tweaking my 355/polishing a turd

[falcongeorge]

I'll start by outlining the combination as it presently exists
Daily driver S10 PU, 3400 with driver, PS, PB, PW
flat hood, underhood air,
flat-top 355 with hyp. pistons, zero deck, 10.5/1
stock out of the box performer RPM heads (yes, I know, but bear with me here)
Comp XS282S (244/252 .520/.540, 110 LSA, 106 ICL)
Performer RPM/ #80779 4 corner idle 750 dp,
Hedman 1.5" shorties/3" magnaflows
MSD 6AL
T700R4, 12" 2800 stall lock-up converter
8 3/4 mopar with 4.56's
Cal Tracs, de-arched springs
dead-hooks on M/T 28" ET Streets
runs mid 12s through the pipes,
6600 rpm shift points
1/2 shift recovery point is currently around 4000 rpm

Before it runs next season, I am swapping the PS box/pump for an aftermarket aluminum vega box, changing the master cylinder and removing the power brake booster(probably 40lbs off the nose?), and swapping the 12" converter for a 9.5" 3200 Yank ( I dont want a 3600, from everything I have heard/read, it would be somewhat loose at part throttle right where I do most of my driving around 1700/2000 rpm). I am hoping the reduced converter weight should make it pull a little better off the shift point.

Restrictions on the combo that I am not open to changing:
The shorty headers are staying, this truck is a true daily driver, I realize the proper header size for the combo is a 1 3/4" primary, any that will fit the truck are at least partially fenderwell (even the 1 5/8 Hookers) and will affect steering lock, non-starter.
The flat hood and underhood air stay, I do not want a cowl hood on the truck, and theres really no space to run cold air ducts. With the Perf. RPM, the air cleaner clears the hood by about 3/4", I can re-work the bracing and pick up a hair more, anything taller than a Super Victor is out of the question, and realistically, that is pushing the envelope, The ABSOLUTE MAX. intake height would be around 5.5".
The 700R4 is staying, I realize the ratio spread is abysmal and a 200R4 would probably be quicker, but the truck already has a nice custom aluminum drive-shaft and crossmember, a trans swap is just more work than I am up for at this point.
With the hyperutectic pistons, the present 6600 rpm shift point is about as much as I am comfortable with, I really dont want to spin it any higher than that.
Its presently getting around 17/18 MPG, I think there may even be more there if I really get after it with a wide range Lambda, start playing with the ifr's, delaying the onset of the mains with a bigger air bleed, tweaking the PVCR's, ect, but I dont see much point in persuing that until at least after the converter change, and with other changes I am considering, it probably doesn't make sense until I complete the other changes.

The goal is an 11.70ish time slip, retaining more or less the same streetability/gas mileage. Ok, now that I have laid out the parameters, on to the stuff I am looking for input on.
1) cylinder heads. especially in light of the fact that I do not want to spin the motor any tighter, should I A) port the RPM's, I am thinking widen the pinch and raise the roof a bit, widen the port floor at the short-side or B) sell the RPM's to a street rod guy and buy a better head. probably a 195/200 intake port? Keeping the 6600 rpm shift point in the forefront of your mind, any head recommendations? Aluminum is a must, one thing I DO NOT want is any more weight on the nose of this pig.

2)Cam. I think the seat duration is right about where I want it, but I am thinking a 108 LSA would pick it up across the board, and really help with the 4500ish shift recovery point, also thinking a smaller spread? Thoughts? Hoping maybe Mike Jones might chime in here? The present cam is really good on the street, once its warm, virtually no noticable lope at around 800 rpm, so I can afford to lose a little idle vacuum/quality if the trade-off is more torque off the shift recovery point. Again, if I really got after the carb tuning, I can probably improve on this.

3)Intake manifold. Basically, looking at three options here, keep the RPM and either go to an annular 850 or mill the divider down, or switch to a Victor Jr or 7530 Team G. Strip Dominator is out, too tall. Are the single planes going to be incompatible with the shorties (I have no prior experience with them)? If so, would crutching the single plane with a shear plate combo end up working better than the RPM?

Ralley and Matt Gruber, before you even start, I dont really need your input here, I dont want this to turn into another mindless rant. Ego driven pissing matches with no empirical evidence are entertaining to read, but they discourage guys that actually have first hand real world experience from posting, so please save the psychobabble for another thread. Thanks.

