Sonix

iTrader: (1)

See sig for current setup, but it's a 10:1 350 with heavily ported 416 heads, and a compxe268h cam.

I was toying with the idea of swapping to a bigger cam this winter. I now have a DD car, so this car doesn't need mileage, or reliability (not that it ever had any semblance of reliability anyway...)

I also never noticed any "big cam" drawbacks with the comp268, and i'm willing to put up with some in my search for power, so I figured i'd go bigger.
I think my heads are taming the cam somewhat as well, since i'm most likely undervalved.

I was thinking about going to a compXE274S, or a solid flat tappet in that ballpark, 236/242 @.050 on a 110LSA. If anyone has a suggestion feel free to let me know, I was thinking about a cam with a tighter LSA as well, ~108.

I don't have the rotating assembly balanced, so i'm going to keep it below 6000RPM or thereabouts. I want to strengthen the mid range (3500-4500RPM range) mostly.

The only issue I have is that I have 100/300lbs 1.25" OD springs on there now. If I went to a 1.43" OD spring i'd need to machine the heads, and get new retainers, shims and locks
I'm hoping to get away with only buying the cam and lifters, and maybe better springs, but not locks, retainers, and shims.

Comp recommends the 983-16's, which is a 1.25" OD single spring so I can re-use my existing locks and retainers.

Do you guys think these springs are sufficient at controlling a solid flat tappet cam up to 6000RPM?

Thanks

Apeiron

You don't need a solid lifter if you're keeping it under 6000.

If you're going to "upgrade", spend the money and put a roller cam in.

Sonix

iTrader: (1)

Well "need" is a rather strong word isn't it? I know some of the solids available are in the xe256 and xe262 range, such that they would run out of duration before you hit 6000RPM anyway.

I figured the better ramp rates would give me power across the board, along with going up to a significantly bigger cam (duration @.050) while keeping it semi tame due to the fact that it's a solid cam and the advertised is still relatively tame ( I know they're measured differently as far as advertised duration, but I understand a solid cam with xxx advertised will feel a size smaller than the hydraulic cam with xxx advertised duration).

Also the fact it's a solid gives me one more tuning tool, I can change the lash *slightly* to change the size of the cam.

Apeiron

You'll get a bigger bang on ramp rates out of going hydraulic roller than you would going solid flat.

Sonix

iTrader: (1)

That's true, but instead of $230 for cam and lifters i'd be looking at $800 or so right? Plus i'd definately need to go to 1.43" springs, and different pushrods as well
Baby steps here. (Solid) Roller will be for a bigger buck motor down the line.

Any thoughts on the solid flat "upgrade" ?

Apeiron

I wouldn't bother.

F-BIRD'88

Take a look at the smaller Isky flat tappet cams. 250@.050 and down.
If you were to swap the rear gear ratio up to say a 3.73 or 4.10 you could run a Isky Z27 #201027. the actual 0 lash gross lift at the valve is .498", not .507".
making the net lift .482" Easily accommidated by your springs. Even allowing for some shimming to increase the seat pressure to 110-115lbs.
I'm using comp 981 springs. Another good choice is Lunati 73943 Isky calls for isky spring #205-D
This is the cam I choose for my "Junk Yard Dog" project which is very simular to your build. I paid$ 160(Can) taxes in. Goes in 4degs advanced (104 in C/L)
Will be very strong from 3000 to 6000+.
Its going to be a lot like a Comp 280H magnum, but with an attitude.

If you want a little less attitude use Isky Z-25 #201025. It's a little tamer. could use 1.6 rockers.

