Stage 1 fuel pump……return line….1/4 mile help

On my 72 GS am currently running a stock 72 small valve 455. In the quarter mile, top speed was 95 mph max, that’s on 5 runs. The car doesn’t feel like it’s running out of fuel, but does feel like it’s capped out at 95. The 1/4 inch return line on the stage 1 pump, is there any gain for fuel delivery by blocking this 1/4 inch return line?
Has anyone installed a simple gasoline compatible valve to shut off flow of the return line while at the track?
Thanks

 

You will gain a little psi if you block the return. If you don't feel it is running out of fuel maybe it is not. You can find a ball valve from lowes or a plumbing supply.
Could it be that's all she has?

 

Im going to obtain a valve snd try it.

It only has a 218/218 @50 comp cam in it (i would never buy this cam.....thats another story) so maybe thats all she has.

 

Whats the rest of your combo?

 

Blocking return definitely helps but crack it slightly open in hot weather or you may get vapor lock.

 

I will install the valve, next time I’m at the track, I’ll close it. For normal cruising I’ll open it. Thanks
Mark it’s a stock 72 455 small valve with a comp 218/218 cam, running quadrajet, 3:42 posi, TSP 9.5 3,000 stall converter. Best time so far 13.94

 

Thanks Larry. A friend has access to a chassis dyno, we will monitor fuel pressure when this happens. Likely not till October. The motor in the car is pretty docile ……low compression, no cam, stock manifolds, zero porting on small valve heads. Best thing going for it is the 3:42’s and the TSP 9.5 inch converter. I weighed the car at the track - with no jack or spare tire, 3755 pounds, add me - 3955. This is a bench seat column shift air car. Has power steering and manual windows. It is probably doing the best it can given the combo, but little mods like closing off return line are easy to do.

 

Best to do to the heads is open the bowls below the valves. Big power hiding in there. They are choked down tremendously. The hole is tiny under our small valves. I run small valve 73 motor. Prob 9.3 to 1 comp x energy 278. Went 12.40@109 w 3000 stall n 3.42s. Qjet and performer 4080 w me in it. Same fuel system then too.

 

I think the valve is a very good idea when you block the return line.

If you put a pressure gauge on, you will notice that blocking the return line boosts the pumps dead head pressure to 12+ lbs. No problem on the track for a few runs, but running around on the street like that risks carb flood over, and the fire that can go with it.

JW

 

Thanks everyone. Im just trying to optimize what I currently have. Plan is to build a stage 2 headed 470 or 482 in the future. Then we should see some 12’s or high 11’s.

 

No
We will see some 11s to mid 10s. Full streeter.

 

That would be something! I’ll be sure to post once I start that process.

 

When I put my 455 in over 20 years ago I used a new regular fuel pump (Non Stage 1 style) I did not have a return fuel line so I just crushed the return line flat and gave it a zap closed with the welder. It has never been an issue. I would probably do it different now a days. If I had a return line I would consider a ball valve on the return to restrict the return.
Greg

 

Before I put a valve on mine I would just put a welding clamp on the return hose when I was at the track. Doesn't have to be totally blocked off...just mostly.
My car would lay over right before the 1-2 shift....this corrected that......

 

With the plans you are marking. Horsepower and Torque not necessarily in that order are on your horizon.
Not sure of your elevation. So that can change et as we know.
It’s not worth putting money into an engine for bragging rights on bore n stroke and heads used.
Use these pieces to your advantage.
Keep us posted. We look forward to your great news.

 

Got the valve to close off the return line installed, also have my new 275/50 MT drag radials and front runners ……the last street legal of the year was on Friday October 8th……they canceled it because the daytime high was too cool, dew would be on the track just after sunset. Our track at Mission doesn’t start racing until 5pm on the Friday night street legal. So have to wait till spring.

 

It's getting cooler in the Pacific Northwest. Where are you racing?

 

I’m in Vancouver BC, the track is in Mission, about 35 miles east of Vancouver. It’s very close to sea level.