Hi everybody!

I recently got myself a GTech-Pro since we don't have many drag strips around here in southern Germany. I have a place where I can do some runs without endangering others.

So after finishing my Chevelle only three weeks ago I made my first runs today and to be truthful I'm a bit disappointed.

Here are the specs:
400 CUI SmallBlock
10.2:1 CR
Ported 2.02/1.6 GM Heads
Edelbrock Performer Manifold, Cam and 1405 Carb
Headers 1.75 inch, 2 inch dual exhaust
TH350 w/ 2400 Stall Speed B&M
2.73 12 Bolt Posi rear

I would guess the engine has around 310 HP and 400 ft/lbs.

Here the (averaged) Data from the runs:

60 ft: 2,347
330 ft: 6,430
1/8 mile: 9,845 @ 73,51
1000 ft: 12,806
1/4 mile: 15,338 @ 89,57
0-60 mph time: 7,397 (6,812 w/o rollout)

Gtech showed:

171 HP
276ft/lbs
:eek:
(It has been showing terribly low numbers for my other cars too, even if you mind about drivetrain loss, air drag etc.)

I'm not sure if the Gtech is way off or if my combo is really that bad. I have read postings here on TC where guys with 350 SB and open 2.73 rear made mid 14's. :(

One thing I have to add, the runs were made with street tires and an almost empty fuel tank, I was getting excessive wheelspin. Traction is way better when the fuel tank is full, gotta try that next time.

What I am especially unsatisfied with is the 0-60 mph time since in Europe we compare the cars by that value rather than by quartermile times. I expected something like a low 6 / high 5 second time. Also the 1/4 ET and speed are quite disappointing.

What do you guys think, how much would my times benefit from using a shorter rear axle like 3.42 or something? How much difference would a change of gears make?
Also, my TH350 is shifting at 4000 RPM flat, could that be the culprit? The cam is a Performer cam made for low end torque so I don't really know if I would really benefit from higher RPM.
How much would I benefit from a 2 1/2 inch dual exhaust? I am thinking about getting the American Thunder Exhaust system.

Thanks!

Olli

Well you'll definatly notice a difference with a numerically higher rear gear ratio. From 2.73 to 3.40s is a difference, but in quarter mile times, it might take a tenth or so off your et. I know over in Europe, it's mainly about speed and curves, so going with a higher gear ration like 3.73s or 4.11s might not be what you want. If anything, I'd suggest maybe some 3.55s or so, slightly better take off, still have some good gas milage, and I'd believe you shouldn't "top off" too quickly. As for going with a 2 1/2" exhaust, GO FOR IT! I don't know how accurate the new G Tech is, but the old model isn't the greatest. Also, what size are your rear tires? That also will make or break your current rear gears and future rear gears. Good luck and have fun!!! graemlins/thumbsup.gif :D graemlins/beers.gif

Try shifting at a higher rpm. I take my Performer cammed engine to 5500 and it's still pulling. Once you get the traction issues worked out, you'll have a better idea of what the car will actually do.

My tires are 255/60 R15. Old tires though, the traction isn't too good. ;)
I really hope the GTech is the culprit, after all it's reading verrrry low on my other cars too.
A 300hp+/400ft+ Chevelle should be doing better than that, shouldn't it?

Olli,
The motor is probably down 50 or more hp at 4000 than its peak (peak is probably in the 5000-5500 rpm range). So the tims will be off. I would try different shift points (probably start with 5000 and go from there. It also sounds like tire spin is killing your times. I would try filling the tank, but a better set of tires maybe required for the best times. If I were to change one thing on your car it would be the exhaust. I think a 2.5 inch system would help it alot. Good luck.

2.5 duals would work better with the 1.75 primary tubes. Add a crossover pipe to help balance the system. I assume you are using the Performer Cam?
204/214 .420/.442...This should make peak power about 5000rpm but is very small for a 400cid engine. Most of these guys are right about gearing 3.55 would be a good balance. But the cam should be bigger. Comp Xtreme Energy 268 (462/.469 218/224) should work with the combonation you have and pull good to 5500. Change intake and the XE274 would make good use of the converter and big headers....... ;)

Originally posted by PONYKILLER511:
2.5 duals would work better with the 1.75 primary tubes. I rechecked the header size and it's 1.625 not 1.75. Sorry about that.

