ATK rebuild purchase |
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leonsup
Newbie Joined: October-25-2006 Location: United States Status: Offline Points: 18 |
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Posted: June-03-2016 at 7:36pm |
I have a 91 Sport Nautique that needs new engine.. I've had good luck with Summit Racing for automotive situations, so I thought I would look into an ATK rebuild but I want the GT-40 heads. Engine with STD heads can ship right away but GT-40 is 4-6 weeks. Anyone have an opinion on this? Maybe another vendor? Extra 45 HP worth it? Any suggestions are appreciated. I am in Cincinnati.
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Orlando76
Grand Poobah Joined: May-21-2013 Location: Mount Dora, FL Status: Offline Points: 3108 |
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That's strange. I purchased an ATK 351 LH with GT40P heads in February on a Monday and it arrived Friday. I didn't request "P" heads but was hopeful. Maybe they assume you want GT40 specifically and not GT40 P? I've had a Jasper, an ATK, a local machine shop, and then ATK again for my rebuilds and have been happiest with ATK so far FWIW.
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1976 Ski Nautique 351 Escort 1993 Ski Nautique purple and black 351 HO PCM |
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leonsup
Newbie Joined: October-25-2006 Location: United States Status: Offline Points: 18 |
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I appreciate it. What difference does the "P" make?
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Gary S
Grand Poobah Joined: November-30-2006 Location: Illinois Status: Offline Points: 14096 |
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They don't crack,flow a little better and easier to get
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Orlando76
Grand Poobah Joined: May-21-2013 Location: Mount Dora, FL Status: Offline Points: 3108 |
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In the marine world not much, slight bump in compression and good for another ~10hp. The plug angle is different on the P's making them more costly mod for the car world due to headers getting in the way. The non p's are more desirable to the auto industry, the P's more desirable to the marine world.
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1976 Ski Nautique 351 Escort 1993 Ski Nautique purple and black 351 HO PCM |
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leonsup
Newbie Joined: October-25-2006 Location: United States Status: Offline Points: 18 |
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Ok, thanks again, & ours is considered std rotation, not reverse, correct?
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Orlando76
Grand Poobah Joined: May-21-2013 Location: Mount Dora, FL Status: Offline Points: 3108 |
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Standard which is left hand rotation is all 89+ CC's.
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1976 Ski Nautique 351 Escort 1993 Ski Nautique purple and black 351 HO PCM |
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leonsup
Newbie Joined: October-25-2006 Location: United States Status: Offline Points: 18 |
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OK, my ATK 351w GT40 is finally here....my installer is not to keen on me getting an Edelbrock intake because of extra work he'd have to do.....you guys think it's worth the extra 20hp?
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Dreaming
Platinum Member Joined: May-21-2010 Location: Tacoma, WA Status: Offline Points: 1870 |
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Leon - certainly the question is related to how you use the boat and what YOU want it to do. I would question how much extra work is involved, and what it is? seems like this should be a pretty direct bolt on intake as long as you get the right one. Warranty might be a question also, I looked at that motor when I was searching and seem to remember that it came with an intake? If it comes with the intake assembled, I would question the warranty issues you may create by swapping parts. One other note, I did not order the ATK due to the fact that they are using a high volume oil pump. if you are going to run a DUI distributor, make sure you use the bronze gear and do the oil passage mod that DUI recommends. It sounds like your cam gear will thank you .
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gun-driver
Grand Poobah Joined: July-18-2008 Location: Pittsburgh, Pa Status: Offline Points: 4127 |
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Keep us posted on how everything works out as someone in the future could use the information provided. |
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Orlando76
Grand Poobah Joined: May-21-2013 Location: Mount Dora, FL Status: Offline Points: 3108 |
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No intake provided.
High volume oil pump? Sh1t I better check on this.i don't think mine does but I didn't ask, in past with other builders I had to specify whether i wanted a high volume pump. FwIW I'm ~50 hours into my motor with a DUI and no problems knock on wood. |
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1976 Ski Nautique 351 Escort 1993 Ski Nautique purple and black 351 HO PCM |
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Dreaming
Platinum Member Joined: May-21-2010 Location: Tacoma, WA Status: Offline Points: 1870 |
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Orlando, I am glad to hear that yours is working well!
Here is where I got my HVOP information on summit - Summit ATK GT-40 Down at the bottom of the page, they state: "ATK Marine rebuilt engines include: * Special marine pistons and rings * Special marine camshaft * Marine gaskets * New intake and exhaust valves * New main, rod, and cam bearings * New valve lifters, rocker nuts, and swivels * Heavy-duty double roller timing chains * Cam sprocket * Crank gear * High-volume Melling oil pump * Brass freeze plugs * All gaskets and seals required for installation " Summit responded to my tech question by saying that I could not customize the engine in any way, so I was stuck purchasing a standard oil pump if that is what I wanted. DUI states a couple of mods that are important to them if you run a HVOP... whether this is a really important issue or not, I am not sure, I don't know enough about the cam gear situation to make that choice, so I would follow the mfg's instructions. |
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Orlando76
Grand Poobah Joined: May-21-2013 Location: Mount Dora, FL Status: Offline Points: 3108 |
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I never thought two seconds about the oil pump being hi volume. We just swapped the DUI over from the old motor.
