Inliners International Forums General Discussion Blown and Injected snowman4839 turbo build

The 250 dyno carb was set to factory specs at first and then only jetted it up by 2. Stock squirter.

Your stumble sounds bad. Like something else is wrong.

Tell us about timing setup.
At idle with or without vacuum line also. How about total timing at 3500 rpm without vacuum.

MBHD - Yes it had a flare on the end on the fitting in the pan. I don't know much about it but it doesn't leak so I'm happy.

IIRC, it's supposed to be like 650rpm I think.

Tom - I have 8 degrees initial (without vac advance hooked up). Not sure what the mechanical is so I can't tell you the total timing.

I've tried fixing the stumble by adjusting timing both ways and disconnecting the vacuum advance and none of that helped at all.

Vacuum advance is hooked to manifold vacuum.

snowman4839,

did you get your larger squirter installed yet?

IIRC, you had just installed an HEI unit?
How did you hook up the power lead? Did you use the factory power/positive lead wire for the points unit?

You can try hooking up yout vacuum advance to the carb port/port vacuum? (the one above the throttle blades), there will be no vacuum @ idle, but once you crack the throttle, you will get vacuum, just so you can see if your engine likes the timing to come in that way. This wont cure your lean condition when you stab the throttle, just something for you to experiment/play with.

http://www.hotrodders.com/forum/port-full-time-vacuum-23169.html

MBHD

Ok so I got the larger squirter installed so now I have a 33 squirter with a 30cc shot and an orange pump cam.

Yes I installed a GM HEI dizzy. I couldn't tell you exactly how I hooked up the dizzy because I had a diagram showing me how to hook it up when I installed it. All I can tell you is that I used a relay that switched on power to the HEI using the old points positive lead as the switch. I hope that made sense

I had my vacuum advance hooked up to ported vacuum for most of the time I had the car. It's funny that you link to that page because that is the exact page I read that made me decide to switch to manifold vacuum. I guess I can try it anyway.

I ended up getting mad at it since the 33 squirter didn't fix the lean stumble and trying a drive around the neighborhood. My AF ratios were all over the place and it would die halfway into throttle and then it'd work fine for the next pull. I had no idea what was going on with it. I got my dad in the car to take him for a drive and he suggested we go get some gas. I got a full tank of 93 and what do you know? 85% of the problems went away. I guess the pump just wasn't picking up fuel and was running the carb out of fuel but I can drive it around and it pulls pretty good now. I still have somewhat of a lean stumble if I move it anywhere past half throttle but I'll play around with pump cams and pump shots and power valves and see if I can't fix that.

At cruise my AF ratios are about 13.5 which I think is great. That's with 71 jets. I have a 6.5" of Hg power valve and I think that's something that giving me that big hole in the middle of my throttle movement because I pull 24" of Hg at idle and about 26" of Hg at cruise.
I notice that under medium acceleration, the AF ratios are stay about 14 as long as I keep the vacuum above 12" of Hg and my ratios never really move above 15 before moving back down to 14 for the rest of the acceleration.
But if I drop the vacuum to anywhere in the range of 7-12" of Hg for acceleration, it shoots to lean and then slowly returns back to 14 for the rest of the acceleration.
If I drop under 7 (as in full throttle), there's a slight stumble and it shoots to about 17 and then smooths back out to 14 for the rest of acceleration.

I think my power valve is too tight since I have so much vacuum so I ordered a 4-door 10.5 power valve today and I want to see if that helps. I also know I need to drill out the PVCRs from stock .060" to the next size which is .064" after I try this power valve because it is still running kinda lean in boost.

But considering cruise is 13.5 and acceleration is about 14 and idle is just a little rich at 11.5-12. I think I'm in the ballpark for a good running car.

btw, IT'S REALLY FAST :-)))))))))))
And I'm running 10psi of boost as it turns out. not 8psi.

Ok, sounds like you are getting some progress.

I think I said before, under W.O.T. you should shoot for 10.8 or so A/F ratio. This should be a pretty safe A/F ratio especially since you have no way of cooling your intake charge.

If you can get a bit closer to the 14's A/F ratio @ cruise, it will get better fuel mileage.

Under medium acceleration (no boost) you should shoot for roughly 12:s-13.s A/F ratio, 14:0 A/F ratio is too lean for medium acceleration.

You never want to be in the 14's or higher like 15 under medium acceleration in boost.

If you see your A/F ratios going lean like 14:0 or so when in boost I assume, this is too lean, I believe you should shoot for in the 10.8- 12.3 range or so when in boost, not in the 13's or 14's & definately not in the 15's

Post vids when you are accelerating, if you like.

Thanks

MBHD

you have no way of cooling your intake charge

X2 - black smoke is better than finding bits of piston in your exhaust pipe.

