496 Stroker/Dart Pro1 Heads
 

Anyone running Dart Pro1 Heads?
I'm thinking about putting them on my 454s +30over
310cc intake/119cc chamber
2.25/1.88valves
I'm toying with the thought of turning my engines into 496 strokers.
Presently 5.88/6.10 112centerline roller cam
Anyone have experience with either Pro1 heads or 496 strokers?
Dennis

The stock heads on a 454Mag flow pleanty for a 454ci motor...you won't see much there in power gains unless your raising your cr to like 9:1 with the alum. Darts.
What exhaust system are you running now?

Back4More,

The compression ratio presently is 9.6:1 with TRW'S
Since I droped a valve at the C.O.PS. run I want to go with 9.6:1 SRP piston's with a quarter stroke crank aka:496ci
Intake is a Victor JR./1" spacer with a Nickerson 960 on it.
Exhaust is Stainless Marine.
Dennis

The WETTE VETTE has a 13.2:1 compression 496" Chev. with fully ported 325 Pro 1 Darts. It also has a stage 5 Nickerson 1050 Dominator, CMI exh, Merlin intake, full MSD, and a Comp solid roller cam 272/280 @ .050 with .714" lift. It runs pretty good.:cool: The stroker crank with 6.385" rods and the appropriate pistons results in a very good torque motor that works well in boats. Take a ride to LaPorte sometime and check it out.

35Lightening,

If Pro-1's are what you want then you should go with the 310cc head that Dart offers in the Pro-1------Do NOT go any larger! I run the 310's on my 540's.

35lightning,
Dan was saying it might have been a rocker or something at the lunch stop...sorry to hear it wasn't.
Maybe Bruce at Wolffie's could set you up.

My engine is currently on the dyno and is very close to what you are talking about. 454 @ 60 over 4.25 stroke w/6.385 rod = 496ci. I have the Dart Pro1 heads that have been worked to remove casting flash without enlarging the ports. I am using JE/SRP pistons for a compression ratio of 10.1 to 1. I am using the 731 crane cam which I don't remember the specs on at the moment. Those are the main features of the long block but a lot of other little things have been done. I am using the Arizona Speed & Marine EFI which is like the HP500efi but I am using larger injectors and throttle body. We are still making adjustments but prelim. #'s on dyno are: 590ft/lbs @ 3800rpm and the torque doesn't really drop until about 5400rpm (560ft/lbs). This is all designed to work with 92 oct. pump gas.

Todd

KAAMA
 

Do you think my boat would be faster with 310's or the 325's that I am running. I have seen 97.8 MPH at 6300 RPM for a best GPS top speed turning a 29 pitch Spinelli through 1.5 gears. I like this subject and want everyone's opinion. Oh ya the throttle response and acceleration are pretty awesome the way the motor is set up now.

Back4More,

I was at the marina pulling off the other head and I had a conversation with a friend that's into cars.
He suggested Bruce Wolff in New Buffalo for my machine work.
I believe that KAAMA had given me Wolff's phone number in a previous post....Thanx

Dennis

panchangalpina,

My cam is a crane 139631.
I think the 731 is close to what I'm running.
I spoke to a shop today that suggested that I use SRP
pistion #142991 which is a dome 10.2:1 at 118cc
I would like to be at 9.6:1 - 9.5:1
They suggested to go to a .051 head gasket which would bring me to 9.7:1
Then take some off of the dome to bring me down to 9.6:1
OR use a .039 head gasket and take more off of the dome.
Is either of these a commom practice?

kaama, can i get bruce wolffs phone number too, i need for someone to build me some horsepower.:D :D :D :D :D :D

35L,
We have used that piston a lot and there is plenty of room to machine the dome. They are a good quality part but not as lightweight as the JE race pistons. They use the same forging for several pistons so there is more material under the dome. You can run slightly more compression with the Alum. heads without the detonation problems. I am not sure that I would run the thick gaskets unless there is no other choice. Also something else that we noticed was the combustion chamber size on the dart heads has been larger than stated, they have been consistant at about 120-121cc. I guess this allows for machining the heads prior to assembly which needs to be done to true up the sealing surface. My suggestion would be to use the .039-.041 gasket and machine the pistons.

