss in both power (maybe 80 hp) and speed. Did you also lose speed? One degree in timing not likely to drop 400 rpm. Have you checked timing yourself to verify his claim? Are you sure your before and after test conditions the same?
On the holley carb, I think changing the main jets not only affects max rpm but also to some extent idle characteristics. So like Thunder suggested, a lake tune may be in order.
jer
the 400 rpm drop is big, but not what i'd focus in on. changing from 66 to 70 jets is a humungous monstrous change. why did he do that? if it were me, i'd really want to know that. i waffle around when i'm going from 91s to 90s, but 66 to 70??? i'd guess that this is having a significant effect on idle characteristics, and could also be causing an over rich condition at wot. the 34-33 timing change wouldn't necessarily have that much of an impact (if that's really all the timing that was taken out of it).
the other question i would ask (me being you to your mech) is how the tach is now receiving it's signal (or what kind of tach you have). you stated what ignition you changed to, but not what it was before? is the tach receiving the signal from the 6, or something else, and is your tach wired to be compatable with the 6? just some things to question.

[Squirtin Thunder]

Good Points BP !!!!
Clap clap Clap !!!
oopps wrong game. I hate it when that happens.
Jim

[cyclone]

Not that this will solve your current problem, but i'd lock out the timing on that distributor if at all possible. It's a jet boat so you can go from idle to wot before the advance can catch up.

[Squirtcha?]

the 400 rpm drop is big, but not what i'd focus in on. changing from 66 to 70 jets is a humungous monstrous change. why did he do that? if it were me, i'd really want to know that. i waffle around when i'm going from 91s to 90s, but 66 to 70??? i'd guess that this is having a significant effect on idle characteristics, and could also be causing an over rich condition at wot. the 34-33 timing change wouldn't necessarily have that much of an impact (if that's really all the timing that was taken out of it).
I would agree with all bp's stuff here. However, if he dyno tuned the motor, I would assume that he'd tune for best hp/performance. It certainly doesn't seem like he'd tune it so it was really really fat, so I can only reason that it needed the 70 jets.
I had the motor professionaly built and dyno tuned.
Do you know if the guy dyno'd it with the 66's, and if so.............what the results. What were EGTs both ways, Hp both ways, etc.
One thing's for sure............something aint adding up here.
Do you have any gps numbers before and after the work? Irregardless of the rpm change (since that might be one of the equipment problems discussed here) Like Jer, I'd be curious to see the speeds before and after.

[roostwear]

My experience is this. Going from a 66 to a 70 is (realistically) a 2 jet jump. Jumping one number at a time makes very little difference. Could it have killed his rpm this much? Possibly, but I doubt it. That would mean his 66 was rich, and going to 70 really fattened it up. My stock old 750dp had 72s. I'm running 82s with the Proform. I doubt it was fat with 66s (unless the power valve(S) are shot. The idle circuit shouldn't be affected by primary or secondary main jets unless the butterflies were opened up or drilled. It should be on the idle circuit alone, then as the throttle opens, the transition circuit and mains come in. I would be inclined to check the power valve(s) and fuel pressure/volume.
What's the vacuum reading at idle? It's an old fashion concept, but going back to basics beats throwing parts at it.
Just my.02

[Squirtin Thunder]

Roostwear,
I thought you only had the Bling Bling. You have surprised me again. I didn't know you were so techy. But then again that boat sure rides and runs good. And don't let me forget that 9". Sweeet !!!!!
BTW
Something is not adding up in this deal, not quite sure what but just not right. If it was dyno tuned that means LVjetboy is righter than any of us thought, dyno HP and Lake HP are tottally different.
Jim

[roostwear]

Roostwear,
I thought you only had the Bling Bling. You have surprised me again. I didn't know you were so techy. But then again that boat sure rides and runs good. And don't let me forget that 9". Sweeet !!!!!
BTW
Something is not adding up in this deal, not quite sure what but just not right. If it was dyno tuned that means LVjetboy is righter than any of us thought, dyno HP and Lake HP are tottally different.
Jim
I was a service technical specialist for an OEM before I took the cush desk job :D
I don't tell everyone everything, ya know.

[riverbound]

Sorry didn't get back sooner, but work is getting in the way of my ***boat time.
BP "why did he do that?"
I have no idea, He said it was running to lean. The motor was dyno'd with the 66s and they used an msd box during the tuning. It was changed to 70s after the motor was put back in the boat. The mechanic and the guy who built the motor are 2 different people.
The tach is a Gaffrig hooked up to the box.
Squirtcha
I dont have any GPS #s
The dyno #s were 511ft lbs. @4900 and 437hp @5100. I dont know what egts were.
The boat is definitely no as fast as it was. Before you could feel the motor pulling hard all the way to 4900, now it seems to dog out above 4000rpms. It will get to 4500 with some work.
Roostwear
The vacum @ idle is 8-10. Its hard to get an exact becuase with the motor idling poorly it wont stay steady.
I just wish I could get this thing right. I have spent way too much $$$ paying professionals to do it for me and I still have never towed it home from the river running (something has broke every single time). As you can tell I'm not running some huge motor its just a little built up stock motor and for some reason noone can get it right :mad:

[roostwear]

You're not that far away... if you wanna drag it to Anaheim Hills we can check it out.

[Squirtin Thunder]

Vacume should be much higher.
I am geting about 12 inches with mine but I am making quite a bit more power, more compresion, more cam . I just don't understand. Roost can help ya on this one. Mike is on the ball. He just needs a bigger shop. Bring lots of gaskets !!! I think somethings need to be checked out big time.
Jim

[riverbound]

You're not that far away... if you wanna drag it to Anaheim Hills we can check it out.
My parents live in anaheim Hills so I am there all the time. I don't want to do too much checking because as of now everything is warrantied. Where are you located and when would I be able to bring it by.

[roostwear]

Saturday or Sunday works. I'm by Kaiser.

[dave186]

whats the reason for putting ignition on a boat? i have an accel 300+ digital box that is currently on my truck and not hooked up. it did a couple things that i didnt like so i unhooked it. it does have a selectable rev limiter and i could see that as a plus for the boat. ive hit a wake a couple times and came out of the water and the tach jumped to 6500 before i got my foot out of it. :supp:

[roostwear]

Here are the specs for the Isky cam you are probably running.
#311281/10280 MEGA, 2000-5500rpm, lift-.565, duration @.050-232°, Lobe center-110°
This is a fairly mild cam.... I would think you should be pulling at least 16 inches at idle. Something else IS going on.

[riverbound]

Saturday or Sunday works. I'm by Kaiser.
I will let you know. My parents live by Canyon High. So maybe I can drop off the wife and kids there and sneek over with the boat.