Found the Problem thats slowing me down!

[a69nova]

To everybody who replied to my past posts about my motor (sbc 355 dynoed 503HP 450TQ), its kinda funny. Few months ago i started a thread about my motor, and how its not running the time I thought it should. Well over the weekend I was putting in my new fuel system and NOS setup, and I was hooking the throttle linkage back up to the carb, only to find out that the accelerator pump arm (for the secondaries) was hitting my 8an fitting feeding the carb :eek: , and the secondaries weren't even half way open! So needless to say I ground down that arm to were it clears and all the butterflies open wide. So after 3 convertor changes and other attempts, endless nights of thinking why this car isn't going faster, and all along its a simple check of the carb linkage! Stupid me! The best I got the car to go was a 11.96 @ 112.4, I'm dying to know what the car will do now with the carb opening up fully at WOT. I still can't believe it, and I raced all last year like that, no wonder it was so damn consistent. Hoping I can get it down into the 11.50s. What should I expect to see?
Mike

[chevynuts88]

I bought a new holley fuel pump $125.00 and it leaked so I tightened it a little more and it cracked..so I bought another one ..now $250.It turned out when I took it apart [the first one] The seat of the fuel line was cracked and it wasn,t the pump! A hard lesson!

[1975ssnova]

I found something simular on my nova,The throttle was not opening quite all the way due to a bent throttle bracket.

[Stan D.]

The worst problems are those that we can't identify, thus spending a bunch of money and still can't resolve it.

If a motor blows up or a tranny goes out at least you know what the problem is.

I spent well over $1k last summer to find a $35 line lock was the problem, and that is why they call it racing!!!!!!!!

By the way since I didn't give you any of the correct answers when we were debating that topic, let's just forget I offered any....bad....advice.

[a69nova]

Hey Stan D you actually were right in the area. I remember you saying how it sounds like a fuel problem, and thats what it really was. I still can't believe that the carb wasn't even fully open and the car still managed a 11.96 @112.4 with a 1.63 60', I hope this thing picks up a little more, and I can get a little deeper in the 11s before the bottle!

I still think I went in a positive direction by going to an ati 8in 4500 stall, the car leaves so much harder as opposed to the 10in.

Can't wait to see

[Nova_Guy]

Back when I was new to hot rods I had a vacumm secondary Holley. My linkage only open about halfway, I thought it's Ok, that back barrels will still open all the way. I didn't know the linkage only lets the rear open as far as the front barrels are open. A buddy helped me fix that problem; a 350 with a 300CFM Holley will run Ok. A 350 with a 600CFM Holley runs much better! I bet my car ppicked up 100Hp in about 10 minutes. Thinking back it probably saved my life! :rolleyes:

[Stan D.]

That would be great to see you dip into the mid to low 11's. It gets you excited again knowing the problem is solved.
Good luck.

[a69nova]

Would a couple mph and few tenths be expecting to much now with the carb opening fully at WOT?

[Real McCoy]

Back years ago we use to run a mechanical throttle stop on a 482 BBC with a 850 carb. The car would run 9.20s flat out and we had to run the butterflys at 10 and 2 oclock to slow it down to 9.90. So if you had the primaries full open and the secondaries at 1 oclock you didn't hurt it much. If the secondaries were at 2 oclock it may pick up some but 2 tenths is alot to expect IMHO. RM

[a69nova]

I'm going to the check the carb tonight to see where the butterflies stopped before I found the binding. If I remember correctly the primaries were not quite fully open, and the secondaries weren't even around 2 o'clock. I'll be able to get a better reading tonight by looking at the pump cam on the secondary, there is a wear pattern on it showing were it stopped opening.

[Steve J.]

I've head that carbs flow slightly better if the butterflys are not quite vertical. Is this correct?