5.7L power tips

[MGallik]

My boat is a 1996 Chaparral 2130 SS with a 210 hp 5.7L non Vortec Merc w/Alpha. I'm in the process of correcting that......<br /><br />What is the difference between the Chevy Bowtie 14096242 and the Chevy 14097494 intake manifolds?<br /><br />I can't quite make out the difference besides the 242 being called a racing part and the 494 a marine. Both have been called the other in my research, but is there a difference? They've both been compared to the older (pre 87') 14096011<br /><br />What are the differences in the Thunderbolt V ignition modules besides the rev limiters?<br /><br />I'm thinking there may be a fast and slow as well as a few with higher or lower initial advance requirements. An example, I'm pretty sure the Mag has a faster advance rate than the L or LX.<br /><br />How much is the stock roller cam better than the stock flat tappet cam in otherwise identical engines?<br /><br />There are only 2 cams used on SB Chevy marine engines but it seems any engine other than the Mag can have either cam. They just make the needed power through a combination of other parts, IE: ignition, carb, intake, etc....

 

[Don S]

Re: 5.7L power tips

Regarding the Thunderbolt V modules, there are some very minor changes in the advance curves and a few differences between Bravo and Alpha drives.<br />Best bet would be to get Mercruiser manuals 17, 25 and 31 together and compare the charts on the timing and advance characteristics.<br />Also look and compare the other engine specs.

 

[John_S]

Re: 5.7L power tips

1900sx,<br /><br />Not sure from your post, put if you are considering going to vortec heads on your 5.7L, here are the concerns I had, from my research:<br /><br />- Flat top pistons and the vortec heads, push the compression to 10:1. The standard merc vortec engine is 9.3:1, which use a low compression piston. Will probably have to run 93 octane, and possibly cut-back some on advance. <br /><br />- According to another post, the vortec engines have less overall advance. Requires new module or new ignition, if so. Initial timing is 8 degrees on the vortec mercs. <br /><br />The good news, going to vortec heads, 4 brl & intake, and if needed, the roller cam & ignition, will probably push the hp to around 300. Probably don't want any more that that with the alpha. <br /><br />I have not looked at the chevy intakes, only the Edelbrocks. Figured the carb choice would be the Edelbrock marine 600cfm, so why not mate it with the well respected Edelbrock Performer intake.

 

[Bondo]

Re: 5.7L power tips

Well 1900sx, Now we're getting somewhere......... <br />

What is the difference between the Chevy Bowtie 14096242 and the Chevy 14097494 intake manifolds?

I don't have the answer here...... I've never had them side by side......<br />Possible Differences could be,<br />Are the Carb Patterns the Same, Square bore Vs. Spread bore ??<br />Is 1 a High-Rise,+ the other a Low-Rise ??<br />Is 1 a Dual-Plane,+ the other a Single-Plane ???<br />Does the Marine manifold have the Carb mount Angled to compensate for the Tilt of the boat ???<br />Is 1 Cast Iron,+ the other Aluminum ?????<br />

What are the differences in the Thunderbolt V ignition modules besides the rev limiters?

Nothing........<br />The T-Bolt V systems use a "Hunt + Seek" method to "Find" the right advance, at the right RPMs......<br />In other words, the timing is constantly moving up + down to provide the Best timing available..........<br />If you're going to "Hot Rod" a boat equiped with the T-Bolt V, Many folks remove the T-Bolt V module,+ Knock Sensor...... And Replace it with the T-Bolt IV module that best fits the Advance Curve needed for the motor that they've built....<br />There are 7 Different Advance Curves available with the T-Bolt IV modules......<br />Depending on Exactly What you've used to build Your motor, there's probably a module to fit Your motor's profile.......<br />

I'm thinking there may be a fast and slow as well as a few with higher or lower initial advance requirements. An example, I'm pretty sure the Mag has a faster advance rate than the L or LX.

As stated, T-Bolt Vs are all the Same.......<br />Go to the T-Bolt IV module to Tune the Advance Curve..........<br />

How much is the stock roller cam better than the stock flat tappet cam in otherwise identical engines?

Some......<br />Roller Cams allow the Valves to Open much Quicker(and close quicker)...... And, there's Less parasitic drag.....<br />Changing Cams is another Huge Quigmire....<br />BIG Cams Don't work well in a marine motor... They move the HP/Torque Too High up the RPM band to do any good....<br />And, You have to keep the LSA within 109* to 112* to keep a handle on Reversion........<br />Truck/RV/Marine Cams are rather Small Cams.......<br /><br />With all this said,<br />The Best thing you can do to learn What Can be Done,+ Where the Best Bang for the Buck is,<br />Find yourself a copy of Dennis Moore's book, Small-Block Chevy Marine Performance.........<br />It's the Best reference book I've ever run accross.......... <br /><br /><br />Good Luck.....

