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2barrelpower
Sitting Bull

USA
135 Posts

Posted - 30 Apr 2015 :  11:41:12 PM  Show Profile  Reply with Quote
So I've been driving my 69 around for about 220 miles since the rebuild.
The idle has improved a lot since adding the four barrel intake/carb. I have a .75" quadra to square, open (undivided) adapter/spacer on the intake.

Initial timing is set to 12. I put the stock vac can back on it, and it looks like it's pulling around 20 degrees, and I have the mechanical advance set for 3200 using some Crane springs.
I have the idle speed set to 1000.
Vac moves between 15-16 at idle. In gear, the vac moves between 10-12, and at speed vac readings are steady.
Temp is fine, 185-190.

Power has improved, but still sucks; off idle power really sucks.
Engine misses sometimes, but much less than it used to.
MPG is about 11-12 for easy 50-60MPH backroads cruising.

I have a 260H cam (212/.44) and 3.08 gears.

The fluttering in the vac concerns me. According to what I read I could have a vac leak at the manifold, sticking valves, loose guides, or a burnt valve.

The heads were machined about ten years ago, bought them off some old guy through Craigslist: valve seats were done and the guides were knurled; springs are stock. I did a little bit of porting myself matched the gaskets and smoothed out the exhaust ports (I know this is a red rag to a bull for some people, but calm down).

I don't think that I installed the cam a tooth off anymore, but I am convinced that things are not right. Where should I look next?

69FB, 350P, 9 to 1, Comp 260H, Stock Valve Train, Performer Intake, 1406 Carb, Hooker Headers, Points Style, Crane XRI, Crane PS20, TH350, stock stall, 3.08 gear, and 235/60/15 Firestones.

Edited by - 2barrelpower on 30 Apr 2015 11:52:03 PM

GtoGuy32
Cochise

USA
842 Posts

Posted - 01 May 2015 :  7:22:54 PM  Show Profile  Reply with Quote
I would yank the heads and valley pan. Have the heads checked and make sure you haven't rounded off a cam lobe or two or more!

It's early spring, you could have it apart and back together in a few weeks time.

That's what I would do.

Dave
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Blued and Painted
Chief PONTIAC

USA
3406 Posts

Posted - 02 May 2015 :  12:39:17 PM  Show Profile  Reply with Quote
first things first. Run a compression test and check for tight valves.


Bull Nose Formula/ 461/ Q-Jet/
TH400/ 3.08 8.5 / R44TS.
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fbird1969
Sitting Bull

170 Posts

Posted - 02 May 2015 :  3:06:22 PM  Show Profile  Reply with Quote
quote:
Originally posted by 2barrelpower


I have the idle speed set to 1000.

Vac moves between 15-16 at idle. In gear, the vac moves between 10-12, and at speed vac readings are steady.

Engine misses sometimes, but much less than it used to.


Is that the idle speed in park or in gear?

I'm not sure about the vacuum thing, I assume you have new valve guides and piston rings since the rebuild? The only thing I can think of is either the cam is not degreed in properly or you have a leak somewhere.

If the engine misses, especially upon acceleration, then I would say to take a look at the mixture quality. I had a problem like that before. Got new metering blocks for the Holley and it never came back.

With my 400, summit 2801, edelbrock 750, and 3.08 rear/24" tire, I was able to knock down mileage around 16 if I was gentle, so there's no reason why you shouldn't be doing better.

Edited by - fbird1969 on 02 May 2015 3:18:35 PM
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2barrelpower
Sitting Bull

USA
135 Posts

Posted - 03 May 2015 :  12:01:20 AM  Show Profile  Reply with Quote
Compression test shows, 150, 140, 145, 147, 150, 150, 145, 145.
The procedure was: engine had been off for two hours, throttle open, all plugs pulled, one squirt of oil, and counted seven grunts.

This is about the same compression before I rebuilt the motor.

Plugs looked nice and tan all the way around. I regapped them to .40 on the account of PS20 coil and XRi.


