A unique BBC application - Page 3 - Hot Rod Forum : Hotrodders Bulletin Board
Hotrodders.com -- Hot Rod Forum



Register FAQ Search Today's Posts Unanswered Posts Auto Escrow Insurance Auto Loans
Hot Rod Forum : Hotrodders Bulletin Board > Tech Help> Engine
User Name
Password
lost password?   |   register now

Reply
 
LinkBack Thread Tools
  #31 (permalink)  
Old 01-24-2010, 08:52 AM
Rickracer's Avatar
ASE Master Tech, Fabricator
 
Last wiki edit: Taurus 2-speed fan control wiring diagram Last photo:
Join Date: Jan 2010
Location: Kissimmee, Florida
Age: 55
Posts: 936
Wiki Edits: 8

Thanks: 0
Thanked 3 Times in 3 Posts
Big blocks are rather hard on the valve train, especially with the more radical profiles, and the fact that most of today's oil don't have the necessary extreme pressure lubricants for flat tappets, plus the fact that rollers can make SO much more power than flat tappets with similar specs. With that in mind, I'd strongly consider going roller. When I was building/rebuilding a 427 for my Vega, I talked to every major cam manufacturer, and they were ALL trying to talk me into a smaller roller than the flat tappet I was already running. I finally called Herbert Cams and talked to somebody who was speaking my language ( I think it was Doug Herbert, but I'm not sure, he mentioned his Dad, Chet, in our conversation). Their first suggestion was EXACTLY what I had in my own mind that I was looking for, and the price was GREAT. I installed it with a set of used rollers I picked up at the track pretty cheap, and after a few thousand miles, one of the lifters wiped out. Herbert had me send the cam back to them for repair, cost was like $50 or $75, I don't remember now for sure, but when I got it back, it looked like BRAND NEW, I don't know for sure if they fixed it or just sent me another one, but either way, I was so pleased with them that I ordered a new set of rollers, along with matching springs, retainers and locks. Best money I ever spent on that motor, and I highly recommend emailing or better yet, giving them a call, and just see how affordable it would be to go roller.
Reply With Quote Quick reply to this message
Sponsored Links
Advertisement
 
  #32 (permalink)  
Old 01-24-2010, 09:06 AM
Registered User
 
Last photo:
Join Date: Aug 2009
Location: CT/MA
Posts: 30
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
Quote:
Originally Posted by Rickracer
Big blocks are rather hard on the valve train, especially with the more radical profiles, and the fact that most of today's oil don't have the necessary extreme pressure lubricants for flat tappets, plus the fact that rollers can make SO much more power than flat tappets with similar specs. With that in mind, I'd strongly consider going roller. When I was building/rebuilding a 427 for my Vega, I talked to every major cam manufacturer, and they were ALL trying to talk me into a smaller roller than the flat tappet I was already running. I finally called Herbert Cams and talked to somebody who was speaking my language ( I think it was Doug Herbert, but I'm not sure, he mentioned his Dad, Chet, in our conversation). Their first suggestion was EXACTLY what I had in my own mind that I was looking for, and the price was GREAT. I installed it with a set of used rollers I picked up at the track pretty cheap, and after a few thousand miles, one of the lifters wiped out. Herbert had me send the cam back to them for repair, cost was like $50 or $75, I don't remember now for sure, but when I got it back, it looked like BRAND NEW, I don't know for sure if they fixed it or just sent me another one, but either way, I was so pleased with them that I ordered a new set of rollers, along with matching springs, retainers and locks. Best money I ever spent on that motor, and I highly recommend emailing or better yet, giving them a call, and just see how affordable it would be to go roller.
I totally understand the advantages to the rollers and would love to go that way. I may give Herbert a call regardless to see what they can recommend. I should have mentioned though that, to my knowledge, reverse rotation roller cam blanks dont exist for a BBC. A buddy of mine looked into the costs associated with going roller on his RH 454 and it would have been north of $2k. Thats not an option Im considering at this time, as $2k could buy a lot of flat tappets! Im well aware of the issues with modern oils, but Ive had good luck with Valvoline VR1 on my flat tappet Fords to date. If thats one reason I cant go super aggressive, so be it- but a sub 6000 rpm cam shouldnt be TOO crazy, should it?
Reply With Quote Quick reply to this message
  #33 (permalink)  
Old 01-24-2010, 09:09 AM
airboat's Avatar
Registered User
 
