Not in Hell anymore, but need advice

[Donziweasel]

I finally figured it out! After 8 months I finally got the "bog" out of the engine. Many of you know I have been fighting a "bog" in the mid range since I took my 1997 16 C's 350 out and installed a comp 264 cam, Vortec heads, edelbrock intake and edelbrock marine carb. After 8 months of messing with everything from ignintion to timing (and one small fire), I finally found the problem. The vacuum on the manifold was only 8 psi, pretty normal for a marine engine, but less than a auto counterpart. When the Edel vacuum secondaries kicked in, there was simply not enough vacuum and I had a lean spot. Soultion- Holley 4150 marine carb w/mechanical secondaries. Thank you to everyone who helped diagnose this problem. The boards definetly helped me in figuring it out.

I am now getting 56 mph (GPS) at 4600 rpm at 7000ft above sea level (which is pretty fast for my altitude, the boat ran 47 mph stock). The only problem is than it really feels like the boat and drive struggle to get out of the hole, even with the tabs I added last year. I am running the stock 1.47 gear with a 19 pitch prop. I really do not like to make an engine work that hard to get up on a plane, and I feel that it should turn 300-400 rpm higher on the top end. Wondering what everyone thought about kicking up to 1.62 gears for the elevation and a 21 or 23 pitch prop? Should take care of the hole shot and the 300-400 rpm on the top end, right?

This part is for info only. The conversion from the Edelbrock (I now know why many of you call it "edeljunk" and now I guess call myself a Holley man), was a PITA. I am not patient and lost two weekends at the lake because I did not want to do a half assed conversion and wanted it to look professional. It took me that long to re-run the throttle cables, fuel lines and make the conversion. The biggest issue was the throttle bracket. Although it fit the edel like a glove, there was no way it was going to work for the Holley. My final solution? A Volvo bracket (don't tell Mercruiser:wink:) that worked perfectly and looks factory. I will try and post some pics of the conversion next week. Once again, thanks for all the help!

P.S. Last year I had the free beer going for whoever could guess the final top speed when done with the engine. Onesubdrvr would be winning with a guess of 55.9 mph. Still not done tuning and I think with gearing a propping, another 2-3 mph might be possible. Here is the link to that old thread if anyone is interested-

http://www.donzi.net/forums/showthread.php?t=46385

[smokediver]

what kind of prop are you running ? I had all 3 gear ratios with various power . the 1.8 with the 4.3 V-6 , the 1.62 with the 5.7 , and now the 1.47 with the 383 . I did change the ratio from 1.62 to 1.47 with the same motor so it seems to me that a gear change is like 4 inches of pitch . If i were you i would probably keep what you got and try a 17 . it will get you 400 rpm's give or take . if you did the change to a 1.62 and are running a 19 now and are looking for 300-400 rpm's then a 21 would probably do you good . But if you have an engine over th 300 horse range , keep the 1.47 ... trust me on this ! I fried a lot (3) of 1.62 gear sets with the 383 and i was driving it with care . just my 2 cents ,

[Carl C]

Welcome back from hell and congrats on picking up 9 mph! Many vacuum sec carbs on cars also never open; I have proven that. It can be fixed by putting in a very soft diaphram spring but it's better to go with the mechanical secondaries and roll the throttle on. Your plan sounds solid to me but hopefully someone with hands on experience with that will offer advice.:)

[gcarter]

I really do not like to make an engine work that hard to get up on a plane, and I feel that it should turn 300-400 rpm higher on the top end.
Don't worry about it, at your altitude, it's not working hard at all. Remember at your ambient atmospheric pressure, it would be the equivalent of slightly more than half throttle at sea level.

[MOP]

I am with "smokediver" a 17" wheel should get you where you want to go and a ton cheaper then changing gears.

Phil

[RickSE]

Sounds good John, now get your butt down here for Powell next week. :wink:

You're pretty close to my old 18, would run 58-60 MPH on Powell @ 3700' with a 21P Mirage. I bet your's would run about the same or a little faster at a lower elevation.

