update: crowbar engine rebuild

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mcm4
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update: crowbar engine rebuild

Post by mcm4 » Tue Feb 05, 2013 9:32 pm

I purchased a BBC 555 Dart engine detuned with a different cam and with a hydraulic roller cam. It was suppose to produce 650 hp with a fairly flat torque curve from 3000 to 5200 rpm

To go with it, I purchased a four blade 86” R style blade to go with this setup. I had heard that a 625 hp airboat motor would pull 5600 rpm at the 2.5” pitch mark. This goes with my Century 3.1 reduction drive.

After installation I was shocked with the results I got.

with a four blade 86" Sensenich R prop, and a 2.3 reduction drive I can only turn 4300 rpm set at the two mark

so I reduced pitch

with a four blade 86" Sensenich R prop, and a 2.3 reduction drive I can only turn 5100 rpm set at the one mark
so I put on the short hub

with a four blade 82" Sensenich R prop, and a 2.3 reduction drive I can only turn 5000 rpm set at the two mark

so I reduced pitch

with a four blade 82" Sensenich R prop, and a 2.3 reduction drive I can only turn 5000 rpm set at the one and a half mark… NO increase in rpm from pitch mark 2 to pitch mark 1.5 as measured from the back of my transom to the trailing edge of the prop and double verified.

So I ran one final test.

I dusted off my Whirlwind AB300 with 3 - 80 inch diameter 14.5 inches wide, Whirlwind Master Blaster Blades with Century 2.3. and the props set at 25 degrees. Bill told me that at 25% pitch mark I should be able to turn 5300 rpm with 450-475 hp.... I ran the test and could not get over 4750 rpm.

It is interesting to me that in the tests, as I took load off the props, I still could not get my rpm much over 5000 rpm

My prop guy said that based on the numbers we have provided to them that my engine is putting out around 450 hp.

I heard that Diamond back puts a 496 Levitator on their boats with a 2.3 reduction, they run a 4 blade 86” R set at the #2 pitch mark and the engine will turn 5100RPM. The levitator engine makes 425hp?

I heard that Waterthunder has a mild built engine that makes 610hp and it will spin the 86” four blade R set at 2 ½ to 5600RPM with a 2.3 reduction.

I have since talked to a racing engine shop in Houston with quite a bit of airboat experience. They looked at the literature/engine specs:

The Howard Cam that is on it has a duration at 050 of 247 and 255 at 360 gross cam lift. It has a valve lift of 612 and degrees of duration at 300 and 308. It has a Quick Fuel 950 and Dart Platinum pro 1 345 cc aluminum heads. It has forged, domed top SRS 2618 Alloy Pistons 10.5:1 compression, single plane pro-comp intake, hydraulic roller rocker and cam lifters.

They said that they were sure that they could get it to produce 1.2 hp per cu inch for my airboat application. They said that it has the wrong intake, it needs a Performer RPM dual plane manifold. They said it had way too much cam. It needed to have a cam with 224 and 230 at 50 degrees. They said the cam needed advanced 3-4 degrees. They said it needed 39-40 total timing versus the 34 total timing that the engine builder recommended. They said it was way over-carburated, it needed more like a 750 cfm on it instead of the 950.

As far as power goes, all I want is for it to be able to turn my 4 Blade 86” R props at the 2.5” pitch mark 5600 rpm, that should put my hp in the 625 range.

I purchased the motor from the company because they originally were very professional and responsive to me, because they said they had sold this engine to airboaters in Louisiana that were very pleased with it, because they could get me the engine in one week, because they were competitive, because what their literature said made sense to me, because they had such a good online business rating.

I would like as much expert advice as I can get, I am open to any and all input.

What does it appear that I did wrong in this situation? What does it appear that the engine builder did that was wrong? Thoughts?

UPDATE: The builder called their contact at Howards cams who is an airboat motor builder. He said the heads they used were way too big. That the Dart 345 heads should be removed and Dart 310 ovals should be installed. He suggested an Edelbrock RPM Airgap model 7562 with oval ports, a Howard Cam 120266010.