 

[Bondo]

Re: 5.7L power tips

Looks like John got in over my post......<br />And,<br />I Agree 100%....<br />Vortec Heads are the Best Heads Ever made by Chevy.......<br />He's right about the Small Chambers on these heads...<br />But,<br />New pistons have come onto the market that have a depression in them under the valves.....<br />This lowers the Comp. Ratio,+ allows you to maintain the Required .040 Quench needed to make the Vortecs preform properly...........<br /><br />I'm using them on the Bored + Stroked 327 I'm putting together for My current Project Boat.........<br />383cid of Raw Torque...................

 

[MGallik]

Re: 5.7L power tips

I'm not really considering the Vortec heads as my engine is very tight. I was thinking I can get close enough to 300hp without a total rebuild.<br /><br />I've looked at and used the Performer manifold in the past but am not sure if I want to use it on a marine 5.7L. The Performer is an aluminum low rise with runners and plenum more closely matched to a 5.0L. You can build your own from a stock, cast iron low rise by opening the plenum (like the openings on the Performer) and chamfering the sharp edges into the runners. There are the corrosion issues in salt water too although thats not a factor for me.<br /><br />The Performer 2104 (87 and up) would still be an excellent choice, but I am looking for that extra 5+hp here and there without going to extremes.<br /><br />The 011, 242, and 494 manifolds are all high rise, high performance, dual plenum cast iron manifolds engineered for the 350. I didn't think of the forward tilt of some marine manifolds. There could be something to that but both the 242 and 494 have been called marine at times and racing at another. I'm beginning to think they are exactly the same, just different numbers due to one being Bowtie and the other OEM Chevy. The 011 is the manifold both the others are based on, it's pre "87".<br /><br />I'll probably get the 14097494 intake as I can find it for $160 new, the Performer can be had for right around $100. I may just get the Performer, it would actually be a very good choice if I don't re cam.<br /><br />My cam choice would be dual pattern as I will keep the through prop exhaust and need the extra 6 to 10 degrees of exhaust duration. I like to run wide open for long periods of time so, with the pressed in rocker studs, I don't want much more than .450/.465 lift. The rpm range will remain below 5000 rpm so more than 214/224 degrees of duration at .50 hurts performance. The 109 to 112 lobe centers, of course.<br /><br />I built many small blocks in the 70's and 80's. I'm not fluent in roller cams. I know a roller has 50% to 70% more duration at .100 than a flat tappet cam. I'm still wondering how much more performance I can get from an equal lift/duration roller. Looking at the specs, I suspect the difference between the stock flat tappet and stock roller cam is slight. But, how much? Is it worth the work and 3 times the cost? If it was rebuilt time, most of this would be mute, I'd just go with it. But again, it's a very tight engine. I haven't had the top off yet and don't know what cam is in there. It's a pretty new to me boat and I'm not sure if I have the clearance to pull the cam without pulling or raising the engine. If thats the case, the stocker stays, I'm lazy and don't need the power THAT much. <br /><br />I like the no brainer Thunderbolt V. There's a lot of power tide up in the ignition and a properly chosen IV would let me use most of it. I've already narrowed the IV's down to the V8-24S used in the "94" 350 Mag, A more conservative V8-22A would be fine too and not burn holes in my pistons. But again, I'm lazy. <br /><br />If I can use the V from am MPI 350 Mag, I'd have all the benefits of the V and a 5100 rev limiter. If the Bravo and Alpha equipped engines use different modules, perhaps the Bravo would be more aggressive. That could be good or bad, Hmmmmm.....<br /><br />A bit long winded, so I'll stop this one here.<br /><br />I'm looking to pick up all the power I can with the least expense and work, for now.....

 

[John_S]

Re: 5.7L power tips

1900sx,<br /><br />With just an intake manifold and 4brl change, you are probably looking at 250-260Hp, and thats if you have the roller cam. Parts would probably come to around $500. <br /><br />Quote " I like to run wide open for long periods of time " "as my engine is very tight". <br /><br />We'll after a season of WOT, the engine will probably be loose enough.. ;-)

 

[bomar76]

Re: 5.7L power tips

poof

 

[Buttanic]

Re: 5.7L power tips

I have heard that earlier flat tappet blocks can be easily modified to use stock GM hydralic roller lifters and cams which can be found quite a bit cheaper than aftermarket lifters and cams. There is a person selling the information on Ebay that shows the block modifications and list GM part numbers for the lifters and othet parts as there are two different types and only one is useable for the conversion. I am looking inti this as I am building up a early 5.7.

