I have a pretty basic 383:

Steel crank
5.7 rods
Flat top KB 5cc relief pistons
Zero decked block with about .035 quench
10.5:1 compression
Edelbrock performer RPM 70cc heads
Edelbrock performer RPM intake
1.5 roller rockers
Qjet with 5/8 spacer
1 5/8 painted dynomax headers
GM L82 cam 224/224 .450/.460 114
Lincoln Mark VIII fan
GM large body HEI with 50000 volt coil

2004R stock converter
12 bolt posi 3.73

I rear wheel dynoed at 280 HP 295 TQ at 4500 RPMs, but my AFR wasn't quite on. If I fix the AFR and run the engine to 5500 or so I am hoping that I could pick up a little more power.


Do you guys have any suggestions for picking up a little more power? This car is my daily driver so I don't want to get too crazy, but it is a heavy (3900 lb with me) ragtop and more power is more better!! Just trying to squeeze out every bit that I can!

I was thinking about having my headers coated, but that's mostly to reduce underhood temps.

I was also considering 1.6 roller rockers??

I am designing a water injection system, but I'm not sure that it will add power but mostly help the engine run a little cleaner and more efficient.

I have an LT1 intake ready to bolt on, but I'm not sure that I want to swap to EFI yet....I have so much fun messing with the QJets.

The one thing that sticks out in my mind (besdides the Qjet) is the cam.

Aw, but I like the QJet! :D

I suppose it doesn't dump fuel like a Holley, but it works pretty well!

I don't think that LT1 intake will work, there isn't a distributor hole, and something about the reverse flow cooling will make it hard to use. I also don't know much about the old cams, but everything i have heard says that those old GM cams won't make good horsepower in your kind of engine. You should be definetly making much more power, like 330/375 at the rear wheels

You're right, but there's a distributor hole now... graemlins/thumbsup.gif

I ran your set-up, except cast-iron heads and dished pistons, with P/glide in a '67 coupe, 3200# consistently 14.0's. I changed to a 10 inch convertor and reduced et's to 13.40's.

My other suggestion would be to lose the weight, on the car, that is. The 962 cam pulled strong till 5200 rpm, time to shift to next gear.....

I'm not really looking to go faster in the 1320 as I am already too fast (less than 14 in a ragtop = rollbar). Last time I was at the track I ran 14 and I had a bogging problem on the 2-3 shift. I think that I have the engine running much better now, so I don't think that it will be too difficult to run mid 13's.


I wouldn't mind changing cams, although with the high compression I'm not sure which cam would work well. Even if I change the cam that would pick up what, maybe 20 HP? The L82 cam is very nice for daily driving and seems to work very well with the compression that I am running.

Looks like a prime candidate for a hydraulic roller cam. Maybe the GM Hot Cam . . . compression might be a little high for that though.

What about the Crane #109831 (part no. is for factory equiped roller engine - not sure what you have) .509/.528 lift, 284/292 adv, 222/230 @ 050, 112 LSA. Your DCR with this cam is 8.0:1. Might be pushing it a little with a stock converter.

This would make you go faster though . . . and you said you didn't want that ;)

This would make you go faster though . . . and you said you didn't want that Let me qualify my statement....

Faster IS better, just not faster in the 1320 (i.e. removing back seats, adding slicks, bigger stall, etc).


A hydraulic roller....hmmm, that sounds nice! My engine is non roller engine (just 1.5 roller rockers), what does it cost to swap to a roller cam. I suppose that I'd have to get one of them retro roller kits and possibly change out valve springs??? How would a hydraulic roller handle the abuse of daily driving? I can be pretty hard on that engine at times, while aggresively passing grandma on the way to/from work!! :D


Here's what DD2k had to say...

L82:

http://www.stratagaz.com/383-L82.jpg


Crane 109831:

http://www.stratagaz.com/383-Crane_109831.jpg


Does that look right??? That's quite a bit of TQ down low!

[ 10-27-2003, 08:13 AM: Message edited by: paulm ]

I'd stick with a flat tappet cam. You've got other places you could spend $$$ on.

I agree with the cam. Those old GM cams have slow ramps. Here's two things to know about these engines:
1. More lift, the better. We're using only two valves, and the engine really needs 3 or 4.
2. The larger the displacement, the tighter the LDA needs to be.

Get as much lift as possible, and choose an LDA around 108-110. 106 would be better, but then the idle gets rough.

I'd keep the Qjet, too. Also, I'd swap that converter, too. The old days of a stall converter slipping like crazy on the street are long gone. Now you can get a 9.5" converter, have it stall about 2500, and you wont even know it's there until you mash the go pedal. Heat is minimized, also.