Do you have ventelation plugs in your prop? I ran mine with the plugs w/mid-sized holes to help get it up on plane. Gearing should help. Every boat we had delivered had the 1.6 ratio for the altitude.

[f_inscreenname]

Don't worry about it, at your altitude, it's not working hard at all. Remember at your ambient atmospheric pressure, it would be the equivalent of slightly more than half throttle at sea level.

At that altitude (at 7000 feet with the definition of a mile as 5280 feet) its a wonder he can breath let alone the motor. Sounds like a mean boat. :yes:
As for the Edelbrock carb. Don’t throw the baby out with the bath water. You had a bad one and it happens but when it does you have a much better chance of fixing the Edelbrock then a Holley.
Not saying one is better then the other. Its like with two guns that I own. Both are .45 ACP's. One is a Kimber. It will hit you from a mile away and is the first thing I think of when I hear the word "Precision". Cost a arm and a leg and I wont even put it in a holster being afraid of scratching it but its the one that sits in a safe under my bed in case it is needed because its perfect and has never jammed or failed in any way, ever and I have put some rounds through it.:uzi:
The other is a Lamma. It was stolen (for a couple years) from my house. Used in a couple crimes and then was ditched (thrown out a car window when it was moving). Its beat to hell, the slide rattles, big scratch marks and everything is semi filed off on one side. It still works and is still right on. Or as good as it ever was before.
The Lamma was never as good as the Kimber from the start but the Kimber couldn’t ever go through what the Lamma did and survive. Its just like that with these two carb’s. Out of the box I would take a Holley any day. Over a carb’s life time, I will take the Edelbrock and be much happier.

[kd5cue]

if going throw in the junk pile,send ro me,ilke webbers-edelbr

[Donziweasel]

Smokediver- I am currently running a 19 pitch. Mercruiser and about every other boat dealer recommends the lower gear (1.65 to1 )for my altitude. This is a general recomendation though that I am not sure applies to a 16 ft boat with a midly modified 350 SBC in it. Still, to get the top end and hole shot, I am definetly considering the gear change and a 21 or 23 pitch. My engine at sea level would probably be in the 315-330 hp range. The rule of thumb on an v-8 is 3% of your horsepower loss per 1000 ft. So, in reality, I am only at around 250-270 hp at 7000 ft. Altitude is a PITA. It took me 3 years to get one boat propped, geared and carbed right. I would love to run this thing at sea level and see if I could get 60-63 mph out of it. I know that I will never buy another boat unless it is fuel injected due to the fact that I run from 7000ft to 3000ft.

GCarter, it just takes a while to plane and rev up. Seems when I did the mods, it changed the torque curve slightly and I lost some low end, but definetly gained in the mid and top end. Tabs help a bunch, but still concerned. BTW, what did your next project turn out to be?

Rick, you are killing me! The only reason I am not down there already is meetings. I will PM you about progress on the company, but to make a long story short, have meetings all this week and next on the sale. Will probably be in due diligence next week and I can't leave. I am sacrificing this year so I can have many more in future with you guys down there. Powell is one of my favorite places on Earth and I am jealous as hell of you guys. Plus, I really wanted to see Don's 18 screamer and engine. Perhaps if you are down there in the fall, the first week of September looks good for me, I can finally join you. Just out of curiosity, how many are going? Looking foward to the pics so take a bunch. Next year we will have to work on getting more of our mid-west and east coasters to the most amazing lake I have ever seen. Have fun and be safe.

F inscreenname and kd5cue, I will probably sell or give away the Edelbrock. It is a 600 CFM Marine with vacuum secondaries. I also have a jet, spring and metering rod kit for it. It has less than one hour on it and it basically brand new. Make me an offer. $25.00 plus shipping will probably do it since I have no real use for the carb anymore. It would be fine for another application or upgrade other than mine.

Carl, it is definetly nice to see the boat perform like it was designed to. 47-48 mph felt like I was standing still. Although I picked up 8-9 mph, it feels like I picked up 30 on the water! There is a big difference between 47 and 56 and it is a lot more fun to drive!:)