Reply With QuoteI've always locked my stuff out too. Jetboats rpm at the wack of the throttle.
Long story short, it's the carb. I have the initial timng now at 18 initial, 36 total. More on the timing later.
Long story long, I broke in the cam with the engine after I built it, got water in the oil, had a engine builder rebuild it for me, got it back 2 1/2 months later, ran great, and within the next week of running it on the trailer runs like garbage. I pulled the front fuel bowl off of the carb and it's full of brown crap, looks like dirt.The guy that built my engine is going to clean it out for me for less than half of what the carb builder wanted. I'm trying to make one last river trip before it's past the season...
The timing. When I broke the cam in I was trying to use my "bought new on eBay from private seller's" MSD Marine distributer, MSD 6AL, and Blaster 2 coil. The MSD box is bad/defective and puts out a constant rapid fire spark just by hooking up the +12, ground, and the tach wire. So I'm hoping that I can "settle" and use the HEI until I can figure out how to go about and how much it's going to cost to fix the MSD 6AL. Anyway, the HEI that's on it now has initial timing at 18, total timing at 36 degree's. From idle to about 2200 RPM it's at 18 degree's, from 2200 to 4000 is the curve and stays constant from 4000 on at 36 degree's. Seems like the HEI's curve is short and comes in late.
At least my first thought was right, it is running lean.
So where's a thread on the best way to go about where you should set your timing without spending a month doing it?
THANKS! For all of you chiming in and trying to help me out.
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Congratulations on it not being anything major. Sounds like you still have some issues to iron out, but at least it's not a rebuild.
I'm sure you already realize this, but make sure to clean your tanks out.
I've always locked my stuff out too. Jetboats rpm at the wack of the throttle.
Nevermind, I just found out it takes a machine to totaly recurve an HEI.
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You can do it with a timing light. One thing you might try that is quick and cheap is to get a recurve kit, use one light spring and one medium spring, keep the stock weights in it, then see what the curve looks like.
Maybe I'm Up In The Night. My Bbc Is 11.5 To One With Aluminum Heads And It Won't Even Think About Runnin On 91, Are You Runnin Iron Heads Or Aluminum?
I think I read somewhere that vacuum advance mech.'s are for mileage and for part throttle (that's why I didn't hook up the HEI's vacuum advance, is that why I'm not getting the amount of advance I thought I would get?), so with two responses telling me that I don't even need a mech. advance...
What's the mechanical advance for? What are the advantages and disadvantages of getting rid of the mechanical and vaccum advances all together?
By changing the springs on the mechanical advance I think it would change when the mechanical advance starts (and ends), but wouldn't change how much advance it will give, correct?
Iron heads, 101cc combustion chamber, closed chamber, oval port, 2.06 intake, 1.72 exhaust, 1969 L36 427 Corvette engine, seemed OK running on 91 on the trailer until it started having the problem's that created this post (dirty carb). I plan on dumping some race gas in with the pump gas before it hits the water, I just assumed running 91 wouldn't be a problem while it's still on the trailer with no load on it.
What's the mechanical advance for? What are the advantages and disadvantages of getting rid of the mechanical and vaccum advances all together?
By changing the springs on the mechanical advance I think it would change when the mechanical advance starts (and ends), but wouldn't change how much advance it will give, correct?
I do not know boats - learning. My guess is you don't need/want a vacuum advance in a boat, at least not a jet boat. If it has one, you do not want it hooked up if you're using a timing light to check a curve. The comment about total advance is correct - the springs won't change the total, just the rate at which the advance changes.
I know zero about a locked distributor other than the timing is what it is set at, period, no change. My impression, right or wrong, is it's suited for an application where the engine basically goes from idle to wide open throttle, or close to it. Hard core stuff. Seems to me like I'd be worried about detonation at a lower RPM, heavy engine load situation with pump gas and 36 degrees of advance. But again, I don't know and have zero experience.
An L36 was originally 10.25:1 compression. Rebuild changes things. Were the heads shaved for flatness? How thick are the gaskets? Block decked? What pistons? Stuff like that. If you know it has flat-top pistons in it, my guess would be you should be safe with 91/92 pump gas.
Does someone have a carb you could borrow? That's a quick/easy way to rule out that part of things.