Last photo:
Join Date: Mar 2006
Location: Canada
Posts: 286
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
Well I learnt something new Guy! Thanks! LS6 had closed chamber heads though didn't they? I think the LS6 pistons with open chamber heads worked out to about 10/1 anyways!
It takes quite a bit more HP to make these boats go faster!
Reply With Quote Quick reply to this message
  #34 (permalink)  
Old 01-24-2010, 10:03 AM
Rickracer's Avatar
ASE Master Tech, Fabricator
 
Last wiki edit: Taurus 2-speed fan control wiring diagram Last photo:
Join Date: Jan 2010
Location: Kissimmee, Florida
Age: 55
Posts: 936
Wiki Edits: 8

Thanks: 0
Thanked 3 Times in 3 Posts
IIRC, Chet Herbert was the first man to ever build a roller cam, and I think they make their own blanks, so it's probably worth a phone call anyway,
Reply With Quote Quick reply to this message
  #35 (permalink)  
Old 01-24-2010, 12:48 PM
Blazin72's Avatar
You got a leaky spark tube...
 
Last wiki edit: Rearend removal
Last journal entry: General Lee
Last photo:
Join Date: Jul 2005
Location: Union, WA
Age: 32
Posts: 2,868
Wiki Edits: 19

Thanks: 0
Thanked 2 Times in 2 Posts
I just want to let you guys with the 454s in your ski boats know that you are making me jealous. I only have a 250hp 351...
Attached Thumbnails
Click image for larger version

Name:	Boat.jpg
Views:	80
Size:	36.1 KB
ID:	43414   Click image for larger version

Name:	351.jpg
Views:	77
Size:	39.3 KB
ID:	43415  
Reply With Quote Quick reply to this message
  #36 (permalink)  
Old 01-24-2010, 04:03 PM
Guy Hiltz's Avatar
Member
 
Last photo:
Join Date: Sep 2005
Location: Nova Scotia Canada
Posts: 1,004
Wiki Edits: 0

Thanks: 0
Thanked 1 Time in 1 Post
The 1970 LS-6 had closed chamber heads,the 1971 passenger car and later crate engines all used the open chamber variety,although IIRC they all used the same pistons.The car versions had a different intake,it was a low rise version,to provide hood clearance,whereas the crate's came with the high rise model.
Guy
Reply With Quote Quick reply to this message
  #37 (permalink)  
Old 01-25-2010, 10:08 AM
Registered User
 
Last photo:
Join Date: Aug 2009
Location: CT/MA
Posts: 30
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
Blazin, dont knock that 351w! This is my first BBC- all of my other boats have SBF's. Its pretty easy to take that 351w and add about 75hp. The holeshot and midrange power are pretty sweet! This is how I set up my Ski Nautique. The cubes of the BBC allow it to swing a pretty serious prop though...

So no recommendations on a cam? Ive yet to call Herbert- Id like to have a basis for comparison before I do. Here are a few Comp bumpsticks that fall within the RPM ranges Im shooting for. A few are from the Marine Energy Line, the others from the Extreme Energy Line. Should I look at other cams? Would another line serve me better? Comments welcome!

XM270H

XM278H

XM288H

XE268H

XE274H

Again, the set up in question involves a 454ci with 10:1 CR, 990 rectangle port heads and a Performer RPM intake. For comparison purposes, I'm assuming we'll be able to put out hands on a decent flowing set of shorty header style wet exhaust manifolds with 4" outlets (straight piped all the way back). I'm looking for the best powerband in the 2500-5800 RPM range.
Reply With Quote Quick reply to this message
  #38 (permalink)  
Old 01-25-2010, 05:36 PM
Registered User
 
Last photo:
Join Date: Aug 2009
Location: CT/MA
Posts: 30
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
Well, I had a friend of mine plug my numbers into his desktop dyno along with the 990 flow data from Stan Weiss and the cams listed above. Looks like the XM278H and the XE274H work the best. The 274 has about a 10hp and 15ft-lb advantage down low, and the 2 cross paths around 5000rpm. The XE274 peaks at 450hp@5000, but is still making 447hp@5500. The XM278 pulls a little longer and peaks at 455hp@5500.

Both make decent power down low 240/247hp and 520/505 ft-lb at 2500, so I dont think I can go wrong with either. If I had to pick one, Id likely go with the 274 for the slight power advantage everywhere but at my intended WOT, and it doesnt give much up there. Not sure if Ill end up with either- but at least I have a baseline now. Ive had good luck with Cam Research (Ford only) in the past, so Id like to find a similar outfit for the BBC... next step is to call Herbert.