Orr89RocZ

iTrader: (20)

Lunati voodoo cams have the most aggressive ramp rates i've seen in hydraulic cams. Look at the advertised duration numbers and the .050 numbers. the closer the .050 duration numbers are to the advertised, the more aggressive the ramps.

comps 268 cam is a 224 duration at .050. Voodoo cam is 227 at .050.

if you want a hotter cam, try the next size up.. the 276 cam. its 276/284 advertised and specs out at 233/241. very aggressive and suppose to make power to 6400 and i know you want to be done by 6000 but this aint too much higher than that. And that rating varies on motors.

else go with the comp 274H. that should net some nice gains in power

SpitotRs305

you will want more gear than 3.23s with the comp 274...just going through this...

had 3.08 sucked... went 3.23 figuring i would save some gas but get alittle more seat of the pants... drove that about a week... now i am shoping for 3.73s... figure 4.10s would be overkill

Sonix

iTrader: (1)

Yea, i'm thinking of finding which vehicles had 3.73 gears so I can go JY diving for those. Perhaps a V6 camaro? Or and S-10?

I'm not going to pay for a new cam and lifters to stay hydraulic and go up one size, that wouldn't be worth the cash for me.
I'll have to make a decent sized jump up. Solid is only a few bucks more than the hydraulic as well.
I'll take a look at those ones you suggested F-bird. Since they are straight pattern i'd look at getting 1.6 SA rockers on the exhaust.

Orr89rocZ, yea, I'm pretty familiar with the voodoo lineup, I had the 268 voodoo before I wiped out 4 lobes and got the XE268 (not because I don't like Lunati, but they weren't stocked locally, and would have cost me another $50 to get that cam, so I got the similar comp one instead on my warantee).

That Z25 looks like just the ticket, 240/240 @.050", 108 LSA. That'd be just GNARLY! That wouldn't make a terribly good nitrous cam would it? I'm just toying with ideas, and I figured i'd do one performance upgrade this winter. (I find it hard to justify throwing away perfectly good performance parts to get new ones, so that's why only one)

-Bigger cam
-Stroker kit
-Nitrous kit

The cam would only run ~$300 or so, stroker would be close to $500 ($200 crank, $150 pistons, then $300 to balance it all up). Nitrous would run me ~$600 as well. I'm thinking of doing the cam. Next year I might go for some bigger heads, and maybe the stroker then.

That ISKY Z25, only needs ~110lbs on the seat and ~320# on the nose? I could shim my current springs for that, but I figured it'd need more spring?

SpitotRs305

i am not sure about the S10s maybe on the 4 cyl they got 3.73s the highest i have been able to find on a V6 camaro are 3.23s but more than a couple with posi... there are alot of the V6s though with the entire rear end hacked out so maybe a good place to look...

it would seem to me that unless you planned to spin this higher than 6k in the future it might be easier to stick with the hydraulic

correction...

the 4CYL S10s got 4.10s most of them with "gov-Lock"

brand new gov-lock units act similar to a posi or limited slip... as the friction material wheres with age or abuse ... it starts to act more like a true locker with a more violent lock some say similar to the older detroit lockers

Orr89RocZ

iTrader: (20)

Does Comp make a nitrous solid flat tappet cam? check some of those out perhaps if they do.

that would be a gnarly cam tho and probly will scream well over 6000rpms. Cuz dont solid cams act like a larger hydraulic cam?

Sonix

iTrader: (1)

I'll be getting a Detroit true-trac for this rear end.

What vehicles do you think I should check for 3.73 gears then? (used that is).

Solid cams act like a smaller hydraulic cam actually. The lash makes it feel smaller.

SpitotRs305

if i had to guess i would say blazers not the old skool k-9s but the newer ones with the V6

Pat Hall

iTrader: (31)

Yeah, the S-10 Blazers/GMC Jimmys are probably the best place to search for 3.73's. A select few of the early thirdgen cars actually got 3.73's, but they're a rare find. At the junkyard, I pulled a set of original 3.73's out of an 85 Z/28 that had the L69 305 HO motor and a T5 trans. If you're interested in 3.42's, they came in probably every thirdgen that had a V6 with the T5 trans. I see those all the time. The automatic V6 cars usually got the 3.23's.

Sonix

iTrader: (1)

Hmm, i'll check the S-10/blazer aisle first then, thanks.

jtrescot

Seems like you acknowledge that your heads may already be holding you back, so why would you want to go to a larger cam? I would look towards heads as the next upgrade, even if it means looking around for used ones to keep the price down. Seems like you could sell your used heads, and with that money, plus what you are willing to spend on cam, lifters, and springs, you would be able to upgrade.