How much do you think the motor would benefit from a change to a RPM (maybe Air Gap) and a X274? I looked up the Dyno Results on the Comp cams site and those cams make very very tempting numbers on a 350 CID. Ok, they are using Dart Heads on the dyno engines, but with a 400 CID and my ported GM 2.02/1.60 heads the numbers should still be impressive. Can't afford new heads at the moment but a cam and intake swap could be something I'll buy myself for x-mas. :D

To sum it all up, first things to do (in this order):

- Change TH350 Govenor to get shiftpoints at around 5000 RPM
- Install 2.5 Inch Dual Exhaust (American Thunder)
- New (stickier) Tires? :D
- New Cam and Intake (XE274 and RPM)

...and when I have some extra money to spare:

- New gears (3.55 Posi)
- Alum Heads with big runners (Dart, AFB)

What do you think?

One last thing, I don't have a forged rotating assembly in my 400, also it is a 4 Bolt. Is it safe to rev it up to 5000 or 5500?

Thanks! graemlins/beers.gif smile.gif

Olli

Don't worry too much about the times your g-tec says you are running. They are usually off; however, you do have some things in your combo that just don't make sense...no offense, just saying. If you were to do all those things you listed, you'll see a huge difference. Changeing the cam, EXHAUST (asap man), and intake would make a big difference by itself. I used to have 2.5" exhaust up to the rear axle, and then 2" out to the back. After replacing this with 2.5" ending before the rear axles, and throwing on a 14" K&N (replacing my stock 14" crap filter) I could feel a difference for sure. It just felt like it was free flowing afterwards. Your change will be more intense than mine was (seeing how you have 2" the whole way), so you will definetly notice even just the exhaust change.

Good luck with it man......i'm kind of in the same boat....but I guess most of us are.

-Ben

it's definately safe to rev it to 5500rpms. i take my 4 bolt above 6000rpms frequently. can you not manually shift the transmission to get the desired shift points? i agreee that the cam is a little small for a 400, but you should be able to get some mid to high 13 sec 1/4mi times with it, i would think. i also think 2 1/2" exhaust would free up several hp. as long as you have stock type heads and that cam i don't see gear swapping being worth the expense, it's a torque motor anyway. also keep in mind that there is alot of margin for error with a G-tech when you spin the tires. definately change the exhaust, you might free up all kinds of power there, but then your traction problems will only get worse.

All right, thank you all for your input, I'll let you know of any improvements I make with the new stuff added.
I will order the Flowmaster American Thunder system soon.

Laters

Olli graemlins/beers.gif

change that exhaust to 2 1/2 for sure thats killing you. then throw that eldebrock carb in the dumpster or use it for a boat anchor and buy a holley 3310 (750 vacume secondary)eldebrock makes excelent heads and intakes along with there other components but there barbs are trash any track guy or dyno guy worth pocket lint will tell you that. thats my 2 cents

A little update,

i did some more runs and the G-Tech shows pretty consistent numbers.

60ft 2,219
330ft 6,309
1/8 9,748 @ 73,07mph
1000ft 12,721
1/4 15,263 @ 89,20mph

With a full fuel tank the car hooked better, but that made no real difference at the ET and MPH.

What really bothers me, those times are really bad, I mean aren't they too bad for a 400 SB with the specs given in my first post? It sounds and runs great, no smoke no nothing. Cylinder pressure is 170 psi cold (does that match the 10:1 CR (aprox.) ?).
I understand, that the exhaust is too small and the cam isn't big enough for the 400 CID, but hey, shouldn't it still run better than that? Even with 2.73s?

I have tried to shift manually as you recommended, this is hard to do with a sloppy column shift when you have to keep her straight, but I felt that I wouldn't gain anything above 4500 RPM, it feels like the peak is around 4000.

