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75 Spectra V-Drive with a Bad Blown 572

78Southwind

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I really didn't want to post this up on RDP's until the Spectra was completely finished but I figured since we are going to do a shakedown run in a couple weeks now is better than never. It's taken a lot longer than expected with some bad luck health wise but never the less the boat is running and I can see the light at the end of the tunnel. For those that didn't know this is Greg's (RIP) old boat with Danny's (RIP) old blower engine. The Spectra was in pieces when I bought it and Gary (Greg's father) who sold the boat to me didn't know much about the boat so there was a little bit of trail and error (ok maybe a lot):D. However, searching Greg's and Danny's posts on the boards was very helpful. The plan was to finish the boat and take Gary out to Parker so he could spread Greg's ashes but Gary (RIP) passed away a little while ago.

I didn't know Greg on a personal level but I knew him as one of my river buds (someone I always made sure to say Hi to if I saw him at the river). I had only ridden in his boat a couple times once when I saw him at one of our AVI trips and another when he came to one of my Park Moabi trips that I use to throw a couple times a year. He had invited Lisa and I to join him at Parker a couple times but we never made it down with him to his stomping ground. One thing I will always remember about Greg is his smile, that guy always had a smile on his face. I use to tease Greg about this picture and told him that it looked like he was trying to hold down his ice chest.

Blown26_572.jpg


The following is some of the history of the boat and the process of getting the boat back together. While making improvements where possible.

The first thing was getting the engine and engine plates installed so the boat could be towed home safely. One thing Greg loved to do was to drive his boat which is probably why his good friends called him "Full Throttle Fuller" and "Gas Dock Fuller." Greg would put miles and miles on the Spectra during an average weekend at Parker, Havasu or Laughlin. I remember reading a thread were Greg had driven all the way from Havasu Marina to Laughlin and then to the Springs and back to Havasu Marina. Well on that day one of the bolts had vibrated out and broke the lower bolt boss.

Blown_572_BrokenBoss.jpg


I wasn't sure what the appropriate fix was so since I had decided to rebuild the engine I asked around to a number of engine builders to see what they thought the appropriate fix was. All of them agreed that new plates would be a reasonable fix.

Spectra Motor Plates.jpg


Once the boat was safely home it was time to get the trailer axle fixed and engine rebuilt.

Gregs_Blown572.jpg
 
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78Southwind

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Jim Lange re-ringed the boat for Greg when he bought the blower engine from Danny. So not knowing much about Spectra 20's with high horse power set-ups I spoke with other owners and they had similar set-ups with high horse power. When I got the boat home I measured the following: The strut angle is 7.8* with a 6" drop. The distance between the transom and strut is 25". The cavitation plates are 9.5" from the transom and end 7.25" from gunnels. The distance between the engine and transom is 20". The centerline of the gearbox is 100" from the transom, 4" from the bulk head and about 15" from the deck/dash. The strut is a drop thru with a brace.

Lew Larson pulled the engine for me and began rebuilding the engine. Once at Lew's I noticed that the rear trailer axle was on it's last breath so I took it over to Arrow Trailers to have them install a new one and repack the bearings with grease. I also ended up getting some new tires for the trailer.

Lew Pulling Engine.jpg


Arrow Traler Fixing Axle.jpg


Strut Brace.jpg


Spectra Transom.jpg


Spectra_CavitationPlates.jpg
 
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78Southwind

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So while the engine was being rebuilt and the trailer was being serviced I searched the forums to get as much information about the boat and engine as I could. Here is some of the information that I found...

Jim Lange (High Tech Marine) re-rigged the boat and rebuilt the engine around 2008.

I sent Jim a PM and this is the information he gave me. The strut was replaced with a fabricated steel drop thru and strut braces, new rails and mounts, relocated V-drive replacing the original Champion V drive with a rebuilt Casale split case, new A22 prop shaft, new Menkens prop, installed new "adjustable" cav plates (originally had NO plates). I never drove it, but from what I've been told, it handles well. The transmission was built by a guy that used to work for Art Carr. I believe it has a Crower crank, Manley rods and JE pistons. All new Manley Severe Duty valves, new oil pump, rings and bearings.

Steve Brule (Westech Performance) dynoed the engine in 2002 and 2004

Greg never dynoed the engine after Jim rebuilt it but the engine was originally owned by Danny Donahue (RIP) and he dynoed the engine at Westech Performance in 2004. I sent Steve Brule an e-mail and he confirmed that the engine made low 900's HP with 5lbs of boost and in the high 900's HP with 6.5lbs of boost.

