Caution! Motorhead discussion.

[AZLineman]

While im sic w/covid (man flu) and tryn to recover and cant physically do shit right now i need a good quality discussion on something useful. Lol. Sic of useless threads, discussions, complaining and non-boating bs. Since I am always playing around with diff set ups, I wana see what everyone else does-experience, not useless opinions.
On roots blower apps, who ………
Boost references their carbs?
Who does not?
Who blocks their PV’s and jet up?
Linkage ratio (or guess) pri to sec?
Please specify 4150’s or 4500’s
Standard roots, hi-helix or screw.
Add any other details you like. This includes Jet, Vdrive and IO. No questions are stupid. Everyone here has diff levels of experience. Once this has been beaten to death i have another one ready Thanks all.

 

[zhandfull]

Does anyone use a roots blower anymore? If they do let’s see some pics too.

They look awesome on jet and v-drive boats.

Had one for a car project but sold it before using. Been regretting it every since.

 

[AZLineman]

There you have it. This thread is worthless without pics.

 

[renodaytona]

Standard roots blower dual 1050 dominators. I had the carb's boost referenced one circuit blocked and one with a 6.5 PV on each carb. Ended up pulling the lines and blocking the boost reference stuff last year as it seemed it was causing some issues. Might go back to the boost reference set up once I get the boat back on the water and running better.

 

[AZLineman]

Standard roots blower dual 1050 dominators. I had the carb's boost referenced one circuit blocked and one with a 6.5 PV on each carb. Ended up pulling the lines and blocking the boost reference stuff last year as it seemed it was causing some issues. Might go back to the boost reference set up once I get the boat back on the water and running better.
View attachment 1136242 View attachment 1136243

Very nice! What kind of issues? Leaning or poor driveability? While I feel that running PV‘s wether boost referenced or not (functioning correctly) gives better driveability and fuel economy at cruise there’s always that fear of lean/detonation variables under boost/load.

 

[renodaytona]

Rich at idle and up to about 2K rpm and then it seemed to clean up. That all went away once I pulled off the lines and blocked the boost reference ports on the carbs and intake manifold. Definitely a tuning issue. I really want to go to EFI but not sure I want that cost, full interior is on my list next.

 

[AZLineman]

Check vacuum below the blower at idle/cruise/wot and size your PV from there would be my guess if you wana go back to boost ref. Maybe open up the primary air bleeds a bit. Injection (efi) is always an option but like you said its a cost issue. I know I can’t afford that shit right now. I kinda like the simplicity of carbs once you get your set up dialed but if you boat in diff altitudes you cant beat it. I would opt for enderle on my Schiada but it’s not in the cards right now. Thanks for the info.

 

[Teague_JR]

Did quite a bit of testing with my roots blower motors in the fountain to verify the carb setup stuff that the old guys swore by. This was one time their theories were confirmed (also TCM did hundreds of carb roots engines this way and they never burned down so proof is in the pudding)

Boost reference the primary power valves in a car or a light boat where you can cruise in manifold vacuum and use 3.5 or 2.5 PV's.

In a larger boat, your almost always at neutral pressure or boost in the intake so boost reference doesnt work well. My fountain at 3200-3500 rpm was at 1 psi manifold boost and 14 inches of vacuum under the carbs. a 10.5 PV (not referenced, reading vac under the carb) made the PV start to open at the top of the primary at 4000-4200. Worked perfect. dual 750 double pumpers but Ive also seen the same results with 1050 dominators and ultra dominators. I guess you could block and jet up if you never want to cruise at 3000 but we are talking pleasure boats here.

 

[AZLineman]

Excellent info. What abt sec side? Your last paragraph is close to how I was set up with a 14/71. When i switched to the psi all the above values changed so i blocked and jetted for safety. Still messn with it. On my new/nxt set up i will try the referenced deal during dyno sesh.

 

[Teague_JR]

Excellent info. What abt sec side? Your last paragraph is close to how I was set up with a 14/71. When i switched to the psi all the above values changed so i blocked and jetted for safety. Still messn with it. On my new/nxt set up i will try the referenced deal during dyno sesh.

no secondary powervalves just jet for WOT air fuel ratio. On a blower motor your PV should always be open if youre in the secondaries anyways.. Its hard to tune PV on the dyno unless you know how hard the boat will load the motor at a given RPM... say 4000 rpm would take 45% throttle and 2 psi boost you can recreate that in steady state on the dyno but you have to have some sort of previous reference to go on. Also keep in mind if youre not using your boat headers on the dyno all tuning will change in the boat.

