OK,

Bought my car 69 CAMARO RS/SS with a 408 motor in it. It is a killer sounding/running motor but has become tiresome for the street. Here is the info I have on the motor and car. 350 block punched out to 408 converted to a four bolt main j&e forged 10:1 flat top pistons, cast crank, 5 7 eagle rods, Dart Sportsman II cast heads, 215 intake runners 205/160 stainless valves, crane roller rockers. Lunati solid lift cam 290/295 duration, 555 lift, 106 lobe separation, victor jr intake , 750 holley carb, hei ignition. This is all running through a built th-350 with a TCI 10 INCH 3500 stall converter and a 12 bolt posi with 4:10 gears. The car never gets below 3500 rpms!! It pulls strong from start to finish (about 6500) but it is very tiresome on the street. I always liked bigblocks because of their amazing torque factor. This motor was definatley set up for racing but I very seldom would go to the track. I dont know really what I should do to it to make it more enjoyable on the street. I guess I need a cam change? Any suggestions what may be the best cam or change I can do with my combination of parts to get me a mean street machine with plenty of low to mid range torque and still be enjoyable on the street? What parts would I have to change? Any help or suggestions would be greatly appreciated! Also, could any one desktop dyno my present combo for me?

Thanks
Mark

What size engine is it? You said 350 punched out to 408 . . . can't be done - a 350 won't bore out that much. Is it a 400 bored out to 408?

On the cam question the 106* LSA is the source of your problems IMO. A wider LSA (like 110*) will even out that power band and make it less peaky on the street.

Dart Sportsman II heads I think have 64cc chambers and 200cc runners which makes over 11:1 in a 408 with flat tops.

We really need to know what your engine size is, compression ratio is, and exactly what heads you have in order to take an educated guess at a new cam.

Also, please describe what you mean by tiresome. It shakes too much? It's a pig out of the hole? The converter is too slippery? Poor gas mileage? Too loud?

A 4" stroke 4.03" bore is a 408, but they are very rare. Are you sure that is what you have?

In my opinion the converter has the most to do with street manners. You might be able to put in a 2600 stall 11" converter and be thrilled with it. My 11" used to drive like a stock one in part throttle situations.

OK,

If the cam I have in there already has a power rating from 3500-7500rpms wouldnt it need a torque converter with a stall speed of 3500? If I went with a lower stall speed, how much lower should I go? I once had a problem with a motor because I did not have enough stall in the converter. The motor is super responsive at idle in park, just dont like starting out at 3000-3500 rpms when I am leaving the driveway. Also isnt the victor jr intake rated for 3000-6500 rpm power as well? Sorry if I sound clueless just trying to get the facts straight.

As you have hinted at, for best performance all components must match. So, if you change the cam you need to change the converter too. You could put a smaller cam in it, but you are still going to have to go to 3500 rpms to get out of your driveway if you keep the same converter.

My thoughts were that if you want to take a one step at a time approach, change the converter first. If that doesn't get you what you want, change the cam.

It's a bit of a compromise as you will lose performance at the track but you seem to be more concerned about street manners. Besides, on the street I think it will still perform great! You might lose a tenth at the track but who cares if it now is more enjoyable to drive.

A converter is easier to change than a cam and I think you will be happier with a converter change than a cam swap.

OK Greg,

Thanks for the advice,one more question. Which converter given my combo would you recommend? Any one company better than another and which range should I get? YOu say about 2600 but which one should I get that will put me in the range since converters seem to be rated within a range. Also, I heard on another board that the 750 carb is too small for this combo and that I should be running a 830. Any thoughts on that? Thanks for all your input.

I see that you have a TCI converter now so maybe just go back with them? If this were an all out race car where maximum e.t. were an issue then converter company may be more important but for a street car any of the major brands would be fine.

I ran the 11" TCI Break Away with good success. It flashed to right at 2800 rpms behind my 406. I also like Coan converters and have heard great things about BTE. Check out their websites as sometimes Coan (coanengineering.com) has some nice sales going but I would say definatley go 11".

I run a 750 Holley (right out of the box) on mine with no problems. Again, maybe a bigger carb would give you a few ticks on a time card, but for the street a larger carb is only going to cost you throttle response.

That will be a great first step. If you still don't like the streetability or drivabiliy you can look into a dual plane intake or a new cam.

What are the .05 duration numbers in that cam anyway? 240ish?

Good luck!

With .555 lift and only 290* duration advertised I would guess that the lobes are fairly agressive and duration @ .050 is a lot more than 240's. With a 106* LSA this engine will not like a 2600 converter.