Gary Williams (Williams Carburetors) built the carbs in 2002

I called Gary and he said the carburetors flowed over 1200.

Bryan Lewandowski (Valley Propeller Service Ventura)

I sent Bryan an e-mail and they still have one of Greg's old props and they are in the process of researching his file.

I also found some of Greg's old posts...

...Mines a 75, heavy lay up ( bottom is 1 3/8" thick) 4 full stringers. blown 572. I re-rigged it, moved the prop 10" forward, reduced the angle by 3 degrees to alleviate the stern lift problem.

...Blown 572 I will trust Danny on the HP, Replaced the champion with a 12 degree casale moved forward right up to the bulkhead with 37, reduced propshaft angle, new custom steel strut, blastplate at the stock strut location prop forward about 10" My prop is not correct but its running about mid 90s and get there in a hurry.

...Gps'ed it today... 50 @ 3000, 65 @ 4k... 85 @ 5k. the prop I'm running doesn't carry the bow worth a shit and I didn't want Wheeler to soil my seat so that was it...The way I see it if I can ever get my Menkins prop duplicated I should hit at least 107 at 6k : )

...I rode in Lynch's boat at 113, felt faster than mine, but I wasn't driving... my pile has around 1000 hp, 37's in the box, 11.75 X 16.5 Menkins 3 blade. I can hit 5400 with a little more than half throttle, I've stood on it from there a few times but not about to look at the tach?

...I have a new Menkins 2 blade that was originally a 11 3/4" X 17. I ran it once and it vibrated my boat. I just got it back from Valley Prop service after having it cut down to 11 1/2 X 16 1/2". You are welcome to give it a try. I also have a Kindsvater 3 blade 11 1/2" X 16 1/2" with only last season on it, does not work well on my boat it gets squirrely above 80, I have Brian At VPS working on that one now to try and match a 3 blade Menkins that works perfectly but is about done hour wise. I had no luck getting in touch with Dallas @ Menkins last year that is why I bought the Kindsvater. I would bet you would be happy with the 3 blade Menkins, I am going to try to Get Dallas to duplicate the one I have.

I found some of Danny's old posts on www.riverracer.net. Shaun the owner of the site had saved a lot of the old Hotboat.com posts and threads prior to the magazines meltdown. The following posts lead me to Greg Shoemaker. Greg Shoemaker was able to put me in contact with Dan Douglas who built the engine for Danny. Dan Douglas faxed me the first dyno sheet which had some cam information and showed a 903 HP pull at @ 6,000 RPM with 5 PSI.

...Well, looks like my boat sold less power so I have a motor that needs a new home. Looking to get rid of it. Motor has 1 hour of dyno time since it was torn completely down, checked out, and rebuilt. Motor maybe has 30-40 hours on it TOTAL. It has all of the best parts in it.

...World Industries block
...Dart Pro 1 polished CNC Heads
...The Blower Shop 10-71 Blower
...MSD 6M Ignition
...Super Chiller
...Two Gary Williams Dominators
...Billet Crank
...ARP fasteners
...Etc.

...Motor put out 989h.p. on 6.5lbs of boost on pump gas. The motor is way over built for where it was running. A duplicate motor on Race Gas put out well over 1200h.p. and there was still room to go. There are no issues with this motor and it starts, idles, runs, perfectly. I can produce dyno sheets and will pay for an independent mechanic to go through the motor and sign off on it. Once that is done, that is where the warranty stops. I am 100% confident in this motor or I would not be selling it. As with anything high performance, there is NO WARRANTY what so ever once your mechanic gives it the green light.

...I can also help whoever buys this motor install it in their boat. You get the motor complete marine (less headers & motor mounts). Everything else is there and is ready to drop it in the boat. This would be a great re-power or something for a new boat awaiting production.

...Just FYI, I am looking to get somewhere around $18-20K for this motor. Call up Pfaff, GT, or Teague. For something similar, you are looking between $40-50K

...Initial is about 8 or 8.25:1. When I say pump gas, I mean 91 octane. That is what we ran it on the dyno at and no problems. Knock sensor didn't detect anything. Just to be on the safe side, I always splashed between 5-10 gallons of av gas into the tank prior to running it. Cheap insurance on the motor. They say that fuel looses between 1-2 octane points per month. Last thing you need is to have the fuel sit in the tanks (either in the boat or gas station) and pump bad gas through a high performance motor. It would live on 89, but I DO NOT suggest running it on 89 (much less running it hard)!