Cam part number 120266-12
Cam and Lifter Set Part no. 2600-6500
Duration Intake 290
Duration Exhaust 296
Duration at .050" intake 237
exhaust 243
Valve w/1.70 intake .635
Lift Rockers exhaust .641
Lobe Separation Angle 112
Intake Centerline 108
valve in hyd.
Lash ex hyd.
Lopey Idle, Hot Street&Bracket Racing 10.0:1 up CR advised

Does this look like the engine guys are on the right track?
Attachments
dyno runs1.jpeg
dyno runs1.jpeg (55.44 KiB) Viewed 1392 times
Last edited by mcm4 on Thu Mar 14, 2013 6:36 pm, edited 2 times in total.

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eagal69
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Re: Help needed with BBC Engine

Post by eagal69 » Wed Feb 06, 2013 7:51 am

Just went thru this myself, sound like it is over cammed and cam needs to be advanced 3 degrees more, I run a 850 holley cam, i spin a 80" R with 2.3-1 century and spin it 5400, which spins my prop at 2347 rpm, Terry with sensnich really help me with my prop set, I can run dry and climb the hill now.
I don't follow trails I make them, 15 x 8 Alumitech,496 Stroker bbc,2.3-1 belt drive 82" 4 blade R.
KRVSA

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Re: Help needed with BBC Engine

Post by flying fish » Wed Feb 06, 2013 8:19 am

If your camshaft is close, advancing +6 and/or retarding -6 degrees will show minimul peak RPM changes. This is not a guess. :)

You should be able to make 625 torque with your CID displacement.

Are you certain your fuel/air delivery system is adequate and working properly???

With yoru current listed setup, something don't add up.

Detonation?
Fuel/air
Something is wrong.---
15' DB - 6.2 LSA - 4 blade 82" R - 2.52 CH-4

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Re: Help needed with BBC Engine

Post by PAINKILLER » Wed Feb 06, 2013 8:52 am

The cam that's in the motor is a good cam(I have a 540 BBC on my computer that has that same cam 248/256 makes 660 torque this is a motor of a guy I know so take it as it is(cam specs 248/256--icl 107- ecl 117-lsa 112 0ver lap 28 the cam they want to use will fall off after about 4500 i would use the heads 310s or brodix race rite oval ports
Last edited by PAINKILLER on Wed Feb 06, 2013 12:19 pm, edited 2 times in total.
MATTHEW 25:35-45 LS 406 82 4bld WaterWalker falcon 2.68 ox box
LS 427 80 3 Bld WaterWalker Maximus 2.68 ox box :rebel:

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Re: Help needed with BBC Engine

Post by bruceharwell » Wed Feb 06, 2013 9:15 am

39-40 degrees timing??? :bom:

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Re: Help needed with BBC Engine

Post by todd glover » Wed Feb 06, 2013 1:58 pm

Just ran a 565 with same heads single plane intake 1150 cfm carb and the cam is 286 @50 and made peak Tq @ 5200 748 lbs and 866hp @ 6800 not sure what's wrong with your boat but the heads should work intake same don't take this the wrong way but do you know how to tune a carb and set the timing was it dynoed before you took it home it maybe a tuning issue not trying to offend just don't want to see you spend money that you don't need to good luck

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Re: Help needed with BBC Engine

Post by torque » Wed Feb 06, 2013 2:21 pm

That motor will work great! If you were drag racing. That whole set up is for turning that motor 7500 rpm. You need to go with all the stuff they said to go with! Its not about HP ITS ABOUT TORQUE on a airboat. That 950 is for 7500 rpm not 5000 rpm everybody thinks bigger is better on carbs an thats not the case.Duel plane intake oval port heads to get you low in power. Stay around 230s or 40s at 50 an bring your lift to 600. The prop is like a dyno mahine. When you get your motor running. Find out what you won't to turn the prop at. Lets say you want to turn the motor 5500 rpm an your bbc is a 555ci My calculator say you should run a 850! But you are going to always have to run less pitch with that 2-3 if you want more rpm an more pitch its hello to a 2-38 box. Hope that i helped you some good luck

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Re: Help needed with BBC Engine