Sonix

iTrader: (1)

Well, I have heavily ported 416's, they're pretty decent, but a far cry from 190cc intake aftermarket heads.
I doubt I would be able to sell them and get anything for them. Any heads I could buy for under $1000 here wouldn't beat what I have now. Vortecs would need a new intake, driving up the price. Also they wouldn't be a huge upgrade over what I have now. I'd need to get into the $1000 range aftermarket heads for it to be a worthwhile upgrade.

Mediocre heads with decent duration can make power, i'm comparing to those super stock engines with a 305, 416 heads and a COLOSSAL (duration) cam turning 11 second timeslips.

I think i'd go for the heads later down the line.

Orr89RocZ

iTrader: (20)

yeah if you dont have the heads, you can run abit more cam. heads would be nice but not necessary.

Pat Hall

iTrader: (31)

Lol, I can so relate. I kept camming up my motor til I finally forced myself to buy a set of AFR's.

F-BIRD'88

Sonix: don;t get all rapped up on the specs. A single pattern cam does not need high ratio rockers on the exhaust side. it won't help. You would want to use a 1.6 rocker on the intake side if any where.
A single pattern cam will make more mid torque than a dual pattern cam will.
the average torque is more important than peak power.
While a "nitrous cam" may make a few more ponies on nitrous, remeber most of the time you won;t be using nitrous. This cam will still make tons of power on nitrous.
Don;t avoid using a 4.10 gear thinking that your fuel mileage will go all to hell.
Once you've cammed up the motor to this point the torque curve is shifted up. The motor is now not happy at low rrpm.(below 2000rpm) but it is happy and fairly efficient at part throttle at 3000+rpm. When set up properly with correct ignition timing and carb jetting, cruising at 100 K/H with say the Z-27cam and 4.10's is not that bad. If you can keep your foot out of it LOL

I wouldn't sweat the valve spring pressure either.
While your 416 heads are ported, they have their limitations. You most likely won't need to rev the motor higher than 6400 6500rpm with a dual plane manifold. Certainly not 7000rpm. Less valve spring pressure makes the valve train last longer over time.
Mine is only set up for 100-105LBS seat pressure.

6800-7000rpm would require 115 to 130 lbs seat pressure and 330 open, but for what you and I will be doing, 6400-6500 rpm is plenty.
I set up my springs like this.
1 .030" spring shim under each intake spring.
A .015"+.030"+.060" stack under each exhaust spring using standard GM retainers and locks and Comp 981 springs. Left out the spring cap oil shields and rotators.

Again, avoid sweating over peak valve lift, rocker ratios etc etc. 1.6 rockers make a difference on small street cams cause they are small.
Many times on a larger cam the valve train stability gets upset at high rpm actually reducing power and increasing wear. .480" net valve lift is plenty for these heads. the duration and valve timing points are much more critical to making power.
If you go with the Z25 or Z27 Let the Isky cam do the work for ya. 1.5's will be fine.

Sonix

iTrader: (1)

Damn, a little late there. I just purchased 1.6 roller tip rockers, SA, from CNC motorsports, to replace my stamped GMPP 1.5 SA rockers.

I'll be going with the Z25. Nitrous is doubtful, but maybe.

I'll check the JY and see what I can find in the 3.73 or 4.10 range. I'll also be getting new tires next summer (the 275/60/R15's I have now are wearing out from age...). I'm thinking about going to a tall tire like a 295/60/R15 or something.
I no longer care about mileage in this car, I have the Delta 88 for road trips, this car will be for ripping up the pavement.

I will most likely lock out the timing at 34* all the time, or something like that, and maybe ported vacuum advance. Dual plane and Q-jet still.
I agree with the rest, I think this setup is what i'm looking for.

