454mag top end rebuild
 

Hey All,

As the title says redoing top end in my 89 Scarab III with 454mags, 460hrs. Currently, the rig tops out at 54 at around 4500rpm. Cruises at around 35mph at 3600rpm. This is gps on speedview phone app so not too sure about accuracy. What I know for sure are my compression numbers:

Starboard: Port:
1 145 2 140 1 135 2 140
3 140 4 123 3 130 4 145
5 143 6 145 5 135 6 89
7 139 8 148 7 133 8 139

If all goes as plan I should have my wood gantry/hoist built this weekend and motors pulled by next weekend. I will be working with Marine Kinetics on the cam. My pockets aren't deep so I'm all over the net looking for those sweet deals and then researching to see if it will work. I was going to leave stock heads and redo valves and worn components but came across what I think is a good deal on some Brodix heads.

BB2 plus with the 312cc intake runner and 119cc chamber bare heads for $1170 a pair. I know this is another rect port head and it's not quite the most optimal on 454 but it's got to be better than my current heads, right? And, these can be milled to increase the static comp.

The other more optimal set are the Brodix Race Rite Ovals. I found these for $1000 a pair but they are Brodix's "overstock" heads with 127cc chambers.(they messed up when casting these and pushed the seats too far into the chamber). I called Brodix and they said the most these can be milled would be to 119cc.

I can go on and on about all this but would like to stop here for now and ask your opinion on these heads and what would be the best approach on THESE heads and my stockers. The performance gains I'm looking for is overall higher mph at cruising and WOT RPM's. I don't pull anyone with this boat just cruise, anchor and beach.

FYI, through the help of this site and a few others I found enough knowledge to assemble a work of art a few years back, a stroked 496 that dynoed at 555hp 6000rpm and 578tq at 4000rpm

Thank you all in advance for reading this long winded intro and for your consideration.

Jeysson

I will be upgrading my account so I can add pics to show the dyno from previous build and progress of current build. Wait till you see the hoist I'm building to pull the motors.

Straight to the point:

Will Brodix BB2 plus heads with rect port 312 intake runner be a good upgrade to a 454mag?

Personally with a build 600hp and below I've never understood why guys (not you) still think rectangle ports are superior. Plenty of dyno data shows that a good flowing oval to be a better choice up to around the 600hp level. And they will be much more responsive in a marine application. I went with Dart Pro 1 275cc alum heads which I'm having milled for more compression. With my combo it should be knocking on 600hp but in a 496 stroker. I would think your smaller motors would love a high flow oval ie AFR 265, DART 275....

I'm no expert, and I think you are wise to have bob M do the cam. Why not just run this by him. Even if the AFR heads are too much (he loves the AFR stuff), you can find deals on other oval port heads on eBay and such. If iron is a consideration, the DART 308 Iron Eagles might deserve some consideration. 1,000 per bare set on eBay. Kind of a oval/rect hybrid head. Less optimal than a true oval, but with higher velocity ports than the larger rect ports, and a .300 raised exhaust port.

Thanks for the info Borgie. I think I just found some bare Race Rites for the right price. Just waiting to hear back from BM on the oval or the rect port. Rect port is a 294 runner and oval a 270.

Heres a video of my buddy's Scarab III that had 454 Mags originally. TRS drives. I helped him do some engine mods. Boat runs mid 60's on GPS. http://www.youtube.com/watch?v=X7olqjFN8p8 Engines stock mag bottom Ends.
Stellings headers
Crane 134561 Flat Tappet cams
Roller Rockers
GM Rect port heads, stock 454 mag heads rebuilds on them.
Professional products Hurricane single plane intake manifolds
Holley 750CFM Double pumper
Stock Merc Ignition.

Boat has a very distinctive idle. He's very happy with the setup. He's turning 22p 4 blade Hydromotives to around 5300 I believe.

Take a look at this article. The cam really could be used in many marine apps from the look of its specs. But more importantly you will notice how easily they made close to 600hp with ovals. Put more cam in it and obviously 600+ is more than doable.


http://www.carcraft.com/techarticles...s/viewall.html

Yes, they are using a 496, but even a 468 with ovals would knock down some quite impressive numbers.

MILD THUNDER: That's a nice setup you posted as well! Very cool boat. I do have a question though. Why did he use a single plane intake? Seems like boats that run under 6,000 rpm would pretty much always do better with a RPM air gap. With the singles giving up quite a bit of low end torque and drive ability, and only benefiting a few hp up top. Just curious.