[bigjoe1]

I am surprised that it is as fast as you say, but the changes you are thinking about will NOT make much difference at all. I think it would be a big waste of time and money. I am not familiar with drag racing with your trans, but you need a much looser converter to run any faster times. If it was a turbo 350, I would use a 4000 to 4500 stall


JOE SHERMAN RACING

[lefty o]

victor jr or perf rpm airgap, and throw those heads out. a set of AFR 195 will make it come alive. shorty headers gotta go, if you have to have a set made. long tube 1 3/4 would be great, but even a long 1 5/8 is going to be much better than 1.5shorties. id probably tighten up the LSA on the cam a few degree's.

[falcongeorge]

Jeez! I was thinking there was more left in it! I was actually thinking about holding off on posting till next year after the converter swap and some more laps!

[falcongeorge]

victor jr or perf rpm airgap, and throw those heads out. a set of AFR 195 will make it come alive. shorty headers gotta go, if you have to have a set made. long tube 1 3/4 would be great, but even a long 1 5/8 is going to be much better than 1.5shorties. id probably tighten up the LSA on the cam a few degree's.

i was pretty much thinking along the same lines on the heads, probably better to just sell them and get something better. I was thinking 195 AFR's as well, but figured I'd just leave it wide open to see what other guys think. Joe kinda took me aback there, I was thinking I should be able to get at least a .30 out of it just with more tuning, the converter change and 50lbs off the nose!

[bigjoe1]

I do agree, the AFR heads would be much better, but being realistic, you might get three tenths, four at the most..Again, more stall speed if it really hooks up loke you are saying.

JOE SHERMAN RACING

P S -- If you get the AFR heads, raise the compression too.

[BOOT]

What yr S-10 I know some of the older ones came with manual boxes, I used one to convert a 3rd gen Trans Am to manual. On the heads since you didn't mention it I'll assume, If your not gonna port the bowls, why mess with the runners? I'd stick with dual plane and not cut the divider with the shorties, rpm is fine. I thought the point of retaining the lock-up was so you could run more stall then lock it up in OD for mileage.

Sounds like you need better heads or nitrous. A friend once told me the advantage of nitrous vs boost on the street is it's not always on.

[falcongeorge]

What yr S-10 I know some of the older ones came with manual boxes, I used one to convert a 3rd gen Trans Am to manual. On the heads since you didn't mention it I'll assume, If your not gonna port the bowls, why mess with the runners? I'd stick with dual plane and not cut the divider with the shorties, rpm is fine. I thought the point of retaining the lock-up was so you could run more stall then lock it up in OD for mileage.

Sounds like you need better heads or nitrous. A friend once told me the advantage of nitrous vs boost on the street is it's not always on.

Its an '82, so it would take the 3 bolt box, pretty slow ratio, and if I am going to go to the hassle of swapping the box, I want to maximize the weight savings with an aluminum box. Not gonna spray it, its just a daily driver shop truck not my only car. I actually bought the truck built (good deal, really nice chassis work under it, and the body is MINT) just think theres more in it without screwing up the street manners. I would do the bowls as well, just kinda took that for granted.

[falcongeorge]

I do agree, the AFR heads would be much better, but being realistic, you might get three tenths, four at the most..Again, more stall speed if it really hooks up loke you are saying.

JOE SHERMAN RACING

P S -- If you get the AFR heads, raise the compression too.

It could stand more compression for sure, I could go 11/1+ on the local 94, and it should help idle vacuum/ PT fuel economy as well.
It hooks good, yanks the front wheels even with less than 3000 flash. The gear spread in the 700R4 is pretty crappy (3.06/1.63/1/.70) so it leaves (relatively) hard, shift right away, and kinda falls on its ass.
Maybe I am being too conservative on the converter, I'll give Yank a call and talk to them about thier looser 9.5" converters, I am running a much steeper rear gear than most of the guys I have talked to about the street manners of the looser 9.5" converters, the same converter will probably feel 'tighter"at part throttle with my 4.56s as compared to a guy who is running it in front of a 3.73.
Someone made the comment about using a looser converter and locking it, well yes, and when I drive on the highway, I do, but locking and un-locking it in typical moderate suburban traffic around town gets old pretty fast, and thats where I do probably 80% of my driving. With the od, I am usually in traffic around 1700/2000 rpm in od with the converter unlocked, right now this works really good, and I have heard that a conservative 9.5" will be tighter at part throttle than my current converter.
Other than the stupid big spread between 1st and 2nd, the current combination works REALLY GOOD on the street. If it just had the same 1-2 spread as a T350 or a 200R4, it would be PERFECT. The 4.56's with the .70 od are just dead on the money for the way I drive.

