[Squidward]

Wondering if you guys had any general advice on how to decode the different parts of a time slip to see where I can get the biggest ROI.

I had 5 passes on Saturday, and ended up with et's between 16.7 and my best of 16.316 @ 84.86. Time slip is attached.

Car is 67 FB. 350P, summit 2800 cam, holley 600 vs, th350, stock converter, 69 logs, 2.5 exh, open 3.23 8.2 bop, hei.

I didn't have any traction issues to speak of, and it seemed to pull consistently. My .4 gain came from shifting at around 5 instead of about 4200.

Thanks for any advice. I know my times don't come close to many if not all the players here, but I figure that all of you were once where I am at. I plan to stick with this 350 for a little bit at least.

Thx again!

[quick67bird]

When the car launched did it bog or fall on its face? How do the plugs look?

Those 350s can be made to run. My 67 Firebird with a 350, homeported 670s, 292s comp cam, Torker II, 750 DP, maybe a 2200 stall, and 4.10 gears ran 13.32 @ 105 at Fallon, NV.

[johnta1]

Wondering if you guys had any general advice on how to decode the different parts of a time slip to see where I can get the biggest ROI.

Higher stall converter.

[Squidward]

Originally Posted by quick67bird

When the car launched did it bog or fall on its face? How do the plugs look?

Those 350s can be made to run. My 67 Firebird with a 350, homeported 670s, 292s comp cam, Torker II, 750 DP, maybe a 2200 stall, and 4.10 gears ran 13.32 @ 105 at Fallon, NV.

no bog. I didn't check the plugs. I drove 20 something miles home afterward, would I still have valid data checking them now?

John, thanks. Do you have a good recommendation for stall speed on a mostly street car? I don't really know how much stall a stock converter has, so I don't know where I am starting. It had GM-9 on it.

Grassy-ass, amigos!

[quick67bird]

No the plugs will not look the same now. They will tell you how your carb adjustment is doing though. I asked about the bog because my stall was not enough for my cam and the car kind of fell on its face until it got into the operating RPMs.

[johnta1]

If the converter is huge like 13" diameter, it's not very much stall.
(lot of TH 350 had that size)

I'd start with a 2000/2200 RPM stall, maybe around 10"/11" converter.

That would probably make it working more in the power range, then you'll want to add headers for more power, then better tires for traction, then bigger cam, then lower stall converter, etc, etc.

[David Holmberg]

I agree with John, plus I'd trying shifting at 5200. If that helps try 5400.

[mchell]

you didn't mention your heads and compression...those could limit your future gains somewhat

a few things that may improve you, and are relatively simple:

timing/curve
carb/intake combo
gear/converter

[goatless]

Playing with the timing can sometimes net huge results, and it's easy and doesn't cost anything. I once helped a guy out the track and we got gains of almost 2.5 seconds by simply getting his timing dialed in!

[Blued and Painted]

Timing curve
Q-jet with iron intake or a bigger holley.
Open up the log outlets to the edge of the flange then blend back. If done on the car, make sure the exhaust valves are closed.
Have fun and talk smack to the chevy guys.

Just one guys

[BruceWilkie]

Originally Posted by David Holmberg

I agree with John, plus I'd trying shifting at 5200. If that helps try 5400.

Agree
Doubt much higher than 5200 needed though. (I used that 2800 cam in a 400 with 350 heads(17's) for a bit and 5000 rpm was about right.(Very torquey combo in a 400 with RPM intake and 750 carb 1.625 headers)

My 350 had a Comp 268HE and was in need of more stall than 2200... Never got a chance to find out...(whoever rebuilt 350 did horrible crank work and thats how the 350 heads ended up on the 400...2800 cam was something my kid was going to put in his bonneville 389)

I think an 11" that can flash to 2800-3000 range can still be quite streetable and pick him up considerably. If he goes with bigger motor later, the same converter will flash higher, yet still be streetable. A tight custom 9" or 10" on your 350 might be an option if you expect bigger better motor later... they can be ok at light load with higher numerical gear yet flash considerably higher when used on a bigger motor.

A good converter is definitely good bang for the buck(IMO best bang for $). Your gearing and cam arent a bad match... But if bigger cam you will do better with higher numeric gear and you'll need more than 2200 stall.

