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4160 Holley tuning

Started by _Bomber Watson_ , Sep 20 2011 04:10 PM

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35 replies to this topic

#1 _Bomber Watson_

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Posted 20 September 2011 - 04:10 PM

Gday guys, slightly off topic but oh well.

I have a 4160 series Holley on my ski boat with a mid mounted 308.

Never really got a decent run on the engine when i first got the boat as everything was #@$^%&, so the current setup is as follows.

Stock (assumed) 308

Stock (assumed) HQ style heads

Edelbrock torquer intake manifold

Squarebore to squarebore wedge

1" carby spacer (just to get the scoop up a bit higher)

4160 series vac sec 600 holley

2" aircleaner spacer

Hilborne style scoop

HEI dizzy

MSD Blaster 3 coil

Accell plug wires

Water heated exhaust manifolds

2x 2 1/2" exhaust

Now, my question is.

When out running, it cruises just fine, goes fine at WOT if you ignore the low oil pressure and oil spitting out of the breathers, but thats a different topic, And seemes to pull alright at part throttle from a standstill.

But if you gun it, and hold it between 75% and WOT from a standstill, or from a slow cruise speed, it bogs right down and nearly dies, you lift your foot off the go pedal and squeeze it back on and its fine after that.

I recently took it out with my Innovate LM-2 hooked up and had a bit of a play.

It was running hell rich but the first thing i did was try to cure the bogging by changing the powervalve from 6.5 to 4.5. Only other one i had laying around really. This fattened up the midrange slightly more but did not solve the bogging.

Next thing i did was drop a few jet sizes. This cleared the afr's up a bit and got me a bit closer to lambada at cruise (light throttle) and had little effect on the bogging.

By this point i kinda made an oppinion of the problem and put the boat back on the trailer.

Now, watching the LM-2, from a stand still holding it at WOT it would pull a nice 12 something to 1 AFR, then as soon as it bogged down it would jump strait to about 17 or 18:1, then if i did the lift off and squeeze back on thing it would go back to the 12's and then 14's when i lifted off to cruise.

I got similar results over several stop start attempts (yeah there fun so we had to do a few)

Now what im thinking is the secondaries are opening to quick and just engulfing the engine with air, after all its as far as i know a stock standard 308 bottom end.

so, how do i cure this. I have seen that you can get different springs for the secondaries, would this be on the money? Any other ideas??

Edit, forgot to mention, i personally think the 2x2 1/2" exhausts are way to big for a stock 308, do you guys recon restricting them somehow would have a positive effect?? The cast alloy water heating manifolds do look rather restrictive, and all of the engines cooling water is dumped out of the exhausts, so perhaps this is part of the reason marinized pipes seem to be bigger than you would usually run.

Cheers.

Edited by Bomber Watson, 20 September 2011 - 04:13 PM.

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#2 _Gunmetal LH_

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Posted 20 September 2011 - 05:57 PM

I'm far from an expert on this so it's just a guess from me...

What's your engine vac at idle?

I understood it as the powervalve should be around half the value of the idle vac.

Also if the powervalve diaphragm(?) is leaking it will just dump a s#!tload of fuel straight through it instead of the correct path.

No idea on the secondary actuator spring but I think it's supposed to be matched to the powervalve? Could be it's too soft?

:dontknow:

Edited by Gunmetal LH, 20 September 2011 - 06:00 PM.

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#3 _Gunmetal LH_

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Posted 20 September 2011 - 06:04 PM

Just had another thought-

Maybe the secondary float is too low? When it opens there's bugger-all fuel there and when you lift off the vac sucks some fuel through?

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#4 _Bomber Watson_

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Posted 20 September 2011 - 07:53 PM

OK, after closely considering your opinion, i gather your about as experienced with these as i am hehehe.

Now, yes i believe your correct re the powervalve. I dont currently have a vac guage fitted bout could graft one in there with cable ties and duct tape, probably not a bad idea.