[KnightEngines]

Shorty headers have got to go, 1 5/8" pipes will take you past 500hp no problem, so if that's all that will fit then they'll still be miles ahead of the shorty's.
I'd switch to a Vic Jnr intake & keep the same carb.
The eddy heads are definitely holding it back, toss up as to whether it's worth porting them or just switch them for something better - I can say tho that they'll work just fine with a bit of grinding by someone that knows what they're doing, but selling them & buying others V's porting them I reckon the $$ factor will be in favour of new heads.
One big advantage of just buying new heads is that you can switch em over a weekend & drive to work Monday, sell the eddy's at your leisure.

[falcongeorge]

I do agree, the AFR heads would be much better, but being realistic, you might get three tenths, four at the most..Again, more stall speed if it really hooks up loke you are saying.

JOE SHERMAN RACING

P S -- If you get the AFR heads, raise the compression too.

Joe, one other question, in light of a ballparkish 6600 rpm shift point, am I right in thinking that a 200CC intake port is what I should be looking at?

[falcongeorge]

Shorty headers have got to go, 1 5/8" pipes will take you past 500hp no problem, so if that's all that will fit then they'll still be miles ahead of the shorty's.
I'd switch to a Vic Jnr intake & keep the same carb.
The eddy heads are definitely holding it back, toss up as to whether it's worth porting them or just switch them for something better - I can say tho that they'll work just fine with a bit of grinding by someone that knows what they're doing, but selling them & buying others V's porting them I reckon the $$ factor will be in favour of new heads.
One big advantage of just buying new heads is that you can switch em over a weekend & drive to work Monday, sell the eddy's at your leisure.

Bingo! Yea, you are getting the "daily driver" part! Thats one of the big reasons I am looking at an aluminum vega box instead of a rack too. I really drive the hell outta this thing. Hell it even hauls lumber...

[cab0154]

If it were mine, I would do the converter and upgades you are already planning. I would do another cam with similar intake duration at .050, and get the most duration at .200 I could. I would also increase the .050 duration on the exhaust due to the little headers. I would also port the heads and intake (or buy better heads and sell the eddys), on that little engine I don't think it being a dual plane will hurt it. I would also get rid of that carb and run an AED 650 HO. Most 850s have a huge venturi and would likely make it a turd with that large cam and low compression on that short stroke, especially with a tight converter and a large gear split/rpm drop. the AED 650 should easily support 500hp, so that should be more than enough for what you are doing. if you have to have a choke (which I wouldn't bother with because all of our AEDs start fine even in the cold without them) then I would call quick fuel.

[falcongeorge]

If it were mine, I would do the converter and upgades you are already planning. I would do another cam with similar intake duration at .050, and get the most duration at .200 I could. I would also increase the .050 duration on the exhaust due to the little headers. I would also port the heads and intake (or buy better heads and sell the eddys), on that little engine I don't think it being a dual plane will hurt it. I would also get rid of that carb and run an AED 650 HO. Most 850s have a huge venturi and would likely make it a turd with that large cam and low compression on that short stroke, especially with a tight converter and a large gear split/rpm drop. the AED 650 should easily support 500hp, so that should be more than enough for what you are doing. if you have to have a choke (which I wouldn't bother with because all of our AEDs start fine even in the cold without them) then I would call quick fuel.

Actually I have a modified 650 here with undercut down-legs and slabbed throttle shafts that I intend to try out on it at some point, especially if I go with a single plane. I'm 99% certain it would be a total turd on the split plenum dual plane.
Keep in mind that while the header primaries are only 1.5", they are also only about 20"-25" long. I know most guys are hating the shorties, I'm less than convinced as to any gains I might see with full length headers translating into better track times, especially if the full-length pipes are less than optimised. My own gut level hunch (and everything that follows here IS JUST a hunch) is that with the dual plane, it probably makes little, if any difference, but would be more of an issue with a single plane, I think then you may see a big hole in the torque curve at some point in the power band, probably somewhere right around 3000/3500rpm. My guess is that the single plane will be much more sensitive to header changes than the dual plane, hence my comment about band-aiding the single plane/shortie combo with a shear/reversion plate.

[bigjoe1]

You perception about converters is WRONG unless you are using some piece of shit converter. A good 5000 stall converter will drive pretty nice, I am not sure about your very low cruise RPM though


JOE SHERMAN RACING