F-BIRD'88

If you're going to go with a tall tire then definatly go with 4.10's. 3.73's will not be enough. I run a 26" rear tire and 4.10's. If you cannot get a set of 4.10's from a JY 4 cylinder S-10, buy new.

Well now you have the rockers to experiment with to see what actually makes the best power on your car.
just be sure the retainer doesn;t crash with the guide boss or seal at full lift. You also probabily will need to lengthen the push rod slot in the head towards the stud for the 1.6's.
use the 1.5's for break in.

F-BIRD'88

What is the first gear ratio of your T-10 trans?
have you ever been to the track with this car?
What are the numbers? how much does it weight?
If you're going to cam it up, getting the right gear/tire combo is critical.
You're way under geared now.

Fast355

iTrader: (2)

My 1987 S15 Jimmy has 3.73s. It was 4x4 with the 2.8/700r4 combination. It has the factory Gov-lock in it too. Look in the glove box on the SPID label. A 3.73 truck will have GT4. Govlock is G80

Sonix

iTrader: (1)

First gear is DEEP, apparently it's 3.42
3.42 - 2.28 - 1.45 - 1

I was running the lunati 60103 with 1.6 Roller rockers (total of .515" lift or something), and didn't hit the retainers. I did however grind the pushrod into the slot.... I had elongated it, but I guess I went a bit sideways, the pushrod made it's own little groove and sat in there... Binded, then broke. After a set or two of pushrods I started dusting off the brain and figured out that mystery. I drilled 1/2" holes and now use SA rockers.
----------
THANKS FAST355! I was hoping there was an easy way to check, before I lay down and get REALLY dirty. For the most part the small S-10 type trucks aren't molested before they get to the wreckers, so factory gears are usually still in there.
GT4 - i'll look for that. Out of curiosity, do you know what the 4.10 ratio is numbered?

Fast355

iTrader: (2)

Sounds about right for the super T-10. My guess is that you should run no more than 3.73

IIRC, it is GT8 for 4.10s. ALOT of the 2.5s had this rear-end. I KNOW for a FACT that a Chevrolet Astro/GMC Safari with the 2.5 4 cylinder OFTEN came with 4.10 gears. If you find a plain jane cargo astro/safari, its worth taking a look for a 4 cylinder. If it has a 4 cylinder, check the spid label for GT8.

EDIT- Just went out and looked at the SPID on my GMC. It also has GQ1 on it, which means 3.73 IS the STANDARD gear ratio for that package. Finding a 4x4 S10 with a 2.8 should be easy enough to find.

Sonix

iTrader: (1)

Never been to the track. I had to rely on the vehicle to get to work (which I no longer do), and every time I bagged on it something broke. I'm running out of stock parts on the car, so I should be good now. haha, knock on wood right?
No idea of weight, but these cars are all the same, so i'd guess its similar to any other 1982 manual tranny car with no A/C, but has power windows and a hatch wiper. Call it 3300lbs or so???


I run 275/60/R15 now, 28" diameter. Looking at my gearing spreadsheet, after going up to 3.73's or 4.10's I can't really go back to a shorter tire, or else my top speed (6000RPM in top gear) would be 185km/hr, or 112MPH or something. I'd rather have it a bit higher, not that I intend on driving that fast, I just don't want to be roaring in top gear all the time.
I can get the tires last minute, that'll be next summer. Gears I might grab tonight, cam and lifters in the next month or so. Gears are most likely in the $50 range, so I can always swap around if need be.

F-BIRD'88

At 6000rpm with 4.10's and a 28" tire (275-60-15) your speed would be 122MPH

Your car will likley MPH in the quarter between 105 and 108MPH with the isky cam.
It certainly will be under 110MPH. that would take 435hp+
With 4.10's your still under geared for the quarter by 1000 rpm.
Althou the steep 3.42 first gear ratio will help.

With the 4.10's you would be geared right for your motor running on NOS.

Would be nice to get your car to the track to see how much horsepower your making now (MPH) then you can guestimate how much power you'll have after the cam swap. then you can gear it accordingly. The MPH is the critical number. The ET is all about traction, shift and launch rpm.