Calculating the HP from the times gives me 220HP at the wheels. Thats definitely not what I expected, I expected more like 270-280 HP at the wheels.

What should timing be for a 400 with that Performer cam?
How much would I gain with just the exhaust, and how much would I gain with exhaust, air gap and XE274?

Thanks guys and sorry for bringing this back, but it keeps me worried... :( graemlins/sad.gif

Olli

hi olli.how does the engine feel compared to g-tech times?do you feel in your pants it`s faster than those times?when i first got my chevelle it went 14.22 with 400 cid engine and 2.73 open rear+manual 3 speed trans.traction with street tires was awful but i felt it could do 13 sec times given better traction.i calculated the power output in 280 hp region.i think there`s something wrong in your combo.have you checked timing,plugs etc.i would also change the carb.those times which your chevelle is running are typical for bonestock sb 400 in heavy car.and with ported heads i would also step up with cam and bigger exhaust.keep tuning and the performance will come!!

Pauli, how are you! Do you have a good carb for sale that would fit the 400 CID? Well I guess the Gtech is not that far off. She pulls good, but not extremely good. I had a chevy dealer set the timing a few weeks ago while she was there for some other stuff, but who knows if they did it correctly. I would like to check timing myself, but I don't know how timing should be with the Performer Cam. I need something to start with.

After trying to rev it up and shifting it manually today, the first thing i will definitely do is installing the 2.5 inch exhaust, i think that will free it up a little, especially from 3500 rpm up.

But I'm still trying to figure out why it runs that bad.

Thinking about every detail the following question came to my mind. How much could bad wheel bearings and misadjusted brakes affect the timeslips? My wheel bearing need to be replaced and since the chevy dealer installed the new drums, spring kits and brake shoes the front wheels don't spin freely anymore. I have read that it is not unusual that the auto adjustment makes the shoes touch the drums, but I didn't think that the wheels would actually stop so quickly when trying to spin them (about a quarter turn when trying really hard). You can hear the shoes touching the drums. I need to ask in the brakes section how to adjust them properly.

Keep the ideas coming guys.

Thank you all,

Olli

greetings from north olli!i know this is not for sale board but since you asked about a carb,i do have a new 9380 holley 850 race dp in stock condition.in fact two of them as they proved to run lean on my 540 bbc.my e-mail address is pauli.junila@luukku.com should you be interested.but however i recommend this carb after you have stepped up with cam and exhaust.check the carb from holley`s site and you`ll see that it`s a god carb with good qualities.(+it`s real cheap).

Hi all,

today my big package from the States arrived. Yeehahw! graemlins/hurray.gif

I ordered the American Thunder Exhaust system, RPM Air Gap Manifold, KYB Shocks, Front End Polybushings, Hellwig Anti-Swaybar and KYB Shocks. Lots of work for the next weeks! smile.gif

I'll let you know how much the exhaust and manifold improved my times!

I'm still thinking about a cam swap and would love to hear all of your opinions based on the new combo I have now.

So what would you recommend?

Laters,

Olli

Olli, based on Chris Corwel's track testing with a Perfromer and RPM, the RPm is worth nothing if the shifts are close to 5000 rpm.

I wouldnt bother with it until you cam the motor, and of course, that's only after you put better gears in.

With the vacuum advance disconnected, shoot for 12-14 BTDC initial timing.

Originally posted by 427L88:
Olli, based on Chris Corwel's track testing with a Perfromer and RPM, the RPm is worth nothing if the shifts are close to 5000 rpm.

I wouldnt bother with it until you cam the motor, and of course, that's only after you put better gears in.

With the vacuum advance disconnected, shoot for 12-14 BTDC initial timing. That's why I was asking for a cam recommendation. I want to adress all the weak spots, but can't afford to do it all at the same time, so I will swap the manifold only when I have the new cam. I will go to 3.55 gears next year. So what cam would you recommend? I'm planning on shifting at 5500-6000 rpm.

Thank you!

Olli

whats your timing set at?