Re the powervalve opening to early and pissing fuel in there, that could be a factor if the engine wasnt LEANING out royally during the boggy spot.

Now your other idea, re the float, thats actually not a bad point.

I set the floats static on the trailer, and on the plane the boat sits about the same level i had it on the trailer. When im having the issue from a stop/start the boat is coming onto plane so the nose is right up, which would mean yes, the secondaries may not have enough fuel in them.

I will investigate this further, but im not sure its the problem as even if your crusing along on the plane and then gun it it still bogs down....

That said the issue is slightly more severe when going from a stop at WOT with the nose right in the air.

Cheers for the comments though, nothing like several heads together.

Cheers.

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#5 _Skapinad_

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Posted 20 September 2011 - 08:08 PM

.

Edited by Skapinad, 20 September 2011 - 08:09 PM.

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#6 _Quagmire_

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Posted 20 September 2011 - 08:10 PM

4160=600 cfm holley according to my blue bible
check float levels
check idle screw for excessive wound out
check power valve
check acelerater pump systems
could also be clogged main jets,power valve not working/channel restrictions,low float level,not dropping far enough,fuel filters,air cleaner
straight from my copy of holley building and modifying by j williams
i can copy and scan it for you if you want?

Edited by Quagmire, 20 September 2011 - 08:10 PM.

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#7 _Bomber Watson_

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Posted 20 September 2011 - 08:12 PM

Cheers for the advice Skap. I assume your reffering to crap in the carby. A . kinda looks like a bit of shit floating around.

Well im pretty sure its clean, when i had the bowls/metering block off on Thursday doing the tuning it all looked spotless, i have only rebuilt the carby a few hours ago, and it has a brand new fuel pump on it. Also when i had the boat apart the first time i cleaned the tank out and replaced all the lines.

Quag, yes 600, as said in my first post. AAAlll the above was covered during the rebuild/initial bench setting then tuning on the trailer...

Does the bible mention anything about the secondary diaphragm springs??

Cheers.

Edited by Bomber Watson, 20 September 2011 - 08:14 PM.

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#8 _Skapinad_

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Posted 20 September 2011 - 08:22 PM

Lol, cant copy and paste on yhis bloodyipad, but seems to disagree with it running lean, anyway: http://www.google.co...HQjPxZdv6uvcbBQ

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#9 _oldjohnno_

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Posted 20 September 2011 - 08:24 PM

Don't get too sidetracked by the powervalve rating, it's not really all that critical. And it'll be wide open when you stomp on it whether it's a 35 or a 65..
Has the carb been molested? It sounds very much like the secondaries are opening too quickly, as they do when the checkball has been removed. So the first things I'd do would be make sure the checkball is in place and that the standard spring is fitted. Using a spring with more initial preload would help a lot - remember that with these carbs there is no secondary pump shot to cover up that huge lean hole when the secondaries open up. So you have to be careful not to let it open too suddenly. Having said that you can still do a bit with the primary pump by using a bigger cam and possibly a tad smaller nozzle to extend the duration of the primary pump shot. This can help fill in the gaps. Use a 5cc pump if necessary.
Size-wise the carb should be pretty close, but the open spacer wouldn't be helping. Losing the spacer or swapping for a 4 hole would help a tad but I think you should be able to get it pretty good just with a bit of tuning.

Edited by oldjohnno, 20 September 2011 - 08:27 PM.

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#10 _Quagmire_

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Posted 20 September 2011 - 08:35 PM

no but says to look at the buttery fly openings and acculorator pump system...for even and unrestricted flow while the engine is turned off

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#11 _Bomber Watson_

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Posted 20 September 2011 - 08:41 PM

Righto, Skap, vid is loading.

Oldjohnno, Yeah the carb has been molested. I made one carby out of two i had and a Holley trickit. Thought i put everything in where it should go but will look at my exploded view again, find this check valve and check it...hehe.

