[steve25]

Glad to hear you got it down the track and did better than you expected.

Let’s go over some important details .

In terms of a full on race motor you want a power band between peak torque and peak hp of no more then 700 rpm with 500 rpm being the smallest .

From this in terms of track times you should see how important the Cam is and also very much the over all gearing to keeping the motor in that power band thru most of the run.

After your shift into 2nd you want the motor to fall right back well into the peak torque band and the Converter should be locked up by around then also.

In terms of a street strip motor which it sounds like you shooting for then the power band between peak torque and hp needs to now be 1200 rpm wide .

Now your looking at a need for producing the best average numbers for those two factors across maybe a 2500 rpm range in terms of having good drivability./ response to fill your needs.

As has been said a few times here there are many times at the track where a combo making better average numbers has beat out a combination making 25 more hp , but in a 400 rpm higher range that the vehicle is not properly set up to run in.

[HWYSTR455]

This sounds like a classic case of a fuel delivery issue, but think it may be a combo of things, like the carb is part of the issue.



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[Gary H]

My bet is a fuel delivery issue.

[Jay S]

The trap speed is generally a better indicator of the HP the engine is getting to the ground than the ET. You could run a 14.1 at 88 mph with about 300 flywheel HP, or 110 mph in a big cloud of tire smoke with 400 HP.

[ericwoo]

Well folks, quite a few of you have been pushing me to focus on the carb and you were right. I was hesitant in buying carb after carb unless I was certain it was going to improve because I already tried a 750 dp. Although I tried that carb before I fixed the heads and advanced the cam correctly. Embarrassing to say but it was also a cheap Chinese imitation.

I just bought a used Holley 670 street avenger for a great price and absolutely shocked at the difference. Now this little 350 is one mean running car.

Now I almost think the power is too explosive haha. This set up just wants to shred the tires if I step on it and I have somewhat wide 265 tires.

This carb is only 70 cfm more than my previous one. I am thinking the significant improvement in power is partially because the fuel rail uses a larger 3/8" line. The 600 holley (4160 #0-80457S) carb that I was using has this tiny built in fuel rail to the secondary.

I might consider buying a larger carb to test in the future but I almost dont want any more power. Regardless, I will experiment to different jets sizes in this 670.

I would not be surprised if this car does 13 seconds or less in the quarter mile now. I need to focus on good tires next so will look at drag radials.

Thank you all for helping an amateur. It's been a long journey for me figuring this out. I am now satisfied !

[AG]

Now I almost think the power is too explosive haha. This set up just wants to shred the tires if I step on it and I have somewhat wide 265 tires.

Wash your mouth out with soap.

Better is the enemy of good, if your 670 Holley is running well optimize it and run it.

[steve25]

That same small fuel crossover tube your thinking was your previous carbs issue is also used on the 800 cfm spread bore as in this photo, so that was not the issue with that carbs performance.

Real good to hear that you can now practically look at the gas pedal a roast the tires!

[Squidward]

Yay!


Adequate street performance is pretty individually defined. I'm in your boat, the 350 in my 'bird is PLENTY when driving around the streets in a city of half a million people. Even blasts from a stoplight barely get to 3rd gear before I cross into the "menace to society" realm. On ramps to the interstate are usually a blast, tho.

All the inner streets here are 45 mph. There is only one track out here. I've had to adjust what I use my car for.

1st gens and x-bodies are great for rowdy 350's.

Glad you cracked the code!!!

[ericwoo]

Originally Posted by AG

Wash your mouth out with soap.

lol yeah I take that back. I was really just concerned with the power being too much for the tires to grip because I am not moving burning out.

I just got back from the track today. I have to launch it not much higher than around 1500-2000 rpm to prevent the tires from spinning too much. I hope to test with drag radials next spring.

Today my best time with the 350 was 13.2 seconds. That's with me starting to let off the gas early because it seems unstable/ unsafe at a high mph. I think I need a front spoiler to help keep the nose down since I put on a rear.

It looks like this thing should be able to do 13 secs or maybe high 12s

[ericwoo]

Originally Posted by steve25

That same small fuel crossover tube your thinking was your previous carbs issue is also used on the 800 cfm spread bore as in this photo, so that was not the issue with that carbs performance.

That's good info to know. I did replace the fuel filter yesterday also, although it was only like 6 months old. Maybe it was put in backwords since there was no flow arrow on it.

Regardless the carb needed to be changed.

[steve25]

How is your car sitting, is the ass end higher then the front and if so by how much?

[Squidward]

Originally Posted by ericwoo

lol yeah I take that back. I was really just concerned with the power being too much for the tires to grip because I am not moving burning out.

I just got back from the track today. I have to launch it not much higher than around 1500-2000 rpm to prevent the tires from spinning too much. I hope to test with drag radials next spring.

Today my best time with the 350 was 13.2 seconds. That's with me starting to let off the gas early because it seems unstable/ unsafe at a high mph. I think I need a front spoiler to help keep the nose down since I put on a rear.

It looks like this thing should be able to do 13 secs or maybe high 12s

Now that's awesome!!!

How many cubic inches do you need to go fast?

