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Another 350 CBS question...

893 views 10 replies 7 participants last post by  OldSchoolChevy 
#1 · (Edited)
Another 350 CSB question...

Hi!
I have a 1992 350cid L05 TBI 2-bolt 85K miles engine from a Buick Roadmaster who I intend to rebuild to carb and use in my rod project.
1992 Roadmasters w/ these engines are rated to 200hp.

What might the following mods do to the hp rating:
-Air Gap intake w/ 600-670cfm carb.
-No AC pump.
-No PS pump.
-Electric cooling fans instead of the belt driven one.
-Electric driven water pump.
-1 5/8" primary tube/3" collector headers.
-2,5" double exhaust w/low restriction mufflers.
-Large KN air filter.
-6 speed manual trans.

What do you suggest should the next thing to do? A new cam? I've heard these engines have a very mild cam, but haven't found any data on that.

Maybe a pair of Vortec heads modified to handle more lift in combination with new, suitable cam?
 
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#2 ·
what is the car you are building the motor for and is it a street car only or "race only"

an airgap intake in Norway in the winter on the street would not be my choice,

the winter temp cold air intake charge accelerated and made colder yet going thru the carb, going into a cold manifold= A/F mix won't stay in suspension...reverts back to liquid gas

one of the members here, posted he had frost on his airgap at 40*F !
 
#6 ·
Good plan

It is a pretty solid foundation you have there.

The Air-gap intake is an excellent piece for the street.

I would suggest swapping in a hydraulic roller cam (maybe around 220@.050 duration), and some vortec heads with the upgraded spring package and machined valve guides (handle extra lift). They make good power and the price is right. I have sourced some Ebay hydraulic roller cams for around $170.

Should make a fun 350-hp or so build. Nice and cheap! I wouldn't build anymore horsepower, or put on real sticky tires, unless you want to replacing IRS parts in that rear end.

Cheers,
Andy
 
#7 ·
AFR heads if you want horses. I saw an article where they put 195 cc AFR heads, a lunati voodoo cam, and a victor jr manifold and made 300 extra. Sorry i can't remember the specs on the cam. I don't think it was too big though. I don't know what Buicks are worth but if you add these you might want to strengthen the internals.
 
#8 ·
You're right, that factory cam has to go. Its a 191/196 @ 50 on a 117 LSA. Put in something like a 214 @ 50 cam on a 112 LSA.

All of the stuff you have listed is a great way to get "cheap" hp, but in general those items don't draw much away. The fan will help you with about 10 hp at the peak if its engaged and you're at redline, otherwise it only takes about 1/2 hp. The electric fan might draw 1-2 hp when its running from the draw in the alternator. No free rides. Cooling takes HP.

I also strongly suggest against the electric water pump. They are a great idea, but they just don't last on the street. A belt driven pump might take 1-2 hp but it lasts for 150k miles. An electric pump might only sap 1/2 hp, but it might last anywhere from 1000 miles to 20,000 if you're lucky. Then the next thing you know you're overheated, boiling, and praying you didn't do any damage.

PS pump will free up a 1/2 hp or so. It basically free-wheels unless you are standing still and steering. The amount of steering you would be doing while asking for full power isn't going to affect power output at all. Let me put it this way, if you're using power steering while you're foot is to the floor, you have bigger problems than hp loss :)

But the rest of your recipe is spot on; replace the cam, vortec heads, headers, and the intake/carb you have in mind are perfect.
 
#9 ·
red65mustang said:
you did not answer: cruise and sreet driven car or race only or how much of each
Not much race with this one.

I want a pretty fast street car with mileage and reliability who makes it possible to drive for longer trips.

The Jaguar IRS can handle a lot more power than most are aware of.
British Cobra kit car builders have used this setup for racing purposes in combination with high performance big block Ford engines & manual transmissions for years. The point is to put it on correctly.

I haven't quite decided on the electric belt driven water pump yet.

Thank you for valuable inputs from all of you!
 
#10 ·
for mainly street do stay with the 600 cfm carb....

reason is,

the air gap intake plenum volume is very big so it is hard to get to a practical minumum 14Hg with a bigger carb (750cfm) for tuning at less than 950 rpm idle and approx 18*+ base timing....for racing, you don't care about the idle

the 600 cfm carb will increase the idle Hg (A/F mix velocity) and make it possible to tune the carb to idle at possibly (?) 14Hg/750rpms/16* depending on the cam
 
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