Vortech heads or machine work?

[akfox1]

I am a new member to the forum and I have a 69 convertible 355, 4 sp. It is sidelined by a valve guide right now. My mechanic said I'm lucky I didn't drop a valve, so the heads are coming off.

I have read that the Vortech heads are really great for torque. I am very interested in getting these heads vs spending hundreds on machine work and parts for my old castings. They are available complete for $400.
The current heads are 882 castings, milled 0.010" I think. That's another reason I want to get rid of these heads, since they aren't real performers. They have 76cc chambers, I think.

My specs are:
350 ci, bored .030" over, flat-top pistons, block decked 0.010" Lunati cam with .458/.458 lift, 218/218 deg duration. Edelbrock performer intake, holley 600 cfm with vacuum secondary. Pertronix ignition. Stock distributor. Hooker headers with 2-1/2" pipes. 4 speed.


My questions are:
Will I have a hood clearance problem?
Can I use these heads with their 64cc (I think) chambers with no problems?
How can I be sure the valves will not contact the pistons?

Thanks for reading all this. Any input is appreciated.

 

[Ken]

Welcome To The Corvette Action Center akfox1!

Hope you find this place suits your needs.

I can't help you with your question, but Chris should be able to provide some insight. If he doesn't reply, we've got enough Sharks here that I'm sure you'll be overwhelmed with response.

I believe though that if you use those heads, you'll have to get a matching manifold because of the bolt angle.

 

[Tom Bryant]

Welcome

Welcome to the CAC. You should have no problem with valve clearance with the flat tops and the lift you are running. You can check by putting a thin layer of clay on the piston top . Then install a head with the gasket you will use. Turn the engine by hand a full cycle so both valves open and close and then check the clay for the valve imprints. You can measure your clearance from this. You will need to use a pair of solid lifters set a zero lash for this test.

You will need to get a Vortec intake from GM Performance or Edelbrock. The Vortec heads use a bolt pattern that is 90 degrees to level whereas the standard heads are 90 degrees to the intake gasket surface.

There has been a lot of hood clearance talk lately. You can do a search on the subject back in this '68-'82 forum or maybe someone else will supply the thread. Sounds like you will have a good package.

Tom

 

[69MyWay]

Heads

Good questions here about what is best. The Vortec is a great head, but will cost more in the long run than some of the other alternatives. Mainly because you are changing the intake right away as the original won't bolt up. You may have valve cover problems as well. Don't the vortecs only come in the center valve cover bolt pattern?

My favorite heads are the Edelbrock aluminum. I have a set on an engine (that is just collecting dust now), but worked amazingly well when it was in a car. The overall price is high, but well worth the effort. Expect to spend about $1,300 with gaskets, bolts, push rods, new plugs etc.

On the other hand, look for some good used heads. I am not trying to pander to you, but will give you an example. I have a set of Bow Tie cast iron Chevy heads that I will eventually sell for around $400. This kind of swap gives you direct bolt fit, higher performance and strength, and bragging rights at the next car show.

I agree, dump those current heads. They are not doing you any favors.

Remember, an engine is nothing but an air pump. The more air you can pack each stroke equates to more power. The cam is the heart of the engine, but can't do anything unless the heads let the engine breathe. Make sure everything matches or you will be unhappy. For example, make sure you have enough rear gear to allow the engine to rev into the power band to take advantage of the larger valves and longer duration cam. Otherwise, you can actually make a car go slower than stock. It has happened plenty of times. If you are not set up from front to rear, you may consider going with a 1.94 inch intake valve-1.5 exhaust instead of the larger 2.02/1.6 available on the other heads. This will keep you in a lower RPM power band, smaller valves often make more torque at a given RPM.

 

[80convertible]

I too was having a valve problem with my old 441 castings. Switched to the vortec heads about 1-1/2 years ago. You will need a vortec specific intake and the heads use center bolt valve covers. I purchased my vortec heads used but rebuilt with better than stock valve springs. I still have not installed the proper cam for these heads yet still dynoed at 250hp at the rear wheels. And thats with a tired bottom half of the engine. Can't wait to install new cam and really see these things flow. For the money you can't beat them!

Regards,

Jim

 

[Roy M]

I started my rebuild about 8 months ago and went with the Vortec Heads. One of the reason was cost but also getting what is about the best iron head you can purchase. I can not give you a comparison between the heads because of the other modifications I did. The engine was bored .030, new 9.7 cr pistons and all bearings with new timing chain. The crank was turned .010 but that would make do difference in the performance.
If you do go with the Vortec heads, you will need to also purchase centerbolt valve covers and another intake manifold as stated in other post. I went with the eldebrock. I also had to change the valve springs due to the cam, which is Comp Cam 268H.
As far as hood clearence, I went with a 14" chrome air cleaner with 2 1/2" in height. This was using the stock q-jet carb. Used play dough to measure the hood clearence and was at about three inches. Have since changed to a Holley Street Avenger carb and only have about 2 inches of clearence. This is with a stock hood on a '79.
As stated earlier, can not say that the heads made that much difference since redid the whole motor. I am now running headers with 2 1/2" true duals into Dynamax mufflers.
I will have to say the car acts like it has 1 1/2 to 2 times the power before the rebuild.

 

[Tom Bryant]

Vortech

Roy,
Sounds like a good combination. I forgot to mention earlier that it is possible to drill and tap Vortech heads to accept the standard manifolds. There is one of the high performance GM Parts dealers that advertise in Super Chevy that sell them already done. I think they were about $40. more. That's assuming you already have an intake you want to use.

Tom

 

[Roy M]

Tom,
You are correct about getting the heads drilled to accept a stock manifold. I believe that I have since seen this option in the Pace parts catalog.

 

[hdjpcp]

You may have already made your purchase but if not, Jim Pace Performance sells Vortec heads drilled and tapped for non-Vortec intakes, $539 is what I paid. I bought very nice chrome "bow tie" valve covers (the Vortec heads are center bolt) from Scoggins-Dickey for $90. Both suppliers advertise in Corvette Fever as well as most other performance mags and both are on the web. You'll be happy with the Vortec heads.

 

[Hib Halverson]

My questions are:
Will I have a hood clearance problem?

No. Not with the Performer.

Can I use these heads with their 64cc (I think) chambers with no problems?

No, if you're going to run it on pump gas.
Your compression ratio will be too high.
Yes, if you're going to run racing gas of a mix of that and pump gas with enough octane to keep the engine out of detonation.

How can I be sure the valves will not contact the pistons?

The "be sure" method is to do a trial assembly of the engine and check piston to valve clearance using clay on the top of the piston. You turn the engine by hand then measure the thickness of the clay. My guess is, with the cam you're using and flat-tops you're not going to have a problem.

 

[akfox1]

Thanks to everyone who responded.

Mr. Halverson was right, the 64cc heads would have blown my compression into the 11 range.
Plus, 69myway and some others were right. It ain't just 400 bucks for the heads, its the new intake, the new valvesprings if you have over .450 lift, the new valve covers, and the 3/4" less hood clearance.

I would like to have the vortechs, it just wasn't in the cards. So, I took my old 882's and had them milled again to 71.5 cc's, added bronze guides, teflon seals, and swirl polished stainless manley valves. I even had some bowl blending done on the exhaust side. $398, plus $130 for new gaskets, ARP bolts, etc. Now running right on 9.5 : 1.

It's all back together now. I'm a little disappointed that I can't feel a big difference, but it runs strong anyway. Speed costs money, right? Maybe I'll try a lighter secondary spring for $10...

This was the bargain I needed to get my convertible 69 back on the road while there are still a few 60 - 70 degree days left.