how different are they. I haven't gotten headers for the 305 because I want 1-3/4" SLPs for the next 350+ sized engine. Am I justified in my feelings? I got 153k miles

------------------
-Tas
'89 Formula WS-6
[soon to be Performace Red =) ]

305, TBI, auto, 14x3 chrome flat based open element with K&N, functional Formula hood, cross-flow Flowmaster, '99z28 rear pipes and tips....

Super GRK_Taz World
EFI & Intake Options
AOL IM: superGRtaz
ICQ 82881207

 

if the collector pipe is 3inch it doesn't really make a huge difference what the primary size is since the primaries are so short. if you were considering full lengths it would be a lot bigger deal. i would get the 1 3/4's just because for the same price you get an extra drop of potential.

lata
tim

------------------
91 Camaro RS-LO3,Auto.
14.301 @ 94.39mph
The car is going street strip for next season. 13's here i come!!!!!
Edlebrock TES Headers, Cat Eliminator Pipe, Borla Adjustable Cat Back,Marche Pulleys, HyperTech Chip,Transgo Shift Kit,B&M Convertor(2000stall),Steve Spohn Rear Rig( all rod ends), Poly Front Bushings,Ported TB, 350 Injectors, Edlebrock Performer TBI Intake, Performer Heads, 1.6 Roller Tipped Rockers
http://www.mycar.net/mafb/registry/detail.cfm?id=299

 

ive heard the reason to get 1 5/8 is so that plugs clear.

 

Tas some of the books that i have read say that primary size is dependent of HP not engine size. so with that said with my exhaust setup i should have good low and mid range power and desent upper RPM too w/ any engine less then 383CI.

i may have misunder the concepts but i dont think so.

HTH,
UnderDog

------------------
1992 Camaro RS
Mods:
14x3 Open element w/ K&N filter, MSD 6a, MSD GM blaster Coil ,MSD 8.5 SC wires, AFPR,Fuel Pressure gauge(60Psi max), 3-Row Al rad. , 180* t-stat, Hooker 1 5/8 headers, 3" Catco cat, 3" Hooker Aero Chamber cat-back, "Ultimate TBI" mods, Nitto 555R Drag Radials

next
SLP Posi,3.42 gears, a/f guage,LCA, 330/350 crate
(all by the 1st of feburay )

Best Time: 15.279@89.02MPH
Underdog Racing

 

I agree with snflupigus with the added clearance for the plugs. The difference in power gains is minimal. If you get the bigger headers, I've seen problems with clearance in the engine compartment. This isn't always the case, they're all designed differently.


------------------
1989 Camaro Convertible
dark silver w/black top
305tbi, auto, all stock
posi w/drum brakes
Check out my site at: http://members.tripod.com/philsriceb...Boy%20Page.htm

 

If you are going to use slp's, the 1 3/4 will hit the steering box. You have to put a dent in them. The 1 5/8 fit and go in a lot better at least for my 91 RS. Also, there are several threads I think on the exhaust board about the difference in performance in the two sizes. As best I can remember, it wasnt till you get WAY up there in Hp and RPM that the 1 3/4 were any help. I am very glad that I stayed with 1 5/8 inch but I don't expect much over 300 Hp/325 Tq. Try to find that thread, it was a real good debate about the two sizes........bob

------------------
91 camaro RS L03 convert,
t-5, ultimate TBI mods,TBI spacer,SLP 1 5/8 headers,
3"cat back, 3.42 torsen posi,alston SFC's,Global West LCA relocation brackets

 

i have the 1 3/4" and they clear the plugs fine. they do however hit the steering shaft. i put them on last fall and put the car up for the winter like two days later, so i still havent taken care of the rubbing problem.

i think what i am going to do though is grind down the steering shaft a litle bit, it BARELY touches, and i would only have to take off a tiny bit of material. it wont take away a lot of strength.

for pics of mine installed, check out my page at http://members.fbody.com/z28boy/evaluation.htm

-brian

------------------
1991 Camaro RS - Ultra Blue Metallic, T-Tops
----------------------------------------------
GM 350 HO Crate Engine - Vortec Heads, Edelbrock Performer Vortec Intake, Holley 670 CFM Throttle Body, Open Air Cleaner w/14"x3" K&N, SLP 1 3/4" Stainless Headers, Edelbrock Victor Series Water Pump, MSD 6AL, Blaster Coil, 8.5mm Super Conductors, Accel Cap and Rotor, Hypertech Fan Switch & Thermomaster Chip, AC Delco Rapidfires, 3" Cat Back, Flowmaster 40 Series Muffler

700R4 - 2,400 Stall Converter, Vette Servo, Shift Kit, B&M Super Cooler

Brian's 1991 RS
Central NY F-Body Association
Join the Third Generation F-Body TBI Web Ring
z28boy@twcny.rr.com IM name: Z28 Boy