Converter brand is MORE important IMO on the street. A good converter will be tighter at part throttle and when cruising regardless of the advertised stall speed. Sounds like your TCI is a bit loose for your preference --- I would look at a good quality 10" converter by ATI, BTE or Coan - BUT once again, we NEED to know your exact cam and engine specs before any REAL recommendation can be made.

If you are willing to change the cam, change the converter to match.

Mark,

Any chance that is a solid roller? I did a real quick scan at the Lunati website and found a .555 lift and 290 duration cam that was a solid roller with 248 degrees at .05. i know you bought this motor already put together so it may be difficult to find out but any info would help.

Eric, I agree with you to a point. I am operating on the assumption that this car is mostly, if not completely, a street car. IF that is the case, he would be better suited with an 11", or a tight 10". A loose 10" converter might make 3 tenths differece at the track but with street tires and ON the street you would never be able to tell the difference between 3700 and a 2700 stall converter.

Yes his engine at present needs a 10" (or 8" even)converter at the track and would not perform at peak with 2700 stall, but he already has a loose converter and doesn't like the way it drives on the street.

If this is more like a 50/50 street strip car Mark, then I would change my recomendations. If however you just want to get some more streetability and try to get there without breaking the bank or pulling the engine, try an 11" converter from a reputable company like TCI, Coan, BTE, ATI or Transmission Specialties.

If you have problems getting it to idle in gear, etc. after the swap (which I doubt you will) then you are going to have to bite the bullit and swap the cam too.

Good luck!

[ 02-06-2004, 06:13 AM: Message edited by: Greg O ]

Greg, A car with a tight converter and a big cam is tough to drive on the street --- have seen a lot of guys with this problem and the carb usually is what gets blamed. The accelerator pump cam cannot be dialed in and the engine pops and spits whenever you nail the gas. That's just my experience . . .

Mark, IMO if you want a tighter converter get a smaller cam to match and vice-versa.

I agree the 106 LSA is making for a very "peaky" street engine. If you swap the converter and not the cam you might have a dog on you hands. You still haven't given enough info for a good recommendation (IMO). How much does the car weigh? If you are strictly driving it on the street or if the street driving is the main issue, I think a cam AND converter swap is in order. I don't know why you would put a larger carb on the engine if you are trying to "de-tune" it. An 830 would be a good choice it you were trying to pick up performance. As far as hurting throttle response that is not necessarily going to happen, but no need for it for what you are trying to do.

The Vic Jr. is fine for your application even on the street. If you are trying to make this a street only car and make it real "easy" to drive on the street, then maybe a Performer RPM would be a good choice. As you can see once you start changing one thing it almost always effects something else. You need to sit down and figure out exactly what you want, after that maybe a more accurate suggestion can be made.

My experience with TCI converters is that they are a little loose. Not a terrible converter though. You can add TCS Performance to the list of very good converters. To get the correct stall speed (that you want) you will need to know, cam specs, vehicle weight, gear ratio, etc..

One last thing, with the 4.10 gears on the street your RPMs are still going to be high even if you change the cam, converter, manifold, etc... I think this may be what is getting old for you. I bet if you added an overdrive or swapped out the 4.10's that would cure 95% of what you don't like. Personally I think I would leave everything alone swap the rear gears for a set of 3.55's (in that range) and go from there. That will drop your RPMs a lot and make it highway friendly. You might be able to live with the cam and converter after that.

Hey Greg O,

Yes from what I was told it is the solid roller cam that you saw off the Lunati website. As far as the weight of the car, it is a 69 camaro rs/ss so what ever a 69 rs/ss weighs is what it is for weight. I also was told that the th-350 that is behind it has all coan internals in it. The car belonged to a guy who bought the motor from a guy named Brian Huron. Brian used the motor for CIRCLE TRACK RACING. The th-350 was bought from another guy who used it for a 383 blown drag car. So what I get is that this guy bought a motor and transmission from people who had them for all out race applications, then tried to put it into a street car. Only saving grace I can say is that the car starts very easy for the most part, has excellent throttle response and sounds super nasty. Just dont like the fact that I drive around town at 3500 rpms all day when cruising. I recently bought a gear vendors OD unit I plan on putting behind the th-350. I will have overdrive which I assume will help. Everything else I am going by what was told to me, since I dont want to rip the motor apart to find out. The original owner of the motor was a guy named Brian Huron from KY. Anyone know him? If you do, would be great if someone could ask him about this combo.

Mark, thanks for the update. The picture is getting clearer. A circle track engine on the street is a tough one. :eek:

If you are driving through town at 3500 rpms but only going 35-40 mph the overdrive isn't going to help. You are staying "on the converter". In fact the overdrive will make it harder on the trans and converter because the 3500 rpms with the lowered output shaft speed will mean more slippage. You need to get that converter out of there soon or you are going to cook that transmission. Slippage equals heat.