...Nope. You didn't miss it, I forgot to add it. It is a 572cid and it was built by Dan Douglas from GS Marine. He owed me a favor and did this motor for me. We worked with a bunch of different builders to get the ideal combination. Tom Papp was in on it, Dougans Machining, PFM, Westech, etc. I ordered the parts and had them delivered to me. We then got together and I watched as it was assembled. Dan Douglas did all of the assembly and then it was dialed in by Steve Brule over at Westech.

...By the end of the day, I was very happy where the motor ended up. It puts out 946@5600 and the lowest we pulled was 4500rpm and at 4500rpm the motor was making 954ft/lbs of torque. (And I was wondering why I keep going through drives). Steve Brule from Westech said that I could get an additional 100-200 H.P. if I wanted to run race gas, but I opted to stop there. I am only running 6.5lbs of boost and the motor is fat and happy.
 

Wmc

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You need to come by when Billy's gets his here on Monday
 

78Southwind

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The cam that Danny was running was a Comp Cams Solid Roller 255 - 265 @ 650 Lift with a 114 Lobe Separation and the cam that was in the engine looked like a Crane Cam. So I called Crane Cams and they said it was their cam but the number was for a cam that was unfinished. Crane Cams told me that they sell unfinished cams to other cam grinders to finish to their specs. It kind of through me off so I did some more research. I spoke with Jeremie and he said that he thought Greg had Chris Straub regrind a cam for him when he broke a lifter. I e-mailed Chris and he said that the cam wasn't his. I then spoke with Tom and he said the cam wasn't damaged when the lifter broke and Greg never replaced the cam.

Spectra Old Cam.jpg


I thought to myself either Danny changed the cam between the 2002 and 2004 dynos or Greg changed it when Jim Lange rebuilt the engine. So I PM'ed Jim Lange and he said that he didn't have the cam information but if he changed the cam back in 2008 he would have put a Bullet Cams cam in the engine. I contacted Bullet Cams and they said if I wanted to send the cam to them they would put it on their cam doctor machine for free. So I sent the cam to Bullet Cams and they said it wasn't one of their grinds. However, the cam was a 258 - 262 @ 660 Lift with a 115 Lobe Separation. While I was doing my research on the cam I found a post by Greg stating that he couldn't run mufflers on the engine because of the reversion. Then later I found a post from Greg stating that he did put a new grind on the cam. With those previous post in mind, I decided to speak with Chris Straub about grinding the engine a new cam. That way if I ever have to run mufflers on the engine, I don't have to worry about reversion. The new cam is a 253 - 273 @ 653 Lift with a 112 Lobe Separation. It also has a 4-7 firing order swap.
 
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78Southwind

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There were a couple things that needed fixing and upgrading on the engine besides installing new barrings. The heads where resurface .003. The intake was resurfaced. The block was decked .006 and we had the o-rings taken out of the block. JMS Racing did the machine work and the valve job.

572 Block Height.jpg


572 Block.jpg


572 Block1.jpg




Cleaning Heads.jpg


JMS Heads.jpg


JMS Heads1.jpg


We found out the Crower Crank was balanced internally on the front side of the engine and externally on the rear side of the engine. I had never heard of this type of balancing before so I did some research and it looks to be a trick to save money on heavy metal balancing costs. The engine was originally in Danny's Carrera Cat and I am assuming from reading his past posts that the engine didn't see much over 5,000 RPM's in that boat. However, he said the engine pushed the boat to 118 MPH and he had broken the drive a couple times. When talking to my engine builder he said he wouldn't recommend building any engine that was going to see 6,000 RPM's with an external balance so we had the crank re-balanced all internally. Later, I contacted Alexi at Boost Power Marine and he said we did the right thing by having it re-balanced internally. The crank also only had one keyway so I spoke to Eric at The Blower Shop and he said that any engine running over 6 PSI should have two keyways so we added another keyway just in case we wanted to turn up the boost. After the balance and machine work the crank received a polish and it was ready to go.

CrowerCrank Slugs.jpg


CrowerCrank Slugs1.jpg


The Manley Rods were re-sized and received new bushings. Jim Lange had three pistons that matched the engine so I bought them and had them balanced with the crank in case we ever needed them down the road.

JE Pistons.jpg


ManleyRod Pistons.jpg


ManleyRods Pistons1.jpg


JE Pistons New.jpg


I also had the carbs rebuilt.

