I wanted to keep the numbers matching engine in my car so I used the original 396. I added a 4.00 stroke crank with 9.8 to 1 compression KB pistons. It makes the engine into a 434. I used the factory 063 heads and added 2.19/1.88 valves and they have a port job with some bowl work done. (They flow 270 cfm @.600) The engine has a 236/244 @.050 .580/.590 lift, 110 lobe separation hydraulic camshaft in it. Using a GMPP CNC machined intake (basically a Edelbrock RPM with more of a factory look) with a modified 850cfm Q-jet. It has Comp 1.72 roller rockers, roller timing chain and the other usual internal upgrades. The engine looks stock externally except for the headers. It dynoed at 428hp @ 5200rpm and 469lbs. torque. Myself as well as the machine shop thought it would put out between 475-500 HP. Is this just a lazy combination or is something mismatched or out of wack? The machine shop routinely builds BBC and most are 1000+hp monsters. However, this was his first stroked 396 so he doesn't know what to expect either. A/F and spark timing have been verified and are where they should be. Should I be seeing more power with this combo, or is this what would normally be expected. Thanks for your input.

How much cranking comp do you get?

I forget the actual number but it was high. 175 - 180 I think. Did a leakdown test too and it is good.

IMHO I think the cam might be a little small to make the numbers you mentioned. How are you using the engine?
Mike

Was the HP corrected or observed?? How recently was the dyno calibrated?? Air temp , altitude etc. all correct?? Can you scan the printout and post for us to see??

How much effect will the smaller cylinder have on shourding the valves???

I have heard it several times that the valve shourding is also why 427s are usually much better performers than 396s, despite only a small increase in bore size and displacement...

I did some homework about 2 years back on this very engine setup...I was planning to build one to replace an original L78 motor in one of the Novas. Here is some info to review....based on what I have read these combos seem to be more torque and less horsepower. Hope this helps...

wilma

http://www.compcams.com/Community/Articles/Details.asp?ID=1047065182

Pat- The engine is still at the machine shop and I havent looked at the dyno sheet yet. I just was told over the phone that it made 428hp and 469tq. Hopefully this weekend I will be picking it up and get some more answers. Don't know too much at this point, I was just a little surprised that it didn't make more power.

Mike- I originally had bought a 226/236 cam for it but the engine builder knew that it would not make the higher power. He custom ordered a 236/244 from comp or erson. The car will most likely go to the track occasionally but be more of a cruiser and show car as it only has 56K miles and looks factory down to the bias belted redline wide ovals.

wilma- interesting article, I read that earlier today and wish they would have posted the cam specs. All it says is edelbrock parts were used. I guess I'll have to look at their cams and guess which was used for that article.

In terms of HP, how much does the stroke matter? Another way to phrase my question would be: Should I be happy with 428HP out of my 396 (with the extra torque from being stroked) or dissappointed with less than 1 HP per cubic inch out of my 434? Does the added cubes from the stroke cause any HP to be gained or just torque?

my 396 (+.060 or 408) made 425 hp and 440 torque on the dyno.

Was the cam installed per spec or advanced at all ??

Did you use the Speed-o-motive kit..???

Did the shop machine any relief in the top of the bore for the larger valves..??? the smaller bore may limit the breathing a little...

What did those heads CC at...???

Is the compression ratio verified by the shop..???

I still think the numbers are strong, especially the torque...

What car is this going in...???

This subject has been bounced around before...perhaps one of the boys can locate the old thread(s)...

wilma

Here's a recent thread...

http://www.chevelles.com/forums/showthread.php?t=257409&highlight=stroker+396

Mike- I know the cam was degreed to spec and had 4 degrees of advance built in but I don't know if was changed any on the timing set.

Wilma- It was not the speed-o-motive kit, but a Eagle 454 crank and KB pistons. The block does have valve reliefs machined in. Heads CC'd at 103 after all work was done. Comp ratio was verified at assembly because initially we thought it was going to need to be lowered. Car is a 69 Chevelle SS396

another thread...

http://www.chevelles.com/forums/showthread.php?t=235930&highlight=396+stroker

jtm60- how is your 396 built to get 425hp and 440tq? Just curious how close it is to mine.

.....

http://www.chevelles.com/forums/showthread.php?t=209933&highlight=396+stroker

The car will most likely go to the track occasionally but be more of a cruiser and show car as it only has 56K miles and looks factory down to the bias belted redline wide ovals.
I think you will have a great engine for your planned use. I wouldn't change a thing.
Mike

Mike- I'm glad to hear that somebody thinks that this power rating seems right for this engine. Everybody around here locally had me thinking that I should be seeing a lot more and that something was wrong or not done as said by the machine shop. Biggest problem is finding people that have done this combo and actually have knowledge pertaining to this.

