I have a 69 vette with the original 350/350 engine in it, it has had the intake and carb updated and had a solid lift cam installed. so the block and and heads are original.

I'm going to have new ceramic headers and 2.5 exhaust run back through some Flowmasters.

And I have toyed with the idea of swithing out the cylinder heads to some performance aluninum heads. and thought if I'm getting ready to pay $450 for headers I better make any head changes now...

I have a few questions for you guys:

1. If I'm not mistaken the original heads that are on the car are the bouble hump heads and they are supposed to be pretty good performing heads? Not sure the original specs, I thought they were 2.02? but they look as if they have been recently rebuilt with screw in studs and guidplates and new springs.

Will I see a huge difference in performance by switching out these original heads for lighter high performance Aluminum heads? If so any cylinder head suggestions?

Or should I just stick with the double hump heads? Not like it does'nt scream the way it is... I guess its that never satisfied need for power....

2. Will I see a fairly noticeable performance increase to go from stock exhuast to 2.5 through Flowmasters?

Thanks for the advice?

 

The '69s don’t use a double hump head, those are limited to the mid year cars and do not have accessory holes in them, but you probably do have 64cc heads with 2.02 valves.

What does updated intake and carb mean and what cam is installed, a LT-1 cam?

Personally I don’t think you'll notice $1K + worth of performance increase if the stock heads have just been gone through. Now if the heads were shot and burning oil etc, the cost difference between rebuilding them vs. a new set of aftermarket heads wouldn't be that much different. If maintaining your cars original value matters, different heads would not help that.

As for headers with the new exhaust, there should be some mild gains to be had. You might want to consider adding a X or H pipe to help eliminate/reduce any possible exhaust drone with those mufflers. You don’t mention what series of Flowmasters you are looking at, some can be obnoxiously loud in the cabin after awhile.

 

Are you sure the heads on the 69 is not a double hump head. I also have a 69 350/350 4sp. and it's double camel hump head. The L 46 came with the AC and 4 sp. I had my heads rebuilt and screw in stud put in. From what the forum members are saying, it's not worth modifing the heads when for near the same price or alittle bit more you can get an alum. head that flows better than the stock ones. I wanted to somewhat retain the stock appearance. But for the money and performance, you can get an alum head for alittle over a G, or less, depending what you get. My stock heads has the holes for my AC, PS. Tony

 

yes, the 186 heads used in 69 are double hump, 2.02 intake valve W/ screw in studs or 194 intake valve W/ pressed in studs, 64 cc with acc. holes. Good heads! But your car will be able to run modern fuel without detonation issues or detuning with aluminum far easier than with the iron heads.

 

My bad you guys are correct, they do have small double humps which are very different looking than the early double humps of the 461, 462 and 291 heads.

 

Aluminum heads will allow you to run more compression and provide much better performance with today's gas.....

 

How much original value will be lost if you switch out the heads?

The Carb and Intake updates I referenced are:

Eldebrock Torker II Intake / Holley 650 Double Pumper

The Cam i beleive is a LT1 Solid Lift Cam, Not possitive but has a little lope to it and starts really pulling hard at 2500RPM

THe rest of the drive train is the orginal 4 speed transmission and the original 4.11 gears. So it's fairly snappy.

So if the engine is rated as a 350/350 and with these few modifications Would would be the guess on the HP It is making?

Honestly I do not want to hurt the value of the car, I thought the most inportant thing to the value was the block stamp being original. but not really thinking I'll ever get rid of it and if the Cylinder Heads would give me some noticeable advatages I figure know would be the time to decide before I buy headers.

two other quick questions I have for you guys is the original block a 4 bolt main or two bolt main? just curious...

And the Torker II intake was on the car when I got it is there a better suited intake for this setup?

My goal with this car is to have a red light to red light plant you in your seat and pull hard up to the 5800 RPM range, Not really wanting to tach it to the moon and pick up the pieces...

Don't get me wrong this car does a great job of this now I just want to maximize its potential

 

Alum disapates heat better than iron, so you can run higher compression ratios (that produce more heat).
Alum heads weigh in at 25 pounds each. Cast iron weigh in at about 70 pounds each. Those iron heads you have now are pretty darn good for iron heads!
As with any engine (or vehicle for that matter) upgrade, you will dump more effort & money into it as you go along. If you are pulling the engine, might as well as go through the whole thing. A half effort will lead to premature failure of componets that were left untouched. If all you are doing is the topp end, then the new, higher compression ratio may damage the old piston rings. And here we go...to replace the rings, you have to pull the pistons, new bearings, heck migh as well have the block hot-tanked, rods shot peened, crank balanced...it never ends!

 

I did not have the good iron heads you have on my car but they had been worked over and they preformed well. I took those off and bolted up a set of edlebrock twisted wedge heads.....huge difference in the mid to upper rpm range!!!!

A good aftermarket aluminum head is going to out prefom a worked stock iron head IMHO. As mentione before you will have a huge weigh savings and the heat will be disapated better.

Since that engine I have built another small block bust used the same heads, I did however had them fully ported and polished and the will flow great, the car pull up through 7,000rpm

If you are concerned about hurting the value but you mentioned you are going to keep the car, just hold on to all your parts....you can always go back to the original setup if needed.

 

Dump that Torker intake and use a good dual plane intake for better low and mid range response. Depending on your hood clearance and air cleaner combo you could use a Performer, RPM or Weiand Stealth with your Holley.

 

Hello keep us updated on which aluminum heads you use, my 69 350hp is almost the same way-370hp solid cam Lt1 same 186 heads with push rod guide plates, I thought about doing the same thing with mine, I have to use octane booster or a little race gas mix, I dont like to detune a engine, I like it to run like it is 1969 again

 

your assumption is that you have the larger valve double hump heads.....you may or may not


if you have the smaller valve ones you might notice a differnce by switching to larger valve aluminum heads.....if you have the big valves im not sure how much extra power you will get....although losing the weight would be the advantage....is it worth the extra money....well a nice tight top end may accentuate a problems in the lower end....so it may be good to leave well enough alone and do the mods you have planned

 

I depends what you want. ALL (OK, maybe not the 305 California smog motors) Corvettes have more than enough low end torque even with wild (248 @.050) for street driving.

If you like the high RPM rush of a 15,000 redlined sportbike or exotic a single plane manifold lets a Corvette really sing in the high registers!!!!

I've run single plane manifolds for over 145,000 miles on my '69 and wouldn't EVER consider a dual plane unless I were had a 300 gross HP/245 net HP or less engine.