Carbs.JPG
 
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78Southwind

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The Pro Race Tech balancer had seen better days and was due for retirement. So I contacted Pro Race Tech in Australia and also talked to their Senior Consultant here in the US about the Harmonic Balancer and they sent me a new one for $150 out the door.

Spectra Balancer.jpg


Spectra Pro Race Balancer.jpg


Spectra Pro Race Balancer1.jpg


In 2012 the dampener plate broke a spring which ended up cracking the transmission case. Greg had plans to change out the flywheel with a flexplate and the drive spline with a TCI Front Pump Drive Kit (spline drive). However, I felt that a Hughes Performance direct drive with a Meziere Billet Steel Flexplate would be a more stout replacement.

Original Set-up

Flywheel.jpg


Spline Drive.jpg


Planned Set-up

Flexplate.jpg


TCI_Front_Pump_Drive.jpg


The current Set-up

Mez FlexPlate1.jpg


Mez FlexPlate2.jpg


Hughes_Performance_Direct_Drive.jpg


Spectra Hughes.jpg
 
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78Southwind

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While the engine was being rebuilt I had the hull over at Scott Schatz's shop SS Performance and Marine where he went through the rigging making sure everything was safe. He started with the blast plate. The old blast plate was a fill plate where the old strut was (acting like a small blast plate). Scott routed out the bottom of the boat and put in an aluminium blast plate. He also added a safety collar to the ruder, blended the bottom and added speed coat.

Blast Plate Old.JPG


Blast Plate.jpg


Blast Plate1.jpg


Blast Plate2.jpg


Blast Plate3.jpg


While the hull and engine were being worked on I polished the rails and brackets.

Polished Brackets.jpg


Polished Rails.jpg
 
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78Southwind

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I am pretty sure that the transmission that came with the boat wasn't the original transmission. I know the casing broke when it had a failure (maybe Greg junked it). However, he had a good core there when I picked up the boat but it was probably out of a car not a boat. So I had SS Performance and Marine send it out to get rebuilt. They used Raybestos Red Clutches and installed a TCI Valve Body with Reverse Order Shift Pattern: Park-Reverse-Neutral-First-Second-Third.

Transmission.jpg
 
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78Southwind

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Greg would be very proud. You've used an open checkbook in all the right places.

Great thread
Thanks, with not having Greg around to ask questions to there were a lot of ups and downs. Also, you would be surprised how the small things add up. I spent more money in improving and putting the boat back together than I purchased it for. But in the end it was all worth it, I hope. :D BTW...I can't wait to see your build.
 

rivrrts429

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Thanks, with not having Greg around to ask questions to there were a lot of ups and downs. Also, you would be surprised how the small things add up. I spent more money in improving and putting the boat back together than I purchased it for. But in the end it was all worth it, I hope. :D BTW...I can't wait to see your build.
I know what you mean about the cost. The fiberglass itself is cheap compared to the parts that you bolt to it lol

I'll start a thread soon on my pile. Keep the pics and updates coming. You've done a ton so far. I admire your ability to stick through it.
 

jetboatmatt

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So awesome to see this boat again!! I never knew Greg but I always saw him giving rides to scare people in Parker!! His boat always sounded amazing!!
Can't wait to see her fly again! Great job man!!
 

78Southwind

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I learned a little bit while completing this build and I will share a couple of my learning experiences. When we started up the engine the fuel pressure gauge would go directly to 15 PSI. I found a bad ground but once I fixed that the gauge was displaying 9 PSI. So I check the fuel pressure with a manual gauge and it was reading just below 5.5 PSI. So I read that the sender voltage should display .5 volts at 0 PSI and 4.5 volts at 15 PSI. Sure enough the sender was displaying 1.6 volts with no pressure which it should have been displaying .5 volts and 3 volts when it should have been displaying closer to 1.9 volts at just below 5.5 PSI.

Using excel these are the rounded up values I came up with for what the voltage should have looked like at certain PSI.

PSI Volts
0 0.5
1 0.8
2 1.0
3 1.3
4 1.6
5 1.8
6 2.1
7 2.4
8 2.6
9 2.9
10 3.2
11 3.4
12 3.7
13 4.0
14 4.2
15 4.5

I called AutoMeter and told them about the sender which is $115 and they told me to send them the old sender and they would send me a new for free.👍

Manual Gauge.jpg


I also learned about mechanical injection style bypass check valves. The Spectra has a loop type of fuel system that pumps fuel through a -8 line to a fitting that splits it to the carbs and the return line that is -6. The return line loops right back in front of the fuel pump. I had wondered what the brass fitting was just after the tee but never opened it up to see what it could be, thinking that the fuel pump must of been modified internally to run the sought out fuel pressure. Well I found out the the brass fitting just after the tee is a mechanical injection style bypass check valve which regulates the fuel similar to a fuel regulator. The springs can be changed out for different PSI and or shims can be added to change the PSI.