The cam is a little mild for a hot perf 434 but even with that in mind i would have expected more like 440-450hp & not the 428hp you got even thought thats not that bad .

Here are a few things to check on the q-jet along with some other items that could also limit/reduce your top end power .

Let me know what you find if you decide to chk these things out.

Scott

================================================== =========

1) Is the secondary cold lockout on pass side of carb stuck in cold position not allowing the lower sec throttle plates to open or fully open?

2) With motor off and hot to ensure secondary cold lock was disabled/unlocked Did anyone hold throttle wide open I look down the secondaries to ensure that the lower secondary mechnical throttle blades were or almost verticle/wide open? If not bend the verticle tang futher back on the prim side/driver side of the carb that contacts/opens the lower mechnaical secondary linkage of carb to hit it earlier which will open them further. Move the linkage to WOT a few times to see what i am talking about.

3) Also,is the upper secondary air valve spring adj loose enough to allow them to be fully open when at WOT at like 3500rpm and above? If not back of the spring load adj a bit a try that that.

4) Was the larger hi flow .130-.135" needle & seat installed?

5) Whats prim jets & prim meter rods are you runnng?/too lean?

6) Whats secondary hanger and sec meter rods are you running,give tip size of sec rods.

The sec hanger could possibly not be pulling the sec meter rods fully out of the fixed sec jets in the baseplate or too wide or fat of a tepered sec meter rod could also cause lean fuel calibration & limit top end hp.

7) Was the what can be at times somewhat restrictive small paper fuel filter removed from the carb and a lrg hi flow inline filter installed in its place?

8) Were you running at least 38 deg total with that cam?

9) The top power was at 5200 rpms,i would have thought that cam should rpm a little higher then that making power in a 434 to at least 5,500-5,600 rps? So with that in mind maybe the valve springs are too weak for the application or were improperly installed resulting in weaker seat/open pressures limiting top end rpm & HP? Have them check the seat pressure on a couple of the springs and if any seen low remove a couple springs to chk open/compressed sprting pressure to ensure they are ok.

By themselves (other then weak/or improperly setup valve springs) most of the above items wont kill your top end hp but collectively for ex if you add up running 34-36 vs 38 total timing/maybe the secondary isnt opening fully vs getting it to open fully/top end fuel delivery is somewhat restricted by smaller resctrictive in carb filter vs removeing it and using an in line hi flow lrg filter/etc by them sleves are no bu=ig deal but collectively/ all together they can easily cause a 25-30hp+ loss if not correct or adj-tuned for max perf and thats the point i am trying to make .

And thats not addressing what i though was a kinda low top end rpm hp too which could be valve spring related too,who knows.

Scott

jtm60- how is your 396 built to get 425hp and 440tq? Just curious how close it is to mine.
To be of any value to you 65,you need the rpm where these peaks occured.
Mike

I have a 396 pro built 430 hp, 440 tq. It is a 10.5-1 roller engine. I wouldn't worry that much about the hp number, torque is what you want and it looks like the engine does great at those numbers.

Scott- Wow, you sure have the bases covered. The carb is a fresh out of the box Edelbrock RPM 850cfm Qjet. I checked all of the mechanical linkage prior to the dyno and it was all good with no binding. Since I was not present for the dyno pulls I don't know how well all of the vacuum operated aspects of the secondarys were functioning. They did say that the A/F was good at all rpms. They tried several different jets and ended up at 74. The rods and hanger were as shipped by Edelbrock. I agree that the rpm seemed a little low for peak power. I thought it would be 5500-5600 too. The springs were checked prior to install and they needed a different height retainer to get the specs to match the cam. Assuming that all the spark, A/F ratio, spring pressures,etc. is all correct, you mention that the cam might be a little small to make the higher HP goals. What would you recommend? How much torque would be lost or would it just moved higher up?

