Which Heads For My 396 - Team Camaro Tech
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post #1 of 20 (permalink) Old Mar 25th, 18, 03:08 AM Thread Starter
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Which Heads For My 396

After doing a Leak-Down test on my 396, I have decided to pull my heads. So I would like opinions as to which heads I should go back on with. I have also decided that the cam I installed is too much cam, so I'm going to replace it as well.

This is my question; I found a guy that has all different kind of heads. I currently have 3904390 Closed Chamber heads. I can have them gone through, or this guy has 353049 (Open), 3964290 (Closed), 3933148 (Open) and 3917215 (Closed) heads that I can purchase. I've already given him the money, I just have to pick one. Which ones would be a good choice for my roller hydraulic cam that probably is going to be 11-430-8 Comp Cams .577 lift, 280 Duration, 110 lobe separation.

To add; My leak-down test was all in the yellow and a couple were in the red. And, a while back I did a compression test and here were the results:
#1 - 135-140
#3 - 190
#5 - 170
#7 - 160
#2 - 150
#4 - 158
#6 - 165
#8 - 155

Thanks everyone!

Brett......

1969 SS 396 X66 - RS Conversion - TKO600 - 3.73 Posi - Paint Code 71-LeMans Blue

Last edited by Brettallen59; Mar 25th, 18 at 03:20 AM.
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post #2 of 20 (permalink) Old Mar 25th, 18, 04:47 AM
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Re: Which Heads For My 396

First choice - alum matching 290,
Second choice - the 290.

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post #3 of 20 (permalink) Old Mar 25th, 18, 04:58 AM Thread Starter
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Re: Which Heads For My 396

I agree with you about the Aluminum choice, but that will have to wait due to budget restrictions, haha. There is one set of used aluminum heads that I'm monitoring. I'll check on their specs...
But you like the 290's? That's a lot of help. The seller told me they are a desirable head. It sucks to have so many heads to choose from and not know enough about them to decide, so any input is very helpful.

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post #4 of 20 (permalink) Old Mar 25th, 18, 05:05 AM
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Re: Which Heads For My 396

Wait and read the suggestions of others. 290's are nice.
But, you want to build for torque - its the force pegging the Seat-O-Pants meter.

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post #5 of 20 (permalink) Old Mar 25th, 18, 05:27 AM Thread Starter
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Re: Which Heads For My 396

I would also like to get confirmation on this statement. Because it is a 396, I'm thinking that the size of valves is limited before they will hit the cylinder. Is that a correct statement? I have been passing on any head that has a 2.250" Intake valve. If I assume my block is a standard 1966 396 block, will 2.25 & 1.88 valves clear?

P.S; I am also adding a TKO-600 and 3.73 12 bolt. Since I have to change out to a 26 spline clutch disc, I will swap out the flywheel for a Fidanza Aluminum.

Brett

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post #6 of 20 (permalink) Old Mar 25th, 18, 06:03 AM
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Re: Which Heads For My 396

Large Dave seems to be one of the go-to guys for big blocks, I am sure he will chime in. Open chambers are larger chamber so this would lower your compression. Square port are for higher rpm, usually less attractive for low rpm street cruisers. Aluminum is nice but not a necessity, I was told just keep the iron with the Procharger, less head movement(the engine builder told me that and I trust him). I am running Merlin roval port cast iron heads on my 496 with a Procharger, they are reliable and great for low rpm. I have seen them for sale used for 500 range a pair, they are set up for roller valve train from the factory.
I am probably not much help just thought I'd chime in.
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post #7 of 20 (permalink) Old Mar 25th, 18, 10:46 AM Thread Starter
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Re: Which Heads For My 396

Big Dave, are you out there?

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post #8 of 20 (permalink) Old Mar 25th, 18, 11:02 AM
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Re: Which Heads For My 396

If you have no heads now I would find a set of Peanut port heads and install bigger valves (requires new cutting and installing hardened seats and of course larger Manley swirl polished reduced stem diameter tuliped valves. I would stop at the 2.19" as your small bore 396 is already shrouding the valves at that size.

Manley 11800-8: Severe Duty Intake Valves BBC | JEGS

A set of 1.88" Manley's Inconel exhaust valves need to be included as well:

Manley Inconel Extreme Duty Valve, Chevrolet BB, 11/32", 1.880" Exhaust, Standard Length, Each - Competition Products

and of course a set of sixteen smaller (but straighter bronze valve stem guides.

Rapid, Bronze Valve Guide Liner, 11/32", Each - Competition Products

While the heads are apart I would pocket port them (especially the exhaust) and straighten out the short side on the intake. Since you are going to be installing new seats there is no worry about nicking the old ones. Great way to learn how to port your own heads.

https://www.summitracing.com/int/par...1060/overview/

https://www.summitracing.com/int/par...0640/overview/

Extended Die Grinder - 1/4" Collet

and of course the knowledge of knowing when to stop grinding:

https://www.amazon.com/David-Vizards...cylinder+heads

or better information that applies to BBC heads only talking abour SBC heads

https://www.amazon.com/Chevrolet-Sma...cylinder+heads

Properly preped with a good cam choice you can get up to 500 to 550 horsepower out of these heads. It is just harder to get there with a small motor like a 396. I would have started with a 496 and put 396 decals on it.