I adjusted the valves hot.
The procedure was: loosen one at a time, then torque to 23 lbs.

Set idle to 850 in park.
Vac is still 15 (steady) in park and 10-11 (moving needle) in gear.

Ran it around the block, and torque has improved, but vac is still low.

How do I check for tight valves?

Also, FBird69, on your Edelbrock 750, are you running an Edelbrock adapter plate or a spacer?



69FB, 350P, 9 to 1, Comp 260H, Stock Valve Train, Performer Intake, 1406 Carb, Hooker Headers, Points Style, Crane XRI, Crane PS20, TH350, stock stall, 3.08 gear, and 235/60/15 Firestones.

Edited by - 2barrelpower on 03 May 2015 12:28:45 AM
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Phil
The Great White Buffalo

USA
7219 Posts

Posted - 03 May 2015 :  06:52:10 AM  Show Profile  Reply with Quote
Whoa, your not adjusting valves if torquing down. So the $64,000 is do you have stock studs (torque down) or (non-stock) adjustable studs with locknuts?

Bowties are for Pee-wee Herman. "Chevy": even the name sounds cheap, but not as cheap as your Pontiac will be with an LS transplant.
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phil400
Cochise

Canada
456 Posts

Posted - 03 May 2015 :  08:58:09 AM  Show Profile  Reply with Quote
To go along with what Phil asked, are you using pontiac rocker arm nuts with stock studs or are you using Chevy style crimp nuts with the stock studs?

78T/A 4-SPEED Marty blue 400/milled 6x-4's/268H,comp roller tip rockers/ performer Q-jet/RA manifolds 2.25" exhaust with x-pipe/ mine since '99 3rd & final owner as long as I'm alive
"sometimes I do what I want to do,rest of the time I do what I have to"
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2barrelpower
Sitting Bull

USA
135 Posts

Posted - 03 May 2015 :  11:24:51 AM  Show Profile  Reply with Quote
My lift is under .450, therefore I can use the stock Pontiac valve train. Everything is stock.

69FB, 350P, 9 to 1, Comp 260H, Stock Valve Train, Performer Intake, 1406 Carb, Hooker Headers, Points Style, Crane XRI, Crane PS20, TH350, stock stall, 3.08 gear, and 235/60/15 Firestones.
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fbird1969
Sitting Bull

170 Posts

Posted - 03 May 2015 :  12:45:07 PM  Show Profile  Reply with Quote
quote:
Originally posted by 2barrelpower

Compression test shows, 150, 140, 145, 147, 150, 150, 145, 145.

Also, FBird69, on your Edelbrock 750, are you running an Edelbrock adapter plate or a spacer?


Your compression is pretty consistent, which is good, even though it's a tad low. But I don't think that would cause the problem you're having.

I'm not running any spacer or adapter plate on my 750. I'm using an edelbrock square bore intake. But IIRC, the adapter plate only has a significant restriction of about 10-20hp, not vacuum/low rpm characteristics.

If you're not completely sure that it's not a vacuum leak, I would either get a new gasket for the carburetor/adapter, or try using some permatex sealant on there.

I have roller rockers with the lock nuts, so I can't really comment on your valvetrain, but I can say that even a small mis-adjustment will hurt performance all around, so I would double check that.
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2barrelpower
Sitting Bull

USA
135 Posts

Posted - 03 May 2015 :  1:53:19 PM  Show Profile  Reply with Quote
I take it you're using an Edelbrock Torker?

69FB, 350P, 9 to 1, Comp 260H, Stock Valve Train, Performer Intake, 1406 Carb, Hooker Headers, Points Style, Crane XRI, Crane PS20, TH350, stock stall, 3.08 gear, and 235/60/15 Firestones.
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Blued and Painted
Chief PONTIAC

USA
3406 Posts

Posted - 03 May 2015 :  4:25:07 PM  Show Profile  Reply with Quote
Oil is added to the cylinder which shows low compression as a diagnostic aid to determine if ring or valve is at fault. Not as a general practice.