[AG]

That's an incredible for a 350 regardless of weight, great job!

[ericwoo]

I apologize for extending this thread to the point of being annoying, but just wanted to state what I found out about my carburetors.

After watching a youtube video, it turns out my original Holley 600 cfm carb from the factory didn't drill out the hole from the primary venturi to the vac secondary! So I have been running only on 2 barrels the whole time. But it still ran mid 14 seconds off 300 cfm which is pretty good imo.

I contacted Holley to ask what size hole it needs to be and drilled it out myself. I just tested my Holley 600 today and this 350 is running mean with that carb. It may even be running better than my Holley 670 street avenger but I think that is because the 600 has a lighter secondary spring in. I'll look into tuning them before the track in the spring to test both.

Seems I have had 0% luck in every aftermarket part in being manufactured correctly. IDK what is up with that but quality control must've been non-existent in the early 2000s when everything was ordered.

I was also curious about the quardrajet. I rebuilt one with the high performance parts with the recommendations for my engine, read through the book with a lot of time put into it. It is possible I did something wrong but my engine did not like it at all. It runs fine as a daily driver but the holley's performance is quite explosive in comparison. Quadrajet seemed to just tame my engine considerably and was a big disappointment. Night and day difference in performance.

Originally Posted by steve25

How is your car sitting, is the ass end higher then the front and if so by how much?

Forgot to reply here. The front was lowered before taking it to the track and the rear is the original height. This may not be the best picture. I recently installed a front spoiler.





I'd bet I can get this 350 to do mid 12 seconds. It is running wild now with these holleys and I havent even got into tuning them to perfection yet.

[VCho455]

Originally Posted by ericwoo

Today my best time with the 350 was 13.2 seconds. That's with me starting to let off the gas early because it seems unstable/ unsafe at a high mph. I think I need a front spoiler to help keep the nose down since I put on a rear.

What condition are the suspension components. Worn ball joints, drag links, Pitman arms and bushings will be much more apparent at speed. I recommend doing or having a quality shop do an inspect the suspension. Front and rear.

I've run hundreds of passes at higher speeds without needing a front spoiler on my goat with a Judge spoiler. What drives fine at 55 can be scary at 100 mph with worn components.

Glad to hear you've worked out the issues and now have a respectable performing Firebird.

[grivera]

That’s great!! a hot 350 now!

[Squidward]

Originally Posted by ericwoo

I apologize for extending this thread to the point of being annoying, but just wanted to state what I found out about my carburetors.

No apologies needed! This has been one of my favorite threads, and I was hoping you would be posting another update soon. I've got popcorn ready, waiting for you to crack into the 12's!

I never got a chance to tune all the bugs out of mine before I stopped racing, so I am living a bit vicariously through you. You are flying that 350 banner proudly!

[steve25]

Good to hear you stuck with it and dug in deep to fix that 600.

Even if you were not to use it you learned something valuable.

In terms of my question you answered my reason for such was this.

When you start off from a stand still weight transfer to the rear tires does not start to take place until the car / chassis is at least level.

The higher your ass end sits above that then the longer it takes to plant the rear tires as well as can be had with a current set up.

[ericwoo]

Originally Posted by steve25

The higher your ass end sits above that then the longer it takes to plant the rear tires as well as can be had with a current set up.

Good to know. Appreciate your help.

Originally Posted by Squidward

I never got a chance to tune all the bugs out of mine before I stopped racing, so I am living a bit vicariously through you. You are flying that 350 banner proudly!

Appreciate your encouragement! I was about to give up. I depended on trusting these aftermarket parts and didnt look into the fact that they can make mistakes. I hope others can learn from my lesson. I'll let you know in the spring what time I get this to run at the track. I'm satisfied with the lil 350, as I wasnt looking to race professionally.

Originally Posted by VCho455

I've run hundreds of passes at higher speeds without needing a front spoiler on my goat with a Judge spoiler. What drives fine at 55 can be scary at 100 mph with worn components.

Good to know. All the front suspension and steering parts were replaced. However, my DIY alignment job isn't perfect. I'll look at that and probably get a professional to do it.

[p4msi1]

Originally Posted by HWYSTR455

I heard something about his health too, not sure I buy it, the walls were closing in on him. He did close the biz, at least under the previous name. Heard someone was going to buy the biz, not sure about that either.

Jim is still on FB posting, and he still owes me an engine. But I'm not going there on this forum....

No doubt P350s can run decent, have seen a number of them that do, and have done one myself. Same stroke as a 400 just a smaller bore. There's been builds that were testing limits, and some of those were supposedly making pretty big numbers, comparable to larger engines. Thing is, it costs as much if not more than doing a similar 400 or 455.

Here's one that's not 'big' power but still a contender:

https://www.hotrod.com/how-to/hppp-1...o-engine-build

Ken's 462HP 350 build:

https://www.hotrod.com/how-to/hppp-0...c-engine-build

And this one, 672HP:

https://www.hotrod.com/how-to/672hp-pontiac-350s

But not sure I buy it all, no real 'data'.


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Jim screwed me over years ago, he is a total fake!