Post by PAINKILLER » Wed Feb 06, 2013 4:28 pm

PAINKILLER wrote:The cam that's in the motor is a good cam(I have a 540 BBC on my computer that has that same cam 248/256 makes 660 torque this is a motor of a guy I know so take it as it is(cam specs 248/256--icl 107- ecl 117-lsa 112 0ver lap 28 the cam they want to use will fall off after about 4500 i would use the heads 310s or brodix race rite oval ports


this is a solid roller that makes 700 tq 255/263 when you down size it to a hyd roller you 248 /256
MATTHEW 25:35-45 LS 406 82 4bld WaterWalker falcon 2.68 ox box
LS 427 80 3 Bld WaterWalker Maximus 2.68 ox box :rebel:

mcm4
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Re: Help needed with BBC Engine

Post by mcm4 » Wed Feb 06, 2013 7:20 pm

update on what engine builder suggests for a cam and said after the mods the compression would be 10.8:1

Howard cam

Cam part number 120266-12
Cam and Lifter Set Part no. 2600-6500
Duration Intake 290
Duration Exhaust 296
Duration at .050" intake 237
exhaust 243
Valve w/1.70 intake .635
Lift Rockers exhaust .641
Lobe Separation Angle 112
Intake Centerline 108
valve in hyd.
Lash ex hyd.
Lopey Idle, Hot Street&Bracket Racing 10.0:1 up CR advised

An online poster to this forum, "torque" says keep lift around 600 and duration at 050 at 230-240

houston expert says duration of 224 and 230 at 050 does not mention lift he said the Howard cam above was too hot


in the engine that is not working right has 612 lift at 300-308 duration and duration at 050 is 247 and 255

so what I have coming from howards has a duration lowered of 10 and 12 degrees and I don't know what lift numbers to compare

houston experts wants it decreased another 13 and 13 at 050 from the howard cam making it 23 and 25 lower than my cam that is in there now

Any consensus on who is right?

Will 10.8:1 compression work in Texas heat 105F many days of the summer and for WOT?

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Re: Help needed with BBC Engine

Post by todd glover » Wed Feb 06, 2013 9:18 pm

I don't know anything about Howard cams but have had great luck with comp cams ask for Gary and tell him or someone from comp your combo and get a second opinion from people who grind cams for a living and actually know what their doing jmo good luck

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Re: Help needed with BBC Engine

Post by PAINKILLER » Wed Feb 06, 2013 10:15 pm

mcm4 wrote:update on what engine builder suggests for a cam and said after the mods the compression would be 10.8:1

Howard cam

Cam part number 120266-12
Cam and Lifter Set Part no. 2600-6500
Duration Intake 290
Duration Exhaust 296
Duration at .050" intake 237
exhaust 243
Valve w/1.70 intake .635
Lift Rockers exhaust .641
Lobe Separation Angle 112
Intake Centerline 108
valve in hyd.
Lash ex hyd.
Lopey Idle, Hot Street&Bracket Racing 10.0:1 up CR advised

An online poster to this forum, "torque" says keep lift around 600 and duration at 050 at 230-240

houston expert says duration of 224 and 230 at 050 does not mention lift he said the Howard cam above was too hot


in the engine that is not working right has 612 lift at 300-308 duration and duration at 050 is 247 and 255

so what I have coming from howards has a duration lowered of 10 and 12 degrees and I don't know what lift numbers to compare

houston experts wants it decreased another 13 and 13 at 050 from the howard cam making it 23 and 25 lower than my cam that is in there now

Any consensus on who is right?

Will 10.8:1 compression work in Texas heat 105F many days of the summer and for WOT?
this is the numbers for the howards cam--237-243/ 112 lsa /108/icl --ivo 10.5--ivc 46.5--evo 57.5/evc5.5 this cam will work just not giving you pk tq @5000 rpm duration of a cam only moves your torque up or down a rpm range ---a expert says a cam over 236 duration does not mean more power more duration just moves the torque up or down the rpm range-- if you want a little better make the 46 smaller an the 10 bigger to tighting the icl(106) also (lsa 110 )some keeping the 237 duration(((Don't count on a cam change to yield significant torque output changes. Once cam duration exceeds about 236 degrees (at 0.050), the engine won't make any more peak torque. The larger cams just raise peak torque to a higher point in the rpm range. Here, Westech (of California) tests two Comp mechanical roller cams on an otherwise-identical Ford 393 crate engine))))
Last edited by PAINKILLER on Wed Feb 06, 2013 11:19 pm, edited 1 time in total.
MATTHEW 25:35-45 LS 406 82 4bld WaterWalker falcon 2.68 ox box
LS 427 80 3 Bld WaterWalker Maximus 2.68 ox box :rebel:

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Re: Help needed with BBC Engine

Post by akblackdawg » Wed Feb 06, 2013 11:09 pm

I'm no technical engne expert, so toss my advice if you see fit, What I do see here is a lot of contradictory information and suggestions. If you like the engine builder and he has lots of experience with airboats, stick with his advice. If not, go ahead and talk with lots of "experts" and get ideas, but when you start spending money and making chages, decide who you are going to go with and follow his advice to the letter. I don't see how you can expect to get it running right using a cam that john suggests, and a carb that dick suggests, and a head that harry want's you to go with. Sounds like the ol cluster f*** bto me. Good luck, Bud
:alaska: If you ain't living on the edge, you're taking up to much space.

15x8 Alumatech hull, with enclosed cab, aluminum cage, LS 3, 6.2 aluminum block ffi, 2.7 Balistic Box, sensinich superwide 3 blade. Built for year around riding in Alaska

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Re: Help needed with BBC Engine

Post by PAINKILLER » Wed Feb 06, 2013 11:37 pm

just to show you this is the cam i have in a 406 sbc i had on my boat 240/248 106 lsa /102 icl --- im going with this cam next 236/236 106 lsa /102 icl as you can see one is a high rpm (6500 cam one is not they both will make the same torque the only difference is the bigger one has a wider torque curve the other is narrow they both will make pk torque close to the same rpm the ivc tells you where the motor makes pk tq and where the piston is at the bottom of the stroke to fill the cylinder with air and when it closes the evo tells how far it will carry
MATTHEW 25:35-45 LS 406 82 4bld WaterWalker falcon 2.68 ox box
LS 427 80 3 Bld WaterWalker Maximus 2.68 ox box :rebel:

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Re: Help needed with BBC Engine

Post by PAINKILLER » Wed Feb 06, 2013 11:50 pm

http://www.streetracersonline.com/articles/camshafts/


http://waharleyriders.myfreeforum.org/a ... t_218.html((( this for motorcycles but the same principal applys to car motors also
MATTHEW 25:35-45 LS 406 82 4bld WaterWalker falcon 2.68 ox box
LS 427 80 3 Bld WaterWalker Maximus 2.68 ox box :rebel:

mcm4
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Re: Help needed with BBC Engine

Post by mcm4 » Thu Feb 07, 2013 5:24 pm

UPDATE:

I removed the ProComp single plane intake with rectangular ports and replaced it with the Chevy ZZ Performance dual plane non airgap intake (supposedly the same as the Edelbrock Performer RPM) with oval ports. The rpm increased from 4600-4650 to 5000 rpm. This at least showed that the single plane was hurting.

The plan is to change out the cam and put smaller heads and valves on to see if that will finally bring the engine back to life.

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Re: Help needed with BBC Engine

Post by flying fish » Thu Feb 07, 2013 5:26 pm

mcm4
I hope you get a good read on your plugs before spending money and know the exact culprit before you throw money at this piece.

Know that your tune is spot on. Then, and if your tune is correct, talk to a cam tech about your exact camshaft and talk to a cylinder head Guru like Joe @ AFR for his runner size reccomendation.

I believe in Joe @ AFR. Joe knows airspeed.

Mark @ Bullet cams also knows how to produce airboat torque with his bump sticks.
Nothing against comp. I just done't have any experience with their reccomendations.

These are just ideas. In the end, it is sure your money. :)
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Re: Help needed with BBC Engine

Post by barhopper » Thu Feb 07, 2013 7:02 pm

I would think a 10.8 to 1 compression your going to have to run some good gas to avoid detonation.