Re lean stumble:

You might try flycutting the metering block mating surfaces - they are "as cast - unmachined" from Holley. Also note the spongy quality of the casting of the carb body on the left. Pray you don't have one of these.

So I figured the 24 HG is really 12 inches @ idle, seems pretty low, but I think that is because the timing is retarded?

If your W.O.T. runs will get richer by increasing the PVCR larger,,, I would drill out the PVCR to the minimal increase in size, you are way too lean @ W.O.T., & if you are going to run more boost pressure, it will be even more lean.

Just do one adjustment @ a time.

MBHD

MBHD,
How do you figure 24HG is really 12 inches of vacuum? 24 would be 24" of mercury. Vacuum in Inches is in reference to mercury most of the time.

Either way, I do not think his guage is reading correct at idle or boost. Most engines will not produce vacuum reading that high at idle.
Iregardless his carb tune is off and needs to get under control.

Snow,
You reaaly need to do tuning , one step at a time. This includes timing and carb.

My 292 has O2 readings like this. idles at 12.75, cruises at 12.5 and full boost is 11.25 or so.
Timing 23-25 at idle (total) , 48 cruise, 27-28 under boost.

Your meter will read different than mine, they all do. Best tip is to add fuel at first and then lean it up slowly with tuning.
Start with a stock setup, unmodified carb(PVCR). Then get started.

24 Inch of mercury [c)converted to pound/square inch = 11.787 699 654 pound/square inch

Unless I am using the incorrect formula?
http://www.onlineconversion.com/pressure.htm

I believe snowman is starting w/a stock set-up,unmodified carb? Yes/no? He has been getting started for a while now.
I think he needs to do some changes quickly if that engine is to survive running 14:0 & up to 17:0 A/F ratio @ 10 psi of boost pressure on 87 octane gas, no intercooler, & a heavy foot, no knock sensor & a loud exhaust w/no muffler,,,hard to hear detonation I would think?

MBHD

Tlowe,
just curious how much total timing you have run @ cruise & when you have gone over 48*,,, what happens, does the engine start to buck & not like it , or ?

MBHD

My engine starts to get a small buckiness to it, almost like it is missing. Been a while since looking at it timing curve, but may have high as 52 degrees.

You've got best mileage @ 48 or so degrees?
Reason I ask because my Syclone seems to only have about 35* total timing & would like to increase it some more to get better mileage.

I forgot, did you ever run the Elky w/no intercooler?
If yes, how much did it improve the power output?

MBHD

Bet yours has a little more than 35 at cruise. Might be hard to measure. Are you able to set the computer timing?

I have always had a intercooler. Bet with 10PSI Snow is seeing 250 degree intake temps. Try grabbing that charge pipe!

Tom, You are about right on snowmans intake temps, his turbo is sized perfect for 15 psi and 400 HP. right in the 80% range.

Snowman, remember a CARB is a poor mans intercooler, the fuel cools off the intake charge in the intake manifold a lot, on a turbo you set the A/F ratio for max HP first (11.0 to 1) then make it driveable after you know the amount of fuel you need for max HP. You need to control the cyl, temp because the fuel amount and the ignition timming effects all of this in the end.
Only change your jets it get your fuel set for max HP then you can fine tune it after you know how much total fuel you need.

Did you up grade the fuel system? this needs to be done first.

Good Luck

Harry

Sorry I haven't responded in awhile guys. Family and working on my reverse linkage has taken up some time.

This is the gauge I have and it says it reads 0-30 inches of vacuum and my car pulls 22 on cold idle, 24 on warm idle, and 25-26 on cruise. Take that for what you will. http://www.amazon.com/gp/product/B000MZUI5K/ref=oh_o01_s00_i00_details

I have a stock 500cfm 2bbl holley right now with 71 jets, a 6.5 PV, and stock PVCR size for right now. All I've done to it is saw off the choke horn and the choke was already removed when I got it. It' been completely rebuilt.

I am running 93 octane for now until I get the other fuel cell I don't have the fuel system yet because I told my parents what I need and I'm going to see what they get me for christmas and then buy the rest after christmas.

My dad just got me a numbered set from 1-60 and closest bit to the stock size is a 53 bit which is 0.0595" but it's actually .06". I'm just going to go up by one bit size and drill it out til I get it as rich as I want it.each bit goes up by about .004"

I noticed that it sounds fine through first, second, and third but if I floor it at a slow speed in fourth gear and let the boost build slowly then it'll build up some and then I can hear it detonating and the AF ratio is maybe a little bit leaner than the other gears. Does this mean it's probably detonating in the other gears too and I just can't hear it?

Could be running out of fuel or need a boost retard.

Higher gear = more load = need of more fuel.

Snowman,

Sorry but first get new fuel system!

Set total timming to 30* to 34*.