With 10:1 compression, you have a great range of cams to choose from. One limiting factor is the torque converter at 2400 rpm stall. Off the cuff, I would say a cam just like Chris's big block cam would fit really nicely. It's Lunati part # 301A9 LUN, specs are given here..

http://www.holley.com/HiOctn/ProdLine/Products/IEC/IECC/Chevy4.html

Would NOT go much bigger with 2400 stall than that , or a similar, cam.

How exactly do you use this car?

BTW, those suspension pieces you bought will make a world of difference in the ride!

Originally posted by 427L88:
With 10:1 compression, you have a great range of cams to choose from. One limiting factor is the torque converter, you plan on staying stock? How exactly do you use this car?

BTW, those suspension pieces you bought will make a world of difference! I have a 2400 B&M Converter. Another reason to get some better gears... I think I'll slowly cook the tranny with the 2.73.
The Chevelle is a pure fun car. I take her out on the weekends to the drive-in theaters, cruising around the Munich Glamour Miles and last but not least I want her to perform really good on the quartermile. She's a really nice cruiser right now with good torque at low rpm, but most of all I want her to be really quick.
Thanks for the cam advice, sounds like a good match.

Use the cam advice as a guide, I wouldnt go any bigger. If you don't mind weak power brakes and a choppier idle, Lunati ( or anyone really) can make that cam for you on a 108 lobe separation ( or lobe displacement angle as its sometimes called) but I'd have to defer to the more knoledgable automatic transmission folks here to know whether a 223/230@.050 cam on a 108 LSA can work with a mild 2400 stall. Something to double check.

When you close the angle ( as in 112 to 108 ), you gain mid range pull ( and lose ET!), but you lose a little on the bottom and top. And , of course, the idle gets much choppier. Gernally then, tight LSA cams prefer a bit more stall. But you might be alright - someone else will have to advise.

If the GM dealaer set the timing to stock specs ( like 2 or 4 degees advanced), it's way off. Go to at least 10 degrees and it should wake the motor up. Watch for pinging in the motor when you increase the timing advance. Or increase the grade of fuel before you try advancing it.

BTW, did you buy a good timing light in that last basket of goodies from the States!? ;)

You should learn some basic maintenance like timing the engine on your own. You could probably spend an hour searching here about it and know how its done. Very easy with a adjustible timing light. Once you know how to do it, you can then vary it slightly and see how the car responds ET-wise.


650-750 cfm is all you'll need for carburetion. DO NOT use a double pumper. The prior recommendation of a Holley 3310 750-cfm vacuum carburetor is spot on. A QJ would be good too, but I'd hate to have to find any parts for them over the pond.

Tune the engine a bit and you should see ET results.

Yeah, it looks like a pure fun car, for sure! Very different too, over there! graemlins/thumbsup.gif graemlins/beers.gif graemlins/beers.gif

Gene, thanks a lot for your advices. graemlins/beers.gif

On the cam issue, i don't want to go too extreme, I don't want to loose all of the low end torque and brake power. I know that I can not have both, it should be a compromise. The other guys said the performer cam I have is too small for the 400 SB, so I want to install a bigger cam that will match the Air Gap and pull better at higher RPM. I'm just trying to find "a combo that works"!

Yes I do have a timing light but it's a piece of *****, it's so dark I can't see anything. I have to get a new one soon and check what the dealer set the timing to. When I installed the motor I set it to 10 degrees BTDC and it ran pretty well even with a carb that was almost clogged from dirt and wouldn't idle anymore without choke. I told the dealer the specs of the engine and cam but i never asked what they set it to after I got it back (it was there for DOT and minor repairs). I definitely should check that because now the carb is cleaned and working perfectly, but there's no improvement in performance. The lack of power above 4000 could also be retarded timing, couldn't it? Or do you think it is the 2 inch crimp bent exhaust that would do that?

Next thing I want to do is install the American Thunder system. Can't wait to hear it and see if that'll improve my times. With timing set again and the bigger exhaust it'll probably pull much better above 4k.

If that's the case I should probably change the shift rpm of my th350. How do i do that? Do I have to order a new govenor?