Loop Fuel System1.jpg


Loop Fuel System.jpg


To get 6 PSI I stretched the spring a little. I am going to dial the fuel pressure in with shims.

Fuel Pressure Regulator.jpg


Volt Meter.jpg


Fuel Pressure Gauge.jpg
 
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SBMech

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Love the fact that Greg's boat ended up with someone who loves it:thumbsup

Never met him, but saw him and the Spectra tearing it up a few times at Parker, you are doing total justice to them both :D

Looking forward to watching the rest of the shakedown, one of my favorite boats rescued and re-homed:)
 

SBMech

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DAMN that sounds good! Looking great, hope to see you out this summer SW :thumbsup
 

vdcruiser

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Glad to see you got her out on the water, sounds and looks good. Have you opened her up yet?
 

78Southwind

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A couple things I learned from the testing we did.

This boat loves to get on the plates and ride there. My buddy said he was pretty sure he was in the 90's for the short blasts that he did. I am thinking he was knocking on 90 MPH but who knows we didn't have a GPS and the day we were going to GPS the Spectra it was blown out. However, he said there was a lot of throttle left in it at that speed. With the rough water out in Havasu we need a Rev Limiter so I purchased a MSD 8768. I then spoke with Chris Straub of Straub Technologies and he said to set the Rev Limiter at 6,300 to 6,400 RPM's.

My best estimation after looking at the Drive Ratio, Boost and the Effective Compression Charts is that Greg was running about 8 PSI. The Blower Shop confirmed my estimation. The Static Compression Ratio was 8.25 to 1 with an Effective Compression Ratio of 12.4 to 1 which seems to be on the ragged edge for pump gas. I am not sure how the chiller plays in this equation. However, from what I have read a chiller will help reduce chances of detonation with pump gas. I am not sure if Greg ran race gas, a mix or pump gas.

We ran about 7 PSI on race gas (110 octane) for the shakedown run. The Static Compression Ratio was 8.4 to 1 with an Effective Compression Ration of 12.4 to 1. I can't imagine having to afford the good gas so we are lowering the PSI to about 5 PSI. This will give us an Effective Compression Ratio of about 11.3 to 1. This will also give us enough leeway for today's low octane fuel.

Just to give you an idea about horse power when Danny had the engine dyno'ed in 2002 it made 903 HP @ 6,000 RPM with 5 PSI and in 2004 it made 989 HP @ 6,000 RPM with 6.5 PSI. So I am guessing it was probably somewhere around 1070 HP when Greg was running it.

20160510_190927.jpg
 
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rivrrts429

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A couple things I learned from the testing we did.

This boat loves to get on the plates and ride there. My buddy said he was pretty sure he was in the 90's for the short blasts that he did. I am thinking he was knocking on 90 MPH but who knows we didn't have a GPS and the day we were going to GPS the Spectra it was blown out. However, he said there was a lot of throttle left in it at that speed. With the rough water out in Havasu we need a Rev Limiter so I purchased a MSD 8769. I then spoke with Chris Straub of Straub Technologies and he said to set the Rev Limiter at 6,300 to 6,400 RPM's.

My best estimation after looking at the Drive Ratio, Boost and the Effective Compression Charts is that Greg was running about 8 PSI. The Blower Shop confirmed my estimation. The Static Compression Ratio was 8.25 to 1 with an Effective Compression Ratio of 12.4 to 1 which seems to be on the ragged edge for pump gas. I am not sure how the chiller plays in this equation. However, from what I have read a chiller will help reduce chances of detonation with pump gas. I am not sure if Greg ran race gas, a mix or pump gas.

We ran about 7 PSI on race gas (110 octane) for the shakedown run. The Static Compression Ratio was 8.4 to 1 with an Effective Compression Ration of 12.4 to 1. I can't imagine having to afford the good gas so we are lowering the PSI to about 5 PSI. This will give us an Effective Compression Ratio of about 11.3 to 1. This will also give us enough leeway for today's low octane fuel.