Turn idle screws 1 1/2 to 2 turns out

Open throttle but do not uncover transfer slots, if it will not idle, drill throttle plates .100 hole. to bypass some air.

Use brown accelerator cam make sure there is a little pressure on the diaphram, .035 squirter. May need a 50cc pump.

Drive at full boost read A/F, need (11.0 to 1) change jets only do not drill anything. When you reach this goal figure the total area of jets and pvrc. INSTALL a 2.5 power valve. Jet down and drill pvrc to keep area the same, a little at a time until driveability is good and A/F is (12.5 to 1) if it tries to bog change to smaller squirter or backfire change to bigger squirter.

Works for me.

Harry

Snowman,


Snowman

You are probably detonating & you cannot hear it. No muffler?

When you are saying it is a bit leaner in 4th gear,,, what is the A/F ratio?

Most likely you are running out of fuel & part of the reason is because you do not have a boost reference line.
I honestly do not understand why you would not install a boost reference line hooked up to your bonnet. Hooking it all up will make the engine a bit safer than the way you are running it currently & cost maybe $10.00.

A quick drill & tap & install a NPT fitting into the fuel pump. http://www.ebay.com/itm/New-Brass-Hose-B...=item19cbd35e25 & hose & you will get more fuel delivered to your float bowl.

MBHD

MBHD,
Boost reference line on bonnet hooked to what?

Harry

To his fuel pump.
He attempted to hook it up but just drill a hole & JB weld the small fitting which broke off or came loose.

MBHD

He needs a fuel system, not just a boost reference.

Harry

Harry,

I know he needs a whole new fuel system.
I also told him the 5/16 fuel line (from the gas tank & fwd) is too small.

I am saying for now at least hook up a boost reference line so it does not run out of fuel as soon.

By the time he puts up a whole new fuel system it will probably be too late KABOOM!, just saying for now to do something in the meantime to get by, it will work better than no boost ref line, which is the way it's been & he thinks it does not do anything.
http://vs57.y-block.info/fuelpump.htm

MBHD

Snowman,

just curious as to how your 4 speed is working out?
Did you get the column shifter to work?

Also, any updates on how you made out for X-Mass.
Did you get some parts for your fuel system or ??

MBHD

Sorry I haven't been posting guys. Things to do.

Yeah I have no problem with the 4 speed working. I've driven it around quite a bit. I have all four gears working great. Only problem is I haven't find a way to get reverse working.

I ended up getting the fuel cell, fuel pump, and a fuel pressure regulator for christmas. I spent my saved money and christmas money on all the fittings and tubes and lines and stuff. I have about 90% but I'm waiting on a few filters and stuff from overseas so it might be a bit.

I also got a new 10.5 powervalve but I haven't installed it yet. I've just been enjoying my christmas break off of school. but now that I'm getting back into the routine, it shouldn't be long before I weld up a mount for the cell and get the new fuel system installed.

There's the setup so far minus the valves and filters I'm waiting on. The cell, pump, and regulator will be in the back of the car with 8AN lines in between all of them. Then there will be one 6AN from the regulator running through the trunk floor, under the car, and up to the carb. I bought a 25ft long spool of vacuum line (in the picture on the left) to run the line to the regulator to for the rising rate.


Walbro 255LPH (67GPH) High Pressure Fuel Pump.


Mallory 4307M Pressure Regulator. Base is like 4-12psi and has 1:1 vac/boost rising rate.

snowman,

The fuel regulator must be as close to the carb as possible and a return line back to the tank from the regulator, you want the least amount of fuel dead headed to the carb. or else the regulator does not work as a return regulator the fuel will get hot, will be hard on the pump, the response of the fuel pressure rise will be to slow.

You need a 2.5 power valve or else don't use one at all.

Just trying to help.

Harry

Why wouldn't the regulator work if it stays in the trunk? I don't see how it would be any different than if it had to travel a long way up to the engine bay rather than just staying in the trunk. They'd both still have a lot of fuel circulating through the lines since my engine doesn't need much fuel as that pump produces. So like 80% of the fuel would just be circulating in the trunk going from cell to pump to reg back to cell which would just provide a cooling effect. You're also talking serious money if I move the pressure regulator to the front because that's another $100 of fuel line because it has to run the length of the car.

Why 2.5 or none? I don't have any extra fuel between 11" and 6" of vacuum but once I drop it below 6" and it gets through the stumble from not having the power valve opening, it works fine. It's jetted perfect for cruising because i get a 13.0AFR on cruise and it stays great for anywhere under 11" of vacuum. If I go under that, it leans out badly until I get the vacuum low enough to open the power valve. I can get a 13AFR up until 11", then between 6" and 11" it shoots up to 17 or 18, and below 6" it goes back down to 13AFR.

http://www.jegs.com/InstallationInstructions/600/650/650-4307M.pdf
This pdf file states

You can mount the 4307M regulator at any angle. For maximum
efficiency, mount it as close as possible to the carb or throttle body. DO
NOT mount the regulator on or near exhaust manifolds.