@60MPH (100Kph) with 28" tires and 3.73's using the isky cam you are under geared (2685cruise rpm) and severly under geared for the quarter mile (4700rpm@105MPH) (4840rpm @108MPH)

In my estimation your best combo now and after the cam swap is a 4.10 ratio combined with a 28" tall street tire (street radial) and a 26" tall strip tire height (slick or ET street) (P235/60-15) Best overall compromise N/A and on NOS. Based on a car+ drive weight of 3530 LBS. Being off by 200lbs or so either way won;t change the numbers.
With the 4.10's and a 28" tall street radial the car will cruise along at 100 KPH at a comfortable 3000rpm. This is where you want to be using a cam like the Z-25 or Z-27.

Orr89RocZ

iTrader: (20)

You think he wont be faster than 108 with a big cam? my buddies 9.5 to 1 compression 350 with stock truck vortec heads, stock LT1 roller cam, and 750 carb laying on a Performer RPM manifold went 99mph in a 4000lb+ 83 shortbed chevy truck. thats a MILD combo and was thru a 3500stall auto. 3500lb fbody it probly would have went 103-104 mph. I dont think it put out more than 350hp. I woudl think a big cam like those listed would make well over 400hp even on those 416 heads

F-BIRD'88

I estimate he'll make 390 to 420hp with the Z-27 cam Thats honest hp, not magazine hp. Good for 105 to 108.5MPH in a 3530lbs street car with all accessories and little or no chassis preperation.
I'm just finishing assembleing essentually the same motor. If either of us make more than an honest 420hp I would be suprised. When ya think about it that impressive thou. Easy 12 sec ride for not too much $$$'s.

Sonix

iTrader: (1)

Whoa whoa, Z25 here, the Z27 is a smidge too wild for me.
I've actually got SFC's, boxed LCA's with poly bushings, and a poly TA mount. I'm going to make an adjustable TA over the winter, along with welding in my LCA RB's. I'll dyno the car this spring (honestly this time!)

1989GTATransAm

iTrader: (3)

I think he should do better than that. My best mph in the quarter was 110.95 with an A4 and 3600 Yank stall. This is with a modded TPI no less. My race weight is 3760. Car is currently under the knife with mods to the TPI.

F-BIRD'88

How do ya get a Third gen to weight 3760LBS?

1989GTATransAm

iTrader: (3)

Easy. My GTA scales at 3510. Then you add my weight of 250 pounds and you are there.

Orr89RocZ

iTrader: (20)

3510 was that with a full tank of gas and spare tire/etc? my car with 1/2 tank or so with no spare no a/c was 3400 even. irocz L98 with full options, power everything, leather etc i have heard GTA's were heavy

1989GTATransAm

iTrader: (3)

No spare tire and maybe a 1/3 tank of gas. Otherwise all options still in place. I do have an electric water pump and aluminum heads.

Sonix

iTrader: (1)

Good god that's a hefty car... Maybe i'll weigh my car sometime... I'd hope it's in the 3200lbs range, but who knows.

I was JY diving today, and saw a blazer with 41/11 pinion/ring gears in it. So that's 3.73's, and i'd guess 41/10 is 4.10's eh? I didn't have enough tools to get it anyway, so i'll have to try again.
Unfortunately all the vehicles I was looking at didn't have the glove box there anymore, so I couldn't even check for SPID codes... I did check a passenger door sticker on an astro-van, and saw no GT4 or GT8 so...
I'll dig around more in a few days.
I'll look for iron duke powered S-10's and Astro-vans, that's my best bet for the 4.10's eh? I might grab those 3.73's as well, so I have some choice.

DLV555

iTrader: (1)

All 200-4R equiped Monte Carlo SS's had 3.73s. I believe the Cutlass had the same gear but that may have been an 8.5" ring gear.

