For the '57, but figured others could learn as well. See sig for current configuration.

Comparing notes with others out at Bandimere, I think I'm about 75% of the way there. But, most of those guys are running 454's, and funds will dictate keeping the 396.

My heads are the 702 castings, no port/bowl work but hardened exhaust seats/valves, bronze guides. Info I saw said 260cc intake ports. I planned on keeping them and cleaning up the bowls & ports. Larger valves, at least on the intake, probably wouldn't work because of the small bore - how about larger exhaust only? Higher stall (something closer to 3000) would probably help, I'm thinking a Stealth might as well. And a 750 DP. I'm sure more gear would lower times, but I have to drive it to the track. I'm wavering on the cam (270 adv, 214 @ .050, .510 lift), since I saw one car (454) this past weekend running a solid Isky with same duration/lift specs, and a bunch of head work amoung other things, put down some pretty impressive times.

Think I'm on the right track? Last race of the season is Sept 20, want to start in on it soon after that.

 

I'm no guru about anything at all, but I'll give you my $.02 anyway.

I would suggest getting rid of those early heads, and get a pair of 820s (402 heads, oval port, small open chamber). For a cam, one of the strongest running ones I've ever had in a street big block was the old Comp HE 280, it was in a 396 in fact; I'd bet a XE284 would be even better.

The Stealth, or a Perf RPM, will be a big improvment. That stock-sized thing is choking you.

I don't think the carb is going to make much difference... assuming your 750 VS is a 3310.

I think the gear you already have is probably about right.

 

I hadn't really considered replacing the heads, for the same reason it's staying a 396. They guy who had all the research info said the 702's were better than what he chose for his 454 (forget now what they were - after all, wasn't considering different heads). But, he also thought the Stealth would be a waste of $200. Are there any specific issues you know with the 702's?

The XE284 is a lot of cam - 6500 RPMs (and that probably assumes a 454). Requires springs that require head machining. The XE274 would still be a step up - more lift and duration, 6000 RPMs, springs don't require pocket machining. Perhaps I'll consider it. Gads, sure adds up quick with cam, lifters, springs (already have the rockers at least).

The current carb is a 3310 style w/elec choke. EVERYBODY's running a DP, especially the guys ahead of me in the season points (except the guy with the '37 Chevy pickup with roots 383 - he's got two 450 VS's on top). As Jester pointed out not too long ago, the VS never really open up completely. And, variation in opening rate will cause variation in power, and therefore 60' and ET. Just need a loose enough converter to keep the DP happy. But, if I had to keep anything from my current bolt-ons, the carb would probably be one of them.

Perhaps I'm somewhat on track with the Stealth thought and current gears.

Did I mention I'm pushing 3900 pounds down the track? Of course, the guy with the 383 '57 Nomad is, too, and he runs 13.2's all the time (but then, he's spent a lot more money on his engine and drivetrain than I have).

 

The 71-72 402ci truck heads are some of the best street heads that came out of GM. If you have the block notched for the larger valves you can squeeze them in both the intake and exhaust sides.

When you choosing a cam look at 3 things, lift, lift and lift. Every BB I've had has run comparatively higher lift cams to what you normally see for a given duration and every one has been able to run with the big dogs, didn't even matter that 2 of the 3 were the baby rat.

 

have you considered manley pro flows? sort of like runnng bigger valves and larger ports and half a chance you'll be replacing a valve or two anyway. and i can't even spell guru let alone be one.

 

The heads were redone in '97, not too many miles on them. All the exhaust and half the intakes were replaced at that time. But, better valves isn't a bad idea.

I know the guy with all of the info picked truck heads, not sure they're the ones you're talking about, though. And, the bores are already notched for the 2.06 intake valves (from the factory).

"Baby Rat" - did you hear me say that? That's what I call it when people ask me what it is. Or, "Mousey Rat". Or "It's a Rat, but the baby of the family."

 

Although not great castings the 702 heads are closed chamber, small valve heads. The chamber is only 96.4cc. It might be possible to stick larger valves inside those chambers but then the valves will be shrouded if they aren't already. That's why everyone goes to open chamber heads. 781 and 049 are the most popular.

Power is made the easiest with heads. Even a good port and polish will wake up any head.

