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-   -   Hp body upgrade (http://www.hotrodders.com/forum/hp-body-upgrade-232885.html)

bygddy 05-14-2013 06:19 PM

Hp body upgrade
 
Look what i got today, Holley HP mainbody upgrade. Went together really nice, unfortunately didn't come with smaller bleeds so I have to wait until tommorow to try it out.
They come set up for 4 corner idle with 75/36 and 75/36, need it to be 75/36 and 36/36
So will see how it works then. Tonight I'm installing an accel adjustable vacuum canister. Woo
http://i41.tinypic.com/30wbj49.jpg

F-BIRD'88 05-15-2013 05:54 AM

When I did mine I had to fine tune the primary idle air bleeds further.
(My donor carb was a 700DP).. Needed a slightly smaller primary idle air bleed to get it just right.
Soldered up the 75 and redrileed with a .062" 1/16" drill bit. Then hand honed it to the size needed with the drill bit until it was dead nuts. It is about .064" +/-. The AFR gauge allows you to really dial in the idle circuit.
It was balky off idle. Off idle lean spot ....Now it is very sharp and smooth.
Depends a lot on which metering blocks (donor carb) you use.

the idle air bleeds in the stock donor carb body are your clue. Have a look.

Richiehd 05-15-2013 05:46 PM

This whole thing sounds interesting, but not sure what you doing? Do you take a regular double pumper and replace the body of the carb? whats the 75/36 36/36 all about? And so now this becomes a Holley hp, but only 2 idle screws?

bygddy 05-15-2013 07:44 PM

Quote:

Originally Posted by F-BIRD'88 (Post 1675739)
When I did mine I had to fine tune the primary idle air bleeds further.
(My donor carb was a 700DP).. Needed a slightly smaller primary idle air bleed to get it just right.
Soldered up the 75 and redrileed with a .062" 1/16" drill bit. Then hand honed it to the size needed with the drill bit until it was dead nuts. It is about .064" +/-. The AFR gauge allows you to really dial in the idle circuit.
It was balky off idle. Off idle lean spot ....Now it is very sharp and smooth.
Depends a lot on which metering blocks (donor carb) you use.

the idle air bleeds in the stock donor carb body are your clue. Have a look.

Yah, i found the post from when you first did yours, I'm likely going to order an AFR guage next month and work on fine tuning....I had a btch of a time finding bleeds today, I did eventually find some and will pick them up tommorow. For now I'm just going to run the reccomended 75-36-36-75 primary and 36-36-36-36 secondary (for 2 corner idle). It pisses me off that Proform includes the extra bleeds for their mainbody for 2 corner idle but the genuine Holley ($40 more) didnt. The metering blocks are from my 4779

bygddy 05-15-2013 07:51 PM

Quote:

Originally Posted by Richiehd (Post 1675904)
This whole thing sounds interesting, but not sure what you doing? Do you take a regular double pumper and replace the body of the carb? whats the 75/36 36/36 all about? And so now this becomes a Holley hp, but only 2 idle screws?

Yah, you can use a 650, 700, 750 vacuum or dp and upgrade it with either a proform or Holley HP mainbody. Chokless, smooth entries, downleg boosters and adjustable air bleeds are the biggest benefits. Much more tunable. For 650 guys its an easy upgrade to a 750 for $150
The high speed and idle air bleeds are the numbers I listed. A standard Holley has to be drilled to make changes, generally only pricey "race" stuff has removable bleeds.

F-BIRD'88 05-16-2013 01:04 AM

1 Attachment(s)
.I had a btch of a time finding bleeds today,
quote


Thats why I just solder up and re-drill re-size my own.


On the stock Holley 4779 carb body what are the sizes of the air bleeds?

Useing a narrow band type (heated) 02 sensor and Summit/Autometer gauge
(you can also read the Narrow band 02 sensor's output with a digital volt-ohm meter)

bygddy 05-16-2013 08:22 PM

OK, so its on and it runs, I installed 36's instead of the 75 iab's as per Holley for a 2 corner idle. Its still pig rich at idle. Went back to the 75's and no real change. Almost as if the Carb isn't responding to the change.
Timing is at 26* initial, with an additional 10* of vacuum.
36* total. On test drive its unreal, snappy, power everywhere, no bogs stumbles etc. Part throttle in OD it pulls clean from low rpm etc. So it seems right across the board, and is def making more power then it was. Any suggestions from anyone who has done the HP or proform upgrade to help my idle? I'm a few weeks at least from getting a wideband so i can't make drastic changes but do wanna clean up the smelly idle.
Here is the set up.
355, 10:1 comp
Pro-filer 195 heads.
218/218@.50
454/454 lift
Performer rpm
4779 with HP main body upgrade with screw in bleeds
Primary are 75 hsb and 36 iab
Secondary are the same.
Any suggestions?

bygddy 05-16-2013 10:01 PM

Would lowering my floats help the rich condition at idle? Right now fuel comes trickling out the sight plugs. So i could go lower. Forgot to mention i did replace the PV so its isn't blown.

F-BIRD'88 05-17-2013 02:49 AM

Define: too rich at idle.... How are you determining this?

Are the idle mix screws active? can you stall it by turning in the idle mix screws?
How many turns out are the idle mix screws when the idle is set correctrly, using a vacuum gauge.?

The float height has a minor effect on the whole fuel curve.

bygddy 05-17-2013 03:59 AM

Quote:

Originally Posted by F-BIRD'88 (Post 1676272)
Define: too rich at idle.... How are you determining this?

Are the idle mix screws active? can you stall it by turning in the idle mix screws?
How many turns out are the idle mix screws when the idle is set correctrly, using a vacuum gauge.?