OK....what are some flat tappet cams that would work with my high compression? What makes a spcific grind not work well with high copression? The XE cams aren't really compatable with high compression....Is that because of the aggressive lobes? Which number on the cam specs shows that it isn't compatable with high compression?

I don't care how lopey it is....Just as long as it's streetable for my daily driver.

Paul,
I will offer another suggestion. I think the cam is fine but the heads are 170cc! On a 383, that would make for one big old torque monster. You might want to step up to a bigger head. Keep the C/R where it is and get some bigger ports so that 383 can breathe. You might benefit from a little less torque at the track after the swap. Just an idea to consider.

-Mark.

What would bigger heads get me in terms of HP? Would AFR's or Pro Toplines get me +20 HP?


P.S. In defense of the Edelbrock RPM's I would add that Lonnie67 uses them on his 383 and he runs low 12's with his combo. He has a different cam (maybe XE274???), lower compression (9.5:1) and a holley carb.

[ 10-27-2003, 11:17 AM: Message edited by: paulm ]

If its a DAILY driver, I would keep it kind of tame. Hydraulic rollers are typically not my first choice for a real street/strip car because of the RPM limitations, but they are very good in street cars. I think that just about EVERY OEM uses hydraulic roller cams these days and they run for many, many trouble-free miles. Its not a reliability question for me personally, but then again I have never built one with a retro-fit hydraulic roller kit. They are a little pricey . . . but in a mild combo I think the TQ return is pretty good.

There's nothing wrong with a hydraulic flat tappet cam for the street, especially if the budget is tight. I would NOT use a solid FT cam in a daily driver personally. Although valve adjustments are not nearly as frequent as they used to be, its still something that needs to be checked from time to time.

As for the 170cc heads, for a DAILY driver they are fine. Especially with a tight stall and overdrive trans. I know a guy that went 12.5's on the motor with these heads in a 383. Granted you COULD make more power with bigger ports and more flow, but you said you didn't want to go faster in the 1320, just faster on the street . . . kind of confusing . . . not sure where you are really trying to go :confused:

Sorry about confusing you Eric.

I am just trying to maximize the performance of my 383. My camaro is my daily driver so I don't want it too radical though. I like the way it's setup now, as it has good power, driveability and when I get lucky I can get close to 20 MPG. I was really just wondering if you guys had any suggestions to tweak my combo a little to get the most out of my engine (taking into consideration that it is my daily driver and a heavy ragtop).

I really liked the hydraulic roller cam idea. That would probably not only increase power, but would also help the engine to run more efficiently.

What are some comments on running an Isky 270 Mega cam in his combination??

108 LCA and install at 106 ICA and shorter advertised duration to build more grunt in the big SB motor or will his dynamic compression ratio go too high even with the aluminum heads??

pdq67

That is the touchy thing....The 962 cam keeps the compression under control. If the IVC much earlier than 73-75 ABDC the DCR pops over 8.

You could gain a little bit (~25HP) with a head swap to say AFR 190's. Might not be worth it to you. The old heads can be sold to off-set the costs so it is not too bad $$$ wise.

The Comp 280HR cam would be pretty good with a DCR of about 8.3 or so which is doable with the aluminum heads. You could gain maybe 50HP there but the swap is pretty expensive. Nothing to re-sell here though. Some people think the HR cams are less reliable but the problems are not well documented. The range of the power increase makes this option look good.

Do both and you would definately have a smile on your face! :cool:

The mill you have right now sounds like a pretty good daily driver setup as-is smile.gif Very simple, streetable, torquey, and reliable. More's law still applies though.

-Mark.

More's law still applies though. True, True, True!!!


Maybe I just need to be happy where I'm at! A cam change sometime in the future may be a possibility though.

What is about the maximum DCR that I could run? Currently I don't have any detonation problems with 87-91 octane fuel. I would want to keep it that way if I could.

FWIW, all I would do would be add a set of full roller 1.6 rockers. That should be worth roughly 10-15 hp with those heads and that cam. That cam only has .450/.460 lift...the heads flow well up to the low .500 range.
Did you install the cam advanced, or straight up? That cam has no advance ground in it...it is a 114 lsa with a 114 ica. Since you have no detonation issues I would leave that alone...just curious. Plus, with a 383 you don't need a higher stall convertor. I assume it would burn the tires to the rims as is.

Yes, straight up and no traction!! :D

Just curious...have you ever measured the cranking compression on it?

Hey, good points Travis.

Even though you have plenty of TQ now you may make more power through the entire RPM range with the cam advanced. I've read that a cam that is retarded from optimal looses more power than a cam that is advanced from optimal. That's why most cam mfr's grind 4* advance in.