Standard spring, unsure. I didnt pull the vac part apart. I do have another one which i also havnt pulled apart laying around so i'll take the tops off both and have a glance. See if i can notice a difference.

Really stupid question, would shimming the spring work just to give an idea if its the problem or not???

Ie throw a washer in there, take it out for a spin and if it helps then were on the right track???

To be honest i really dislike the 4160 series with there single squirt, silly pipe joining the primary and secondary bowls that i always manage to nearly loose the o ring off and the stupid non adjustable metering block/jets in the secondary, but i have very little budget for the boat atm so im kinda stuck with it for now....

Cheers.

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#12 _oldjohnno_

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Posted 20 September 2011 - 08:54 PM

Yeah shimming or stretching the spring would be ok as a rough test, and if it proves to be successful you could buy a Holley spring assortment to fine tune it. Try the big cam/small nozzle combo too.

Don't be too quick to knock the old 4160, they might look a bit agricultural but properly tuned they are every bit as quick as a 4150. I think you'll be pleasantly surprised when you get it dialled in...

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#13 _Bomber Watson_

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Posted 20 September 2011 - 09:07 PM

Righto, i'll collect some bits then take it out on the water again.

Yay more fun.

Best thing about a boat is you dont need to go to a drag strip/run around constantly looking over your shoulder to tune it hehehe, just drive 5 minutes to the river, slide it in the water then hold the bastard pinned.

Cheers.

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#14 mick_in_oz

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Posted 20 September 2011 - 09:14 PM

Everything that Johnno said.

Another thing that can cause a similar problem to what you have is if the primary jet is way toooo small, the jet becomes a little slow to initiate and the pump shot gets used up before the primary jet starts to flow properly, or the secondary throttle opens. Yes i know what theLM2 is telling you, its fat, blah blah, but at the end of the day it needs what it needs, for the sake of a jet change, its worth the time. Go up maybe 6 sizes and try it. Also a lil unsure about the observation of the AFR vs PV change, they will add the same amount of fuel, just at a different opening point (manifold vacume) I had this trouble as described with my 780 Vac when i used to run the small pri jets.

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#15 _Bomber Watson_

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Posted 20 September 2011 - 09:23 PM

Yeah mate cool as, I know the LM-2 is just a tuning guide and nothing else.

Might try that as well, looks like i'll be out on Sunday with a washer and my jet kit lol.

Was kinda hoping it was running pig rich as frOck ME ITS THIRSTY hahaha.

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#16 _Bomber Watson_

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Posted 21 September 2011 - 01:35 PM

OK quick update, today is shed cleanup day (last day of holidays) so obviously i was working on this.

I pulled the vac sec module (is that the right word?) apart and had a look, couldnt find a check valve (ball bearing) and the spring was very very light, and a bright zink kinda color.

Went and found the old vac sec module that was on the carb on the boat when i got it and pulled it apart. first thing i noticed walking back from the junk shed to the main shed was how much stiffer it was to push in. I spotted the check valve in its little slot so noted that, and the spring was substancially longer and plated in a gold zink kinda color, like the hardened washers you buy from bunnings. I measured the free lenghs and the goldy colored spring was about 9mm longer.

The diaphram out of the second module also felt "stiffer", if thats possible, and looked a bit better so i put the diaphram, spring and check valve from the second module into the housing of the first module (cause it was clean) and put it back on.

We will wait to see what that does next time i take the boat out. I wont play with anything else between now and then. See if i can find an assistant and get out Saturday arv or Sunday. Will take my jet kit, LM-2, old vac module so i can mix and match, and various other things.

Now, what will i feel if the spring is now to stiff, now that the check valve is in place?? Im guessing it will just kinda run out of steam half way through the rev range and then perhaps come back on hard when the secondaries finally open instead of being nice and linear??

Seems i totally overlooked this part during the rebuild, had never played with a vac sec carb before.