FYI I have always heard carbureted PSI blowers distrubute cyl to cyl like shit. I would dyno with 8 air fuel meters unless you like buying spare pistons. Or if its complete in the boat do some plug reading

 

[renodaytona]

I’m going to re-do all the vac lines once I’m ready to reinstate the boost reference. I will get a gauge on it and see where I need to be. I think it was close but something went sideways. I’m leaning towards a vac leak that I have yet to track down.

 

[Teague_JR]

I’m going to re-do all the vac lines once I’m ready to reinstate the boost reference. I will get a gauge on it and see where I need to be. I think it was close but something went sideways. I’m leaning towards a vac leak that I have yet to track down.

If you’re going to boost reference you should run a 2.5 power valve… your 6.5 is making your bottom end fat.. maybe idle mixture adjustment as well

 

[rivermobster]

I did a 57chebby big block complete blower rebuild and tune. I removed the power valves completely and jetted up accordingly.

Locked the timing at 25 degrees and made carb adjustments from there.

No Dyno, just seat of My pants. No boost reference. Ran great when it was done.

Customer picked it up and said, it has Never run this good before! The drivability was was perfect at all loads and speeds.

Changed the squirters, pump cams, primary jets and dialled the throttle plates in.

I think a lot of people don't understand how critical throttle plate position is. It has to be in a certain spot or the carb circuits won't work as designed and off idle/tip in driveability/performance will suffer.

With dual carbs it HAS to be perfect, on both carbs, with zero play in the linkage.

It's tricky to rock a rhyme!

 

[AZLineman]

no secondary powervalves just jet for WOT air fuel ratio. On a blower motor your PV should always be open if youre in the secondaries anyways.. Its hard to tune PV on the dyno unless you know how hard the boat will load the motor at a given RPM... say 4000 rpm would take 45% throttle and 2 psi boost you can recreate that in steady state on the dyno but you have to have some sort of previous reference to go on. Also keep in mind if youre not using your boat headers on the dyno all tuning will change in the boat.

FYI I have always heard carbureted PSI blowers distrubute cyl to cyl like shit. I would dyno with 8 air fuel meters unless you like buying spare pistons. Or if its complete in the boat do some plug reading

Yea the PSI‘s can be finicky to set up and for carbs they like the front loading side by side config better than in line (sideways or inline) I do check all 8 plugs frequently but I will be swapping to a side-by-side (have aquired one) set up in the future. Psi def suks some air and changes the upper signal. Carb base plate ports are pulling 25” of vac @ idle (16-25”surge) blower port (with internal 90) and manifold both at 5-15” surging. @ 3k a steady 25” at base plate and 15” blower and manifold. Still need to get some 4K plus and WOT values when I can actually have someone else watching. Need flat water. Lol. 4.5 PV’s worked for me non boost ref when i ran the 14/71.

 

[AZLineman]

Had to throw some pics in. First two pics are one of my backbup motors (big chief deal) one with mag 14/71 one with psi just to show the diff. It’s kind of a sterling 1550 clone that came out of a 46 skater that got converted to turbines. The other 4 are my current configuration in my boat now. Larrys 522 9.8 block dart heads and 950’s. 70% overdriven @ 33 deg of timing.

 

[rivermobster]

Had to throw some pics in. First two pics are one of my backbup motors (big chief deal) one with mag 14/71 one with psi just to show the diff. It’s kind of a sterling 1550 clone that came out of a 46 skater that got converted to turbines. The other 4 are my current configuration in my boat now. Larrys 522 9.8 block dart heads and 950’s. 70% overdriven @ 33 deg of timing.

33 degrees locked timing??

What kind of fuel do you run??

 

[AZLineman]

33 degrees locked timing??

What kind of fuel do you run??

Yes locked @ 33. I run 100LL w/1/2 oz per gal of MMO. That’s what I ended up with when the late great Norm Drazie help me set this thing up originally before he passed. I thought he was out of his mind but the density that that screw blower compresses the air through the engine at plus the intercooler with cold river water allows me to do so. Because of fuel prices right now and the fact that AV has gone through the roof like everything else I may have to drop it to run 91 for puttn around.

 

[rivermobster]

Yes locked @ 33. I run 100LL w/1/2 oz per gal of MMO. That’s what I ended up with when the late great Norm Drazie help me set this thing up originally before he passed. I thought he was out of his mind but the density that that screw blower compresses the air through the engine at plus the intercooler with cold river water allows me to do so. Because of fuel prices right now and the fact that AV has gone through the roof like everything else I may have to drop it to run 91 for puttn around.

Drop the timing first. I doubt you'll even notice the difference.

Much safer at 25. Probably have to make some idle speed adjustments, but that's it.

 

[AZLineman]

Agreed. I’m curious how many peeps run straight AV, mix AV with premium or just run premium in there supercharged or turbo mills. Timing as well.