IMO this cam wont idle smooth or show factory vacuum in a 350. Could i be mistaken?
-- http://www.compcams.com/Company/CC/cam-specs/Details.aspx?csid=1194&sb=0


Bull Nose Formula/ 461/ Q-Jet/
TH400/ 3.08 8.5 / R44TS.

Edited by - Blued and Painted on 03 May 2015 4:29:26 PM
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2barrelpower
Sitting Bull

USA
135 Posts

Posted - 03 May 2015 :  6:22:25 PM  Show Profile  Reply with Quote
This guy is getting 17in with a 220 duration cam, but he does have higher compression than me.
https://www.youtube.com/watch?v=KgcZW7JNhvk

Isn't seat to seat timing important for vacuum characteristics? I figured the 260H should be tame at idle and comparable to the stock U cam (269).

I guess it's conceivable that it could be too big for a 350, but I would be shocked if it was.

69FB, 350P, 9 to 1, Comp 260H, Stock Valve Train, Performer Intake, 1406 Carb, Hooker Headers, Points Style, Crane XRI, Crane PS20, TH350, stock stall, 3.08 gear, and 235/60/15 Firestones.
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2barrelpower
Sitting Bull

USA
135 Posts

Posted - 03 May 2015 :  8:04:16 PM  Show Profile  Reply with Quote
Ok, something weird just happened. Vacuum went up when I pulled the vac line going to the tranny. I then tried the same thing PCV valve. https://www.youtube.com/watch?v=bwRZ1HSCe08

PCV line is hooked up the manifold, just how it was on my 2barrel manifold.

Am I missing something here? I figure Vac would go down.

Edit:
Resolved, idle was too rich.

69FB, 350P, 9 to 1, Comp 260H, Stock Valve Train, Performer Intake, 1406 Carb, Hooker Headers, Points Style, Crane XRI, Crane PS20, TH350, stock stall, 3.08 gear, and 235/60/15 Firestones.

Edited by - 2barrelpower on 03 May 2015 10:08:25 PM
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phil400
Cochise

Canada
456 Posts

Posted - 03 May 2015 :  9:39:36 PM  Show Profile  Reply with Quote
Tighter LSA will give choppier and lower idle vacuum, @ 110 the comp cam is much tighter then the stock one @113~115, also a single pattern-110 LSA cam with log manifold will idle rougher because the intake charged will diluted with exhaust gas.

I can't explain the vac going up when creating a vac leak other then it seems the engine wants more air at idle.

Sorry cant help more more.

78T/A 4-SPEED Marty blue 400/milled 6x-4's/268H,comp roller tip rockers/ performer Q-jet/RA manifolds 2.25" exhaust with x-pipe/ mine since '99 3rd & final owner as long as I'm alive
"sometimes I do what I want to do,rest of the time I do what I have to"
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2barrelpower
Sitting Bull

USA
135 Posts

Posted - 03 May 2015 :  10:11:00 PM  Show Profile  Reply with Quote
Phil, could you explain more about how the intake will be diluted with exhaust gas.

69FB, 350P, 9 to 1, Comp 260H, Stock Valve Train, Performer Intake, 1406 Carb, Hooker Headers, Points Style, Crane XRI, Crane PS20, TH350, stock stall, 3.08 gear, and 235/60/15 Firestones.
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fbird1969
Sitting Bull

170 Posts

Posted - 04 May 2015 :  12:01:46 AM  Show Profile  Reply with Quote
quote:
Originally posted by 2barrelpower

Phil, could you explain more about how the intake will be diluted with exhaust gas.


The intake charge (not the intake manifold itself) will be more diluted with exhaust gasses with the log/oem style manifold because the log style manifold is less efficient, resulting in more back pressure, which allows less of the exhaust to escape during the exhaust stroke.
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phil400
Cochise

Canada
456 Posts

Posted - 04 May 2015 :  07:25:08 AM  Show Profile  Reply with Quote
^^^^^^^ That's what I meant, couldn't have explained it better.