Todd

pachangalpina,

What compression ratio can I run with the Dart Pro1 heads
and still run on 93 octaine?
The gas I run is the pollution formulated for Chicagoland.
It seems to make engines run more lean.
I would also preferr to use the .039-.041 head gasket.
Dennis

Just got done building the same motor for a 454 ss truck.
Parts: Stock 454 4 bolt block
Eagle crank & Rods Srp pistons 10.1 to 1
Crane Hyd Roller Cam
Performer Rpm Aire gap Intake
Large Oval Port heads Iron 2.19 , 1.88 vales
Hp 520 with 850cfm carb
Torque 570ft
Motor maxed out at 5400 rpm

35lightning,
It seems that 10.5:1 with alum heads is the max without detonation. I would not recommend going that high but around 10:1 should be safe with the Dart heads. I can not say how the oxogenated fuels perform compared to the 92 here in the South but we have noticed differences on the dyno from brand to brand and from station to station, very minor differences. Do you have a knock sensor on your engine? This is a good way to help protect against det. and also check your total timing. One of the keys to prevent det. is to keep the system cool, boats do this easily because they have an endless supply of cool water, the alum heads help also because they are easier to keep cool. I believe the Merc thundervolt V system has the built in knock system, if not MSD has one for their system that retards the timing when detonation is detected.
It is my opinion that with the mentioned combination that 10.0-10.2:1 will be safe. Hope this helps.

Todd

If the combustion chambers are polished it will also allow a little more compression before detonation. I have seen a few guys run 92 octane with 10.5 compression in boats with no probs, but they are running larger than recommended cams to bleed down some cyl. pressure. Their motors/boats still run very fast regardless of the larger cam. To small of cam will work the other way and raise cyl. pressures which will lead to earlier detonation. I just run 110 octane and forget about it. $3.00/gal.:mad: The power is worth it I guess.:rolleyes:

Wette Vette,

I'm no engine expert---I just talk like one! :D ;) :p Anyway, you might be okay with 325cc heads while utilizing a mechanical solid roller cam in a 496. But, if it were me I would have chosen the Dart 310cc head or even (from what I have heard) a Brodix 300cc head. From what what I read/learned and experienced that a marine engine runs better with high velocity air/fuel charges. Anything too large will not be as responsive as it could be with the right head/intake runner size BESIDES idle quality will suffer and have poor drivability at the docks. It's not how fast you go---it's how fast you get there.

On another thread "36spectre" said it well when he stated that when you're in a match with another boat, the outcome is usually decided within roughly 10 seconds. How true it is, as I have seen that formula unfold many times over several years with guys and their boats.

Docker Dave, sure---be glad to help a boater in need of horsepower. :p

BTW guys, I've seen Doctor Dave build some nice stuff for some guys and their boats that I know of and they're happy with the work he has done. He lives within 15 miles of Wolff's shop.

kaama, what you didnt know...i secretly take all my jobs to wolffie and when he's done, i just paint it up and collect all the bucks!:) :) :) :) :) :) :) :) :) :)

Cool, hopefully we can get some of these guys over to Hardy next weekend and we can let them rip.:D Will you be ready by then KAAMA? If not bring your boat over just so we can check it out. I know you have been working all summer long and it would be cool to see it run for the first time next week.;) I will be helping JDNCA1 install his fresh 632 this weekend so the WETTE VETTE will be parked and we will be ready to run next week. JDNCA1 put a box on and just had his motor dynoed at 850 plus hp so we are hoping for some big radar numbers when we are done. I actually agree with you KAAMA on the port volumes not needing to be very large to support good HP, as long as they are ported properly. ;)

Hopefully my boat will be ready for running by next weekend for the Hot Boat weekend at Hardy Dam. If not I may still bring it up (by popular demand---Wette Vette) and hang out for a while and meet some of you guys.

How about you Doctor Dave? You need to bring that 35' Cig and show them what big cubed blower motors sound like with 5" DRY tailpipes!!! :D :D :D They end up having ALL KINDS of wild hardware up there. Plus I know you'd like it.

..........Back to the post,

While using SRP piston #142991(10.2:1),Eagle H beam rods and crank, do you have to clearance the block for stroker crankshaft?

I need real advice here!!!!!!!:) :rolleyes: :)

No, 4.25 stroke will fit.

wette vette is correct, should not have to clearance on a 4.250 stroke.

Thanks guys,,,,
I appreciate your advice.
Just trying to build some decent motors.
This is the best place for me to find info.

......Back to work:
I'm presently using the OEM harmonic balancer that was on my
454 Mags.
The engines were balanced internally when I did the last upgrade.
The machine shop that did my work setup the flywheel and damper(OEM) for internal balance
Do I need to go to better damper now that the horsepower is being upped?

Also with the piston/head/cam combo that I have presently posted on,will I have valve clearance problems?

Dennis

An aftermarket dampener would be a good idea. I use a Fluid Dampener. With .714" lift and SRP pistons there are no clearance issues between pistons and valves on my 496. You always have to check this to be sure, but SRP pistons are made to be used in roller cammed motors and have quite a bit of clearance built in.

35LIGHTING, i am curious about how they set up your dampner and flywheel for internal balance, did they change them with neutral balance units?
dave

DOCTOR DAVE,

When I was upgrading my 365 mags,I brought in the flywheel and balancerS to my machine shop.
I believe they where then neutral balanced?????
The rotating assembly is internally balanced as I have the balance sheet.
I don't have the engines apart yet as I'm still farting around getting 'em ready to pull.
When I pull the flywheel and damper off I'll take a pic and
you can see what was done to them.