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Re: Help needed with BBC Engine

Post by Waterthunder » Thu Feb 07, 2013 7:19 pm

Work with your engine builder they want to improve the way your engine runs they seam like some good guy's I spoke with them on the phone a bit today. They are going to make some cylinder head, intake and cam changes you should be pleased with the results. I have no problem helping if you need any more info.
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Re: Help needed with BBC Engine

Post by PAINKILLER » Thu Feb 07, 2013 7:56 pm

good luck
MATTHEW 25:35-45 LS 406 82 4bld WaterWalker falcon 2.68 ox box
LS 427 80 3 Bld WaterWalker Maximus 2.68 ox box :rebel:

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Help needed with BBC Engine

Post by bbboswell » Thu Feb 07, 2013 10:23 pm

barhopper wrote:I would think a 10.8 to 1 compression your going to have to run some good gas to avoid detonation.
Yep, race gas is in your future!

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Re: Help needed with BBC Engine

Post by akblackdawg » Thu Feb 07, 2013 10:48 pm

Waterthunder wrote:Work with your engine builder they want to improve the way your engine runs they seam like some good guy's I spoke with them on the phone a bit today. They are going to make some cylinder head, intake and cam changes you should be pleased with the results. I have no problem helping if you need any more info.
I would commit to WT's suggestion. You gave the builder your money, you must have trusted his judgement then, WT seems to think the builder will set it up correctly, call and chat with Dave about this before you start spending the big bucks. I think you will come out with what you want then. Bud
:alaska: If you ain't living on the edge, you're taking up to much space.

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mcm4
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Re: Help needed with BBC Engine

Post by mcm4 » Fri Feb 08, 2013 12:17 am

Waterthunder wrote:
Work with your engine builder they want to improve the way your engine runs they seam like some good guy's I spoke with them on the phone a bit today. They are going to make some cylinder head, intake and cam changes you should be pleased with the results. I have no problem helping if you need any more info.

Thank you, I asked them to call you and told them that I was confident that if you gave them advice it would be spot on. As of this evening they told me that they were not going with your recommendations because you were not used to dealing with real big block chevy's. Instead, they are going with the suggestion that they got from Howards cams. I am nervous about is because everyone that I have talked to has said that the cam was way too big for the airboat application ,

as of tonight they want me to install this cam

Cam part number 120266-12
Cam and Lifter Set Part no. 2600-6500
Duration Intake 290
Duration Exhaust 296
Duration at .050" intake 237
exhaust 243
Valve w/1.70 intake .635
Lift Rockers exhaust .641
Lobe Separation Angle 112
Intake Centerline 108
valve in hyd.
Lash ex hyd.
Lopey Idle, Hot Street&Bracket Racing 10.0:1 up CR advised

and a procomp dual plane intake, and dart 1 310 heads with rectangular ports.

Will you tell me what cam , heads and intake that you would suggest? either in this forum or in a pm?

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Re: Help needed with BBC Engine

Post by flying fish » Fri Feb 08, 2013 7:50 am

mcm4

Yep, that is what I would do. Ask Waterthunder for help and then tell him he don't know what he is talking about in a public forum.

You can't even spell airboat motor and trying to tell a GURU he is FOS.

Just the way is see it.- :)
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mcm4
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Re: Help needed with BBC Engine

Post by mcm4 » Fri Feb 08, 2013 10:26 am

flying fish,

I absolutely did not tell dave at water thunder that he did not know what he was talking about, nor did I even think it. I have re-read my post and don't see where you got that.. At any rate, to set the record straight, I did not tell Dave he did not know what he was talking about.

In fact, I, as the owner of a problematic engine combination, asked the engine builder to call Dave at Water Thunder and seek his advice. Dave indicated that if I was patient things would work out. I was told directly that the builder had chosen to ignore Dave's advice, I was not happy that the builder chose to ignore Dave's advice.

What I was seeking was Dave's advice so that I could make sure that any changes that were made to the problematic engine were in line with what Dave suggested.

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Re: update: how long of a crowbar should be used

Post by mcm4 » Tue Feb 26, 2013 10:08 pm

lifterissue2.jpeg
lifterissue2.jpeg (92.13 KiB) Viewed 2392 times
lifterissue.jpeg
lifterissue.jpeg (83.82 KiB) Viewed 2392 times
It took at 24" crowbar to try to budge the Howard lifters from my BBC engine. They had a really hard time removing the lifters from my engine, does anyone know what causes a new engine to have lifters that tight? How much power should that rob from my engine?

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