I would go with the stock rect port heads you already have and spend the money saved on top quality valves and an all roller valve train. For cam I run the 139011 crane in my 454s and have been very pleased.

Mainly for appearance. The hurricane intake is a copy of the dart HP500 intake. We weren't gonna be pulling skiers with it , so we didn't care if the engine gave up a little low end torque.

That article has some good info. Realistically , a 500 inch big block with 10.5:1 compression, should make those numbers with a good set of aftermarket heads. I'd like to see them test a 308 iron eagle against the other heads.

Ah I see! They actually did test the Dart 308 heads and they produced less hp. I need to locate the article. Before I bought my 275 oval pro 1's I spoke to a engineer at DART at length. He said that the 308 head are awesome but that the 275 outflow them and the aluminum composition obviously allows more compression to be run. That and the 275 head makes more torque sooner. I was seriously considering iron eagle 308's until I saw the dyno pulls and spoke directly to dart. Don't get me wrong the 308's are a definite step up from the 088's, but fall short of the PRO 1's.

Some folks won't accept the fact that oval ports are better under a certain HP. But results don't lie. The 088 rect port head is ok, and I agree it should be considered for a build that's restricted budget wise, but it's proven that the AFR 265 and DART 275 flat out spank this head into the gutter HP wise. Some folks don't like the fact that their big port heads are getting trounced by high velocity small ovals. To each their own I guess.

One thing to remember regarding the above article is that this 496 tested was using a pretty mild camshaft: 224/232 DUR/ 555/565 LFT 112lsa

Add a larger cam into the mix and the full potential of these heads will be seen!

MT - good running boat your buddy has in that video. I miss that skyline. I grew up in NW Indiana just 55mi from downtown CHI. Live in Vegas now but with I could enjoy Lake michigan in my boat.

Borgie - thanks for that article. Yea, I've been looking everywhere for info on this. If the change happens it WILL be the Brodix Race Rites. I'm trying to find some comparative data on the rect/oval port race rites. They both flow about the same but different shape so........what's the deal here? I'm almost positive I wouldn't even feel the difference between the two but I figured if I'm buying new might as well try to find the best combo I can afford. Also, switching over to oval would require me to switch intakes now also instead of later. A necessary evil ($$) I suppose if I want the best combo. Already picked up some blue holley 800's so I'll need an adapter for the time being if I keep the stock intake.

BT - Thanks for the input. That is still a possibility. I was already set on new valves and definitely replacing worn parts, i.e. springs, rods....I figured if I can get my heads back to a stock quality standard and upgrade the valve train components I would be happy. I don't pull any skiers/tubes and I don't race anyone and don't gun it out of the whole but I do like to open it up while cruising. She comes on plane pretty easy as is. I already spoke to RM Builder about some quality solid cams and about the added expense but less headache roller conversion. I put new heads out of the equation until I came across these bare Brodix heads and for what they can be had for. I like the idea of bumping up my compression and still running 87 gas. Plus new tech and lighter ass end. Dumping the stock exhaust for some 496 aluminum mani's and al heads would yield around 375lbs savings.

I've spent all weekend prepping the boat for motor removal and building my gynormous gantry. Just finished it up tonight so motors should be coming out next weekend. 11W x 13' 4" high at it's lowest point. That gives me room for the chain hoist and clearance out of the bilge. I already listed my current heads on local CL so if any takers want them then I'll get new heads. If not I'll reassess once I remove them and check them out.


Thank you all for your comments.

If its an aluminum magnum intake, you don't need an adapter for the Holley's. They have holes tapped for square bore and spreadbore carbs.

Griff - yes, it is the stock aluminum and I see the extra holes. Won't I need some sort of adapter for a square carb to spread intake?

I'm not debating you on those heads working nicely. I just always try to figure in cost vs gain. Without a doubt, the GM rect ports suck. For starters, the huge intake runner is vastly oversized, for a 454 especially. What they lack in intake port velocity, they definitely do not make up for it on the exhaust side. The exhaust ports flow is like a small block chevy head. Its what mercury had to work with though at the time. I definitely recommend someone wanting to upgrade, to go to a newer aftermarket head. For the cost, its hard to beat a Dart 308 Iron Eagle as a replacement, as they will out perform the GM's by far, still retain the durability of Cast iron as far as marine, and can be had ready to bolt on for under 2k a pair.