Like Travis said, if you could get your cranking compression we could determine if advancing the cam would put you over the edge. Or at least make an educated guess.

IMO, paulm, you need to decide what you want to do.

You don't want to go faster(et), for the added expense of installing roll bar. And I suggest, if you install a bar, might as well go with frame connectors also.

But, getting back to the subject, alot of good suggestions here. Your graphs prove the VE is good, and could improve on more torque, i.e.,VE. Torque is the force planting you butt into the seat. A great rush I might add, especially when the wind pushes back the jowls and makes a smile. The faster the torque is applied, the acceleration factor goes straight up to the ceiling. Hence, a quicker et.

But, you decline in this area. One should get a chalkboard and divide it in half: PROS & CONS. You might even want to include a dart board to really help with those choices when coming upon a stumbling choice.

Good luck, your bog at the high end of the rpm is due to lack of fuel, as in secondaries either coming open too late, or fuel bowl empty.

Travis, Eric,

I did check the cranking compression but that was early on when I was troubleshooting a problem. I think it was around 180 (I don't remember)?? I should check again though as now the motor is broken in etc. To do this:

1. Remove all plugs
2. Open throttle valve
3. Make sure I have a strong battery and crank
about 3 times?

I follow what you are saying (kind of) about advancing the cam. Does that mean that I would turn the cam sprog counterclockwise a tooth? I have never done this and never seen anyone do this so I am a little clueless as to the procedure. How does that affect performance and how can you simulate this action in DD2K? Wouldn't that also change my IVC point? Currently IVC at 75 ADBC which puts DCR at 7.743. Changing the IVC to 71 ABDC puts DCR at 8.029.

Here is the info that I used to calculate my DCR:

IVC 75
bore 4.03
stroke 3.76
connecting rod length 5.7
cylinder head volume 70
head gasket bore 4.06
head gasket thickness .035
deck height 0
piston to cylinder wall clearance .003
top ring land height .225
piston dish/dome volume 5cc


Everett,

I am not going to install a rollbar, which means that all of my performance mods will only affect "seat of the pants" as opposed to "ET". My ragtop will never be a strip car, but just a daily driver and nice cruiser. It really is setup pretty well now, but like Mark said "Mores law still applies"!!

I don't have as much experience as you guys so I wanted to get your opinions on how to "tweak" my combo to suck every drop of performance out of it. I don't think that I would like changes that would hurt daily driveability, dependability or take my mileage from 17-20 down to 10-12 just for the sake of yelling woohoo when I mash the gas pedal! I already have a very good all around dependable, powerful and economical daily driver that has a way higher "cool factor" than most of the other cars out there. Like I said, I wanted to tap into the members vast experience level and see what kind of suggestion that you have to improve on (in my mind) and all around good setup!

Okay, I believe in the same theory, "If it ain't broke, don't fix it." It seems you're just about there, and I understand about not making it a strip car. I agree, I wouldn't either, its waaaay too nice!!

But, if you're gonna change cam/lifters/rocker arms/heads to gain more power, is the cost per hp gained worth the money spent? You can always make your car go faster, but you lose the streetability, it's a trade-off. The only "cheap" way to make your car faster is to put it on a diet, lose the weight. Do you really need an interior? Do you really need any other seat than the driver's seat? Etc., etc,....

I appreciate the research you're doing to gain, its the only way, and yes, there is alot of knowledge here, I even learn......

Everett,

I forgot to address your comments about the bog. I tried everything that I could think of. I swapped to a bigger fuel pump (Holley 110 GPH), adjusted the secondary spring many times, adjusted fuel line pressure from 3-7 PSI, modified the QJet internal "carb stuffer" to make more room for fuel, removed the in carb filter and lastly replaced the stock steel lines with -6 AN braided steel and ran them away from every heat source. I still get a bog if I have to sit and idle or drive slowly as I think everything under the hood heats up.

The last two things to try are to have the headers coated to reduce underhood temps and add a return line off of my regulator that has a small restriction to keep fuel flowing so that it doesn't have a chance to sit in the line and heat up.

Cooler fuel = wrap fuel line with foil and attach clothespins every 3-5 inches. An old trick to prevent vapor lock. Just from the pump to carb. I'd probably run a 5/16 in return line.

Advacing cam is done by bushings on the dowel pin. If one advances with cam sprocket teeth, depending upon manf, 6-9* per tooth.

On taking compression test, go for 5-6 comp strokes rather than 3 strokes. With my engine, I had 180 psi. OEM (962) cam works well straight up. I found no improvement adv/ret cam timing.