Another question, what exactly does the check valve do?? Just acts as a bit of a restricter i assume? I take it this being missing would be a pretty big factor and most of my problems?? As i said i'll take the old vac module that has all the internals from module 2 in it when i go out to see how it performs with the lighter spring as well.

Cheers.

Edited by Bomber Watson, 21 September 2011 - 01:40 PM.

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#17 _Bomber Watson_

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Posted 21 September 2011 - 01:50 PM

Oh yeah, forgot to add, the 1" spacer is a 4 hole one not open.

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#18 _oldjohnno_

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Posted 21 September 2011 - 02:04 PM

I'd be very surprised if this doesn't make a huge difference. Don't stress too much about too much spring tension, if it's too weak it absolutely kills the performance but if it's a bit too stiff the effect is much, much less dramatic. Trial and error is the best way to tune but the standard spring is nearly always very close and the potential gains are small.
The check ball is there to stop the secondaries from opening too quickly, without affecting the closing speed (though some used a fixed brass restrictor instead). There's a very popular old wives tale that says if you take the ball out the car goes faster. And I must admit it does feel faster. But it will actually ET slower nearly every time. The reason it feels quicker is that you feel the surge after the brief hesitation caused by opening the secs. too quickly. If you can feel the secondaries "kick in" you're doing it wrong.
Is this an 1850? If so I'd start off with something around the 68 to 70 range in the primaries and go from there.

Edited by oldjohnno, 21 September 2011 - 02:07 PM.

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#19 _Bomber Watson_

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Posted 21 September 2011 - 02:13 PM

Currently has 68 jets in the primary's. It did have 71's in it before i started frOcking around.

It felt a bit "crisper" with the bit of fuel taken out, and i'll leave it where it is for now, i hate changing more than one thing at a time, although when your on the river and have to keep going back to the bank to change something its a slow and painfull process haha.

Unsure what 1850 is? What does that mean?

And aaahhh the old "feels faster" trick, much like putting a 2bbl holley on a stock holden six....heheheh.

Seeing though i'm trying to get it sorted so i can pull skiers out of the water with minimum fuss i'll be trying to tune it for the most linear acceleration i can get, so a "surge after a slight heasitation" isnt what im chasing at all. That kinda stuffs enough to throw a skier strait off.

I am rather keen to try go get it sorted, because i admit it does pull rather hard when its actually working properly, but i suppose ~ 200hp and a lot of torque in something that weighs less than 600kg will do that hehe.

Cheers.

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#20 _oldjohnno_

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Posted 21 September 2011 - 08:27 PM

1850 is the model number (usually stamped onto the choke horn), it was an extremely popular carby. Millions of them ended up on street smallblocks and they generally worked well.

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#21 _Bomber Watson_

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Posted 21 September 2011 - 08:44 PM

Well there ya go, i thought a 4160 was a 4160.

The choke horn takes effort to get to so you will have to wait for a reply hehe.

Cheers.

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#22 _oldjohnno_

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Posted 21 September 2011 - 09:07 PM

4160 refers to the carb "family" ie. square bore, secondary metering plate, side-hung floats. Made in a wide range of sizes and with either mech. or vac. secondaries.
4150's are the same but have a secondary metering block and usually have centre-hung floats and 4 corner idle.

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#23 _Bomber Watson_

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Posted 21 September 2011 - 09:10 PM

Well dere ya goes.

Shows what i konw about 4bbls

Cheers.

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#24 makka

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Posted 22 September 2011 - 12:44 AM

dj, can you see the carby whle your driving the boat? would be interesting to watch the linkage from the diaphram to the secondary butterflies and see how fast it opens....

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#25 _nicko61_

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Posted 22 September 2011 - 08:26 AM

mate be very carefull pulling carby apart and working on it in th river as fibreglass and petrol and spark are not a good mix especially in a boat where fumes will sit low in the hull and any petrol spilled will sit on top of water in boat and out,
vac sec on a skiboat is unusual, all my ski boats have been double pumpers

Edited by nicko61, 22 September 2011 - 08:32 AM.