1.625 4 tube headers should help but IMO even long branch will do better than logs. 2.5" exhaust through unrestricted mufflers can support 500 hp so mostly pay attention to bends and mufflers... Summits 2.5" turbo mufflers work very good at least at 12 sec or slower level and low cost.(avoid using stock style transverse muffler)

Dial in best shift points by trying an rpm point several times then change rpm point and compare averages.
Do similar with timing changes until you find what your combo likes best.
Find best initial advance... on a street motor I usually get motor hot and well heat soaked then advance till I get starter objection then back off 2-3 degrees then limit total timing to whatever gave best track numbers.

Get familiar with your carb and get a good book on it... If Rochester Cliffs book is best I know of.

Part of knowing a good safe tune is reading spark plugs.
The method here http://www.wallaceracing.com/plug-reading-lm.html is a pretty good guide but not always easy to do at the track... however with a street car and some deserted highway you can do this pretty easy and not go much over 60-70 mph maybe slower. Follow instructions in link and you can get your tune very good. Best to find leanest cylinder and make it happy.

Best bang for NO/low $ is taking weight out. Usually losin street comfort features like heat n AC can shed quite a bit. Power brake booster not too much but it is extra weight. Same for power steering. Usually 1st 150-200 lbs is easy... after that you get into lighter components which add cost but ditchin seats and creative drilling is free.

At some point your going to have traction issues... Posi sticky tires and suspension work/parts.

If you want real fast from your 350 and stay very streetable a turbo or two will get you there. Check the boost section for more info. If a 350 falls in my lap I have a pair of small turbos that should get me in 700hp range below 6000 rpm with stockish heads good rods n pistons and attention to details.



Dont be afraid to play with a 350... not a 400 or 455 but still a fun piece. Beatin up 350 sbc Camaros is fun except you automatically get accused of running a 400 or 455. and sometimes you might surprise a ss396 or bigger and they certainly wont believe you only have a P350 under the hood. Enjoy it.

I'll throw this in too... A friend in mid 70's built a 68 Tempest for M/SA and eventually went mid 12's and only locally competitive... Setup as 350 HO motor with stocker "cheater cam" and well blueprinted motor...Not a full tricks stocker motor more of a very well done bracket race motor that met NHRA rules. Fairbanks did the trans and convertor for the ST300 2 speed(Frank who owned Fairbanks then, runs Dynamic these days)4000 stall convertor iirc.The gearing was 4.10's. Car had more left but uncle Sam sent him off to England, then growing family kept his car budget tied down... last I heard from him was late 80's and car was in storage in PA and he was stationed in California...

So.. 40 years go by and knowledge base we have now along with better parts options... I think you can build a 350 that does far better than this yet remain reasonably streetable.

[Squidward]

Wow. Great stuff. I really appreciate it!

Timing is around 20 initial, 16 mech by 2200, with another 14-16 on the vac advance running off ported. The 20 initial puts it just at the point where there is a once in a blue moon sluggish starter. I haven't yet detected any detonation.

Any timing suggestions?

Heads are stock 69 47's. 1.96/1.66 IIRC.

Bruce, the exhaust is a Summit kit with Summit mufflers. Turbo is in my tentative plans for a 72 350 for my Lemans. Still waiting on rods/pistons to return from machine shop. Concerning weight: Sorry! A/C is a MUST. Just put in Classic Auto Air in 2013.

John, I will get a looser converter. As suggested, it will suit a bigger motor as well. I will eventually put a 67 400 in it once I check out the bottom end.

But in the meantime, I want to squeeze some more out of this cheapie, and hopefully surprise a few people along the way.

Induction is a 600 cfm 80457 Holley on an Offy single 4bbl intake.

Could this carb/intake combo be a constraint? I didn't think so given heads/cam/exhaust, but had no other baseline for comparison.

Thanks again!

[goatless]

Your timing sounds like it should be in the ballpark. The guy who picked up 2.5 seconds had his timing waaaayyyy low.
Every combo likes things a little different. If you can get to a test and tune try bumping the timing a couple of degrees at a time as long as it keeps picking up MPH, if it drops off then back the timing down a bit until you find the sweet spot that makes the most power (highest MPH).