Thanks again for your help, guys!
Reply With Quote Quick reply to this message
  #39 (permalink)  
Old 01-25-2010, 07:05 PM
OLNOLAN's Avatar
Registered User
 
Last photo:
Join Date: Apr 2009
Location: Louisiana
Posts: 1,004
Wiki Edits: 0

Thanks: 209
Thanked 63 Times in 53 Posts
Hey Trb

Hey Man, Sounds like you've got a serious project going on now. I've been to busy too post some info for you. But I have it now. Sounds like you have a 454 that may have been assembled with a grab bag of parts(not uncommon w/marine engine builders). They used whatever GM had available that suited their needs. I don't know if a rebuild is in your plans, but its going to be hard to determine just what you have without a complete teardown. Here is what I found in my books; While the pistons and heads make it appear to be an LS6 engine, the block and intake say it isn't. Your block appears to be a later light duty truck block(14015445)produced~'75-'90. LS6 is 3963569. Your heads are the LS6 real McCoy(6272990)('71 open chamber)(probably old style valve seats,not hardened). The LS6 heads with hardened seats is the 14096188. Your intake is from '68-'69 396/427(3933163). LS6 intake is 3963512. Your pistons are the early closed chamber LS6 design, because they are std. bore, it makes me think it was a purpose built engine. Also drops the compression about a point using the closed chamber piston with open chamber heads. L2349 specs; 10:1 with 119cc heads,.265 dome, 5/64,5/64,3/16 rings,press fit pins,4.25 bore,comp. dist 1.645,658 grams weight, dome volume 30.6, bore clearance .004. As far as the cam is concerned, you may want to pull the original and see whats in there before deciding on where you want to go. From my experiences with boat cams, don't get too greedy with the duration, use generous lift(check piston to valve clearance) Use a wide LSA for idle quality. If it were me, I'd have the original reground to whatever you want, because it gonna be a special order anyway, you'd just as soon save the cost of the reverse cam blank and only pay for a repair/regrind. Hope the info helps. olnolan
Reply With Quote Quick reply to this message
  #40 (permalink)  
Old 01-25-2010, 09:41 PM
bentwings's Avatar
bentwings
 
Last photo:
Join Date: May 2002
Location: St.Paul, Minn
Age: 72
Posts: 1,786
Wiki Edits: 0

Thanks: 0
Thanked 13 Times in 12 Posts
Olnolan already suggested a blower but you have way to much compression for that. Dreaming a little, it would however give you an instant almost 100 hp at the start and probably 150 to 175 top end with no rpm change. You probably aren't going to go 10 mph faster but you will be in the rarified field of fastest Natuque's around. The starting blast would be great. I doubt a person could hang on to the handles on a barefoot start!!!

You could probably put on the larger high pitch prop and go a little faster with no change of your top rpm but you already know that boat drag is exponential.

Reality says that the RPM manifold and about an 800 vacuum sec carb with a yellow spring would be the way to go. In this case the Air Gap would work too as the outside air is usually balmy and your under hood air temp can get pretty high. You won't really need the heat passage.

Keep the rect heads. They are helping you.

I'd just freshen the motor and do your cam what ever you decide. I think you have a pretty good idea of what the boat needs.

Once again I'd suggest an AFR gage to get the tuning exact. You will need the data logging feature too as your runs will be longer. You will need a good Holley book to understand exactly how the carb sections work with each other. You will be amazed how much you get by just getting the carb really tweaked to your operation. You can make adjustable air bleed with brass set screws. See the book.
AFR stuff;
http://www.innovatemotorsports.com/


I'm not a big nitrous fan but for the relatively short bursts and for just wasting fuel and blowing rooster tails and general screwing off it would be hard to beat. Even a 50 or 100 hp shot would be just plain fun. With a boat weight isn't a real big issue so you might even consider getting the whole bottle instead of just a couple 20# ones. Hard to beat $$$ per hp.

Don Hampton blowers is really big in boats if you still want to go after a blower. I think you can just flip the front cover around on a 6-71 and drive from the right side instead of the left for rev rotation. The rotors would still turn the same direction. Install the idler system on the left side of the motor. I haven't done this however.

