Accel plug feedback/starting issue

[midnightbluS10]

The Holley needle and seat O-ring is size 008, 5/16" OD x 3/16" ID s 1/16" cross section. The local hardware store should have some.

My (very) limited experience is that the hardware store will have the right size, however, the material is un-suitable for the purpose. My generic O-rings lasted a week or two. They cold-flow, stop sealing, and need to be replaced again.

The end of my Holley needle/seat O-ring problems came when I ordered Viton O-rings.

It is a pure mystery to me why Holley doesn't sell a small quantity--six or ten--of O-rings separately. The Holley O-rings are not as nice as the Viton I bought, but they're entirely adequate. Problem is that they won't sell them without buying a bunch of other stuff (a "hardware kit") at the same time:

https://www.summitracing.com/parts/hly-34-7bk

Pretty sure you can get viton o-rings as a pack at the part store. O'Reilly usually has a huge case full of various sizes they sell as singles, also. Most others should, too.

[MadBill]

..If the engine is making 7-8 at idle you need a 4.5 or so power valve otherwise it'll be open when its idling.

There was a video posted here not long ago of an engine idling with a wide band gauge plumbed in and an external hand pump actuating the P.V. It showed no variation at all with the PV open vs. closed.

[Tuner]

Tuner if this thing is making 7-8 in at idle do you recommend an 8.5 or 10?
Local place has some, wanna pick them up in the AM. Cant remember what AED put in there and cant find the sheet.
A little more PT umph wouldnt hurt.

If the engine is making 7-8 at idle you need a 4.5 or so power valve otherwise it'll be open when its idling.

This PV should be 1/2 idle vacuum is just plain wrong. Please stop repeating it and furthering the wrong information. The valve should be chosen by observing the vacuum characteristics in the RPM range of the power band.

It is more correct to say the PV should open at about 1/2 load.

As an example, a 500 HP engine should open the valve at close to 250 or 300 HP. Depending on displacement and valve timing, that might be 10" vacuum at half=throttle and 4000 RPM.

Twenty years ago a 358 SBC 18* head 'Nascar Tour' engines with a 390 carb would make well over 600 HP with 10" intake vacuum at 7500 RPM and idled with about 5" vacuum. A 2.5 valve would never open, the vacuum would never be that low unless you lugged the engine in the pits.

You don't want a powerful engine to be lean at high output, except in rare circumstances such as racing fuel economy where engine life is a secondary consideration to winning a race.

Anyone serious about carb tuning that hasn't already done so, needs to spend a lot of time observing a vacuum gauge on a running engine when it is being driven and railed on, so to understand the part-throttle vacuum in a radical engine is much higher in the power band RPM than it is at idle and at low RPM. Idle has nothing at all to do with choosing PV opening point. The vacuum at part-throttle in the RPM range near peak torque and maximum HP is the important factor.

[cv67]

good idea, have a vac gauge with plenty of line, will give that a try have plenty of pv

[cv67]

Gotta love mom and pop auto pts where the owners a gearhead last of the mohicans
they got the viton quick fuel needle and seats but there are .100 and .110

.110 no?

Power valves they have the quick fuel 4 window and reg holley whats the difference

[statsystems]

Gotta love mom and pop auto pts where the owners a gearhead last of the mohicans
they got the viton quick fuel needle and seats but there are .100 and .110

.110 no?

Power valves they have the quick fuel 4 window and reg holley whats the difference

.110 N&S.

The four window PV's flow more than a stock Holley. Unless your PV restrictors are really big (IIRC over .085) the stock Holley will work. Either PV is ok.

[Schurkey]

Viton tip on the needle, or Viton O-ring on the outside of the assembly?

[peejay]

This PV should be 1/2 idle vacuum is just plain wrong. Please stop repeating it and furthering the wrong information. The valve should be chosen by observing the vacuum characteristics in the RPM range of the power band.

THANK YOU!

PV switches between "cruise mixture" and "power enrichment" when out on the road. I don't think anyone is idling at 50mph, so why should idle vacuum have anything to do with that?

[cv67]

After all this.....it was the gas thats it.

Put some fresh 91 in it, dumped a little down the carb and first crank it fired right off
Go figure, in my EFI 5.3 the old gas runs in it but has takes a splt second to catch .

Needs some carb adjustment as if the tip in is off, could be a fuel pump but sure was good to hear it for a minute.

Mystery solved..

[John Wallace]

Fourth post!