78T/A 4-SPEED Marty blue 400/milled 6x-4's/268H,comp roller tip rockers/ performer Q-jet/RA manifolds 2.25" exhaust with x-pipe/ mine since '99 3rd & final owner as long as I'm alive
"sometimes I do what I want to do,rest of the time I do what I have to"
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2barrelpower
Sitting Bull

USA
135 Posts

Posted - 04 May 2015 :  11:51:54 AM  Show Profile  Reply with Quote
Would headers help?

69FB, 350P, 9 to 1, Comp 260H, Stock Valve Train, Performer Intake, 1406 Carb, Hooker Headers, Points Style, Crane XRI, Crane PS20, TH350, stock stall, 3.08 gear, and 235/60/15 Firestones.
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Blued and Painted
Chief PONTIAC

USA
3406 Posts

Posted - 04 May 2015 :  9:13:18 PM  Show Profile  Reply with Quote
Probably not much difference at idle with the 2 different type exhaust manifolds.

When you reduce the Lobe Separation Angle you increase valve overlap (length of time in degrees when both intake and exhaust valves are open). It's good for filling the cylinder in the power range but creates an internal vacuum leak most noticeable at idle.

The lift and duration numbers are not big but the LSA makes it act big.


Bull Nose Formula/ 461/ Q-Jet/
TH400/ 3.08 8.5 / R44TS.
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2barrelpower
Sitting Bull

USA
135 Posts

Posted - 04 May 2015 :  9:43:34 PM  Show Profile  Reply with Quote
Interesting.

I drove it on the highway today; at 55 on level ground, I get 16 inches of vacuum, but only 11 mpg. My friend thinks that my vacuum secondaries are kicking in at cruise. I'm going to put in stiffer springs and see if that helps. Does anyone have any other ideas?

69FB, 350P, 9 to 1, Comp 260H, Stock Valve Train, Performer Intake, 1406 Carb, Hooker Headers, Points Style, Crane XRI, Crane PS20, TH350, stock stall, 3.08 gear, and 235/60/15 Firestones.
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phil400
Cochise

Canada
456 Posts

Posted - 04 May 2015 :  10:43:51 PM  Show Profile  Reply with Quote
I don't think Headers would help with the idle either. 15~16 at idle seems pretty good for a 110 LSA cam I wouldn't even sweat that.

I have no experience with eddy carbs other than setting the idle mixture, but I've read and heard that they don't get the best MPGs, if your serious about getting better mileage start looking for a Q-jet.

78T/A 4-SPEED Marty blue 400/milled 6x-4's/268H,comp roller tip rockers/ performer Q-jet/RA manifolds 2.25" exhaust with x-pipe/ mine since '99 3rd & final owner as long as I'm alive
"sometimes I do what I want to do,rest of the time I do what I have to"
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2barrelpower
Sitting Bull

USA
135 Posts

Posted - 05 May 2015 :  01:51:00 AM  Show Profile  Reply with Quote
I had a 1406 on a 350 Chevy, 222 cam, 115LSA, got 18mpg. I know the QJet is king, but the Ebrock is not a disaster.

69FB, 350P, 9 to 1, Comp 260H, Stock Valve Train, Performer Intake, 1406 Carb, Hooker Headers, Points Style, Crane XRI, Crane PS20, TH350, stock stall, 3.08 gear, and 235/60/15 Firestones.
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fbird1969
Sitting Bull

170 Posts

Posted - 05 May 2015 :  3:08:09 PM  Show Profile  Reply with Quote
You have the 1406, correct? That one is supposed to be calibrated for fuel economy. I would double check to make sure something isn't out of whack like a jet or metering rod.

Try setting up the carb for performance. I know it seems like the opposite thing to do, but my 750 had the richest jets AND rods in it, and I got 16mpg with a 400 and 3.08 rear. I was pretty surprised, but remembered that edelbrocks are a bit too lean as-is.