I wanted to keep the numbers matching engine in my car so I used the original 396. I added a 4.00 stroke crank with 9.8 to 1 compression KB pistons. It makes the engine into a 434. I used the factory 063 heads and added 2.19/1.88 valves and they have a port job with some bowl work done. (They flow 270 cfm @.600) The engine has a 236/244 @.050 .580/.590 lift, 110 lobe separation hydraulic camshaft in it. Using a GMPP CNC machined intake (basically a Edelbrock RPM with more of a factory look) with a modified 850cfm Q-jet. It has Comp 1.72 roller rockers, roller timing chain and the other usual internal upgrades. The engine looks stock externally except for the headers. It dynoed at 428hp @ 5200rpm and 469lbs. torque. Myself as well as the machine shop thought it would put out between 475-500 HP. Is this just a lazy combination or is something mismatched or out of wack? The machine shop routinely builds BBC and most are 1000+hp monsters. However, this was his first stroked 396 so he doesn't know what to expect either. A/F and spark timing have been verified and are where they should be. Should I be seeing more power with this combo, or is this what would normally be expected. Thanks for your input.Who built it?

I wanted to keep the numbers matching engine in my car so I used the original 396. I added a 4.00 stroke crank with 9.8 to 1 compression KB pistons. It makes the engine into a 434. I used the factory 063 heads and added 2.19/1.88 valves and they have a port job with some bowl work done. (They flow 270 cfm @.600) The engine has a 236/244 @.050 .580/.590 lift, 110 lobe separation hydraulic camshaft in it. Using a GMPP CNC machined intake (basically a Edelbrock RPM with more of a factory look) with a modified 850cfm Q-jet. It has Comp 1.72 roller rockers, roller timing chain and the other usual internal upgrades. The engine looks stock externally except for the headers. It dynoed at 428hp @ 5200rpm and 469lbs. torque. Myself as well as the machine shop thought it would put out between 475-500 HP. Is this just a lazy combination or is something mismatched or out of wack? The machine shop routinely builds BBC and most are 1000+hp monsters. However, this was his first stroked 396 so he doesn't know what to expect either. A/F and spark timing have been verified and are where they should be. Should I be seeing more power with this combo, or is this what would normally be expected. Thanks for your input.that would explain the low power numbers

George,what would you recommend for a head,if this 434ci motor ran out of head at 5200 rpm with a 236/244@.050" cam?
Mike

George,what would you recommend for a head,if this 434ci motor ran out of head at 5200 rpm with a 236/244@.050" cam?
Mikei wouldn't until i was sure those flow numbers were correct, i'm hoping that's a misprint, 270cfm @ .600" lift is awfully low

No, my printout for the head flow shows 270 @ .600 lift. From the comments I'm guessing this is too low. Considering I paid 1K for the heads to be ported, and a 3 angle valve job I'm guessing I should have had more flow. Engine was built here in Phoenix by a shop that does 2000+ hp alky and nitro drag race and marine racing big blocks. Most of the engines in his shop easily approach or exceed 100k. When I look at them I see nothing but high dollar parts.

Does the flow data sheet list the size of the fixture? A lot of heads flow real great on big bores, but get choked way down on a smaller bore.

No, the flow data sheet looks very generic and does not list the size of the fixture. What should 063 heads flow with a mild porting job?

No, the flow data sheet looks very generic and does not list the size of the fixture. What should 063 heads flow with a mild porting job?that's a good question, if we only had a baseline to compare it with.. but judging from the measly flow numbers @ .600" lift i'm guessing less than a stock pair of 049's.

I've got the flow numbers in front of me now and it looks like this:

.400 - 242.2cfm
.450 - 246.6cfm
.500 - 253.1cfm
.550 - 259.7cfm
.600 - 263.6cfm
.650 - 267.0cfm
.700 - 271.8cfm

This is for the intakes, exhaust values are at 68% of that. What should 063 heads flow?

George, looks like we were posting at the same time. From what I've heard, the 063 heads and the 215, 802, 820, and the 290's all flow about the same. All are smaller chamber heads that may have shrouding issues. I wanted to use what I already had, but now I'm wondering if this is why my power output is lower than expected. If I have 263.6cfm @.600 after porting, what did I start with?

i wouldn't until i was sure those flow numbers were correct, i'm hoping that's a misprint, 270cfm @ .600" lift is awfully low


Here is some real world info:
pair of stock closed chamber 215 heads...no porting,stock castings,stock 2.06/1.72 valves...car runs consistent 12.85-12.90 @ 105-105.5 MPH

swap heads to a ported pair of 063's with 2.19/1.88 valves that basically flow around 260-264 cfm at .600 lift and with no other changes car bangs out a 12.55 @ 108 MPH..and backs it up with a 12.56 and a 12.61 due to a slower 60 ft.
this is a 4000 lb car with 3.31's and a 223/231 @.050 cam

So from your experience the modified 063s worked well and picked up some power over the stock 215s. I see that your 063s flowed the same as mine. This is definitely good information. I guess I still am wondering if my power is limited by cam, heads, or some other misc. parts combination or if everything is correct and this is just the power that this particular engine combination gives.