Last edited by bentwings; 01-25-2010 at 09:51 PM.
Reply With Quote Quick reply to this message
  #41 (permalink)  
Old 01-26-2010, 05:45 AM
345 desoto's Avatar
Registered User
 
Last photo:
Join Date: Sep 2006
Location: Skaneateles, NY Summer/Port St.Lucie, FL Winter
Age: 70
Posts: 416
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
A couple of things to consider...the first of which is to remedy the soggy foam. That in itself will get you a NOTICEABLE improvement in perceived power. We had a 21' Thunderbird Formula with a soggy deck. Tore it out and replaced it...WOW, what a difference. Second is hull design. Adding a bunch more speed on a hull not designed for it MIGHT lead to stability issues. Trim Tabs on a shaft drive will help your hole shot, but they won't get any more of the wetted surface out of the water when the hull is up on plane. Are you going to use the boat for skiing? If so, replacing the soaked foam will get you into great skiing range....without spending unnecessary money on the engine. If it ain't broke, don't fix it...however, you MIGHT consider a roller cam/lifters. You'll get more of what you're looking for with a roller. As far as top end, I guess you don't HAVE to run it full (6,500 RPM) throttle if stability becomes an issue...

Last edited by 345 desoto; 01-26-2010 at 05:59 AM.
Reply With Quote Quick reply to this message
  #42 (permalink)  
Old 01-26-2010, 08:11 AM
Registered User
 
Last photo:
Join Date: Aug 2009
Location: CT/MA
Posts: 30
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
desoto, the soggy foam is being remedied... its out! We're about to start rebuilding the structure (all composite, no foam). It should be a tad lighter than it was from the factory, not to mention all the water weight the foam was holding last year. Im hopeful we'll see a noticeable improvement in holeshot just with the weight loss... any top speed gains will be a bonus. I have to say that the boat didnt slow down much, even with a boat full of people!







Yes, we're planning to use the boat to ski- well, barefoot, actually. The top speed is a bonus, as we dont 'foot over 45mph. Being able to pull multiple barefooters comfortably is a requirement, though.

Bentwings, great tips- thanks. Yes, Id love to install an A/F meter to tune this thing... but it does get a little tricky with the wet exhaust. My buddy had a piece machined with a port that installed between the manifold and riser, so that may be something I can emulate, depending on what type of manifolds I end up with. Until then, Ill have to rely on plug chopping... I did convert the secondaries to a block with replaceable jets in anticipation of dialing it in though.

A blower would be very cool if I could make it work with the reverse rotation- that may something Ill be researching in the future. Its out of the budget this year, though. Ive heard nitrous is an easy way to make gains, but Im not crazy about the idea. All motor would be a cooler way to go, IMHO. Everything we've discovered about the motor so far indicates that its too fresh to justify tearing into- but eventually Id love to put together a 496 stroker for it. This year, Im just trying to optimize what Ive got with a few select parts!

Olnolan, great feedback- thank you! Are you suggesting that my CR is about 10:1 like I think, or is it lower? The plan now is to at least measure the valve lift on the cam and proceed from there. If I were to pull it, would a shop be able to measure it up and tell me what Ive got? It sure would be nice to have a baseline. A regrind is certainly an option, but Comp says they have the reverse rotation blanks and can custom grind whatever I want for ~$300... so thats my back up plan. Id prefer to find a smaller outfit that really knows BBC's and how to make them work in a boat application like mine.

Many thanks to all!

Last edited by TRBenj; 01-26-2010 at 08:17 AM.
Reply With Quote Quick reply to this message
  #43 (permalink)  
Old 01-26-2010, 08:43 AM
OLNOLAN's Avatar
Registered User
 
Last photo:
Join Date: Apr 2009
Location: Louisiana
Posts: 1,004
Wiki Edits: 0

Thanks: 209
Thanked 63 Times in 53 Posts
Yep

Yep, Its zackly what you thought according to my piston book,says 9.99:1.
It should go a bit quicker without the extra baggage. Properly chosen exhaust and camshaft should wake her up. Something gives me a feeling that its got a tiny cam in it, does it have any lope in the idle? For best performance the exhaust should push out water for the shortest distance possible with the least restriction. All the big offshore powerboats use real short tailpipes for this reason. 10:1 may need premium w/octane booster added. If you indeed have the old style valve seats, lead substitute additive may be needed also. As far as propping goes, you understand that pretty good already. The only difference in your prop theory and mine is the fact sterndrives are limited to 5000rpms input or they go caa-boom. With your 1:1 box that can handle about anything you throw at it, your only limit is when your engine goes caa-boom. I have learned a bunch of top speed tricks from an old outboard drag guy and a few more from my buddy that is a propeller specialist, but I'll save them until you get it going again. olnolan

oh, yep, any automotive machine shop should be able to set the cam up in v-blocks, check and chart it for duration and lift.