 

[MGallik]

Re: 5.7L power tips

This article may help. Read it Here.

 

[MGallik]

Re: 5.7L power tips

OK, I was out getting the lay of the land today.<br /><br />I won't have to pull or tip the engine, I have plenty of room to change the cam. I bought the stock roller cam and all the goodies that go with it today. I also picked up a 2104 Performer, It'll do and I paid less than $110 out the door brand new.<br /><br />I'm a Quadrajet guy but the stock carb was a Webber. Looks like I can get a stock bolt on with the right jetting for under $100 off Ebay. What do you guys think?<br /><br />I've never done a boat engine in chassis. I noticed a linkage on the starboard exhaust elbow. Should I take the linkage off or pull the elbow to get at the rocker cover?

 

[John_S]

Re: 5.7L power tips

1900sx,<br /><br />- You paid about what I have been seeing for the 2401. Hard to complain about a new intake for that price ;-) <br /><br />- Not a q-jet fan, but see someone has some marine Q-jets on ebay from 350 crusaders. One day left, and still waiting for a starting bid of $20. Would put in a rebuild kit, before installing. http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&rd=1&item=4507402501&category=31286 <br /><br />- From my inspection of my '97 5.7L, you shouldn't have to pull the elbow. Now, if your exhaust manifolds have never been changed, might want to replace them at this time.<br /><br />- Need a new flame arrestor such that everything will still fit under your engine cowl. Shouldn't be an issue since you got the low rise edelbrock.<br /><br />Did you find a way to determine if you had the roller or flat hyd lifters, without pulling the intake? Merc dealer able to tell from engine serial number? Selec and Merc manuals didn't help me, in this regard.

 

[MGallik]

Re: 5.7L power tips

I pulled a rocker arm and removed a pushrod. The flat tappet cam uses 7.8" pushrods, the roller cam pushrods are .63 shorter. I have a flat tappet cam installed.

 

[Bondo]

Re: 5.7L power tips

I have a flat tappet cam installed.

It seems that You have a pretty good handle on these motors.................<br />You do realize that, You Can't install a Roller Cam in your motor without Machine Work...... Right ????

 

[Buttanic]

Re: 5.7L power tips

Aftermarket roller lifters can be use in early flat tappet blocks without machine work. GM roller lifters cannot be used without machine work to the block. The GM lifters are readly avaible either used or re-built at prices much less than aftermarket lifters which may off set the cost of machine work to the block.

 

[MGallik]

Re: 5.7L power tips

I was under the impression that all blocks later than 87 or so are set up for roller cams.<br /><br />My block is a 1996 and does have the 72 degree center intake manifold bolt holes. <br /><br />It should have the longer tappet bores with the flat tops, the 3 bolt holes for the retainer tray, the shoulder with 2 bolt holes on the front for the cam retainer, and one piece rear main seal.<br /><br />I could be wrong, I'll have to look it up......

 

[MGallik]

Re: 5.7L power tips

Yep, 1987 and newer blocks are all pre machined for factory roller cams.<br /><br />Another bit of interesting trivia. It appears that only the Generation II 4.3L and the 350 Magnum small blocks have roller cams. All other SB Mercruisers are flat tappet.<br /><br />If anyone knows this to be otherwise, please post it, but I just happened across that statement in the Clymer 1995 to 1997 Mercruiser manual. I also found that statement in the 1987 to 1994 manual on page 260.<br /><br />Looks like I'll easily be in the 260+ hp range...

 

[John_S]

Re: 5.7L power tips

1900sx,<br />The selec 1992-2001 manual and merc oem service manuals for 305/350s, do not make that claim. The '97 Merc brochure says that all V6 and V8 engines have roller cams. But a '97 boat could have an older engine. Also, the response I got from this ebay seller: http://cgi.ebay.com/ebaymotors/ws/e...&item=4507943004&rd=1&sspagename=STRK:MEWA:IT was that it came out of a '96 5.7LX. <br />But, like you, don't have any first hand knowledge if it is true or not.

 

[tommays]

Re: 5.7L power tips

Clymer 1995 to 1997 Mercruiser manual. I also found that statement in the 1987 to 1994 manual on page 260.<br /><br />pretty much everthing in the clymer 95-97 manual is bad info notice the gen1 drive pictures which should be gen2 big difference <br /><br />tommays

 

[bluewater19]

Re: 5.7L power tips

Just so you know my 1991 4.3 has a roller cam. I would think that 5.7's would also.