4160 Holley tuning

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

even when the donovan 302 chev was removed and social motor went in it had a double pumper fitted as they seem to like them in boats ,
could not help myself i had to show off my old boat god i miss it

Edited by nicko61, 22 September 2011 - 08:36 AM.

Someone might be able to confirm this for me- Isn't the check ball ALSO there to prevent damage to the secondary actuator incase of a backfire?

Someone might be able to confirm this for me- Isn't the check ball ALSO there to prevent damage to the secondary actuator incase of a backfire?

No, it works the wrong way to help there. Maybe you're thinking of the check ball they added to the later carbs to protect the powervalve diaphragm?

Nicko makes a really good point about fires in boats, a guy I know lost his SBC powered boat to fire about a year ago. It had been sitting for a while, he jumped in and turned the key and it went woof.. I don't know what precautions you could take, a big co2 extinguisher maybe?

Edited by oldjohnno, 22 September 2011 - 08:47 PM.

Ah cheers oldjohnno that sounds like it.

Alrighty.

Yep strait off the bat massive improvement. No more massive flat spot

She's still not quiet dialed in properly as of yet but a lot closer. Im pretty sure i need a fair bit bigger powervalve as suprisingly she's running 14" HG at idle, as i discovered by finally fitting a vac guage.

Biggest PV i have is a 65, going to get a few around the 75-85 mark and see what that does.

Its running a touch lean through the mid range, comes out of the water really fast, then leans out a bit and balks a little half way onto plane and then it comes on the main curcuit and just takes off.

Full throttle from idle and holding it gives me low 12's coming out of the hole, then it leans out to mid 14's, then goes back to low-mid 12's when it comes on the full circuit.

Thats about as good as we could get it today with the stuff i have. A definit improvement from when it first hit the water today, ended up going up two main jets so its got 70's in there now and richening up the idle circuit a bit to try to mask the mid range lean out but not 100% successfull, better but not quiet right.

Havnt played with the accelerator pump side of things as of yet.

Want to get this thing sorted so i can put a 50 shot on it hehehehehehehe.

Cheers.

Edited by Bomber Watson, 25 September 2011 - 02:26 PM.

That's good news. I'm not sure that you fully understand how the powervalve works though. There are no "bigger" or "smaller" powervalves, the only thing that changes is the vacuum level at which it opens. And despite about a million magazine articles to the contrary, the idle vacuum has got three-fifths of frOckall to do with powervalve selection. It doesn't matter at all whether the powervalve is open or closed at idle, the main circuit isn't operative with a closed throttle so keeping in mind that the PV simply augments the main circuit then it doesn't matter at all whether it's open or closed.

The "right" way to select the powervalve is like this: measure the vacuum at a fairly light but steady cruise. In a car you might do this on a flat road at say 100 - 110kmh. Let's say it pulls 9". We want the PV closed under these conditions so we need a PV rated at less than 9". That's easy enough to do but we don't want one that will close at WFO. So the next test is to open it up wide and let it accelerate until it just won't go any faster (yeah, tuning can be fun). Let's say you get 4", you now need to find a PV with a rating of between 9" and 4" to ensure that it's (A) closed at cruise for economy and clean running, and B open at WOT to prevent a high-speed leanout. The numbers indicate the vacuum level under which it starts to open eg. 65 indicates 6.5" vacuum. There's normally at least a couple of valves that will work just fine.

If it turns out that you need more or less fuel from the powervalve (and usually it's close enough not to matter as stock) then you need to make the powervalve channel restrictions bigger or smaller. If you screw the PV out you'll see two holes in the metering block at the 9 and 3 oclock positions in the tapered section just out from the PV thread. These are the PVCRs. You can drill or plug these to change the amount of power valve enrichment but it's rare that they aren't close as stock.

Don't underestimate the amount of tuning you can do with a Holley accelerator pump. If the steady state jetting is ok you can cover up a multitude of sins with different cams and shooters. The other thing I should mention is not to take the AF readings too seriously, the only thing that really matters is how fast it goes, regardless of what the numbers say. I'd be surprised if 72s in the primaries don't get you very very close.

Edited by oldjohnno, 25 September 2011 - 03:20 PM.

Sorry, we got mixed up there due to my terminology.

I was referring to them as "bigger" and "smaller" as a simple means of determining between the sizes, obviously 65 is a bigger number than 45.

I understand they do not flow more or less due the the size, and also understand that the number refers to how many " HG they open at.

I've never been involved with pro tuning circles, so just have a basic terminology i use with some friends of mine who like me like to tinker, We all know what were talking about but sometimes i'd nearly bet that someone standing to the side listening in wouldnt work out if were talking about cars of space ships.

Also i dont fully understand everyones hatred of an air fuel ratio meter. Its getting a few dislikes in this thread.

At the end of the day im a very novice tuner, and to be honest if i had it out and was holding it without anything hooked up i wouldnt be able to tell you if the slight hesitation it has is due to being to rich or to lean or whatever... The LM-2 lets me get a bit of a view of whats happening so i can get a basic scope of where it is and where it should be.

Im not out trying to tune it to a specific number, merely looking at it, noting the afr when its performing well and also noting the afr when its not performing so well. Now if the afr is leaner when its not performing so well obviously its got a lean spot, if its richer when it hesitates then obviously it has a rich spot.

I understand where your coming from to an extent, sure if i was determined to get it (random figures) bang on 12.7 when im on the throttle and bang on 14.9 at light throttle (which would be impossible in a boat anyway) then i could understand. But thats not what im doing here.

