Im new to this site but from what Ive read there are alot of gear heads and alot of racers on here! Im in the process of building my first BBC and could use some advice! Its a 396 2 bolt block punched .030 and its an early 60's block so I know Ill need to groove the rear cam journal for oiling! I have the heavy duty GM 7/16 dimple rods with ARP wave loc bolts topped with TRW 11.5 to 1 forged slugs (pistons) along with chrome molly rings and a stock forged crank with ARP stud kit!! The entire rotating assembly will be balanced!! The heads are the original 396 heads with the peanut style closed combustion chambers with stock small valves! They have dual racing springs with dampeners and some mild porting! Timing will be kept in check with a Pete Jackson "noisy" gear drive and a HEI distributor!! Oiling will be a moroso 7 qt racing pan with a diamond windage tray & HV Melling oil pump! A 750 twin squirter demon carb on top of an Edlebrock RPM Performer air gap intake will feed the engine! It will breathe thru hooker super comp headers and a 3" exhaust that will include an "H" or "X" pipe and flowmaster mufflers! The trans will be a built up 400 Turbo with a 3000 to 3500 stall! The rear end is a stock 12 bolt posi and will house 390 to 410 gears! I’m figuring this engine should redline between 6500 to 7000 RPM! 2 Questions CAMSHAFT??? I was looking at a Comp 292 Magnum Hyd. camshaft or a Lanati Voo-Doo camshaft....Any suggestions? I want this car to be a weekend warrior at the drag strip or a cruise into town but definatly not a power touring car! 2nd question....Should I swap these heds out for an open chambered head like edlebrock performer rpm, Merlin or RHS 24-degree heads! Im open to suggestions here and please dont be shy as Im here to learn. I want this ride to be right!! Ive also heard that a gear drive can cause problems with main bearing wear is this true? Thanks for any tips and info!

First. WELCOME! :waving: It looks like you have a good handle on your setup. I think a set of AFR 305cc heads would really wake that motor up. I will leave the cam selection to the experts on this site. Good luck with the build. P.S. Do you write for a mag? Your post reads like a HOTROD mag write up:thumbsup:

As far as the gear drive I myself don't like them. It puts a lot of harmonics into the valvetrain from the crank. I would run a double roller chain and be done. As far as the heads, yes an open chamber head will wake the motor up. I had the 781 casting open chamber ovals with 2.19/1.88 valves on my 408 and it handled 500 hp. As far as the cam, the mag 292 is an ancient piece, both the Lunati Voodoo series and comp cams Xtreme series offer much more performance from modern technology. Otherwise it sounds like a healthy piece, Welcome and good luck.

They call those heads with small chambers as bathtub shape chambers. Use them, great for a 396 motor. Depending on what pistons, you will be between 10.5 to 11.0/1 CR. Personally, I would go with a solid flat tappet cam in your application. Stay somewhere around 235-240* at .050, you can go with a 112LSA for a decent idle. Lift upwards of .550+ works well with these heads. If you really want hyd flat tappet, maybe go with a 112LSA to make it more streetable. Personally, on 396 motors, I like a "blower" cam [LSA of 112-113 with a good 10-12* extra exhaust duration. From personal experience, something like a 230int/242ext on a 112-113LSA works good on these.

You say you're running "peanut port heads" yet everything else seems to be set up for higher rpms....might want to look into a set of oval ports or maybe even rectangular ports....don't think them peanuts will breathe much over 4500-5000. I'm guessing you must have a 325 hp version of the 396?

I don't think that they are peanut port heads. I think that they are just closed chamber heads which are great.
drennon99,
What are the numbers under the valve cover area on those heads?

Other than the noise gears I had the same set up on my nova when I first built my 396 for the street/strip. I went into the 12's with a Crane cam #134571. I also had the TRW slugs in it with 106cc closed chamber heads. Same intake with a holley 750 DP. When I finally started running mid 12's with 9" slicks I twisted the rear tubes. Be sure to have a shop weld your 12 bolt tubes to the carrier or you will do the same and find your tranny laying on the ground when you launch. After I had someone add the roll bar and ladder bars I had that car running in the mid 11's.
With that same engine in my new Nova tubbed with roll cage and all that the car went into the 10's so it is a great street engine that will run fine on pump gas with plenty of power.
I'm going to use that same cam in a 396 for the Chevelle for street use only. So have fun a don't drool too much thinking about it.

Oh yea I had that cam 4 deg advanced.

Wow, how common is it to twist axle tubes???

What did you do to make it run 11's? Ntrous? Blower?

Twisting tubes is very common. I think the suspension helped put it in the 11's but I'll have to check all my old notes from years back. Remember it ran 12's with just slapper bars. After the ladder bars and roll bar it hooked a lot more than it ever had.

Is this common on all 12 bolts? Or just leaf spring type 12 bolts?

You say you're running "peanut port heads" yet everything else seems to be set up for higher rpms....might want to look into a set of oval ports or maybe even rectangular ports....don't think them peanuts will breathe much over 4500-5000. I'm guessing you must have a 325 hp version of the 396?

The heads are oval port heads and the combustion chambers are peanut shapped or bath tub shapped! Ill get the numbers tonight and post them! If I remember right I think their 3872702 which is 65-66...oval..CLOSED..396, 427, 98cc chamber! Just trying to go from memory but I think the block is 3855961! The only number I could find on the crank is 6223: 396,402,427...forged, 1053 steel! Would I be better off investing in a set or Merlin, Brodix or AFR heads??