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post #9 of 20 (permalink) Old Mar 25th, 18, 11:48 AM
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Re: Which Heads For My 396

Quote:
Originally Posted by Brettallen59 View Post
I agree with you about the Aluminum choice, but that will have to wait due to budget restrictions, haha. There is one set of used aluminum heads that I'm monitoring. I'll check on their specs...
But you like the 290's? That's a lot of help. The seller told me they are a desirable head. It sucks to have so many heads to choose from and not know enough about them to decide, so any input is very helpful.

Brett.....
Your #390 heads you already seem to know are 67' closed chamber,oval port.If you buy the 1970' #290 heads,all you are gaining is another set of closed chamber,oval port heads with about 2.5 cc larger combustion chambers.#049 heads are really good street,mild strip heads especially with a little work.#049 heads also already have induction hardened exhaust seats.With the #049 heads you will however loose about .65 of a full point of compression.Do you know what the casting # of your block is?I could tell you what block you have
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Re: Which Heads For My 396

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Originally Posted by Larger Dave View Post
I would have started with a 496 and put 396 decals on it. Big Dave
Old school sleeper trick.
Good in reading more experienced members giving suggestions.

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post #11 of 20 (permalink) Old Mar 25th, 18, 12:46 PM Thread Starter
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Re: Which Heads For My 396

The casting number is 3855961. Pad stamp is T0506EDH 6K196388. The bores of the block look to check around 4.110. I will bring home some telescope gauges and Micrometers from work tomorrow to get a more precise measurement.

If I was going to change the engine at all, I would pull a John and swap it for an LS!

Brett......

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post #12 of 20 (permalink) Old Mar 25th, 18, 04:00 PM
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Re: Which Heads For My 396

Casting #961 is for 65'-66' 396.It is a 2 bolt main.I know this because 65'-66' were the only two years where a 2 bolt & 4 bolt used a different casting #. T0506=Tonowanda May 6th,ED=Chevelle 325HP,stick.H= Holley carb.6K196388;6=1966,K=the assembly plant , 196388 is the sequential portion for the VIN of the car it came out of.396 std. bore is 4.094,so 402 is 4.125
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post #13 of 20 (permalink) Old Mar 25th, 18, 05:36 PM Thread Starter
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Re: Which Heads For My 396

Quote:
Originally Posted by SmirchIs#1 View Post
Casting #961 is for 65'-66' 396.It is a 2 bolt main.I know this because 65'-66' were the only two years where a 2 bolt & 4 bolt used a different casting #. T0506=Tonowanda May 6th,ED=Chevelle 325HP,stick.H= Holley carb.6K196388;6=1966,K=the assembly plant , 196388 is the sequential portion for the VIN of the car it came out of.396 std. bore is 4.094,so 402 is 4.125
Yeah, and it didn't have an oiling groove in the rear cam journal. The guy who rebuilt it did not know that and put a standard cam in it. That's why I couldn't get any oil to come up through the pushrods. What is the next bore up from stock? I thought it would be .020? 4.114?

Brett....

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post #14 of 20 (permalink) Old Mar 25th, 18, 06:50 PM
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Re: Which Heads For My 396

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Originally Posted by Brettallen59 View Post
Yeah, and it didn't have an oiling groove in the rear cam journal. The guy who rebuilt it did not know that and put a standard cam in it. That's why I couldn't get any oil to come up through the pushrods. What is the next bore up from stock? I thought it would be .020? 4.114?

Brett....
I believe it would be 4.125" unless you had custom pistons made and that would be expensive.I don't remember +.020" pistons for a 396,but that doesn't mean they weren't available.You said you thought your bores were about 4.110(hard to believe) which is an awful lot of wear from standard,thus taper & out of round in your cylinders would not clean up at +.020.The 4.125 bore is 396+.030 or also standard bore 402 which is a common piston.70'-72' cars were marketed as 396 cu.in. but were actually 402's.Don't worry,there is still more lives in that block after+.030.It's a shame about the cam deal,but yes all the 65'-66' big blocks needed that groove in the rear cam journal.If you put an old grooved cam in a 67' & up block the oil hole in the rear cam bearing needs to soldered shut redrilled to .060" (If I remember correctly) or you would have low oil pressure ecspecialy when the engine warms up.
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post #15 of 20 (permalink) Old Mar 25th, 18, 07:43 PM Thread Starter
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Re: Which Heads For My 396

Quote:
Originally Posted by SmirchIs#1 View Post
I believe it would be 4.125" unless you had custom pistons made and that would be expensive.I don't remember +.020" pistons for a 396,but that doesn't mean they weren't available.You said you thought your bores were about 4.110(hard to believe) which is an awful lot of wear from standard,thus taper & out of round in your cylinders would not clean up at +.020.The 4.125 bore is 396+.030 or also standard bore 402 which is a common piston.70'-72' cars were marketed as 396 cu.in. but were actually 402's.Don't worry,there is still more lives in that block after+.030.It's a shame about the cam deal,but yes all the 65'-66' big blocks needed that groove in the rear cam journal.If you put an old grooved cam in a 67' & up block the oil hole in the rear cam bearing needs to soldered shut redrilled to .060" (If I remember correctly) or you would have low oil pressure ecspecialy when the engine warms up.
I mean, well I have digital calipers and the bores measure 4.106/4.113 ( I thought that was quite a bit of variance). There looks like .030".040" gap between the piston and the cylinder walls. There is no ridge. Here are some pics;






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