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1976 Ski Nautique 351 Escort 1993 Ski Nautique purple and black 351 HO PCM |
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halfnelly
Senior Member Joined: January-14-2013 Location: Maitland, FL Status: Offline Points: 253 |
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Oil pumps are cheap and the pan isn't difficult to take off on an engine stand, why not just swap it out with a standard volume before it goes in the boat? Either that or just use a thinner viscosity oil to take the load off of it. Any pressure loss would probably be made up by the increased volume anyway. No way in hell I'd ever run a bronze gear in a boat, they only last about 5000 miles in a car! |
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TRBenj
Grand Poobah Joined: June-29-2005 Location: NWCT Status: Offline Points: 21171 |
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Longblocks don't usually come with pans installed. You'll want to match the pump pickup to the pan anyways. I'd plan on a new pump and pickup (match the old if reusing your pan). Avoid a HV pump on a Ford, especially a tame one.
Compensate for the wrong oil pump by using the wrong oil? Sheesh. |
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halfnelly
Senior Member Joined: January-14-2013 Location: Maitland, FL Status: Offline Points: 253 |
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It'd obviously depend on how they set clearances and what oil they recommend. Just saying no reason to go 20-50 just for the sake of going 20-50 if the pressure is adequate with a thinner oil. |
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TRBenj
Grand Poobah Joined: June-29-2005 Location: NWCT Status: Offline Points: 21171 |
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Obviously. Choose oil weight based on the set clearances and rebuilders recommendation. Not based on the HV pump.
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Dreaming
Platinum Member Joined: May-21-2010 Location: Tacoma, WA Status: Offline Points: 1870 |
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I don't have any experience with the bronze gear, but it sounds like saving a cam gear is probably more important than the hassle of checking the distributor gear. Certainly a new oil pump is the most reasonable long term fix, but for someone with a running boat, the gear might be easier. I saw the HV oil pump as a conflict when looking at the ATK, and therefore ordered a motor that was set up to my preference, I don't see anything wrong with the ATK, I just didn't want to monkey with the oil pump on a motor that was under warranty
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Orlando76
Grand Poobah Joined: May-21-2013 Location: Mount Dora, FL Status: Offline Points: 3108 |
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Unfortunately a warranty is piece of paper one can wipe their a$$ with.
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Please support The Cystic Fibrosis Foundation
1976 Ski Nautique 351 Escort 1993 Ski Nautique purple and black 351 HO PCM |
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Dreaming
Platinum Member Joined: May-21-2010 Location: Tacoma, WA Status: Offline Points: 1870 |
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Do I sense a tommy boy reference in the works here you speak truth for most companies, hopefully you never have to use that warranty paper, not to get your engine fixed either.
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MrMcD
Grand Poobah Joined: January-28-2014 Location: Folsom, CA Status: Offline Points: 3735 |
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I have zero issue with using a High Volume Oil Pump. Many of the major rebuilders installed them in every engine in the 1990's through 2003 or so. Then they started learning about wasted horsepower and used more stock oil pumps, it is not a lot but it is a waste of free horsepower. I doubt if it exceeds 5 Horsepower on a stock 351W. On a Pro Stock Warren Johnson engine back in the late 90's they picked up 30 HP by shutting off the oil pump completely during the actual drag race. When they floored it coming off the line the oil pump was shut down till they let off at the end of the 1/4 mile 7 seconds later. That was on a 1,000 HP 500 inch drag engine.
On these Low RPM boat engines I don't think you are wasting much horsepower switching to a HV pump. All owners are happier if they have solid oil pressure at idle so many production engine rebuilders used the HV pumps as the standard and sold it as an upgrade over factory. Were they needed? Nope, but they did not do any damage other than a minor amount of efficiency lost. I would run the HV pump and never lose any sleep over it in your new engine and I see no reason to run any oil thicker than 30W in these boats. With 30W your engine should hold a steady 30-40 PSI at idle and it only has to have 10 psi at idle. (but I would hate to have that low of oil pressure) Running 20-50W in engines designed for 30W loads the engine oil pump as much as installing a HV pump so why bark at a HV install and then use 20-50 with a stock Oil Pump? |
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TRBenj
Grand Poobah Joined: June-29-2005 Location: NWCT Status: Offline Points: 21171 |
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The concern with a hv pump is not the lost hp... It is the extra strain it puts on the oil pump drive and cam gear. Ford windsors are not particularly beefy in this area- chevies are not a problem.
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MrMcD
Grand Poobah Joined: January-28-2014 Location: Folsom, CA Status: Offline Points: 3735 |
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I understand and the same concern applies to switching from 30W to 20-50W. It is hard to pump thick oil, adds load to the same drive. I run 10-30 and don't worry about it but each can run what they wish.
I can share Melling Oil pumps sells thousands of the HV pumps each year. If 5% failed they would have warnings out but I have not seen them yet. |
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