I almost wonder if that's actually an 8" in there...I have a loose 10" that flashes to 4400 but I can move the car at 1500 rpms if I go easy on the throttle and cruise 35 mph at 2000 or so.

You are probably faced with a cam and converter swap no matter how you slice it. Like I said, you could take a step by step approach if you want. Give one of these converter shops a call and see what they tell you. A tight 10" may be the best bet.

Edit note: I got the cam specs on the web. It is grind 50157. Maximum street performance. 248/248 duration at .05, .555/.555 lift, 110 LSA, 106 ICL. You might be able to get away with that 11" after all.

[ 02-06-2004, 12:18 PM: Message edited by: Greg O ]

Coan builds some of the best stuff, so you shouldnt have any problems with their trans. But I have to agree with Greg O, the stall is whats makin it seam lazy, It could be an 8" for all we know thats too loose for youre combo, it may flash over 5000rpm, probably not what you want on the steeet, or what you need.

You guy's better find out what the motor's CR. is before recommending he change cams b/c IMHO a 290 degree cam needs like 10.5 to 11 to 1 CR. to run crisp like he says it does..

Dropping back to a 276 or even a 280 cam may be the ticket if the DCR doesn't increase above pump gas use??

(His cast-iron heads may cost him a 1/2 to 3/4 a point of CR. vs aluminum heads????)

And maybe, just maybe the converter he has may match up better to the smaller cam, but I really don't know being a "row the oar's" guy!!

Otherwise drop a stick in it and this stuff doesn't much matter then, again imho, b/c you can always slip a clutch... I did enough times on my over-cammed 406 anyway's....

pdq67

The future OD is even more reason IMO to go smaller on the cam AND tighter on the converter. A nasty 106* LSA cam and OD could be pretty rough ;) If not smaller, at least go wider on the lobe separation -- that should keep the DCR low enough.

Generally speaking, if the engine is OK on pump gas now and you were to increase LSA from 106 to 110 THEN you could shorten the advertised duration to 282*/287* and keep the exact same dynamic compression ratio (in other words, it would still run on pump gas). If you go with a cam that is shorter though, just make sure it has fairly agressive lobes because I'm sure you don't want to kill too much power.

A mid 280* cam would work MUCH better with a tight 10" converter. graemlins/thumbsup.gif

ps. I run a tight 10" Coan converter on the street and behaves quite nicely when cruising at 2000-3000 RPM. It flashes to 3500-3800 at the track so it still pulls hard. I run a cam with a 110* LSA and 294* advertised duration, but no OD.

OK,

What about installing a six speed? How would this effect the car? Would you still need to reve the clutch to get the car at the right rpms for street driving? How would this hurt or help? Thinking more and more about changing to a six speed from D&D PERFORMANCE.

Mark,

Not sure if you re-read my last post after I edited it, but I found your cam specs and you do already have a 110* LSA. The 106 number they gave you was the intake centerline. So you are half way home!

A tight 10" from Coan would do very nicely.

The more I thought about your current converter the more I think it flashes to probably 5000 or something. If it takes 3500 just to get it moving at part throttle, the flash stall would be much higher. I run a loose 10" and a buddy runs a tight 10" on the street and they do fine.

Now that you have the cam specs (248/248, .555/.555, 110 LSA and 106ICL) give Coan or someone a call and see what they recomend.

A six speed would solve a lot of your issues but would seem to break the bank. If you have it in the budget and have the time and desire to perform the swap, go for it!

Originally posted by Greg O:
Mark,

Not sure if you re-read my last post after I edited it, but I found your cam specs and you do already have a 110* LSA. The 106 number they gave you was the intake centerline. So you are half way home!

A tight 10" from Coan would do very nicely.

The more I thought about your current converter the more I think it flashes to probably 5000 or something. If it takes 3500 just to get it moving at part throttle, the flash stall would be much higher. I run a loose 10" and a buddy runs a tight 10" on the street and they do fine.

Now that you have the cam specs (248/248, .555/.555, 110 LSA and 106ICL) give Coan or someone a call and see what they recomend.

A six speed would solve a lot of your issues but would seem to break the bank. If you have it in the budget and have the time and desire to perform the swap, go for it! AAAhhha, a 110* LSA makes all the difference :D Sounds like Greg is right . . . just do the converter IMO.

graemlins/thumbsup.gif

I believe Luniti cam#50157 is 244 at .050 ??
The way the car is set up I would try a little tighter converter that is of quality. My experience with TCI is their converters are high quality boat anchors.