 

[Good Stuff]

Larry Peto 548 with 8/71 dual 950’s running 91

Dyno peak was just over 930 at 8lbs
Running about 6lbs now and haven’t messed with it. Should be in the 850+HP ballpark I am guessing

 

[AZLineman]

Larry Peto 548 with 8/71 dual 950’s running 91

Dyno peak was just over 930 at 8lbs
Running about 6lbs now and haven’t messed with it. Should be in the 850+HP ballpark I am guessing



View attachment 1136603

Cool. Looks like a Next deck? Knowing Larry you are running power valves non-boost referenced and they work great. On the print out he gives you what’s the jetting and timing?

 

[Good Stuff]

Cool. Looks like a Next deck? Knowing Larry you are running power valves non-boost referenced and they work great. On the print out he gives you what’s the jetting and timing?

Yes it’s the Next/Domn8er. Pretty sure it was a dealer boat that Domn8er got when they bought out the stuff from Next. Has a HIN plate riveted over the HIN on the transom and “Next” written in the bottom of some of the upholstery sections that can’t be seen. Bought it used with the engine already set up in the boat. I reached out to Peto but mine was from before he started storing the dyno files with his new digital setup. I have all the build invoices and such but no dyno sheets just verbal from the previous owner. Larry did tell me everything sounded about right for how he would have set it up on HP though. And yes not boost referenced. Timing is fixed and I haven’t checked it or the jets.

 

[Checked Out]

First pic was my carb set up for years, 509 bbc 6-71 10% over, 750 carbs w/quickfuel metering plates, no power valves and factory jetting, I think it was 74/84 Phil Bergeron had me set idle screws 1/8 to 1/4 turn out, ran great never had an issue… second pic is this year, same motor, put on hi helix 8-71 with new Enderle bug catcher set up at Alkydigger, both at 29 degrees locked out, straight av gas with marvel mystery. Everyone said mechanical injection doesn’t work? I’m loving it!

 

[AZLineman]

First pic was my carb set up for years, 509 bbc 6-71 10% over, 750 carbs w/quickfuel metering plates, no power valves and factory jetting, I think it was 74/84 Phil Bergeron had me set idle screws 1/8 to 1/4 turn out, ran great never had an issue… second pic is this year, same motor, put on hi helix 8-71 with new Enderle bug catcher set up at Alkydigger, both at 29 degrees locked out, straight av gas with marvel mystery. Everyone said mechanical injection doesn’t work? I’m loving it!

That’s exactly what I’d like to do. What do you like better about it besides the cool factor? Hows it run compared to carbs? I’m sure it’s better wide open by far but hows the cruise and drivability? Looks like you have a primer pill on the back of the hat.

 

[Checked Out]

That’s exactly what I’d like to do. What do you like better about it besides the cool factor? Hows it run compared to carbs? I’m sure it’s better wide open by far but hows the cruise and drivability? Looks like you have a primer pill on the back of the hat.

Everything is very consistent and predictable, great idle and real nice cruise, no stumbles or coughs getting on plane, have to run rich at idle to get the throttle response since there is no accelerator pump so there is a little black on transom but not much more than the carbs. Was told a bird catcher was too much for a gas cruiser and doing a bug was the key. There is a small primer tank and pump with a button on the dash to prime for easy start, bought as a kit.

 

[AZLineman]

Everything is very consistent and predictable, great idle and real nice cruise, no stumbles or coughs getting on plane, have to run rich at idle to get the throttle response since there is no accelerator pump so there is a little black on transom but not much more than the carbs. Was told a bird catcher was too much for a gas cruiser and doing a bug was the key. There is a small primer tank and pump with a button on the dash to prime for easy start, bought as a kit.

Very cool, thanks for sharing.

 

[rider68]

I got a standard 8-71 no strips. two 850 4150s. I converted the carbs to boost referenced myself 4.5 power valve in the primary none in the secondary. Also converted them to run on E-85. with new metering blocks, larger needles and seals. Runs great so far. It is in a 21 foot whaler day cruiser, v-drive.

 

[rivermobster]

I got a standard 8-71 no strips. two 850 4150s. I converted the carbs to boost referenced myself 4.5 power valve in the primary none in the secondary. Also converted them to run on E-85. with new metering blocks, larger needles and seals. Runs great so far. It is in a 21 foot whaler day cruiser, v-drive.

Who did all the fuel lines? Looks good!

 

[AZLineman]

Very cool. Lets see the Whaler.

 

[mesquito_creek]

I got a standard 8-71 no strips. two 850 4150s. I converted the carbs to boost referenced myself 4.5 power valve in the primary none in the secondary. Also converted them to run on E-85. with new metering blocks, larger needles and seals. Runs great so far. It is in a 21 foot whaler day cruiser, v-drive.

