defiant1

Is one cylinder head type better or more sought after than another? I see people list what they have when describing their motor; is this to inform others what size valves they have to work with??

I have #6 heads on my 350. How can I use the specs from these heads to help me gain more performance (adding intake, carb, dual exhaust, etc.)?

I base my question on the idea that I want to install a new camshaft to increase my midrange power, but I am trying to wrap my head around how all the engine components work together so I can have an efficient running motor that is strong throughout the power band.

I am sure this is clear as mud, but any insight would be appreciated.

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cutlassefi

5, 6, or 7's are fine. By your bumper it looks like a '70, but if you have 6's it might be a '71? If so it's low compression, cam choices will be limited. If it's a '70 then compression will be 9.0:1 or better, much better but still other variables to consider, i.e. gear ratio, intended use, budget etc.

defiant1

I have a '70 car and motor and as you indicated I have an estimated 9.0:1 CR (factory specs). I am looking to eventually upgrade the rear end to no more than a 3.42 as I have 2.56 now and like the fact I can take my car on 600 mile round trips and can enjoy the ride without dealing with the high RPM and of course decent gas mileage.

I have 2.5" dual exhaust with stock exhaust manifolds. I will be installing a 4 bbl intake (ID #16) and a 4 bbl Quadrajet this winter. I am researching camshafts options (if feasible) that will allow me to use the stock cylinder heads as is with an anti-spin rear end (3.08, 3.23, 3.42) and still gain performance in the mid range.

Of course, I do not have money to burn so I am trying to approach this smartly and only add components that will work well together and not cause the motor's performance to unnecessarily suffer at the low or high end of the power band.

If this is not possible or practical to do it piece by piece then I will have to save my pennies until I can afford to do it all at once.

Basically, I am looking for a street/strip (more street) machine with good overall performance. I find the car is lacking when I accelerate at highway speed and would like to rectify that.

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cutlassefi

I'd do the gear first, IMO a 3.23 would work well.

defiant1

So, if I understand you correctly, I should see how the car performs after the rearend change and adding the 4bbl intake and carb? And then go from there?

BTW, thanks for taking the time to respond.

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cutlassefi

Exactly. No problem.

Aceshigh

I am putting a T-56 6 speed with a .50 final gear ratio in my 1970.
So I had to choose the best gear set option and I chose 3.73's for the best highway RPM's.

At ~65mph I'll be turning 1500rpm in 6th gear with my 27" tires.
My point is, if you want the best of what's out there, you have to consider an OD trans.
Then you can get deeper gearing without sacrificing highway RPM's.

A cheap alternative that's an automatic OD trans is the 2004R built up.

Warhead

How many miles on the engine, and have you worked on the tuneup at all?
How is the oil consumption?
Is everything in GOOD shape?
For example, on high mileage engines, I have seen the mechanical advance lock tight, resulting in no changes in advance as engine speed increased.
Result...poor performance.

There are literally 1000 things to look at to wake up performance.
I love the idea of going to a mid 3 series gear, but it may affect your mileage.

Check mechanical condition first.
Identify any problematic issues, and rectify.
Optimize tune.
Dual exhaust-H pipe, or X pipe.
Optimize tune.
4bbl, cold air induction, carb spacer.
Optimize tune.
Gears
Optimize tune.
If performance is not good enough, then go deeper into the engine.
JMO
Jim

defiant1

Aces

I hear what you're saying and if I didn't have a fresh rebuilt TH350 in it already I would have looked at going that route.

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How many miles on the engine, and have you worked on the tuneup at all?

There is 154,000 miles on the car and original motor. Unfortunately, I do not know the history of the engine. When I pulled the valve covers I noticed newer parts on the passenger side cylinder head vs. drivers side. I thought it was odd, but I talked to a few ol' timers and they mentioned that back in the day, they would only rebuild the problem side and not both.


How is the oil consumption?
Does not burn oil. I replaced the rear main seal, oil pump and oil pan gasket while motor was in the car. Knock on wood, so far so good.


Is everything in GOOD shape?

I installed a Pertronix unit, replaced the weights, cap and rotor, wires, plugs, installed new weight springs. Have 23* for the mech. advance. I have become more intimate with a timing light than I ever wanted to, but I finally got the motor running tip top.

Other items of note:

Dual exhaust-H pipe installed.

4bbl & carb spacer will be installed this winter. (Thanks for reminding me about the carb spacer, I forgot about that. BTW, thanks again for the 2BBL carb gaskets you sent me, the thick sucker did the trick).

I will see if I can't find a cheap way to install a cold air induction system.

I contacted monzaz (from this site) and am picking his brain for options for the 3.23 anti-spin.

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Warhead

Sorry, but I had forgot ALL about that!
Keep up the good work, the car looks GOOD.

Good luck with it.
Jim

defiant1

What size (height) carb spacer and what type (open, divided or 4-hole) do you recommend?

Using a Edelbrock Performer intake and Q-jet carb.

I don't want to sacrifice my low end too much. But would like to see a little more midrange get up and go.

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