Which brings up the cost again. 500 bucks each for the race rite bare castings is a good price. However, keep in mind what you will have in these heads, by the time they are fully dressed and ready to bolt on. Stainless intake valves, extreme duty Inconel ex valves, springs, retainers, machine work, etc. It adds up quickly.

Another nice option for a 454 Mag Upgrade on a budget, is the edelbrock 290cc ovals. With the 110CC chamber, it will yield around 9.3:1 using the stock 454 mag bottom end. Usually you can find them for around 900 each, ready to go just add your springs. Now your getting into a price point that doesn't hugely exceed rebuilding the stock GM heads.

At the end of the day, its all about the budget for most. A pair of stock 454 mags, are gonna need pretty much the following parts, not just heads, for a nice upgrade

Exhaust manifolds. Stock irons have to go.

Intake manifold

Carb

Roller rocker arms

Cam and lifters.

Gaskets, etc

A lot really depends on how much power you want to make, and how fast you want to go. Hands down the biggest improvement on those engines, is a cam swap and exhaust. My buddy's scarab in the above video, gained a bunch just by ditching the stock exhaust, larger cams, roller rockers.

I redid my 454's two years ago. I am running Dart 308 Race series aluminum heads with some port work, a 236/245 114 LSA hyd roller .630 lift, B&M 420 blowers making 6psi, no chillers. They made 804HP at 6000RPM and been running great for 2 seasons. My boat with stock 454 Mags, would run about 65mph. It runs upper 80's now and still need to play with props.

Engine masters did a build up related to what we are talking about. They took a 454HO crate engine, and did a top end upgrade. In stock form, the crate engine is similar to a 454 mag as far as bottom ends. Forged components with mini dome pistons. This engine was actually going in a Jet boat.

Baseline engine.
Stock GM Iron rect port heads.
Edelbrock Performer Dual plane
Holley 850 carb
211/234 HR Cam .510/.540
8.75:1

New setup
Dart pro 1 310 Rectangle ports
Dart Single Plane intake
Holley 850
236/242 .521/.540 HR cam
8.55:1

By adding the darts, they lost a little compression due to the larger chambers.

Baseline engine made 434HP at 5200RPM, 486FT lbs at 3800. Peak numbers.

Modified Version made 524HP at 5600RPM, and 518FT lbs at 5000RPM.

You might say, well, yes, but what about the low speed numbers????

At 3200RPM stock, 464 FTlbs. Modified 472 FT lbs. At 5200 where the stock engine peaked at 434HP, the modified version was making 509HP.

A 8.5:1 Aluminum headed engine should be able to run on 87 octane all day long. 500+ft lbs of torque, and 525HP is nothing to sneeze at considering the compression ratio, 454CI, and RPM band.

The other engine article posted was comparing a 496CI 10:5:1 setup using good flowing oval port heads. Of course that's a stump puller combo. The oval Brodix on that 10.5:1 were making 597HP at 5600. 73HP more than the above engine with almost 2 full points less compression, and 42 less cubic inches. No magic there.

A 10.5:1 marine engine in a heavy old scarab, using a somewhat small camshaft in quest for peak torque down low, is a recipe for detonation on pump gas. Its unrealistic. And, the camshaft part # in that article is for a ford small block, so who knows what it really had for a cam.

Oval port heads can work well, especially in a street engine, where low rpm stump pulling power is needed. They definitely have their place. Nice thing about the 310 Darts talked about here, is that if the 454 mag owner bought them, ran them, and decided a couple years from now to build some 502/540 Short blocks, he can reuse those heads. I know of several marine 540CI builds making 700+ with them. Not gonna happen with some 265 ovals.

For the record the DART 275 ovals made 595hp with 9.8:1 compression, not 10.5:1. 9.8:1 is actually a perfect range for a aluminum headed marine performance engine. I think we are losing sight of what the original poster is looking for power wise. The smaller oval heads are better for a 600hp and below engine in a boat. That's just impossible to argue. From your above post it sounds to me like you are saying low end torque is irrelevant in a performance marine application. I would much rather have a 496 which makes more low end torque sooner than a 496 that makes it later both being 600hp engines.

Truth be told I think the ovals from 265-290 are perfect for what the OP wants. He never stated he wanted 700hp or did I miss that? I guess I'm just perplexed by some of you that think the oval headed engine will be somehow much slower than a compatible rectangle port aftermarket head. But I guess AFR 265's are fancy peanut ports and a 600hp marine engine featuring them is only good for pulling skiers........

Dude chill out. Nobody's picking on your oval port heads.