P.S With the setup I have with Pro1 heads will I need to install a stud girdle?

Dennis:) :)

The higher you twist a motor the bigger the ports need to be.
Up to 5500 rpm you should use small port heads.

35Lightening,

I'm pretty sure you WON'T be needing a stud girdle---especially if you're using a hydraulic roller cam

BTW, Doctor Dave and the Wolff may be coming up with me as guests on my boat at Hardy Dam. What a rough bunch! :p :D

35lightning

I would port the chambers before cutting the dome on the pistons. It may screw with the thermal dynamics by making the dome thinner than the deck of the piston. Also by porting the chambers airflow will be increased. Look for a final volume of 125-128cc's after port work. One other point, make sure the valve grind is OK. Most of the brand new pro one heads that have been in here needed the seats reground to square the seat to the guide. Even though the valve may seal with the valve spring pulling it tight, the valve will flex every time it opens and closes, wearing the valve guide or fatiguing the valve. They dont know this at Summit or Jegs so dont be afraid to spend a few bucks more at a reputible shop.
While you have the motor apart, make sure the bore bottoms are champfered and the block is bore notched for airflow. This will lower compression 2-3 cc's.
Dont waist your money on a girdle for a hydraulic roller cam, with the relitively short valve lifts and low spring pressures it wont load the stud enough to make a difference not to mention the hydraulics themselfs acts as a buffer. my 2cents JimV

One other thing you may want to mention to your engine builder(he may already be aware of this). I have been around several people using Eagle cranks that have found they have been as much as .0010 out of concentricity on the journals. To some people this is no big deal, but personally I think it can lead to premature bearing failure.


I have an Eagle in my 468, and it was out .0005 . They make good cranks for the money, but I always check.

Good Luck :)

I would like to add that i have two friends running hydraulic roller cams with 150 and 160 on the seat, 420 open spring pressure. They both have broken ARP rocker studs twice, one using Comp Cams the other using Harlan Sharps. You may want to reconsider the theory about no stud girdle.

jspeeddemon,

I'm using hydraulic roller lifters (Comp part # 887), ARP rocker arm studs, Crane Gold aluminum roller rocker arms, titanium retainers and Comp #930 valve springs with about 130-140lbs on the seat and about 370-380lbs over the nose. All this on Dart Pro-1 aluminum heads. I was originally using ARP rocker arm studs that were a little on the shorter side for the exhausts. They have 50 hours on them from last year with no problems, but this year I have since then replaced them with a longer ARP stud that almost bottoms out within the stud bosses so that there is less chance of failure. We had to cut them for fit. Anyway, no problems thus far and I know of EVERAL boating guys running hydraulic roller cams without problems thus far. Not sure, but I think your spring pressures may be a little too high bro.

I run the Darts and have had great luck with them although they are a little harder to build heat with, not bad. I have to agree with jspeeddemon, a girdle is a good idea, never too safe.

Bruce Wolff does a great job, I can not say a bad thing about him, he has always delivered on time and the bill has been in the range quoted.

Hey Scott----Yep, Bruce IS the Big Bad Wolff! That boy is gifted and cetainly knows how to tune an engine!

As I said, he has always done a great job for me and even fixed some of the other peoples mistakes as well.

jspeeddemon

No need to reconsider. We have had 0 failures with the Arp studs/hydraulic rollers. A stud girdle forces you to use tall valve covers causing clearance problems with the headers. I'd check the spring height for coil bind.

'Talked to Bruce Wolff last week.
His quotes were not at all outragious.
His name seems to be mentioned quite often when talking performance engine work.
I'm going to get him to do my machine work.
Dennis

If you feel rocker stud flex may be a problem, run Jesel or T & D shaft rockers. Stud girdles will not clear most marine valve covers that are required with marine exhaust. I do agree that flex should be minimal with a hydraulic roller under 6500 RPM and roller rockers with no girdle will be fine. I have the Jesels and they are pretty cool. Valve lash doesn't move and is easy to set and they fit under stock valve covers that can be removed without pulling the CMI's.

Kaama,

When I did the upgrade I installed a crane 139631 cam with the suggested 99886 crane springs which was part of a "camponent kit"
Springs where installed at 1.859 and 380lbs. open. which is what is on the camcard.
Crane has gone to spring 99896 after having a rash of cracked springs on carbed hp500s - 1999 and older
I have friends who have hp500s and are comming up with cracked springs.
Teague has sent me comp#929 springs.
I wonder what the difference is between those and the #930 you are using?

I'm going to be going to Hardy Dam saturday.
Never been there before so I don't know what to expect.
I'll be riding shotgun on my friends 30' Daytona Eliminator with 825's..........