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Am I choking my 588ci? Need Doms?

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Nordicflame

New member
Just curious as to some thoughts here...

My motors are 588ci (4.56 x 4.50), 10:1, Valako fully ported Dart 325s
(flow at .650 is 400/301), Custom RMB cam in the mid to upper 240s with
significant lift, High RPM Morels, 8205PLUS springs at 175# seat, CMI
Sport Tubes.


Here's where I'm concerned: Intakes are Merlin 4150 marine versions that are simply port matched and the carbs are HP1000s (ProSystems) with a 1" 4 hole HVH . The carbs wet flow tested around 898. Not being much of a carb guy I've come to understand that the HP1000 is not much more carb than an 850 so it has me wondering. Also it seems the intakes have fairly small runners from gathered info.

Being in a fairly light boat (Nordic 35) it will literally throw you back in the seats from 3500 to 5200 and then hover around 5300-5400. Like it just stops climbing but doesn't seem like it's ready to. The cam is designed to pull up 5800.

I have a set of ported tall deck 4500 Victors that I can switch to if I purchase some new Doms so I just wanted to get some feed back from some that may have made this swap.

I think MER has had a similar experience on the dyno lately that he kindly shared and thought maybe he could re-share his findings.

Notes:
If it matters my A/F ratio goes from ~13.0:1 4500-5000 and then quickly to 11.6 at 5000-5400.
Also I have tested some props that should have spun higher but they really didn't.

Thanks,
Dave
 
Last edited by a moderator:
Hydralic or Solid rollers?

What are the flow numbers on the 325's after porting? why small runners with that size Cu. In?

Cam seems small but I'm not a cam guru. I would expect more duration to give you better top end.

I have forced induction but I have 580 cu. in. with 254/262 and .636 lift, solid roller and it's fairly mild.

I guess the carb could work but that big of an engine I'd go tunnel ram or dom's. but hey, it's easy to spend others money!
 
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What is your vacuum reading at 5400? I have a 572 on dyno today with 930 wet CFM 4150 C&S carb making 700 HP when it should be 775-800 HP. The vacuum went up from .9 @ 3200 RPM to 2.1 @ 6200 RPM, l also have similar O2 readings. I just ordered Pro Systems 1150's.
 
Geronimo36 said:
Hydralic or Solid rollers?

What are the flow numbers on the 325's after porting?

Cam seems small but I'm not a cam guru. I would expect more duration to give you better top end.

I have forced induction but I have 580 cu. in. with 254/262 and .636 lift, solid roller and it's fairly mild.

Have you propped the boat for 5800 rpms?
Click to expand...

Hydraulics, flow numbers are in the post...
 
Brian41 said:
What is your vacuum reading at 5400? I have a 572 on dyno today with 930 wet CFM 4150 C&S carb making 700 HP when it should be 775-800 HP. The vacuum went up from .9 @ 3200 RPM to 2.1 @ 6200 RPM, l also have similar O2 readings. I just ordered Pro Systems 1150's.
Click to expand...

My ProSystems base plates don't have vacuum ports because I wanted black ones :ack2: My bad.

Sounds like your on the same path and maybe I can piggy back your info :)

What intake were you using and what will you be using?

Thanks,
Dave
 
Maybe the carbs are going rich because they're being forced to compensate for the lack of CFM so they're sucking more fuel...

Cam seems short on duration for a 588" NA engine, no?
 
Intakes are Victor 454-TD's custom done by Wilson manifolds,they are Dom base with Wilson 4150 adapters. Heads are AFR 325 with CNC bowls cut down to 114 CC with intake correction make static compression of 9.9 to 1. Cams are from Bob Madara.

Carbs will be here Wednesday I will rerun them and post # then.
 
Geronimo...
My thoughts on rich condition are the same :)

Solid vs hydraulic, apples to oranges. These cams are actually not much less than yours :sifone:
They were also designed around a few factors such as high altitude, exhaust, etc...

Brian, please post your results!!!

Thanks Guys
 
On a buddies boat with a similar setup although single engine he gained 300+ rpms going to a 1050 over the 950 holley, no other changes. This was on a 540 with 651 cam (I think). On my 548 I am running an 1150 dom on a merlin X intake, ported Iron eagles and a RM builder(244, 250 630 lift), didn't try a smaller carb to compare but it runs real well and will pull to 6000 easily.
 
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Nordicflame, Looked over your post. I had a 604 with Dart cnc 335, 4150 intake and a HP 1000 carb. This was not my original build. Bob and I did the Hi rev lifters as you know along with his cam. We were expecting to pick-up from 734 hp to about 775-800 hp. I made a pull after the break-in and only made a 6hp gain, I was like" what the he--", called Bob, HEY ARE YOU SURE ABOUT THIS CAM? We talked about it and decided lets try a dfferent intake and carb, I had a dart 4500 ported on the shelf and a Holley 1050 that was just used on a 800hp solid roller engine. Gave it a shot, first pull 775 second pull 815 hp @ 6000rpm. The original run didn't go rich, it just was weak and fell off. Didn't you run on dyno first? If so, what results did you have at that time. Talk with Bob, see what he says about this.
 
Brian41 said:
What is your vacuum reading at 5400? I have a 572 on dyno today with 930 wet CFM 4150 C&S carb making 700 HP when it should be 775-800 HP. The vacuum went up from .9 @ 3200 RPM to 2.1 @ 6200 RPM, l also have similar O2 readings. I just ordered Pro Systems 1150's.
Click to expand...
Are you going to change the intake?
 
Since we're on flow, and an engine is a pump, will the CMI sport tubes handle the increased flow of the correct intake and carb?
 
MERPerformance said:
Why are your spring pressures 175# on the seat?
Click to expand...

Mark,
If my memory serves me right Bob wanted me to run more in the 200 neighborhood but with the .664 lift it was getting close to the spring limit.
Again, going on memory only here :(

Thanks for your input.

By the way I believe WetteVette is making some very serious hp with his 598 tunnel ram motors with the Sport Tubes at 6000+ rpm. Of course he has two Doms :D

Dave
 
Nordicflame said:
Mark,
If my memory serves me right Bob wanted me to run more in the 200 neighborhood but with the .664 lift it was getting close to the spring limit.
Again, going on memory only here :(

Thanks for your input.

By the way I believe WetteVette is making some very serious hp with his 598 tunnel ram motors with the Sport Tubes at 6000+ rpm. Of course he has two Doms :D

Dave
Click to expand...

I know a 598 with solid roller and dart intake and 1050 dominator makes around 800 HP @ 6 K rpm.
My spring press is 225 @ the seat.
 
Nordicflame said:
Geronimo...
My thoughts on rich condition are the same :)

Solid vs hydraulic, apples to oranges. These cams are actually not much less than yours :sifone:
They were also designed around a few factors such as high altitude, exhaust, etc...

Brian, please post your results!!!

Thanks Guys
Click to expand...

I agree to that.

Like I said previously, my cam is mild for my cubic inches and I have forced induction. I believe total duration on my cam is something like 298* if I remember correctly. I also set for .016 instead of .020 they call for. ;)

Your cam is pretty close to a Crane 651 which is 244/256, .632" lift which was advertised up to 572" give/take.

Looking forward to seeing if the Dom's work!:driving:
 
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