You have a raging boner over a 496 that made 600hp with 10:1 and aftermarket heads in some magazine article with a unknown camshaft.

I've had buddy's bolt box stock edelbrock marine rect ports on a 502 with same compression and a Hyd roller make the same numbers.

There's a lot more to putting a solid marine engine together than flow numbers or intake port shape/size. I'm not saying the rectangles are superior to the ovals. But there's more to a package than that. Cam size, bore size, valve sizes, piston design, chamber design etc. plus a engine on billy bobs dyno vs a good dyno can tell a different story

I am not defending "my heads" and im far from being pissed off on a boat forum by some guy i really could give two s**ts about. I would venture to say that the small oval has proven itself beyond the flow numbers and different magic dynos and I'm speaking in marine applications not your cousins 70 Chevelle. I realize it's the combo and the sum of the parts, but it all is made or broken power wise in the heads. If he wanted to make above 600hp sure I agree rect is the way.

And I'm sure your buddy's make this power all day long blaaaah. All talk

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Whoa guys, getting a little heated in here. This should calm everyone down a bit, an actual dyno sheet from my previous build a few years back.

MKIV block 498 stroker
Ultradyne 230 intake 238 exhaust, 601 lift with 112 lobe sep
Heads were gm performance aluminum with Baker stamped on them. My machine guy said they looked like ovals that were hogged to be rect. there was a steep ramp at the bottom of each runner. Cam and heads were bought used from a gentleman who said they came out of his marine 502. I used flat top pistons and heads were milled to achieve 9.8 static comp. It was dynoed on 87 gas. Almost forgot, RPM airgap and BG Demon 850 marine carb.

Never quite got it tuned in on the water before selling the whole thing due to getting my scarab. This motor was in a 89 Maxum 23 open bow that originally had stock 454 with B1. It ran great but I just couldn't leave well enough alone and built the new motor and cannabalized the stocker for accessories. Ended selling the stocker for $400 just to get it out of the garage.

I agree with you that the ovals you mentioned would work great on a 454 mag. But , I wouldn't discount a small rectangular port either. I'm not suggesting bolting on a pair of 360 darts on a 454. Something in the 300-310cc would work just fine also, and can be had at a reasonable price.

You were raving about how those aftermarket ovals will stomp a GM rect port head on a build like this, and they would. But it's not the port shape size , as much as its the crappy flowing GM port designs

"A raging boner"

LMAO!!!!!

good head will cause a raging boner!

Lets try to get back on track here. Turned into a which head is best, who knows engines and who doesn't, etc.

Lets talk about the 454 Mag for a minute. Its weak points are

Flat tappet sissy cams

GM 1960's castings for heads. They can work depending on your goals, but any good aftermarket head would be a improvement.

Exhaust Manifolds. They suck if trying to make anything over 375-400HP.

Intake Manifolds. They are decent, the old days cutting down the center divider and adding a 1" spacer helped them out.

Quadrajet carb. Great carb, but if serious about power, they can be limited, and tuning can be a little tougher than a holley.

Rocker arms. Stamped steel style.

Some of the strong points are
4 bolt mains
Forged Cranks
7/16 Dimple rods
Forged pistons

Now, I know your not at sea level, so that will change things. But, generally speaking, to get a Scarab III to run mid to upper 60's, is gonna take around 500HP per side. Mid to upper 70's, around 600HP per Side. In the 80's, 650-700HP per side. Once you establish what you'd be happy with as far as speed/power, then maybe we can start spending your money. If you'd be happy with 75-100HP increase per engine, there's really no reason to go spending 10k dollars worth of fancy aluminum heads, exhaust, roller cams, and other goodies.

The 365HP mags respond well to a cam swap, exhaust upgrade, roller rockers, intake and carb. The old 420HP, 440HP, and 460HP 454 based mercury engines used basically a 365HP bottom end and heads. They got better exhaust, better valvetrains, intakes and carbs. If your gonna be using the 496 exhaust manifolds, I'd be careful with cam choice, from a reversion standpoint. They are a improvement over the old iron manifolds, but they aren't long riser'ed dry pipes.

