Holley DP carbs, educate me!

x2

 

I checked his site, he only offers the 455 pump, but its worth asking if he could do an arm swap!!

 

Yep, that's what Im wanting!
I remember you mentioning awhile back you had a set-up like that, thanks for the pic Larry:TU:

 

With the Stage 1 and Q-Jet, I tried "CC" rods (richer) I slowed a bit. Went back to "CE" rods
With the SP3 and Q-Jet I picked up mph when I leaned out the primary (43 rods 73 jets) and went back to "CC" (richer) rods on the secondary.
I VERY briefly thought that (going back to the Stage 1) but nope, not gonna do itp
Im too hard headed, stubborn, and don't give in too easily, LOL
The only thing that has changed is the way the air/fuel is delivered to the heads, Im confident my heads and lower end are more than capable of responding to the SP3, just gotta figure out this thing (SP3):grin:

 

Larry,
Another thought just came to mind, with your carb/fuel line pictured there, do you have interference with your heater hoses coming off the manifold?
On mine, unless I use my 4 hole spacer (1") the fuel line runs right into my heater hoses, I don't mind the spacer, but it jacks everything else up, hell, the aircleaner stud nearly hits the center of the hood, I guess you cant use your hood with the SP3 and a Holley, LOL

 

x3 I don't think anyone's doing this. Honestly though, I think we need to treat this intake a bit differently than traditional single planes. It's almost like 2 in 1, in the sense that it'll work best untouched (or maybe some cleanup) on moderate engines, and don't port it out unless you intend to go balls out top end full out racing. The runners are designed this way out of the box for a reason. TA isn't lazy and didn't open them up for a reason, but left room for those who did need them opened up with enough material to do port work.

I think this is the problem. Not necessarily saying there's nothing else going on with the engine, but that's too much intake for his combination. The only way to fix it now is to either go back to the dual plane (boooo) or use a smaller square bore carb with dual accelerator pumps, and perhaps a better (higher) stall. I don't want to be the bearer of bad news, but maybe it's best if he sold this intake to someone who wanted a hotter combination and buy a new SP3 and use it as is with a 650 DP. Either that or match his engine to the ported intake.

This goes back to the 'bigger isn't necessarily always better' motto. Don't go nuts and kill it with too much love.

There is SO much that's involved with engine tuning/racing, but going back to the basic fundamentals when it all becomes overwhelming and work your way up from there.

No harm in tossing around ideas.


Gary

 

I understand the mixture velocity slowing down from over porting, but that doesn't explain my near zero loss of low end torque, but loss up top Am I not understanding somethingo No:
Still not throwing in the towel yet, but the weather is deteriorating day by day, I wanna try my squarebore this Saturday, even if it is vacuum secondary.

 

First of all, track slips are cool and all, but they do not tell the whole story. Sorry guys. Yes it does help, and it is a big piece of the puzzle, but it's no substitute for a real dyno run. I would make more progress tuning a car on the street on some nice lonely backroad than I would at any track. Too much time in-between runs, not enough runs, and peer pressure. Everything is needed to get a full picture, not just a few track runs.

Your engine will see peak torque and hp maybe twice during each run, right? Once for take-off, once for shifting into 2nd, then again when it shifts into 3rd (if it gets that far, depending on gearing, powerband, etc.).

From 1/8 mile to 1/4 mile wind resistance is increasing dramatically, which puts greater resistance against the car. What moves resistance? It's not HP...

High torque engines will always show better performance at greater speeds vs a low torque engine. So how is it you're gaining torque and losing HP? Seems the other way around to me.

A few dyno runs, each with your dual plane and then with single plane, will tell the story. Who ported your intake? Did they port it like they would a Chevy intake? How many Buick intakes have they ported, and how many SP3 intakes have they ported? This is brand new territory for this intake....altering it in any way from its out of the box state is a crap shoot, especially when no one knows much about how it's going to do, and the only one that I know of who gave it a chance (in unported form) was a guy who put it on a stocker and used a Qjet. Is it any surprise it lost power? I suggested putting on a smaller bore carb, such as the Holley 650 DP, and all I heard was crickets.

Another one I read about was someone who put it on a high RPM screamer, and wondered why those smaller runners didn't make any more power than his modified Stage1 dual plane. People are doing everything bass ackwards.

I'll keep more of my thoughts to myself for now until more information is released, but I think I'm beginning to see a picture here. Stop treating this 350 like it's a Chevy or a BBB, and then we can begin to make progress. Not speaking to you directly here, just in general to whomever will listen.


Gary

 

Actually it acts more like a sbc with the SP3 on it than it does with a stock or the TA stage 1 cork intakes. Because the deck height of the sbb 350 is so high it makes the intake very wide for its CID. But with its close bore centers(4.240" vs. the BBB's bore center of 4.750") makes the intake almost square which doesn't leave much room inside the intake for the runners to flow a lot of air unless an oversized carb was used as a crutch to get the air around those long corners of the wide dp.

Now with the SP3 and its huge plenum which would be very similar to how a sbc S/P intake would flow corrects the math with a sbb 350 so now it needs less CFM to keep making power at higher RPMs;

http://www.wallaceracing.com/intakecfm.php


I wouldn't say exactly like a sbc because it still has longer runners which will make it different than a sbc but still will be similar and a good point of reference for the SP3. I don't think that the porting is slowing Mark down the second half of the track either, there has to be something that's not right somewhere possibly the fuel pump like some say or maybe the A/F ratios or possibly his distributor is cutting out at higher RPM? Weather permitting hopefully Mark has the chance to figure out what's going on this Saturday?