Cam choice will depend. You do have a 396. A mild cam in a 454 would be more aggressive in the smaller 396. The Xtreme Energy cams are a very good choice. I use a 294 and it's not enough for me but my heads are not prepped to take a bigger cam yet (springs, guides etc).

Go with a DP and get rid of the 3310. That's a 30 year old technology carb.

Converter stall will depend on cam selection and rear gearing.

Your 3.73 gears will probably be fine. What size are the tires?

 

Five7, yeah, I've heard you call it that several times but you're not the first person whos refered to them that way to me. Personally the 396/402 is my favorite engine to play around with, kind of fun being the underdog.

 

I just learned about the smaller chambers this weekend. I always thought they were 106cc. The TRW pistons were supposed to be 9.7:1 w/106, so guess I'm a little higher than that (do have thick compositon gaskets, though). I have been running 85 octane pump gas (it's a high-altitude thing) with 40 degrees total mechanical with no pinging problems since I put on the HI-6.

I'll make sure the valves are as unshrouded as I can make them when I do the heads. Shucks, those Manley valves are "only" $10.99 each...

The tires I've been running (just because I have them) are 265R50x15 TA's, 24.75" tall. I was loaned a set of 26x11.5-15 M/T Streets this past weekend - a whole new experience for me. Had to curl the inner lip to get them to fit. If I increase stall and power, the TA's aren't going to cut it, so my own set of DOTs are in order. I picked up a half-used, mounted pair of 26x8.5-14 ET Drags for $40 this weekend, haven't tried them yet (it was a DOT class last weekend). With about 1800 pounds on the rear axle, I think 8.5's would be adequate. I have a set of 28" tall radials I can put on to get to the track.

On the cam, the XE274H still sounds pretty good to me. Either that, or the solid Magnum 280 - about the same lift and duration, but you know the advantages of solids. Since it's a '66 block, anything I get will need a groove machined in the back journal - just something more to spend money on.

Obviously, I'm leaning less and less towards "street", more towards the "strip" side of street/strip. Still have to be able to drive it there, though (no room or budget for a trailer).

 

Actually the XE274H is the cam I picked for this go-round in the Camaro.

I figure it should be about as large as I can go with the 9:1 comp I'm stuck with for now.

 

i put the manleys in my little engine, i got off a bit easier that you will, i only needed 12 valves.

 

I assume those are the "Race Flo" valves, as they're called in Jegs. Undercut, 3/8" stem, swirl polished, stainless, hardened tips, etc.

I'll have to check my block casting number, but Mortec indicates the same block (3855961) was used for '65/'66 2- & 4-bolt 396's as was used for '66 2-bolt 427's. Is that possible? Am I sitting on a 427 just waiting for the boring bar? A few years back, my dad said all I needed to have a 427 was to bore it out, since the strokes are the same. I said the cylinder walls would be too thin. I sure wouldn't mind being wrong in this instance.

 

five7 can you say "sleeve it"? i beleive that would take care of the too thin walls after opening it up to 427 specs. yeah that sounds like my valves, maybe i got the name wrong and mine came from jegs.

 

I should know better than to trust Mortec. But, a casting should be a casting, no matter what they bored the cylinders to in the end. In the early days, they may have cast the cylinders the same regardless of the final bore they intended. Guess that should be deferred until a "real" GM numbers book is consulted (wasn't seriously considering it for this round, anyway).

Remember 4.00" bore 283's? Okay for the early ones, don't try it on a '65 block. Also rumors that the pre-production '67 396 Camaro that Chevy let Hot Rod mag drive was really closer to 500 ci.

(BTW, "Pro Flo" was used on the Summit site tech description of the Race Series valve underhead angle/radius.)

 

The very early 396 blocks will easily go to 427. Just check the thickness, with the heads off, at one of the large water passages at the very front or very rear of the block.

Most early 396's cylinder walls almost seem 1/2" thick.---Not exactly but if you reach in at those water passages you will see what I mean.

I've even seen these blocks even go .060 over above the 4.25 overbore of the 396.

I've even seen some of the later 'K' blocks (396-402s) go out to 4.25 bore but they don't "feel" near as thick as the early blocks.

Some of the truck-pullers in this area punch out late model 454s .180 over, then throw in a little Hard-Bloc.

jms

 

I've also heard that the real early 396 blocks can be taken out to 4.25". I'm still waiting on someone to try it and confirm it as true.