In my opinion, what makes someone a good engine builder, is knowing combinations, and what each combination will produce. To be able to meet a customers budget, and most importantly, deliver a reliable product. HP doesn't mean squat if it doesn't stay together. In todays world, you can almost make 600HP from a big block chevy by accident. Making a 600HP marine engine that lives takes a little knowledge. I'm not gonna keep going back and forth on the whole oval vs rect port thing. I posted up a video of a buddy's old scarab III's setup, and Borgie seems to question the choice of parts used. Could he have made more power with different parts, surely. In that 10k lb scarab, 20HP doesn't mean $hit. He liked the look of the single plane intake, so we went with them. he could care less if the boat goes 65 or 65.8mph. But I can tell you this, that kid runs the ****T out of that boat every single weekend. Theres no cruising, its WFO everywhere he goes. Theres no issues whatsoever with the engines. A blown TRS, sure. But the engines run great, 89 octane.

For the record I never disagreed with "parts" used in the scarab III build, only the intake. And you bring up several good points regarding the 454 mags strengths and weaknesses, however I do disagree that marine engine building is somehow black magic. Certain things need to be addressed differently in a marine engine, yes, but building a reliable marine motor is not reserved for only the few top builders out there. Many of use have the skills to do this kind of thing. After all the basic rules are satisfied, good quality machining and attention to detail make or break a hp marine engine. I for one do my own work besides the machining.

And for the sake of clarification I realize valvetrain is one of the most important aspects in any performance marine application, especially the big block Chevrolet. Takes good roller lifters, best springs you can reasonably afford, best pushrods, high quality retainers and locks, marine endurance roller rockers.... And blue printing everything. Inconel valves are a must on the exhaust side etc.... However you don't need to be an engineer or a veteran engine builder to assemble a reliable setup. I've seek plenty of " the best of the best" built by "Jesus himself" let go. S**t happens sometimes. But if it were a shade tree guy doing it, the failure resulted from his lack of marine building knowledge, all things being equal. Makes me laugh how people here eat this s**t up regularly.

Well, I have plenty of time to think of what will be done. Pulling the motors this weekend and opening them up will give me a better picture of what's needed. Plus, I just spent quite a bit on bigger oil coolers, carbs and exhaust so need to recoup some $$. This will be an ongoing project with end date around the March-April 2014. For now, after motors are pulled I'll focus on redoing my bilge, painting outdrives and odds and ends while still deciding on a package for the build.

While I do appreciate all of the head combo suggestions if I do change heads they will be the Brodix aluminum heads. I found them to be the most affordable for a set of bare heads. Aside from machining and specific clearance checks that I may not have the proper tools for I plan on doing a lot of the assembly myself this time around. New valves will be on order no matter what head is used so I consider them a sunk cost as is. The springs come with the cam and the rest of the hardware is just that, hardware. Dolar for dolar a set of bare aluminum aftermarket heads for around 1200 is pretty good when doing alot of the work yourself.

No, it bolts right up and works fine. The same magnum intake was used for QJet carbs(spreadbore) and Weber carbs(squarebore) straight from Merc.
I used a Holley 800 on a mildly hopped up 454mag with no problems.

Good to go, thank you.

Motors are out of the boat and in the garage. Going to do leakdown tests tonight on all cylinders to have a good idea across the board. Think I may have a buyer for a set of heads already. Check out the pics below. Pulling the motors was easy, set up and prepping boat for removal was the hard part.



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Is that a wooden gantry? 6x6?

3 6x6x14 planks make each column. the center board is cut down to fit a 2x8x12 which is the cross member. Everything else are 2x6's. All through bolted. I already recouped money spent on building this by removing the motors myself. Every place I called around here wanted $200-500 for ONLY removing the motors and this is after explaining to them that all mounts would be undone and ready to go. Rediculous!

Oh my. A single 2x8 over a 12ft span would scare me lifting the engines. Looks like she was flexing a bit in the pic, but apparently it worked for ya!

I noticed that also in the pics but not sure if that is due to the photo lense on my phone or actual flex. I tell myself it's my phone. The angled supports at the top are the same as the columns, three boards with the middle one cut shorter so the crossmember rests on it. It's pretty stout. Even with the wrenching of the chain hoist it didn't move much.

Leakdown test completed tonight. This test wasn't as straight forward as I thought it was going to be. On a few cylinders I was able to hear/feel air coming out of more that one area with one greater than the other. I listed the area with the greater leakage first in the results below. Where I listed crank as the area of leakage I felt the air escaping out of the breather holes in the valve covers, someone please let me know if that method is wrong for detecting leak from crankcase. Also, on stb motor I already began disassembly so my distributor was loose and I could see bubbles at the base where I labeled crank as the leakage.

Well, if my methods are correct it looks like my worst fears with these motors came true. I'm going to have to get into the bottom end; I was hoping for just a top end rebuild.