The float height has a minor effect on the whole fuel curve.

Mixture screws are app 1 turn out, maybe 1 1/4. Yes they are responsive and will shut the car off when dialed too far in. Using a vacuum guage I'm showing a steady 15hg in drive at 650rpm.
By "too rich" I'm saying it makes your eyes water anywhere near the back of the car, and very very minor dark smoke at idle at the tailpipe.
Your Canadian, you know how some mornings its just cold enough to very lightly see your exhaust when the car is warming up, that's what its like.
Yes I nknow I need a wideband but can't make that happen until next month.

ap72 05-17-2013 09:31 AM

a wideband won't help you at all on your idle. In fact it can make things worse as they do NOT give an accurate reading at idle, use your vacuum gauge.

F-BIRD'88 05-17-2013 12:30 PM

By "too rich" I'm saying it makes your eyes water anywhere near the back of the car, and very very minor dark smoke at idle at the tailpipe.

Yes I nknow I need a wideband but can't make that happen until next month.


quotes

This does not indicate a "rich" idle. What it indicates is raw unburned fuel in the exhaust.
Poor combustion at idle. Misfire... late combustion.
If the idle screws are active like you say then the idle circuit is not too rich.

But the combustion is not complete. One or more cylinders are misfireing at idle
one or more cylidners getting a different afr mix at idle (leaner,,,,vacuum leak.)
manifold plenum too cold. poor fuel mix/vapourization... fuel pudding in the manifold. Cold...
late spark advance at idle. Ignition system fault causing missfire... cross fire spark scatter. cap coil rotor wires
leak in the header gasket at the head.
all these will throw off idle idle. leaky valve. liquid fuel will not burn. poor fuel mix (there is enough fuel but it is not mixed well-evenly to all 8 or vapourized well)

A simple heated narrow band will do 98% of the job for you, for peanuts.
A wide band is nice but the simple home built NB gets it done.

Blue smoke burning oil
black smoke misfire
white smoke water leak, cold engine, water vapour, water in exhaust
white smoke trans fluid burning.

You cannot smell a "rich" or a lean air fuel mixture.
A stinky exhaust/burning eyes is incomplete poor combustion....
start with the ignition system.
Do not idle or try to tune you car in the garage, even with the door open.
Take it outside.

check for a header gasket leak. check for correct throttle position at idle.
check condition of the igntion system "new" is always suspect.
Possible rotor cap phasing alignment issue Scatter/misfire
do a simple cylinder balance test to find the weak cylinder(s)

Again : look at the idle air bleeds on the old stock donor holley carb body.
What size are they? pri/sec.

POOR ENGINE GROUND.

bygddy 05-17-2013 04:27 PM

Quote:

Originally Posted by F-BIRD'88 (Post 1676359)
By "too rich" I'm saying it makes your eyes water anywhere near the back of the car, and very very minor dark smoke at idle at the tailpipe.

Yes I nknow I need a wideband but can't make that happen until next month.


quotes

This does not indicate a "rich" idle. What it indicates is raw unburned fuel in the exhaust.
Poor combustion at idle. Misfire... late combustion.
If the idle screws are active like you say then the idle circuit is not too rich.

But the combustion is not complete. One or more cylinders are misfireing at idle
one or more cylidners getting a different afr mix at idle (leaner,,,,vacuum leak.)
manifold plenum too cold. poor fuel mix/vapourization... fuel pudding in the manifold. Cold...
late spark advance at idle. Ignition system fault causing missfire... cross fire spark scatter. cap coil rotor wires
leak in the header gasket at the head.
all these will throw off idle idle. leaky valve. liquid fuel will not burn. poor fuel mix (there is enough fuel but it is not mixed well-evenly to all 8 or vapourized well)

A simple heated narrow band will do 98% of the job for you, for peanuts.
A wide band is nice but the simple home built NB gets it done.

Blue smoke burning oil
black smoke misfire
white smoke water leak, cold engine, water vapour, water in exhaust
white smoke trans fluid burning.

You cannot smell a "rich" or a lean air fuel mixture.
A stinky exhaust/burning eyes is incomplete poor combustion....
start with the ignition system.
Do not idle or try to tune you car in the garage, even with the door open.
Take it outside.

check for a header gasket leak. check for correct throttle position at idle.
check condition of the igntion system "new" is always suspect.
Possible rotor cap phasing alignment issue Scatter/misfire
do a simple cylinder balance test to find the weak cylinder(s)

Again : look at the idle air bleeds on the old stock donor holley carb body.
What size are they? pri/sec.

POOR ENGINE GROUND.

OK, so ignition is "new" and worked before my changes, its actually not as bad as I thought, yes its smelly, but black smoke when rolling and getting into the seconadties. Plugs look dark and rich, idle isnt as bad as I thought and I will measure the old bleeds when i get something to measure with. I changed plugs just now, and jetted down a touch, it was 72/80, I'm now 68/76 and going to go drive, pull plugs and see what it looks like. Miss fires are not present, it idles calm and smooth with no stumbles. Ground is something that got my attention tho now that u mention it. It was grounded at the cast heads and I did reinstall the same ground on the alum head. Now I wonder if its not sufficient.

bygddy 05-17-2013 04:28 PM

Oh and vacuum is rock steady at 20 in park, 15 in hear. Does not move at all. Mixture screws are very responsive. 1 and 1/4 out on each side.

bygddy 05-17-2013 09:43 PM

70/78 seems to show the best results with the plugs, and no more black smoke when I jump on it. It does now have a tip in stumble, almost like a lean bog for a second....may try changing the pump cam to #2 position and see how it works.


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