Like Mark said, if the porting is what is slowing it down it should of revealed that from the off the line performance and slowed down there as well, not just the second half of the track. Something weird is going on here, I hope for Mark's sake it isn't anything expensive to fix!

I like your theory though Gary about it having less torque is what is slowing it down the second half, if nothing broken or not right is found then you can be right about that? The gearing is making it 60 ft close to the same but the lost torque is what is slowing it down on the second half? That's as good of a guess as any I would say, seems kind of weird though.

Well like I said the SP3 is a game changer and with a new game there is a new set of rules that need to be learned.


Derek

 

Gary, no disrespect but you street tune your car and run the same car that is track tuned and you will be watching taillights for 1320 or 660ft I promise you. Run the track tuned car from a 30mph roll in the street and the outcome will be the same. Can't drive a dyno buddy

 

The intake was port matched (gasket matched) same as my heads were years ago. I had the Stage 1 ported the same way.
Before I had the intake ported, I had talked to Mike at TA, he had said it certainly wouldn't hurt to gasket match to within .040 to .060 of the gasket opening and up to an inch inward, that's all that was done.
Mike at Michaels Racing Engines did the porting, he's done plenty of Buicks, so I trust his experience.
Believe me, I keep going thru the small stuff in my head also, such as:
First start up with the SP3, same characteristics as the Stage 1, a bit cold blooded till warmed a bit, no backfiring, popping, all is normal.
Idle vacuum is the same, at 750 rpm hot idle in gear, 9 in.hg. Very mild lope from the 413 cam
I can idle it down to 550/600 rpm in gear hot.
No weirdness around town, such as surging
Temp the same
Oil psi the same, 'course why would that change
After the intial start in the morning, it starts with a flick of the key, no extended cranking.
But Im suspect of the gremlin that has recently popped up the last few weeks:
Loooooooooong cranking when sitting for a day or more, does a fuel pump loose its prime?
If its weak, is it still possible for it to be able to supply enough fuel to run to 6000 rpm, and me not notice? ( not nosing over )
I have a NOS AC Delco pump coming, Im also going to look into a RobbMc pump, Larry suggested I ask if the can put a 350 pump arm on one of their pumps.
The long cranking isn't normal.
Another thought I had, when I replaced the fuel pump before BPG (Airtex pump) all was fine, but Im wondering if the stock type pumps do well with the engine being pushed to 6000 rpm over and over again verses a stock engine that sees 4800 MAYBE a handful of timeso No: Just thinking here.

 

Interesting, make sure all of your connections going to the fuel pump and from the pump to the carb don't have any pressure leaks. Even though gas doesn't leak with the fuel draining back out of the line you can have a pressure leak somewhere. Also check the rubber line from the tank to the frame rail line. Maybe a fuel filter you're using could be the culprit? The cheap screw together glass filters will do that as well. Also if you have a return line check to make sure that isn't making the lines loose pressure.

Its a crap shoot but who knows it could be something that simple? o No:

That probably won't cure the 10 mph loss but could stop the pump to carb line from draining and siphoning the bowels dry?

You may need a different spark plug with a hotter heat range or cooler? o No:

Check the distributor as well, make sure that is up to running 6,000 RPM. Or you could have a wire going bad that arcs at higher RPM? o No:

A few ideas to look at if you feel like it that I thought I would throw out there.

So the intake wasn't ported as much as some of us thought it may have been, so nothing that should cause the 10 mph loss there I wouldn't think? o No:

Hmmmmm? If I think of anything else I'll get back to you. GL



Derek

 

First thing you would not be able to tune better on some back road compared to going to the track. What are you going to use your butt?

Yeah the dyno will tell you the whole story but going down the track will be the same as running on a dyno.

You have wind resistance which is the same as a dyno pushing against the engine

Torque gets you going but torque falls off as the rpm gets to 5200rpm where at that point the HP takes over. Hp caries you out the top end of the motor not torque. 5250 is the cross over point between TQ and HP. all engines do this.

All you can do is change the jets to get the engine to run its best given what the weather is doing.

If he had the Holley double pumper on there you can change jets in between rounds, I can do it in about 10 minutes taking my time.

You need this much time to let the engine cool down some Obviously you have never been to the track.

Get the AFR meter and you will get it figured out.

BTW the place he went to is the same place I had my motor built 20+ years ago and they build 455 motors too. They know what they are doing

They built Sonney Seals motor over 20 years ago and they Built Roger Reeds motor back then too both 350's and if you know who Paul Pirnet is which I know you don't they did his motor too. (455) over 600 hp with a TA 308s cam.

Demko, go out there and pull the valve covers off and see if you have a broken spring some where.

I am telling you Demko get off this site and talk to people that have actually raced a car at the track. There are actually about 2 people here that have done that and it aint me.

and you cannot compare a Buick with a Chevy that I agree with.

What dist. are you running

Call you know who. Today.

Talk to Michaels too.

 

Mark,
A few posts back, you mentioned that your rockers were making a racket. You better check things out real well. They should be quiet!

 

Tuning on the road is when using an A/F meter. To be used for dialing in the carb jetting. Butt dynos don't work, sorry.

It is pretty much impossible for a fuel pump to drain a float bowl of fuel. The lowest point of the needle and seat would still leave enough fuel for the engine to start. If your tank was not vented it may cause some pull back when the temp cools.
What could be happening is your main wells are leaking which is common on a Q jet, OR with a dropped base air filter its trapping more heat around the carb and boiling out the fuel when the engine is shut down.

 

Im fighting a drain back issue on my brother's car , put the stock filter with a check valve and it seems to have cured it so far anyway, in the past I always pulled them things out thinking they hindered flow but only so much can get past the needle and seat anyway