Port
1. 22% intake / crank
3. 50% exhaust / crank
5. 40% crank / exhaust
7. 30% exhaust
2. 15% crank
4. 27% crank
6. 85% intake / crank(small)
8. 33% crank / exhaust

Stb
1. 18% crank / exhaust
3. 10% crank
5. 22% crank
7. 30% crank
2. 45% crank
4. 80% intake / crank
6. 18% crank / exhaust
8. 25% crank

Stroking to 496 would be ideal but the sudden cost of all new rotating assemblies is too much right now. Thinking of maybe 468. The added cost of only pistons and machine work is more doable. I will be performing the assembly myself.

Do a search on OSO about bore notching a 454. It seems to help out a bunch on a stock block and also I would think on a 468". A couple of years ago the were a couple of threads about it.

When doing your leakdown test, get yourself a rubber mallet. When you hear the air blowing out the exhaust port, or intake port, give the valve stem a sharp tap with the hammer. Many times the valves get a chunk of carbon and wont seal all the way.

Either way, you're this far into it. Engines are out. I wouldn't bore anything unless it needs it. And if it needs a bore, I'd go .030 over. The extra couple HP you'll gain going from a 4.280 bore, to a 4.310 bore, really isn't worth it. Keep the cylinder walls thicker, and have more room for another bore if something happens.

Your stock cranks are good pieces. The stock rods are too. But, something to think about, is getting NEW rods. Today, you can get a set of H beam rods, for not a whole lot more than it will cost to recondition your old rods, install new arp bolts, disassemble, etc. You might have 200+ dollars into the original rods, where a new set of H beams can be had for 200 more. Plus, the old GM Rods will bring 75 bucks or so on ebay if they aren't damaged. The H beam is a superior rod, with floating pins.

Pistons, my buddy is running the SpeedPro replacement forged ones like your engines currently have. Decently priced, and have the coating on the skirts.

Since your budget is tight, theres nothing really wrong with keeping the flat tappet cam, just going a bit larger than stock. I also recommend the crower cam saver lifters. They have a groove cut into the body, which helps get a little more oil on the lobes. The stock intake and carb isn't really hurting power at that level.

Do a nice rebuild, with slightly hotter cam, better breathing exhaust, and you'll be good for a while.

I agree with the above, however I would run a scat 4340 I beam, bushed for floating pins, with ARP2000 7/16 bolts. Rated to 900hp, and you can get them new direct from SCAT for $381.00. They are called scat pro comp series. One of the best I beam designs out there. I am personally not a fan of reusing stock rods due not only to the economics, but the forgings are inferior/old technology vs the current 4340 offerings, and the rods have been fatigued from use. Not worth the risk IMO.

Are you thinking about Brodix heads still?

Here are the SCAT rods

http://i1140.photobucket.com/albums/...ps5e6f23b8.jpg

http://i1140.photobucket.com/albums/...ps466af9c1.jpg

4340 H Beam with ARP 2000 bolts will be stronger than the I beam setup, although the I beam will be plenty for what he's doing.

The I beam is good to at least 900 hp. Way overkill here, plus it fits the budget. These Scat rods have one of the best reputations as far as I beams go. If it were a 900-1000 hp motor, yes I agree H beam. For this application, money wasted... And usually the rod never breaks, but the fastener. I think the I beam is overkill for what he's doing, but at $381.00 with arp 2000 bolts, why the heck not?!

See, as hard as we try, we just can't get along! Lol

Thank you all for your suggestions. Leak testing is complete, I already returned the tester to my mech friend. He only has one for the shop so had to do my testing quickly. I already have the exhaust I plan on using, 496 aluminum mani's and stainless risers. Also have the carbs which I picked up from the classifieds, Holley 800 Merc blue carbs.

I agree with you with only boring (if needed) to the smallest amount needed. I will assess once heads are removed as to what's needed. I'm really not wanting to get new rods. If I can get away with using stock rods I will for the cost savings. With new rods and pistons I might as well step up to a new rotating assembly and that's not what I'm trying to do here, would like to but just can't. Remember, heads and valve train are still in the works also. Just quoted $225 for boring and honing all cylinders per block if I drop it off to them bare, not bad for machine work that may be needed.

Just found out this morning that I have one set of 990 heads and one set of 188's. If I can sell these for asking price I may reconsider my options. I already planned on spending for valve train and heads, this bottom end stuff is extra so see what I can recoup from selling heads and stock exhaust before making concrete decisions.

Jeysson