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-   -   holley 650dp for my 355 (http://www.hotrodders.com/forum/holley-650dp-my-355-a-230920.html)

prettyboyced 03-19-2013 02:11 PM

holley 650dp for my 355
 
i have a sbc 355 afr 190 xfi 280 cam 576.570 lift rpm intake 1 3/4 headers 3500 stall turbo 350 trans 3.73 gear 18 intial and 36 total timing i have a holley 650dp and it runs rich at wot i have to step .040 quirter to get rod of bog at take off and 64 in the primarys and 76 in the sec 6.5 power valve floats are good trickle out when i shake the car . i heard im suppose to disconnect the sec and run it lean in the primarys till it surge and go up 1 jet and tune the sec at the track for 1/ 4 time. will this cure my richness 1st time dealing with a holley

Richiehd 03-19-2013 02:39 PM

Quote:

Originally Posted by prettyboyced (Post 1658379)
. i heard im suppose to disconnect the sec and run it lean in the primarys till it surge and go up 1 jet and tune the sec at the track for 1/ 4 time. will this cure my richness 1st time dealing with a holley

Not sure about that, I will tell you I think the 64 is a way lean. I would step up to at least a 68 or 70. Make sure your throttle blades are set as per info on this site (read about transfer slot) is it 4 corner idle? Check your vacuum at idle, vacuum advance off and plug port. Take your reading divide by 2, that should be your power valve number. Start there. How do you know its rich at WOT?
Regular Holley? or Holley HP?

prettyboyced 03-19-2013 04:19 PM

Regular holley 4777-2 stock jets were 67 and at wot the car was sluggish and wasn't building rpms fast I disconnect the sec and with 67 it was ok but when I put in 64 I had more power

cobalt327 03-20-2013 02:08 AM

Quote:

Originally Posted by prettyboyced (Post 1658379)
i have a sbc 355 afr 190 xfi 280 cam 576.570 lift rpm intake 1 3/4 headers 3500 stall turbo 350 trans 3.73 gear 18 intial and 36 total timing i have a holley 650dp and it runs rich at wot i have to step .040 quirter to get rod of bog at take off and 64 in the primarys and 76 in the sec 6.5 power valve floats are good trickle out when i shake the car . i heard im suppose to disconnect the sec and run it lean in the primarys till it surge and go up 1 jet and tune the sec at the track for 1/ 4 time. will this cure my richness 1st time dealing with a holley

Which 4777? You can try 73 jets in the secondaries. 64 pri. is bit small, but if it's not showing signs of too lean it might be OK, but in my experience the stock jetting was very close (primary 67, secondary 73 for 4777-3/4).

A 65 PV might be too high, depending on the idle vacuum (in gear if AT). This wouldn't make it rich- it would be too lean, but it needs to be selected correctly, regardless. A post explaining selecting the right PV: http://www.hotrodders.com/forum/1976...ml#post1657515

lg1969 03-20-2013 09:23 AM

Prettyboyced, The combo is good, The mistake was using Holley 650DP. DP carb do not work well in cars with automatic trannys. In some cases it will bog right off idle if you floor it. That is caused by not enough air flow going threw the secondary at low RPM. As soon the secondary are open quick you also loose air flow on the primary, resulting a bog. Too much gas and not enough air. You should of used a Holley 650 vacuum secondary. It's even worst when you are using a big cam. Hope this helps

lg1969 03-20-2013 10:22 AM

Quote:

Originally Posted by F-BIRD'88 (Post 1658639)
This is not true.

Oh Really... I had similar problem years ago. Using DP with an automatic. It was a mistake. I have been playing around hotrodding for over 35 years.

lg1969 03-20-2013 12:23 PM

BTW: DP will cause rich condition when accel pump dumping raw gas then a lean condition when accel pump has used up the shot. VS carb will only give lean bog condition because the secondary has open early.

lg1969 03-20-2013 12:44 PM

You can get max performance using vacuum secondary carbs, also. It's not just for a stock setup.

lg1969 03-20-2013 12:55 PM

In that area yes I agree.

Richiehd 03-21-2013 06:46 AM

There is always something to learn here.

BigMo 03-21-2013 08:05 AM

Ive used DP's on the street and the track many times with no issues....big converter and enough gear and you are there....primary jet needs to be AT LEAST a 70, I would go with 72's in the front and 80 or so in the back. Agree, the pump squirt too big, back it down, and i know that PV is not right. A little tweaking and you should have it.....couldnt agree more on the timing, and I think the min clearance over the air horn is like 3/4", and that is marginal at best. A few inches needed for sure.

spinn 03-21-2013 11:44 PM

What I liked about the double pumper was that it gave you the same metering every time. It was completely mechanical and no door opened variably for load. That meant part-open throttle points were consistant. This gave the vehicle a solid predictable factor that you could not live without at the track. Some of the roughness you might not want driving around, in those cases a vacuum secondary works better.

My tastes have always favor mechanical secondary carbs. Not double pumpers , but Qjets, AVS, and edelbrocks afb. For that normal muscle car performance, they work fantastic. Not that anything else doesn't.

cobalt327 03-22-2013 01:54 AM

I compare a DP to a stick shift- it takes some finesse, you can't just rug it anytime and always expect to accelerate seamlessly. But once you learn how to drive w/a DP, it's not any harder than any other carb IMO.

vinniekq2 03-23-2013 10:48 PM

650 dp = 283 carb,even with and auto and 3.08 gears it wont bog.a 750 is perfect for a mild 355,even with stock converter,,,I used a 750 on my old 283 in my 65 Acadian,it never bogged.I now use a 950 dp with 3.50 gears,@ 60 mph I can floor the gas in fifth gear and it does not bog,,,,,
having air bleeds is a very good mod if you are seriious about tuning

BigMo 03-24-2013 08:54 AM

Tend to agree with vinnie......hopped up 355 wud go with a 750 for sure.....


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