If you have $$$ to spend, don't bother with aftermarket heads, the factory oval ports low plenty for a 400" big block. Spend the extra $$$ in the valvetrain. If you've got 800.00 to invest, go to "street" solid roller cam setup, with lift in the .600 range - that's what I would do. I would tell ou to go hyr roller, but it is going to limit your RPMS to about 6200. A good solid roller is well worth it when you want to make HP.

What about my RPM?? Will my stock heads beable to flow especially with a .600+ lift camshaft?? Remember the combustion chamber is like 98cc with the small valves!!

Is this common on all 12 bolts? Or just leaf spring type 12 bolts?
Not sure about all, but I know I spun mine (leaf) and I've seen a few others do it. I had just told someone they should get there's done and a few weeks later they spun theres and distroyed the trans.

Any car with decent performance should have the tubes welded. The tubes are only pressed in and tack welded.

You have good heads for what you are after. Spend the money else where. All you need is good valve job with 2.19 /1.88 valves, bowl job and gasket match. I am also using closed chamber "215" heads that spec out to - 96.4 combustion chamber volume. Using TRW # 2399 pistons my final chamber volume (yours will depend on several factors) is 101cc and with these heads yields about 10.7 to 1.

Jim

Pro67chevy, 5 cc's is a major increase in chamber volume (96.4 - 101). This must be the result of the bigger valve work, perhaps? I would have thunk only about 2 - 3 cc's at most.

Charles

I have the same heads you have sitting in my basement still stock and still full of old oil. I have had people very interested in buying my 702 heads. They are suppose to be one of the best oval heads GM had. Who cares if they are oval ports! I have seen them run 9's with ovals so they will flow plenty. I got the piston # for you they are L2287 TRW.
I ran the 206 head on my car with a 109cc I think? Not sure.

Charles, You're right, thanks for the correction. It's been a while since I looked at my notes. Here are the measurements:

BORE 4.310
STROKE 4.000
Head cc 96.5
Gasket cc 10.88
Piston dome -9

Final Chamber: 98.3cc

COMP. RATIO 10.63:1



Jim

Ok after talking to several people Ive decided to stick with my old closed chamber heads! I am going to have bigger valves installed along with more port work! Right noe I think their just gasket matched! 6200 to 6500 Red line! Im still not sure on a camshaft yet! But from what Ive read most advise against the gear drive!! Bummer.....I love that sound but nothing beats expierance and thast why Im here!! Looks like a double roller is going on my list!

I ran a similar set up for a while. I had 12.5:1 TRW pistons with 96cc closed chamber heads. The cam I used eas a Competion Cams 305H which is a 305 duration and a .571" lift on IN. & Ex. Nothing but tire smoking, shaking fun.

I have the 702 heads, worked of course, on my 427 BBC and it's pushing 450 HP, very good iron head!!!!!!

Would strongly encourage you to drop the hi volume pump. Standard is fine, all the HV will do is add parasitic losses, especially at high rpm. Standard Melling will come with a "mechanical lifter" spring. Use it.

The cam you need is #1350 on this page....on sale to boot.
http://www.crower.com/sp/gs_cams.shtml

I like the price of that cam but what kind of performance will that camshaft give me? Also since its a solid cam and Ill be running it on the street and some weekend drag racing how ofter will i need to make adjustments? the specs on the cam are as follows: Adv duration: 268 / 274..... Dur @ 050: 236 / 240.....Lobe lift :331 / 338....Groce Lift:563 / 575 ..........Sounds like a pretty healthy cam. What kind of RPM range can I expect out of this solid lift cam?

Its about 7 degrees smaller than my 433 bbc cam, so it should be quite similar , peak power maybe 6200-6400 rpm. I would certainly ask the techs at Crower that question before you buy.

Take away around 8 dregrees to compare it to a hyd cam, eg, a similar hyd would be like 228/232 @0.050.

I *suspect* my cam is abit more aggressive profile, and the only trouble I had was it took about 5 lash settings before it took a "set" initially. Then it became a once a year deal unless I overreved ( 7500 ). Thye good news is that it ( imho) is much easier to set lash on a solid cam. Very precise.

One more caution, BE SURE the shop has put bigger valves in those cc heads before. It takes a bit of expereince to know how much of the chamber wall to remove to unshroud the exhaust valve. Behind that wall is a water jacket. IF they go too far, a massive problem will ensue. HYDROLOCK!

Glad to hear your going with the double roller timing chain.I had a gear drive in my 396 for about 100 miles and it drove me crazy.I took it out and found that it was rubbing against my timing cover and I did clearance it like in the manual.As for the heads ya I was told that my closed chamber heads were good but needed some pocket porting.Im going to have that done along with some bigger valves then Im running a bigger cam.

i would have to say dont over look the header size-396 respond better with a small primary tube size header. larger tube headers seem to reduce power a lot. stay with a small tube header.

396 engines love to rev not uncommon to get best 1/4 miles times running 6500-7500 rpms depending one what cam. even a small 233/239 @ .050 will go 6500 rpms for best mph and e.t.'s in my combos

i had a ZL-1 cam that made best mph at 7500 rpm shift points but i limit the moter to 7000 rpm chip and slower times so the stock unbalanced bottom end would live, it last 5 years of nitrous and pounding before a bearing spun going to work running it at 4,500 rpms down the highway just to keep up with traffic