Around Xmas I'm planning on installing a new cam and the RPM Air Gap.

I'd love to have a Holley 3310, but you won't believe how expensive these things are over here (around 500 bucks! :mad: ). Maybe somebody can give me an adress in the states where I can get them cheap, or even help me getting one, doesn't have to be new.

Thats it for now,

Olli

P.S.: Thanks again Gene! graemlins/thumbsup.gif

Olli,

my friends were in munich a few years ago for a pigeon show, they loved it ive always wanted to visit, i will soemday, at 24 years old ( in a week anyway) i have plenty of time god willing. ive been saying how much i liked the new holley street avengers for some time now to just about anyone that asks, i got the 770 manual choke and have been very impressed with it ( i would reccomend the 670 for your application). after putting the carb on it turned 3 cranks them started, it was so well tuned from the factory all i had to do was change the vacume secondary sprig so they jump in quicker, i may bup the jets up a size but even thats not hard, the spring change took maybe 2 minuets and a philips screwdriver. whatever your carb choice i would be glad to help you find one cheaper here and handle the shipping to you if you wanted, a friend of mine owns a little performance shop and can get the street avenger to me for $350 total, that was for my 770, the 670 may be a hair cheaper. i too am looking into a cam and intake swap on my big block. on your shifting issue, as long as you have a tach you can just manually shift the car and get your desired shift points, if i leave my car in drive it runs slow too ( shifts at 2600 on its own) and its a cammed, ported head 30 over 454 with 3:73's. your shift point has alot to do with your et's. also like has been said tire spin will KILL your et reading on a g-tech, im willing to bet if you can get some traction, swap your exhaust and shift your car manualy youll be a bit surprised. shoot me an email or a PM if you need any help getting your carb

Jay

Isn't a edelbrock 1405 a 600cfm carb? That seems to me a little small for a 400 inch motor doesn't it? I have the same carb on a 327 if i remember right.

Daniel

Daniel, for sure Olli needs another 100 cfm.

Olli, always bear in mind that this is a system of component parts, each with its own contribution, adding its own characteristcs to the system.

So when you say , is it the 2" crimped exhaust? Well , it's most likely the 2" exhaust plus the cam, plus possbily incorrect timing, the carb, etc.

The exhaust and suspension mods will make it much more fun to drive.

If it were me, I think I'd almost time it by ear. It's a very imprecise method, and if you don't hear the pinging in the motor from too much advance, you might cause some damage. Essentially, you keep bumping the timing up until it does ping, and then back it down just so it doesnt.

At the same time, I would check the float level on that Holley carb. Check it while hot, and make sure the level is right up there. If you loosen the site plug slightly, and it doesn't weep fuel, go ahead and raise it some. If you havent dont this before, run a search here. It can get messy if you dont keep the set screw and nut in close contact with one another.

Methinks there's more in the car as it sits now. Timing, fuel, etc.

$500 for a 3310! Naw. You can get them for as little as $189 here in the States. I'm sure we could think of a way to ship one, even in pieces, for much less! The way the dollar is going versus the euro, Holley carbs should be cheap in the near future!

Hey Olli,
I used to look at your website before I got my chevlle running again, your car is pretty damn nice. I also think that there is a lot lef tin the engine just how it is. I am one of those guys that ran mid 14's on open 2.73's, and my 350 burns 1 quart of oil every 60 miles!! No cylinder pressure was above 120!!! When I raced I shifted at 6000, about 5300 through the traps. small tweaks like raising the floats, a jet change, and more timing advance will make a HUGE difference.

Any chance that you've weighed your car? My car does come in only at 3160lbs...

I think the exhaust will help, let it rev a bit higher...

You'll also love the ploy bushings and shocks...Keep us informed buddy!