Just to give you an idea about horse power when Danny had the engine dyno'ed in 2002 it made 900 HP @ 6,000 RPM with 5 PSI and in 2004 it made 989 HP @ 6,000 RPM with 6.5 PSI. So I am guessing it was probably somewhere around 1070 HP when Greg was running it.
I agree, you're on the very edge and it's tough to run pump gas in that configuration and boost.

I think I'd still run a few gallons of race gas because you can never be sure the quality of fuel you're getting. One slightly bad fuel station and you're going to see detonation. I'd think aluminum heads will help though.

I'm sure you'll figure it out the more you run it and get comfortable with its mannerisms.

Really stoked you saw the project through to the end.
 

SBMech

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11.3 to 1 you still are going to need at least 97 to make it, the aluminum heads will help, but with the randomness of fuel, I'd try to stay over 100 octane.

Mix race fuel, Blue Flame is available in 50g drums, Take a few 5 gals with you in the truck.

That much money into the motor and re-rigging it, gas cost has to be the least expensive part of owning her :D
 

78Southwind

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11.3 to 1 you still are going to need at least 97 to make it, the aluminum heads will help, but with the randomness of fuel, I'd try to stay over 100 octane.

Mix race fuel, Blue Flame is available in 50g drums, Take a few 5 gals with you in the truck.

That much money into the motor and re-rigging it, gas cost has to be the least expensive part of owning her :D
I hear you. I will probably throw a splash here and there before and after storing. There's a couple places out in Bullhead and Havasu that you can get race gas too.

I think these formulas are all junkyard math anyways. I spoke with Chris and he said that's where he would run it on pump gas. To show some of the math I am going to run a 5.2" bottom pulley and either a 5.7" or 5.9" top pulley. This should give me an underdriven drive ratio of 8.77% or 11.86%. At approximately -10% (underdriven), max boost should be 5 PSI. Thus, Effective Compression Ratio (ECR) = ((boost / 14.7) +1) cr = (ECR) = ((5 / 14.7) +1) 8.4 ECR = 11.257. I have seen some other formulas out there but I figured I would stay with the one TBS uses. From what I have read you should stay below an ECR of around 12 to 1.
 

vdcruiser

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I run my blown 548 at 11/12 psi of boost on 100LL av gas with 30 deg timing and 8.3 compression with no problems. It will also run on 93 octane without issues. I do run a innercooler and 120 deg of water temp though. I also don't run it for long distances at wide open throttle.
 

78Southwind

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I run my blown 548 at 11/12 psi of boost on 100LL av gas with 30 deg timing and 8.3 compression with no problems. It will also run on 93 octane without issues. I do run a innercooler and 120 deg of water temp though. I also don't run it for long distances at wide open throttle.
Did you lengthen the center strakes at all? Do you happen to have video of the boat running at speed?
 

warpt71

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Im pretty sure Greg was running strait AV gas as we made it a point to stop at a 76 gas station in Agoura Hills that had it on the pumps when we went to the TPM in 2010
 

vdcruiser

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Did you lengthen the center strakes at all? Do you happen to have video of the boat running at speed?
I have not lengthened the strakes, I keep wanting to talk to someone that has actually done that. Its talked about a lot, but I have not talked to anyone that has done it on their boat. I have a old video of the boat running at speed, not that good, but I'll see if I can find it.
 

SBMech

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I run my blown 548 at 11/12 psi of boost on 100LL av gas with 30 deg timing and 8.3 compression with no problems. It will also run on 93 octane without issues. I do run a innercooler and 120 deg of water temp though. I also don't run it for long distances at wide open throttle.
Curious, why such low timing? Most BBC want to run at around 38-40 all in, are you running it retarded to keep it from pinging or detonation from the low octane fuel?
 

Outdrive1

Outdrive1 Marine Sales https://www.outdrive1.com/
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36 is probably a good compromise I'd lock the distributor out too.
 

SBMech

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36 is probably a good compromise I'd lock the distributor out too.
I hear you want really light springs to get it all in around 2400-2600 for a boat motor, you run yours locked out completely for racing?
 

Outdrive1

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I hear you want really light springs to get it all in around 2400-2600 for a boat motor, you run yours locked out completely for racing?
It's pretty common to lock out the timing in a blower motor. I think it's safer also.
 

vdcruiser

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My timing is not locked out, tried it one time and it made the motor surge real bad. Been advised for a long time not to run more that 30/32 degrees of timing with a blown motor on pump gas, or in my case AV gas, to avoid detonation. Motor has been trouble free.
 
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