Could the bog be coming from raw fuel dumping into the secondaries from the bowl? There is no "top" on the bowl where the sec needles are located. I'm sure the accel pump works well. You might try a different vac source for the dist vac adv. Sometimes, I've found full time vac works best.

Yes, I swapped to manifold vacuum for the advance...It works great!

The O2 sensor indicates a lean condition when the engine bogs....It is definitely running out of fuel, whether it is turning to vapor, or a blockage in the fuel line (although that would happen when it's cold as well) it is definitely a lean condition. It doesn't only happen under maximum load....If I have to put along behind a tractor or something on the road, when traffic clears and I mash the pedal to pass it will bog just as I am even with the slow vehicle....I'm thinking that's vapor lock as it happens at different RPMs only when hot.


Ahhh, so the sprocket has little notches to fit the dowel at straight up, retarded or advanced! I remember seeing that! I even had to pay attention to make sure that the correct slot was used! Thanks Everett!!

Adjust the secondary spring to more than 1 1/2 turns. Secondaries opening too fast. Fuel is there, just too much throttle for engine to catch up. Another thing you might do is to open up the discharge(squirter) nozzles to the next drill bit size with a pin vise....

I have tried over 1 1/2 turns of spring tension. It starts to distort the spring, the car feels sluggish and it still bogs when hot!!

On the dyno it worked fine as underhood was nice and cool and the hood was open so no heat soak could occur.

As long as things don't heat up under the hood (caused when idling without enough airflow) she goes like crazy through the gears maintaining a steady 13:1 AFR.

Either a different brand/mixture of fuel, or drive when its cool.

Have you guys thought about a heat insulator for the base of the carb? Might help.

What is your ignition curve like?

-Mark.

Yes, I installed a 5/8 phonelic (sp??) spacer. It works great! After driving home the engine is too hot to touch, but the carb is only warm! I don't think that the fuel is boiling in the carb, but in the fuel line or regulator. Fuel line is -6 AN braided steel from tank to filter, rubber from filter to pump, -6 AN braided steel from pump to regulator, 3/8 steel (about 2 inches) from regulator to carb.

I have a large body HEI with a 50,000 volt coil. My timing curve is about 20 mechanical all in by 2500 RPM. I have varied initial timing from 12-14...12 or so seems to work best, which gives me 32-33 total all in by 2500 RPM.


I forgot.....One thing that happens that I thought is strange is that when I shut down the engine after the ride home and open the hood I can see bubbles for a couple of minutes in the clear filter. I don't know if that's the fuel boiling in the pump or lines....Strange... :confused:

Originally posted by paulm:
Everett,

I forgot to address your comments about the bog. I tried everything that I could think of. I swapped to a bigger fuel pump (Holley 110 GPH), adjusted the secondary spring many times, adjusted fuel line pressure from 3-7 PSI, modified the QJet internal "carb stuffer" to make more room for fuel, removed the in carb filter and lastly replaced the stock steel lines with -6 AN braided steel and ran them away from every heat source. I still get a bog if I have to sit and idle or drive slowly as I think everything under the hood heats up.

The last two things to try are to have the headers coated to reduce underhood temps and add a return line off of my regulator that has a small restriction to keep fuel flowing so that it doesn't have a chance to sit in the line and heat up. Is the internal carb stuffer the float? I was going to recommend setting the float a bit higher.

Have you put a thermometer under the hood somewhere to see what the actual temps are? I'd do that and compare that reading to the boiling temp of gasoline (whatever that is) to see if you're on the right track.

Also, have you addressed the well plugs in your Q-jet?

Just some thoughts.

No it's not the float, but a piece of plastic that fits in the fuel bowl. It is supposed to direct fuel toward the jets. I have adjusted the float level several times. I have it set to the maximum height before it will overflow. I really don't think that my engine is sucking down all of the gas, because I think that the holley 110 GPH pump can move more fuel than the 383 can burn.


No, I haven't taken any underhood temp readings.


Yes, all of the plugs have been epoxied and show no signs of leakage.


Here is a pic of them:

http://www.stratagaz.com/Quadrajet/06%20-%20Fuel%20well%20plugs.jpg


Here is a pic of the bowl stuffer:

http://www.stratagaz.com/Quadrajet/19%20-%20Bowl%20stuffer%20install.jpg


And here it is installed:

http://www.stratagaz.com/Quadrajet/20%20-%20Bowl%20stuffer%20installed.jpg

The filter should be downstream from the pump not before it. Might help the situation, might not.

-Mark.

Really?!?!

I wonder why I thought that I needed a filter before the pump. From the factory the filter was after the pump. I'm not sure what I was thinking.... :confused:

I suppose that could screw with the pump as it has a restriction to pull gas through....