Viel Gluck! graemlins/beers.gif

Olli,
I did not know you lived so close to Munich.
I was in Munich all summer ,once a week!
Matter of fact i was at the Oktoberfest on
the 1st of Oktober.Anyway shoot me your phone number via my email which you have! I can always bring over smaller parts for you!What are Chevelle friends for!!Right now I wont know when the next time I will be in Munich,but I will be in Germany sometime in December for sure.
I'm working on some issues with my ride to much power and no traction,just burning rubber like crazy. I love it though! You will get that 71 up to speed in no time,
Take it easy,
Fritz

Ok guys, first of all thank you ALL for your replies! graemlins/thumbsup.gif

You are making some very good points there. I will check timing as soon as I get the timing light which I ordered yesterday. I'll do some test runs and see how it improves while advancing the timing. I don't know how accurate the G-force is as far as times and speed, but it definitely has been showing consistent numbers, so it'll be ok to see the improvements.

After that I'll install the exhaust system and check again (hopefully no snow yet when I'm done).

One thing I need to know, how do I change the shift points? Do I have to replace the govenor? I can shift manually, but the column shift is so sloppy that i have shifted from 2nd into Neutral before. That is NOT good! I'd prefer to set the shift points.

Gene, the 500 Dollars are no joke, 460 Euros, thats even more than 500 Dollars. Can't believe it myself, the price must be fifteen years old.

People, if you really can get me a 3310 for less than 200 Dollars, then PLEASE get back to me (E-Mail). I can transfer the money via Western Union. I'd really appreciate your help and I'm sure I can reciprocate.

Laters! graemlins/beers.gif graemlins/beers.gif

Olli

BTW: Gene, that vid is very impressive! :eek: graemlins/hurray.gif

So, can anyone help getting a 3310?

I do believe your combo with sticky tires should be running in the 13's somewhere. I know it is hard to get traction with a 400 small block with a 2.73 gear and no posi.

You might want to try putting the tallest tire you can put on the car to minimize wheel spin. I know that sounds like it kills the gear ratio but it might allow you to get better traction and use that torque.

Another thing is the carb. The carb your running is no good for performance but is a great carb to just start up and drive anwhere with no problems. I think a Q-jet or a 750 Vaccuum Holley would be the best set up for your engine. The Q-jet will have better traction since it has smaller primaries and those big secondaries will have supreme top end power.

Timing has to be around 35+ total for that engine to run the 1/4 mile in good fashion. Don't go more than 42 or so though.

As far as your compression goes if you have 76 cc heads with a flat top piston with 4 valve reliefs you probably have around 9.3-9.5 to 1 compression. A stock 400 dished piston will bring around 8.5 to 1. Just food for thought.

It sounds like your having problems getting into the 5000 rpm range. That motor should pull into that range easily with the parts you have. Like I said the timing could be retarded way too much thus it won't pull very well through the RPM range. Another thing is fuel delivery to the fuel pump from the tank. Any bad hoses or kinks could spell trouble for performance.

Getting your traction down in the 2.0 range in the 60ft time will bring your et. down quite a bit but you need that power above 4000 rpms especially with a 2.73 gear. When I had my Elcamino with a 2.56 it ran better times running across the traps in 2nd gear instead of shifting to 3rd. I was hitting around 5400 in 2nd instead of running around the 3500 rpm range in 3rd.

Larry, I do have 3973487X (75cc) heads with flat top pistons, I don't know about PDB and gasket thickness though. I'm just stating what I know from the previous owner. I have checked compression a couple of weeks ago and i got around 170 psi. I don't know how accurate that reading is, I don't trust the pressure gauge I have.
You are right, I'll have to check timing and I'll try to get a Holley 3310, but I need help getting one from one of you, because the prices over here are insane.
I do have a fuel pressure gauge at the carb, but that won't tell me what's happening while making a run. graemlins/clonk.gif How do I check if everything is ok with the fuel delivery?
I really think that the lack of power above 4000 is the problem. Like you said I should be able to run across the traps in second, but it feels like it's pulling better in 3rd than in second and above 4k.

Olli

Need your help here: There's a holley carb for sale here on Ebay Germany, but no numbers given, can you see from the pic what it is? It only states 750 cfm. Maybe I should jump on it? What could it be worst case?

Thanks,

Olli

Edit:

http://www.chevelles.com/forum/ultimatebb.php/topic/9/17869.html#000000