As others have suggested- the next step for me would be a higher stall converter. I've had good luck with the Hughes GM25. It's rated for 2500 stall but may be a little lower behind your 350. It's not too expensive and it drives like a stocker in normal driving. Of course once the stall is higher you're going to have traction issues. So then tires... then posi rear... then more gear...

[LiL Jack]

You needs Naws!

[BruceWilkie]

Originally Posted by Squidward

Wow. Great stuff. I really appreciate it!

Timing is around 20 initial, 16 mech by 2200, with another 14-16 on the vac advance running off ported. The 20 initial puts it just at the point where there is a once in a blue moon sluggish starter. I haven't yet detected any detonation.

Any timing suggestions?

Heads are stock 69 47's. 1.96/1.66 IIRC.

Bruce, the exhaust is a Summit kit with Summit mufflers. Turbo is in my tentative plans for a 72 350 for my Lemans. Still waiting on rods/pistons to return from machine shop. Concerning weight: Sorry! A/C is a MUST. Just put in Classic Auto Air in 2013.

John, I will get a looser converter. As suggested, it will suit a bigger motor as well. I will eventually put a 67 400 in it once I check out the bottom end.

But in the meantime, I want to squeeze some more out of this cheapie, and hopefully surprise a few people along the way.

Induction is a 600 cfm 80457 Holley on an Offy single 4bbl intake.

Could this carb/intake combo be a constraint? I didn't think so given heads/cam/exhaust, but had no other baseline for comparison.

Thanks again!

I have an Offy hi rise... IMO NOT a good match for even a 455 in that RPM range... That manifold is actually pretty good but better for 4000+ range! Its basically a single plane with a divider that has very short runners and lots of plenum... certainly not favorable to size and rpm of your combo.

I think a stock iron with q-jet or even an adapter on it for your 600 picks you up considerably... Performer would be a very good match to the cam and doubt you'd lose much low end with an RPM intake.

(My 350 had an RPM intake several 750's Edelbrock, Carter n Holley plus a big modded thermoquad from a Dodge. Holley was better than the AFB's except mileage and TQ was best mileage but no other advantage noted over the Holley. 750 was plenty for the 350 and the 900+ available from the TQ was never used.)

On my 350 I never track tested difference from iron with a thermoquad on it, just some stop light racin against my wifes 400. From 0-30 she still seemed to have same lead but from 30mph up I was catching up sooner with the RPM/750's.(her motor was very mild back then but not happy my 350 was faster...68bird vs her 69, both convertibles with 2.56 gear).

Sorry so long but think your intake is holding you back alot! Stock iron or performer and save some weight! Also think there is some to gain goin larger than 600 carb... Q-jet or vacuum sec 750 Holley would be my pick... (cfm @ double CI +/-50 cfm on a dual plane has always worked well for me on street/strip combo's. Single planes can often get by with less and likely helping your low speed driveability.)

Can only guess but I think a manifold swap nets a huge improvement.

[Squidward]

Intake choices are the current Offy 360 4bbl, Performer RPM, 78 factory cast iron, or a crosswind 4bbl that would need the FI ports plugged.

Carb choice is either the current VS 600 Holley, Buick 350 qjet, or Olds 455 Qjet. The last one I would have to fix - after rebuild something didn't work right.

[LiL Jack]

Factory Cast Iron gets my vote.

[Squidward]

Oh, yeah... forgot I also have a 495106 4bbl intake (70's egr?).

[Old Man Taylor]

I would use the 78 cast manifold with the Buick 350 carb. Remember that if you buy a converter for this engine that it will stall lower than a future more powerful engine. The stall RPM is proportional to the torque of the engine.

[Squidward]

I just rebuilt my 72 Olds qjet tonight in preparation for carb/intake swap. I found a big vacuum leak at the choke where I had done an electric conversion, so hopefully that is why it never really worked right.

my 72 Buick qjet runs lean from what I think is a very worn throttle shaft. It picks up quite a bit of rpm's when I would cup my hand over the choke horn.

Jim, why do you recommend the 78 intake? Off the top of my head it was toward the bottom of my list.

I am going to start with the carb/intake and see what that nets me before creating too many variables. After that, I am thinking I will do some headers, and then maybe the converter. Converter last, tho.

Thanks again!