 

I've heard all sorts of things, but that doesn't make them true... the farthest I've ever taken an early 396 block was .060" and it made me real nervous. I know somebody else who hit water in a 65-66 block at .060". Could be a fluke, I don't think it's worth the risk myself. If I want a 427, I go get a 4.25" block; but then I can't resist putting a 4" crank in it. Oh well.

You're right about the cam journal, in that block you won't have any oil to the lifters without it... most of the cam companies will charge you the regular custom fee ($25) to do that for you. I've heard of people doing it with a die grinder, but for the length of time it would take, it would be profitable to pay somebody else to do it.

The only ones I know of anybody reliably going any farther than that are the tall-deck blocks.

You definitely need some heads though. Those early heads don't hold a candle to the 402 heads. I'd rather have a set of those than most square-port heads, unless it's a really all-out application, like into the 10s. Basically that's where you're getting beat right now.

 

If you indeed have an early 396, it WILL go WAY more than .060---unless your block has somekind of monster core shift.

I've not only heard about it, and read about it, but also have done it many times.

When I ran big-blocks all the time (street, strip, oval-track, truck pulling), .060 overbore was just a clean-up point. REAL oversize began after that. Even on late-model blocks (late model to me is early 1970s to date).

Like I said earlier, examine a big-block at the water passages at the front or rear (on the deck), with the heads off and you will see what I mean.

One side of the cylinder wall (of early 396s) is about as thick as the total between the two cylinders of a typical 350.

OK---just now found my OLD (second revised version, from 1977) copy of "How to Hotrod Big-Block Chevys" by Bill Fisher & Bob Waar.

In the section on pistons (page 101 in my book) under maximum bore sizes, first paragraph:
"It's no secret that the 396 and 402 blocks can be safely bored to 427/454 size of 4.251 inches. And, Chevrolet sells 0.060-inch oversize pistons for this bore--so you can probably figure on this working out safely in the 427/454 block. Bore sizes larger than this in any of these blocks can be accomplished -at your own risk. We do know that some 4-bolt 396/402 blocks have been bored to as large as 4.311 inches, but not always successfully. We have heard of 427/454 blocks being bored .0125 to 4.376 inches. If you want a 4.44 inch bore, trade $2,500 [remember this is a 1977 book] for a Can-Am block. Chevy has two pistons for that bore size to cover three different strokes.
Hotrodders learned long ago that cubic inches are the only absolutely trouble-free hop-up trick. They know that bigger bores are the logical way to go. As Tom Medley (publisher of Rod & Custom Magazine) said way back in 1947, "When in doubt, bore it out!" Fortunately, the big-block Chevy has unusually thick cylinder walls. These are nominally 0.260-inch thick (if there's no core shidt) in high-performance 396 blocks.
The 366 block is a thin-wall casting and anything over 0.125-inch overbore will be getting risky.
Aluminum ZL-1 blocks can be overbored 0.030 inch."

---end section of Maximum bore sizes.

Remember, when you bore an engine to 0.060 over, you don't remove 0.060 from ONE side of the cylinder wall. You only take 0.030 from one side. Look at the thickness of the early block's cylinder walls and you'll see they are VERY thick. Then you'll understand how easily they can be bored to much larger sizes (barring major core shift).

If you have doubts about any oversize attempt, have the block sonic-checked for thickness.

If it was mine, and the block was not cracked, and didn't have major core shift, I would have no problems taking it out 0.100 over, not to mention going ahead to 0.125 over.

jms

 

Like I said, bigger bore really isn't the intent right now. And, searching through junk yards for different heads, with the assumed expense of going through them (guides, valves, grinding, porting, etc.) really isn't a do-able thing right now, either. My intent for the time being is to improve what I've got, trying to keep the cost down to justifiable levels. Working over the heads myself, Stealth intake, and higher stall converter (which will probably make sticky tires necessary), will probably be the extent of it this winter. Maybe cam & DP carb, if I can sell the carb/intake I've got now.

"Muscle Car Review" mag had an article in '95 about the Rat. I spent some time reading it over again tonight. Interesting, the first year of the 427, they used the same small valve/closed chamber heads they used on the 396.

If I ever get the itch to really dream, I'll have the block sonic checked for 4.251" bore. Should be able to handle heads at that time as well, if I'm considering that...

Thanks for the input and ideas.