SB 350 - Need some advice

[Sherlock_Holmes]

Hi everyone!

I'm about to buy my first small block car, with a 350 inch engine

The owner told me it "only" is around a 145 hp engine.

First of all, how do i check that?
And i know there is a lot of different 350 engine, all with different output.
So, whats the difference on those engine? The heads? Valves, exhaust etc.?

If i want to remove the "limits" (get more HP) where should i start?
Would a new exhaust (3") and new manifold do the job? Or do i need, valves camshaft etc. to get more power?

Thanks in advance

[rspears]

Sherlock, welcome to CHR. I see you're from Denmark, which hopefully will guide some of the replies to be more towards the simple facts. The easiest way to really check the horsepower output on your engine is a chassis dyno that measures rear wheel horsepower, but finding one in Denmark may be a challenge.

If it's indeed a low HP 350 there's no "bolt on's" that will give you huge boosts in power. A 3" exhaust would be a mistake - too big, and it won't scavenge as well because the flow velocity will be too low. If you're on a budget and simply wanting to get a little more power you can buy a set of good, aftermarket headers and a new intake & carb package that will get your engine breathing better. If you're wanting to go bigger, then you're faced with changing heads and cam. The problem is you really need to decide on your plan before you start spending money or you may buy things that you'll only replace later.

Hopefully one of the guys who know far more than I do will chime in here, like Glenn Sexton or TechInspector1, and provide you with some of their wisdom in detail. I know Glenn recently posted details of a SBC build that's tried and true, from bare block to performer.

Good luck with your project. I've been amazed by some of the cars coming out of Denmark in recent years! Some fantastic engineering, and attention to detail.

[techinspector1]

Great post Roger.
Sherlock, here's the skinny....(that's "Navy" for "here's how it works")....
Any internal combustion gasoline engine is just a big air pump with spark plugs. The more air and fuel you can push through it, the more horsepower and torque it will make. Actually, an engine makes only torque, which is then converted mathematically to horsepower. Any production engine, such as the one you have, was originally designed at the factory to accomplish a specific purpose and was offered to the public for sale at a specific price, which was as low as possible in order to attract buyers. Generally speaking, these engines/transmissions/differentials in cars and trucks were designed to haul the family on a vacation trip or to take Mom to the grocery store a couple of times a week or maybe to take Grandma to Bingo down at the Catholic Church once a week. Because of the rather mundane duties they were asked to accomplish, the drivetrains in these autos were designed to operate in a specific rpm range, for instance just above idle to about 4500 rpm's, which would be about the max revs used for passing another car or truck on a high-speed road or highway. They might rev a little higher than that, but they aren't making much power because of the operating range of the camshaft.

Now, along comes us hot rodders with our "need for speed" and we feel strongly that the stock setup must be modified to give us our adrenalin rush. Most rodders, however, begin at the wrong end of the vehicle, with most of them rushing right out and buying an aftermarket camshaft for the motor without knowing anything about what they are doing, often resulting in less performance than the motor exhibited when stock. Any part that you change in the motor must be coordinated with the rest of the parts in the motor. It all has to be a COMBINATION OF PARTS that work together toward a common goal. Let me put that in bold caps again to emphasize my point....COMBINATION, COMBINATION, COMBINATION. Get your entire plan together before you ever put a wrench in your hand. Plan your work and work your plan.

It has always been my opinion that most rodders could FIRST do some rear end work, like changing the ring and pinion to a numerically higher gearset and limited slip arrangement of some kind, upgrading the rear suspension system and tires and could therefore scratch their itch without ever touching the motor. The factory used a gearset that would keep rpm's and engine noise low and contribute to good fuel mileage, because most of the buyers they sold to were interested in the vehicle getting them from point A to point B with the minimum amount of fuss and fuel cost. If you carry this hot rod fever on to the front of the car, you're going to eventually need rear end work anyway, so why not do it first and enjoy increased acceleration at low cost....well, low compared to getting into the motor/transmission. Depending on the amount of power you are looking for, the stock rear differential may or may not be able to handle the new-found power from your hot rod motor, so while you're planning on upgrading the gears and such, you may need to be looking for another differential to swap into the car/truck. A good all-around performance gearset that will work with a 3 or 4 speed auto or a 3, 4 or 5-speed manual is 3.73:1. Now, if the motor will be a really hot build, then you may need more gear than that, depending on the camshaft timing. Some fellows will run 4.11, 4.44, 4.56 or even 5.12, depending on the COMBINATION. Try to hitch a ride with someone in your area who has a hot car with a 4-something gearset in the differential. I can guarantee that it will put an ear-to-ear grin on your face. My first such ride was in a '57 Chevy with a hot 283 with two 4-barrels, a four-speed and 4.56 gears when I was 16. I still remember it vividly.

This is just a quick skim across the top of the exercise, but hopefully it has set the main facts in your mind.
Oh, and by the way, these performance gearsets work great with an overdrive auto or manual transmission for cruising on the highway. A 700R4 twisting through 3.73:1 gears works great.