Sonix

iTrader: (1)

I'm not going to find a monte carlo SS in the wreckers, and I think you're right Cutlass's didn't have the 7.5" I don't think.
But the 3.73's i've found, now i'm searching for 4.10's to round out my collection of 7.5" rear gear parts

Fast355

iTrader: (2)

http://home.earthlink.net/~rhocott/AxelCodes.html

Lots of factory 4.10 gears for the 7.5".

Some of mention

HXF: 7.5”, 3.73 posi (1987 Astro)
FAP: 7.5”, 4.10 open (1988-1989 Astro)
FAR: 7.5”, 4.10 posi (1988-1989 Astro)
FSD: 7.5”, 4.11 posi (1985-1986 Astro)
HZG: 7.5”, 4.11 posi (1986-1987 Astro)
KJX: 7.5”, 4.10 open (1987 Astro)
KJY: 7.5”, 4.10 posi (1987 Astro)
KRU: 7.5”, 4.10 open (1987 Astro)
KRW: 7.5”, 4.10 posi (1987 Astro)

This is just funny, IMHO
8BJ: 7.5”, 2.41 posi (1981-1985 Regal)
3BK: 2.14 posi (1986-1987 Regal)
2PSG: 2.41 posi (1978-1980 Firebird)
2PTG: 2.56 posi (1978-1980 Firebird)

Sonix

iTrader: (1)

Thanks! ahh, 2.14 gears, who needs overdrive eh?

Fast355

iTrader: (2)

I've driven a Malibu that had the 4.4L V8 (267 with the feedback dual-jet carb, remember those), 200C, 2.14 posi. The 2.14 posi is about as pointless as it gets in that car. It won't even fry a tire with the extreme lack of torque. On the highway doing 70 mph, the car got GREAT mileage though. Just wouldn't push its way out of a paper bag.

F-BIRD'88

Hey fast: thanks for the link with the axle ID codes.

Sonix

iTrader: (1)

Hey F-bird'88, what do you think of this cam in comparison? The Z-25 is on the right, the 524 on the left. A slight split pattern, with a tighter LSA, and much more valve lift. A smidge larger.
Think it'd work better?

F-BIRD'88

Y I looked at That one. it will make good torque with open exhaust.
The .534" lift requires better springs than what I have. (981)
The idle and manifold vacuum will be lower than the Z27 I picked.
I liked the Z27 better overall. Easy driving, easy on my valvetrain. More optimum timing and LSA for what you and I are doing.

If I was going to build with the 524 grind I would use a single plane manifold and higher compression. They are all very close. I just feel that the Z27 is my best bet overall. I wanted something like the Comp 294S magnum but with a lift and design lift rate that my 981 springs and stock rockers would handle and a 108LSA. These isky flat tappet cams are designed to take a lickin and keep on tckin'

I may experiment with some other cams later (nitrous friendly, smaller , bigger, but its nice to have a good overall baseline cam to work with first.

Remember with a single pattern race(y) cam and headers you get more average torque. makes a difference in how the car "drives" (very subjective) and accelerates. The isky Z27 looks to me like something I can work with.
Advance it, retard it, play with the lash and rocker ratios. This makes way more difference than wether the thing has a few deg more exhaust duration or a bit more peak lift.

327???

Now wait just a minute......

You can find deals, you just need to wait and check the for sale section often.

Did you ever get the q-jet to run good? I'd get a Holley 750 DP before a monster cam.

Sonix

iTrader: (1)

Yea, my Q-jet runs quite well. I'm lacking fuel in the top end, but I think that's more of a fuel pump problem. Never got a chance to fix it, I had to rely on the car so I didn't have a chance to tear anything down last summer.

I have a spreadbore intake, and no particular love for holleys.

Unfortunately, unless I saw AFR's for $200, it wouldn't really be very cheap. Once they're shipped, then cross the border into here, it becomes MUCH more expensive. Besides, I'm not ruling out aftermarket heads, just...not yet. No reason I can't put them on later

327???

I forgot about all the BS at the border. I got my trickflows for $850, brand new. It was cheaper to drive 6hrs to go get them, I had to go through canada to get to michigain from new york.

If ya like the q-jet then use it, It'll supply all the air you'll ever need.