I think I read somewhere that vacuum advance mech.'s are for mileage and for part throttle (that's why I didn't hook up the HEI's vacuum advance, is that why I'm not getting the amount of advance I thought I would get?), so with two responses telling me that I don't even need a mech. advance...
What's the mechanical advance for? What are the advantages and disadvantages of getting rid of the mechanical and vaccum advances all together?
By changing the springs on the mechanical advance I think it would change when the mechanical advance starts (and ends), but wouldn't change how much advance it will give, correct?
Iron heads, 101cc combustion chamber, closed chamber, oval port, 2.06 intake, 1.72 exhaust, 1969 L36 427 Corvette engine, seemed OK running on 91 on the trailer until it started having the problem's that created this post (dirty carb). I plan on dumping some race gas in with the pump gas before it hits the water, I just assumed running 91 wouldn't be a problem while it's still on the trailer with no load on it.
Right. On the MSD distributor you change a little bushing that sits on a little post under the weights. The wieghts lift off and then you can see thee limiter bushing. It is a stop. The smaller the bushing the more it lets the wieghts travel. Hence more advance curve. The springs control only the rate.
If you are at 10 at idle, for instance, with a bushing that allows 20 deg. mech. advance you will end up with 30 totaL. the springs will determine what RPM it is all in by.
So if , for instance you wanted 35 total, instead of setting the initial at 15 you would leave it at 10 but change the bushing to allow 5 more deg. of travel. Then change to a lighter spring so it would still all be in at the same time.
I can't tell you how to do it on an HEI. I have only ever used MSD's. They have color coded bushings and springs and a little chart that tells you the characteristics.
I would think that because your engine is getting worse as it runs that it is not necessarilly the set up, but something failing such as a coil, module or pickup magnet or eye. If in fact it is ignition related.
A quick spin on a distributor machine will tell a lot. Call your local auto electrical shop and see who can test it for you. Might end a lot of gues work.
Just be glad it doesn't look to be your cam. I was hooked up to the truck with the boat loaded for the maiden voyage when I discovered mine was shot.
Tommy
Right. On the MSD distributor you change a little bushing that sits on a little post under the weights. The wieghts lift off and then you can see thee limiter bushing. It is a stop. The smaller the bushing the more it lets the wieghts travel. Hence more advance curve. The springs control only the rate.
If you are at 10 at idle, for instance, with a bushing that allows 20 deg. mech. advance you will end up with 30 totaL. the springs will determine what RPM it is all in by.
So if , for instance you wanted 35 total, instead of setting the initial at 15 you would leave it at 10 but change the bushing to allow 5 more deg. of travel. Then change to a lighter spring so it would still all be in at the same time.
I can't tell you how to do it on an HEI. I have only ever used MSD's. They have color coded bushings and springs and a little chart that tells you the characteristics.
I would think that because your engine is getting worse as it runs that it is not necessarilly the set up, but something failing such as a coil, module or pickup magnet or eye. If in fact it is ignition related.
A quick spin on a distributor machine will tell a lot. Call your local auto electrical shop and see who can test it for you. Might end a lot of gues work.
Just be glad it doesn't look to be your cam. I was hooked up to the truck with the boat loaded for the maiden voyage when I discovered mine was shot.
Tommy
Yea, I'm very happy the cam appears to be good.
With the adjustability of MSD distributor's, it makes me wish I would have bought mine new. I'm sure they come with "extra parts" when they're new, right?
Anyone have any more thoughts on the advantages/disadvantages to locking out a distributor on a jet boat?
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Yea, I'm very happy the cam appears to be good.
With the adjustability of MSD distributor's, it makes me wish I would have bought mine new. I'm sure they come with "extra parts" when they're new, right?
Anyone have any more thoughts on the advantages/disadvantages to locking out a distributor on a jet boat?
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You know, I have never bought one new in box. They either came with what I bought or got them like new from somebody.
The one in my boat 454 is a ready to run Pro-Billet. Probably one of the most popular models. The bushing and spring kits are at any speed shop. Around $20.00 for a complete tuning kit. (bushings, springs, chart.)
Tommy
BBC tuning help wanted is an understeatement.
W.O.T. 3900 RPM
48.7 mph
rides like sh!t.
runs like sh!t.
place diverter AFU
bilgde pump problem, took on a lot of water, not a good combination.
burnt my forehead on super flockin hot headers.
severely disapointed
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