.

[36 sedan]

In the late60's/early 70's I had a '62 vette with 4.88 gears behind a built 350 and a 4 speed. It was hard to keep the radio knobs on it and the front wheels on the ground, boy was it fun!

[techinspector1]

It was hard to keep the radio knobs on it

LMAO.....thanks for that.

.

[glennsexton]

Welcome to CHR Sherlock!
As Roger has already suggested, 3” would be way too much exhaust for this engine. I also appreciate that parts’ are not as readily available in Denmark as they are here in the United States. We also do not know what kind of car you have or how much money you want to invest. If you have a small car like a Nova or Camaro and say 1,500 Euros we can help you build a respectable engine that will sound great and run strong. If you have an Impala or a big Buick, we’ll need more money for the same type of experience!

Can you tell us a bit more about what you have and what your goal is? What car do you have, what is the budget and what is your goal? Do you want to go fast or cruise in a daily driver.

Best,
Glenn

[Sherlock_Holmes]

Hi everyone !

Wow ! Thanks alot for all our replys and welcomes greeting

Let me start with some more details.
I'm looking to buy my first small block car (Chevy Impala 73)
I though the different between the 350 engine was small things like carbs and heads.
I have read "how to build max performance chevy small blocks on a budget" and now it's all about combination. But yesterday i saw this:

I really see no reason to go as far as swapping the whole top end. We're skipping a few basic steps people. If you're planning on incremental upgrades, the order should ALWAYS be:
1. free flowing 2.5" mandrel bent dual exhaust and mufflers
2. exhaust headers

(Some people will stop here, having been surprised at the difference in performance.)

3. aftermarket dual plane intake manifold (with the factory cam, I would recommend the old standby Edelbrock 2101 Performer or generic Summit/Jeg's equivalent, or step up to the 7101 Performer RPM type if a cam/head swap is in your future)
4. cam swap... you can do the cam now, and swap the heads later. Something along the lines of the Comp Cams 268H will wake up the engine quite a bit.
5. cylinder heads. This part gets dicey, as some people will tell you to buy nothing less than AFR 210s or some such thing, while others will fly the Vortec head banner until the day they die. Car Craft magazine recently did a head to head shootout of budget aftermarket heads and found that even the Jeg's house brand heads do quite well at a much lower price.

If you do these steps in order, you will still get to enjoy your car, as it's not usually apart for more than a weekend or so at a time. You will also get to find out first hand what each modification does for the feel of the car. By the time you get past step 5, you are ready to tackle the bottom end of the engine if need be, as you are very familiar with how it's all put together.


But i do also now, that everyone can write everything on the internet, so i want to check that

The car is gonna be my daily driver, and run on unleaded 95, so i dont need a 500+ hp engine. I have a 250-300 hp engine in mind?

But ! The car is original born with a 454" engine. Would i be better of just buy one of those ? in Denmark they cost around 3.700 $ (renovated one - 350 hp) And i could sell the old 350" for around 1.300 - 1.400 $

I hope your understand

[Sherlock_Holmes]

I hope i understand all my thoughts

EDIT: I make an long post before this one, is that gone, or does i need to be approved by a moderator?

[mrmustang]

I hope i understand all my thoughts

EDIT: I make an long post before this one, is that gone, or does i need to be approved by a moderator?

Long post are fine, it is when you add links or attachments that your posts require moderation.

Try not to add any links to your posts and they should show up without the need for moderator attention.

Bill S.

PS: I removed the link in your post above, don't add it back or the post will automatically disappear and need to be moderated again.

[34_40]

Welcome to the CHR Sherlock, good to see you here! In response to your question(s).. the old hot rodder adage goes, "there's no substitute for cubic inches", and it still holds true! If your building a cruiser and want great torque / horsepower without breaking your bank then do the big block.

After a short "probationary period" the mods will lift the restrictions for links, it helps cut down the spammers and we hope you'll understand our need to help protect the membership!

[Sherlock_Holmes]

Hi again everyone !

I finally bought the car, and i rum smoothly but got a little cold start problem:
3 pumps on gas, turn key:
If i put it in drive it will just stall. I have to let i stay idle, with the footh on the gas for a minute or two, before put it in drive.
When hot start there is no problem at all. I think it's a choker problem?
I have changed the distributor cap and rotor, cable, plugs and air filter

[Sherlock_Holmes]

And for the record with the performance parts. I think i keep the 350" standard, and when i found a good solid 454" i will change for that !

[glennsexton]

And for the record with the performance parts. I think i keep the 350" standard, and when i found a good solid 454" i will change for that !

That's a smart decision!

Nice looking ride - probably not too many of these in Denmark.

Have fun and drive it alot.
Glenn

[firebird77clone]

The only way that sled will ever scoot is if you get that big block back in it.

[rspears]

I expect that you'll get a lot of enjoyment from it just as it is, and I agree that your cold start/cold stall issue is probably a choke problem, but you might also consider getting a carb kit and going through the whole thing, cleaning it up and bringing all adjustments back to spec.