Also,
I believe if you have a trunk mounted fuel cell, you need to have a piece of sheet metal (a certain thickness)to cover the whole back area where the back rests in the back set.

I guess look up NHRA car saftey requirements to make sure.
If you are going to a NHRA track or just be safe in general.


MBHD

I read that. I knew the angle didn't matter but I just wanted to know if anyone had problems mounting the regulator in the back. I can deal with a little inefficiency if it saves me $100 as long as it still works.

I read that too but I'm going to weld up an angle iron and sheet metal cage for saftey to protect the cell. But I will install a piece of sheet metal between the trunk and interior if my track requires it.
I tried looking up the NHRA fuel cell rules but never found much useful info.

On a turbo you use the power valve as a secondary fuel enrichment for boost,that is the reason for the 2.5 power valve.

As I have said before with a turbo you set the max fuel first then tune for driveability, after you know the total fuel demand for your HP. I have never had a carb back fire other than at full boost, you have many other issues to fix first.

Ask anyone about the location of the regulator, there are many reasons to place it as close to the carb and NO reason other than $ not to do it.

Harry

Page 63 of the NHRA rule book says .024 steel or .032 aluminum bulkhead if fuel cell is in trunk. Listen to the guys on the regulator. It needs to be as close to carb as possible. My engine is fed with an AN-10 with AN-8 return. There are cheaper, safe ways to go besides the braided stainless and aluminum fittings. If cost is an issue, which it certainly is for me look into other materials.

Just had an idea if you really want the regulator in the rear.

You can run the line from the pump to the carb then return a line from the carb to the regulator then the tank. But you will still have the slow responce of the fuel pressure rise to the regulator diaphram. And it will cost the same.

Harry

Well I got some time today to swap the power valve and enlarge the power valve restriction size. I changed the PVCR size from stock .060" to 2 numbered drill bits up to .067". I also changed the power valve from a 6.5 to 10.5 and now it runs FANTASTICALLY.

I used to have a large lean hump from anywhere between 10.5" and 6.5" of vacuum but now that is completely gone. It does however stutter if I stab the throttle fully but that seems more like a accelerator pump problem. If I do a normal controlled hard acceleration and roll into the throttle relatively quickly, it starts at low 13, jumps to low 15 and rolls back into a low 13 or high 12 as it gets into boost. I know it might need one more size up on the PVCR but I'm going to wait until I finish out the new fuel system and get it installed.

All in all... the 10.5 power valve and two size jump on the PVCR size did wonders. It runs great but I just can't stay in boost or it runs out of fuel in the carb.

Thats great its running better. You also changed atleast 2 or more things with your carb. Harder to tell what really did make it run better.
But to give you more tips on tuning the Holley.
Harry is right, the PV needs to be relatively low in #, like 3.5-4.
The 10.5 PV you have is open practically all the time. So you are getting fuel from
1. Main jets
2. PV and its channel restrictions.

What I am wanting you to do is.
Jet the mains for normal driving (cruise). Have the PV open only when the vacuum is low (like 3.5-4) ,IE when you starting to get into the throttle and drill the PVCR to supply the fuel needed when under boost.

Lets see some video of this car under boost. Tom

Hey guys,
my first post here on this site.

I have read & re-read this post so many times I figured it's time to sign up as a member rather than a surfer.

Tons of hard work and info here.

This is my next project and as some of you already know I have spoken to you either by email or phone call.

Keep up the good work truely inspirational.

Thanks,
Stu

Tom - I don't see why you guys are saying that 10.5 is going to always keep the PV open. I keep 26" of vacuum at idle. I keep about 20-22" of vacuum at cruise. I keep 12"+ at medium acceleration. <12" of vacuum at hard or full acceleration. I cruise at 13.0 AFR and boost at about 13.2AFR. It's running great. I'll try to get some video up soon

RedMan* - Thanks man. That post really means a lot. Send me a message if you have any questions and I'll help you the best I can. And welcome to the forum!

I just went back through and noticed I didn't have any pics up of the rebuild/paint/reinstall. So here those are.

Snowman, Where is the vac. gauge hooked to the engine, is it a boost and vac. gauge?

Harry

Snowman,

I thinks it's time to change this: "1969 Buick Special Deluxe. Chevy 250. What could be better? "

Need to add turbocharged.

Maybe this?

1969 Buick Special Deluxe. Turbocharged Chevy 250. What could be better?

MBHD

I had given the formula in a previous post to figure his actual vacuum.
Because there is no way the engine can produce 26" of vacuum @ idle.Only on a different scale it produces 26"'s
Here is the website to use the conversion.

http://www.onlineconversion.com/pressure.htm


MBHD