Second… let’s see the whaler

 

[Kachina26]

Motorhead

Gearhead

 

[AZLineman]

Motorhead
View attachment 1138027
Gearhead

Lmao. Thanks for the clarification.

 

[Kachina26]

Lmao. Thanks for the clarification.

Appreciate the boating content.

 

[rider68]

Who did all the fuel lines? Looks good!

I have fabbed everything on this engine. The black hoses are my boost reference hoses. It was a little nerve racking converting the carbs for boost reference but now that i have done it twice its easy. I will see if I can find some old pictures of my whaler. I have it torn apart right now redoing some of the rigging and cleaning things up.

 

[BamBam]

Who did all the fuel lines? Looks good!

I'm pretty sure the stainless fuel hardline setups were available through BDS in the past

 

[rivermobster]

I'm pretty sure the stainless fuel hardline setups were available through BDS in the past

Makes sense.

And they did they do the fittings so you could pull each bowl off independently? Ya don't always see em like that. That's a pretty cool set up he has.

 

[AZLineman]

I have the one from Teague that you can pull each individual line off

 

[AZLineman]

Changes comn. Working on new carb set up. Fresh 1090 BG dominators sideways on a front loading too plate from PSI. Got some cool cnc’d phenolic spacers from dead on racing. Gonna try boost ref the pri side and jet big/block sec side to start. Working on arrestor options then fuel dist block/lines then linkage.

 

[Goodtime$]

I’m either in Covid or sinusitis land today
588 dart big m
Needed a sleeve- Eddie Knox kboat motor that didn’t live for dark horse team.
Got it cheap - sleeved It at shaver

Blower is a basic 871 take off of a Daytona I’m re doing for buddy turning motor in 540na

Carbs got done by c and j
Crower cam
China rods crank I think
Dart 360 heads

Assembly by Jimmy van dyke

I have since got a belt drive and nice damper for her
30 degree - low boost - going into a jet boat

 

[Goodtime$]

540 I took blower from

 

[AZLineman]

Very cool. Looking at the valve covers are you gonna run a vacuum pump? How are you setting up your carbs?

 

[Goodtime$]

Very cool. Looking at the valve covers are you gonna run a vacuum pump? How are you setting up your carbs?

Those arent my covers. I just got basic eddie ones with breathers.

Carbs are boost referenced -3an - ill check jetting card and report back.

 

[Goodtime$]

Jetboat beer budget shit

 

[Goodtime$]

Bostick 572 / 1071 combo
Made 1000hp

 

[AZLineman]

Very nice

 

[Goodtime$]

The biggest question I have for motorheads is nerd shit. Most of my customers want / demand EFI platform powerplants.

I would love to build inhouse a 598/604 tall deck EFI NA motor. But the Imtron, Motec, Mefi, Holly is a mess and beyond my simple dominator 1050 budgets.

Has anyone done a simple MEFI LS coil on plug to a BBC ?

 

[AZLineman]

Do you mean something like this?

 

[Goodtime$]

Something prettier - like ramjet style intake w throttle body.

 

[Good Stuff]

Something prettier - like ramjet style intake w throttle body.

Something like this would probably be the easiest way to pull it off. A stripped down “motor swap” harness designed to run an LS on MEFI

CBM MOTORSPORTS™ LS SERIES STANDALONE WIRING HARNESS FOR GEN III / GEN IV LS USING A MEFI 4 ECU

Take a look at our CBM MOTORSPORTS LS SERIES STAND ALONE WIRING HARNESS FOR MEFI 4 ECU, as well as other CBM Wiring Harnesses available for sale here at cbm motorsports.

store.custombuiltmotors.com

 

[BamBam]

Something prettier - like ramjet style intake w throttle body. View attachment 1141271

I like the thought of that clean set-up, however the limiting factor with that manifold is airflow. I ran one (AZ Speed Marine) on my 502 and it was awesome. I tried to run it on my 540 and was limited on the dyno. I know I had a long runner and the short runner version will work on a 540 but I really doubt you can get over 650HP with that manifold. A 598 is going to need more air than that manifold will give (especially N/A). You would probably be better off with a big single plane and a 2000CFM throttle body with MPFI. I am running a setup like that on my 548 and make 711HP @6200 through a Holley HP. Coil on plug can get more complicated on a BBC unless the platform started that way because you need to set-up a reluctor wheel and piece the system together. Holley uses a dual pick-up distributor (cam and crank) or you can use a crank trigger for the crank side and let the dist. pick up the cam signal. Just one guys opinion.