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)
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?
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
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.
The rev limiter is set for 6000 rpms. That was the redline the engine builder gave me.
OK sounds good just trying to help
Jim
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
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.
Good Points BP !!!!
Clap clap Clap !!!
oopps wrong game. I hate it when that happens.
Jim
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.
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