New heads

[WILMASBOYL78]

Dave...I have always set initial in the 16-18* range and total at 36*..all in by 3,000 rpm. Each motor likes something a little different...time will tell what works best. Sounds like a fun project.

-wilma

[HawkX66]

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: WILMASBOYL78</div><div class="ubbcode-body">Dave...I have always set initial in the 16-18* range and total at 36*..all in by 3,000 rpm. Each motor likes something a little different...time will tell what works best. Sounds like a fun project.

-wilma </div></div>
Thanks Wilma. We'll start there and see what happens.

[Salvatore]

hardened seats not necessary Dave.

[EZ Nova]

<span style="font-weight: bold"> As per Mark Jones (VortecPro) and MYSELF, DO NOT GO 2.19 VALVE WITH THE SMALL BORE 396/402'S!!!!! </span>

The Valve are too close to the cylinder wall, and as Mark's own words &quot;FLOW LOSS WOULD BE HORRIBLE&quot;. There is no way that this engine would require any more then 2.06 intake for what you're doing.The bigger valve DO help quite a bit, but they need the bigger 4.250+ bore to actually work. The narrow bore of this engine would actually HURT performance. You're far better off doing some port work then paying for new valve and and related machine work.

Now on my lil 402, I used ported sq port head and comp 660 roller. It ran strong, 10.47 in '69 Nova. So I think the cam should be fine for wht your doing, just do NOT open those heads with the small 4.094+ bore.

[HawkX66]

Thanks a lot John. I'm actually just heading to the machine shop now. That's the first time I've heard that. What you're saying makes sense, but I've talked to quite a few guys that have flowed these heads with the 2.19s and they said they flowed well. I don't know what to think because obviously I don't know better either way. I have a 4.155 bore. It's a 40w bored .030 over.

[EZ Nova]

I personally have felt this way for a while. BUT I recently seen Mark's comments on this over on TC.

Mark's on here as well, you could PM him and get his insight as he's really good with GM iron ovals, as most know. Do some math, you have 4.155 bore. Minus (2.06+1.72). That only leave you with .375 OVERALL space in the bore. Now take away another .130 for the 2.19 valve, and you have .245. So it does get tight on the &quot;bore-side&quot; of the intake valve. This is the issue with the bigger valve in the small bore 396/402 blocks. Even RFD has a different head for max performance on small bore 4.250+ blocks.

There was a thread over there where Mark told a guy NOT to use even an aftermarket AFR oval head even. Same thing, YES they can flow, but from MY UNDERSTANDING from my guy, is that the flow backs up the one side of the valve on the 4.096-4.155 bore stuff. Unshrouding of the valve plays a major part in making Hp. You not trying to make 650-700Hp here, so don't go through the added cost of valve/labor! PUT those funds towards a good port on what you have. They will support 650+Hp in that form of ported/2.06 valve combo.

[WILMASBOYL78]

I think these tech discussions are great...in fact, it is one of the things I like about the TC site...lots of 'motor heads' swapping recipes.

Neat stuff..

-wilma [img]<<GRAEMLIN_URL>>/biggthumpup.gif[/img]

[HawkX66]

I love them too. I'm learning a ton. So here is my &quot;dilema&quot;. I'm sitting here at a coffee shop deciding what to do. I talked to the machinist. Good guy that builds racing engines.
I was mainly going to 2.19 because of a little pitting on two of the intake seats. To go 2.19, clean, surface the heads and set up the valves, it would cost me $525 in labor if the guidesite are good. He mentioned going aluminum like everyone else has. My problem is that with the pistons I'm running I'd need a 100cc or so chamber. All the aluminum heads with 100cc chambers that I've seen are north of $2k. I could have a real nice set of heads, but iron for less than $1k.I can handle spending a little more if it's what I need to do, but I don't want to waste cash... One more thing, I plan on going bigger cubes at some point, so going 2.19 might not be right for the 402, but it would be when I swap them over to a igger cube motor right? I'm not planning on competing with this set up.

[WILMASBOYL78]

If you plan to use the heads again on a larger engine...then do the 2.19 upgrade and other work now and it will save you time/money down the road.

-wilma

[VintageMusclecar]

Funny, the L78's sure seem to run awfully damn good with a 2.19 intake valve (and 1.72 exhaust).

Guess the factory got that wrong?

Both edges of the chambers (intake and exhaust side) will overhang the perimeter of the bore. If you look at the deck surface of your block you will see the factory cut reliefs on both sides to address this:



Just for reference, here's a view few people take the time to see--the chamber bolted to the block from the piston's view (this is from my own 496):



For those who imply a 2.19&quot; is too &quot;big&quot; for a 402, may I remind them of this--the BOSS 302 and 351 Cleveland also used a 2.19 intake valve (--on a 4&quot; bore!), and those engines are nothing to sneeze at.

As usual, take it FWIW.