Last edited by OLNOLAN; 01-26-2010 at 08:50 AM. Reason: added info
Reply With Quote Quick reply to this message
  #44 (permalink)  
Old 01-26-2010, 09:12 AM
Registered User
 
Last photo:
Join Date: Aug 2009
Location: CT/MA
Posts: 30
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
10:1, good good. That means my desktop dyno numbers were based on the right info. From what Ive read on here, the BBC needs some compression to respond to a cam, so while its definitely on the high side, thats not all bad. We ran 93 octane all summer and it wasnt pinging with the new HEI (DUI) distributor. Total timing was right around 36-37 degrees (initial was 12 or so).

Im not a believer in "lead substitute"... I think its a marketing scheme. Im running non-leaded gas on all of my boats, even the old ones (1971) that supposedly require the lead. Im putting the money Im saving on the substitute away to pay for a valve job someday.

Im guessing it has a tiny cam in it too. We didnt gain any top speed with the smaller prop that let it turn up to 5200 (the other one only turned 4900), so it wasnt making any more power higher in the RPM band. The stock 330hp cam would have peaked around 4400-4500 with the peanut ports- maybe a bit higher with the 990's... so a cam making power up to 5500 should hopefully wake this thing up. I cant say that it had any lope at idle- it was pretty smooth, idled down to 600-700 rpm just fine and started very easily. My fingers are crossed that it still has the original cam in it- that would give us a good opportunity for more easy power! Great info on having a machine shop measure the cam... Ill add that to the list of things to do ASAP.

We cant change the length of the exhaust, obviously, but we're eliminating the mufflers and going from 3" hose to 4". Even if we go with some classic aluminum log manifolds, they should flow better than the cast iron pyramids... plus save 50-80 lbs. True headers would be nice and we're keeping our eyes open, but they may not be in the budget.

Youre correct- the Borg Warner 72C is a stout tranny and will handle all the power we can throw at it. It doesnt care how many RPM's we turn either- it would see more strain if we tried to turn a steeper prop... which we're not.

Feel free to clue me on on any speed secrets you know- not all will translate to a direct drive inboard but some may help. We're still using the boat to ski, so prop options are limited- but any info helps! Luckily the hull seems to get up out of the water pretty nice for a ski boat, which is certainly helping us. My other Nautique wont even break 50mph, even with a 350hp 351w pushing it! A few guys I run with have tweaked their hulls to get the bow up more at speed- this involves grinding the "hook" out of the last few feet of the hull... but those were flat bottomed boats. Not sure how that would affect this v-hull. The flat bottomed boats tend to run faster with a bit more weight in the back seat (people, lead, coolers, etc), but this boat didnt respond in the same way. Im still learning!
Reply With Quote Quick reply to this message
  #45 (permalink)  
Old 01-26-2010, 10:07 AM
bentwings's Avatar
bentwings
 
Last photo:
Join Date: May 2002
Location: St.Paul, Minn
Age: 72
Posts: 1,786
Wiki Edits: 0

Thanks: 0
Thanked 13 Times in 12 Posts
I forgot about the wet manifolds but doesn't the water that cools the manifold get dumped into the pipes a ways aft of the manifolds. I had a humps on my my old boat and the water entered the pipes aft of that then out the transom. If so you could inatall the 02 sensor between the manifold and the humps. It can not get wet however. You could even run a temporary one into a check port for it then remove it for running after you get it set up.
Reply With Quote Quick reply to this message

Recent Engine posts with photos

Quick Reply
Message:
Options

Register Now

In order to be able to post messages on the Hot Rod Forum : Hotrodders Bulletin Board forums, you must first register.
Please enter your desired user name (usually not your first and last name), your email address and other required details in the form below.
User Name:
If you do not want to register, fill this field only and the name will be used as user name for your post.
Password
Please enter a password for your user account. Note that passwords are case-sensitive.
Password:
Confirm Password:
Email Address
Please enter a valid email address for yourself.
Email Address:

Log-in

Human Verification

In order to verify that you are a human and not a spam bot, please enter the answer into the following box below based on the instructions contained in the graphic.




Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools

Posting Rules
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On


Similar Threads
Thread Thread Starter Forum Replies Last Post
bbc what gears to run.? chevelle4542speed Engine 5 12-07-2006 05:47 PM
96 to 00 BBC Question Mustangsaly Engine 6 02-20-2006 07:03 PM
BBC Big Block Questions Mustangsaly Engine 6 01-21-2006 06:59 PM


All times are GMT -6. The time now is 02:04 AM.


Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2014, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0 PL2
Copyright Hotrodders.com 1999 - 2012. All Rights Reserved.