Performance specs for the 1405 carb:

Metering Jets
- Primary .100,
- Secondary .095

Metering Rods - .070 x .047

Step-Up Spring - orange (5" Hg)
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2barrelpower
Sitting Bull

USA
135 Posts

Posted - 05 May 2015 :  3:59:37 PM  Show Profile  Reply with Quote
I'm going to start tuning up the carb in a few days. I'll keep what you said in mind.

69FB, 350P, 9 to 1, Comp 260H, Stock Valve Train, Performer Intake, 1406 Carb, Hooker Headers, Points Style, Crane XRI, Crane PS20, TH350, stock stall, 3.08 gear, and 235/60/15 Firestones.
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2barrelpower
Sitting Bull

USA
135 Posts

Posted - 10 May 2015 :  01:48:15 AM  Show Profile  Reply with Quote
I bought an Edelbrock 2696, square to quadra adapter. I picked up three inches of idle vacuum (18) by installing it.

The open style 2692 I was given and the 2731 plate that I bought both did not isolate the two sides of intake which reduced idle quality in the way that a Torker would.

Here's a quote from a 2005 Hot Rod article, "Manifold Destiny", that I read that convinced me to properly divide the carb:

Perhaps the greatest benefit to lower rpm and part-throttle operation with the 180-degree design is that it also largely separates the communication of the induction pulse from the exhaust system. With a single-plane, the wide-open intake valve of a cylinder at peak piston speed on the intake stroke is communicated directly into the plenum, as it should be. At the same time, another cylinder in the overlap phase is also open to the same plenum. At low speed, especially with high-overlap cams, and most acutely at part throttle, this tends to draw exhaust gasses into the cylinder in the overlap phase. This reversion causes rougher low-rpm running and a penalty in torque production until the air speed and overlap tuning effect overcomes the tendency towards reversion at higher rpm. With the 180-degree system, this pathway is greatly reduced, improving idle quality, vacuum, and part-throttle responsiveness.


I'm going to fiddle more with the jets, rods and timing tomorrow.

69FB, 350P, 9 to 1, Comp 260H, Stock Valve Train, Performer Intake, 1406 Carb, Hooker Headers, Points Style, Crane XRI, Crane PS20, TH350, stock stall, 3.08 gear, and 235/60/15 Firestones.

Edited by - 2barrelpower on 10 May 2015 6:12:19 PM
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Cliff R
Cochise

USA
535 Posts

Posted - 28 May 2015 :  08:39:04 AM  Show Profile  Visit Cliff R's Homepage  Reply with Quote
The 1406 is a POS right to start with, and an even bigger POS used on a stock intake with an adapter.

It will fair better with a fully divided adapter, but those carbs are based on a design that wouldn't get thru emissions clear back in 1968, so don't expect sparkling performance or fuel economy from it.

The cam is also a poor choice for what you are doing. Pontiac engines hate small cams on tight LSA's right to start with, so it will not make the best power, or be all that efficient, especially with 350cid and 9 to 1 compression.

My advice, yank the cam and install a Crower 60240, 210/222/112 LSA. Find a later model q-jet and completely/correctly rebuild it and calibrate for what you are doing, convert it to E-choke at the same time.

My 455 making nearly 600hp gets 5 more mpg's than your set up, with 3.42 gears and 3500 stall converter, so there is a LOT of efficiency left on the table, and LOTS of room to grow with your set-up.......Cliff

If you can read this, thank a teacher. If you can read this in English, thank a Veteran.
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2barrelpower
Sitting Bull

USA
135 Posts

Posted - 29 May 2015 :  11:35:52 AM  Show Profile  Reply with Quote
Thank you for the recommendations.

69FB, 350P, 9 to 1, Comp 260H, Stock Valve Train, Performer Intake, 1406 Carb, Hooker Headers, Points Style, Crane XRI, Crane PS20, TH350, stock stall, 3.08 gear, and 235/60/15 Firestones.
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tjs44
Cochise

USA
412 Posts

Posted - 29 May 2015 :  7:36:48 PM  Show Profile  Reply with Quote
2X what Cliff said.Modded factory intake and a properly preped QJ would be way better.Tom
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