Sorry if thats not the "proper" way of tuning an engine and i also apologize if i cant tune an engine with a bit of poly pipe to my ear and a vac line over my cock like some older guys seem to think they can but it seems to work on previous engines i've had....

And the kit is so god damb cheap from the states i dont really know why everyone hates them so much. If i had spent 5k on it yeah sure little rich boy playing with toys most people cant have but it cost me like $400 so who cares??

Sorry if that sounds a bit harsh, i dont mean it to be and i have nothing but respect for your opinion oldjohnno and really appreciate your input and your time helping me, but i just dont get how using the meter the way i do is so damn wrong??

Now, back to topic. vac at a slow cruise speed (obviously 100 in a car doesnt work, so i'll use 30mph in the boat, basic skiing speed and im pretty sure still on the idle circuit) is IIRC about 12"HG.

Pinned from either that speed or from a stand still drops to about 2" HG.

So basically what your saying is my PV is about the right size.

Going from the 45 to the 65 did make a slight difference and improve the hesitation (seat of pants, not by the meter), hence why i thought bigger (there's that terminology again) might be better. Again novice tuner. Apparently that difference didnt exist and i was dreaming??

I did think about drilling out those horsepower holes a bit (more of that terminology lol), or PVCR's as you call them. I did this to the blow through 2bbl on the grenade engine and it definitely helped a LOT. I dont have jet drills so i can only go to the next 1/64th (which i did on the nade) which may be to much for this combo... Still could be considered though. Perhaps a set of jet drills on the next summit order.

Might look at playing with the squirters. To be honest the reason we didnt get that far is because She was getting low on fuel, we spent quiet some time frOcking around, as well as a few high speed blasts 10k or so down the river and back just cause its fun.

I dont really have a large amount of spares. Not sure what the squirter on the carb is now, but i know i have a 25 as a spare. Pretty certain the one on the carb now is bigger. I notice summit sells kits of squirters and the cams so i might get a kit of each, seeing though they seem to be quiet important. Perhaps even a 50cc pump conversion to test??

Cheers.

Edited by Bomber Watson, 25 September 2011 - 04:50 PM.

Sorry if thats not the "proper" way of tuning an engine and i also apologize if i cant tune an engine with a bit of poly pipe to my ear and a vac line over my cock..

That's gold. No need to be sorry about anything, it seems we just had a simple misunderstanding of the lingo and it also seems you had a good understanding of the PV all along. Anyway its all good and I'm glad you're on the right track. Hate the AF meter? Nah, I think they're a great tool for getting in the ballpark and they can be a massive timesaver. I think what we've been trying to say is that getting in the ballpark is what they are brilliant at but nothing more - when you don't know someone at the other end of a forum personally or what their experience and knowledge is then it's safest to go right back to basics. If my advice sometimes comes across as being patronising I'm sorry it's not my intention. And I guess any method that works is as good as any "proper" way..
Anyway I'm sure you'll have it running sharply after another session or two. The reason I keep bringing up the acc pump is that the Holley pump is a bit unusual in that it is actuated through a spring and because of this it can keep squirting for a second or two after any throttle movement has stopped. When the steady state jetting is good but you just have niggly transient hesitations the pump can be a really handy tool for tuning these out. It's just a matter of finding the right cam, cam position and nozzle combo.

Haha, yeah i should probably google my lingo before putting it on an internet forum as i understand how it can be confusing.....Trust me spend a week around me and you will be speaking fluent gibberish as i do. Its quiet fun and great quality around the pits.....Gets a lot of head scratches.

Re the squirters, yep yep, currently eyeing this off

http://www.summitrac...rts/HLY-36-184/

Looks like it might do the trick.........Or atleast bloody well should do as it appears to have EVERYTHING.

And this

http://www.summitrac...arts/HLY-20-11/

Unsure if i'll need the 50cc but from your explanation of the Holley accel pumps im just kinda guessing more CC = the same affect but for longer...Coupled with the tuning ability of the kit above that and the original 30cc probably got everything in that area covered.....So would be handy to have in the parts bin as a tuning tool.

Cheers.

Edited by Bomber Watson, 25 September 2011 - 05:53 PM.

If you think you'll be doing a bit of work with Holleys in the future then investing in some parts sounds like a good idea. The big 50cc pumps enable the use of the bigger cams (the little pump doesn't have enough stroke to handle them) so that by using a big cam/small nozzle combo you can extend the shot duration.
I'd also grab a secondary spring kit while you're at it. Tuning a boat is a bit like tuning a heavy car; you'd normally use a tad more jet, a bit longer pump shot and possibly a bit stiffer secondary spring than what you'd use in a light car. When it's right there'll be no steps or surges whatsoever.
When you get the pump kit take half an hour to try different cams and screw positions in it (carb on bench) while you watch the action of the pump lever. You'll soon see how it reacts to different settings and then you'll have a good idea which ones to try when you get it in the water. I'm positive that it'll take very little time to have it accelerating seamlessly, and when you get to that point it might pay to have a quick play with the ignition timing too.

Fantabulous.

Yes im sure this wont be my last time tweaking Holleys hence im not afraid to buy full kits rather than individual bits.

Ign timing i actually forget where i set it, low 30's total i believe, its a bit of an effort to check it you have to pull the front seats out haha.....But yes thats on the list of things to frOck with.

Cheers.