IMHO,the smaller bore of the 396 probably limits the breathing of your heads.
That cam and heads you have would make 480-490 HP and 520-530 ft/lbs TQ in a 454

regardless,the motor you have will actually perform well in the car...

I'm sure your right about that. If I started with a 454 then I would be at the power levels you mentioned and I was hoping for. I imagine that is why my engine builder thought those levels would be attainable. He admitted it has been many years since he built a performance 396 and mostly does 468 - 732 cubic inch. He probably figured that being a 434 instead of a 454 wouldn't change the power that much. I have read a lot of info stating that the 396 bore size limits the engine when compared to other BBC.

Found an article from Car Craft from 2005 regarding BB Chevy cyl. heads and flow bech info....here's some data:

the 702 and 290 were almost identical, eg; .600 lift intake they were 254 and 257 respectively...this was with stock chambers and small valves.

the 049 heads faired a little better with 264 at .600 lift

the 049 was better on the exhaust side at 173 vs 161 for the others....again the 049's were with small valves

aftermarket heads were much better.....


as others have mentioned the bore size is limiting factor here...but your torque is so good, I don't think you will miss a few ponies....remember torque is what gets you going..let the other guy worry about the horsepower:p

I agree, torque is definitely king. I've built plenty of 500 Cadillacs, 440 Mopars and 455 Buicks for Jeeps, pickups and other misc. projects and have always preferred having torque to hp. I was just hoping with a BBC to have my cake and eat it too. High HP & Torque. My Chevelle has 3.90 gears so I don't imagine that getting it off the line will be much of a problem, except for the F70-14 Firestone Wide Ovals going up in smoke.

Wilma- I just reread your post and noticed something. The Car Craft article stated that the exhaust @ .600 flowed 161cfm on the 290s. My flow data sheet has my exhaust flowing 189.9 @ .600 and 198.5 @ .650. Looks like maybe he spent more time porting the exhaust side of the heads.

Well, that would make sense, since the exhaust is the weak side of the BB. The BB Chevy engines have always responded well to exhaust improvements...that is why most guys installed headers the moment they got the car home from the dealership. The aftermarket heads really shine in this area, with flow numbers that can keep up with the potential of modern cam design....BUT....you have a good setup and with a 3.90 gear you will be worrying about holding on...not how much horsepower you don't have;):D

I was just hoping with a BBC to have my cake and eat it too. High HP & Torque.you can, that's the nice thing about the BBC.. it's all in the way you design and build the engine, your current design will provide gobs of torque but other factors in the combo are limiting peak horsepower.. your obviously not happy with it so i've pointed out areas that have room for improvement if you desire more top end power with minimal losses in low end torque.. with small chamber heads you must be careful and not use a piston design with excessive dome height as it can interfere with combustion and flame front propagation.. this is the good thing about small chamber heads, they allow the builder to have a healthy installed static compression w/o using domed pistons.. from what i can gather the general concensus from most members here on the board seems to be; build the motor for maximum torque with no regard for maximum horsepower, well.... torque and horsepower are proportional, as the horsepower increases the torque follows suite.. on the same note your 427 is a stroker, strokers are deisgned to maximize torque by increasing the stroke w/o increasing bore size, so engine mods should be geared to take advantage of the strokers natural torque curve, but don't leave horsepower on the table, that's all i'm trying to say..

Well, I talked to the engine builder today and he is going to run it on a different engine dyno. Seems he also had another engine recently (360 mopar) that should have made 380hp but fell way short on this same dyno. The dyno he normally uses and trusts has been booked up solid by some racing team so he used another one that used to be accurate. Evidently he won't be using it again other than just for engine break in. He also feels that after looking at the dyno numbers and peak power rpms that there is probably another 25-30 horse to be found with the combination of a more accurate dyno, timing adjustments and some higher octane fuel. Once its run again, I'll post back to give an update.

To be of any value to you 65,you need the rpm where these peaks occured.
Mike

sorry lost track of this thread...my info on this topic was posted long ago....

http://www.chevelles.com/forums/showthread.php?t=23363

http://www.chevelles.com/forums/showthread.php?t=205427&highlight=396+lunati+dyno&page=2

Hello, pretty interesting thread here as I am putting together a "stroker" 396 for a '68. It doesnt seem that this combination gets alot of respect here. Alot of folks seem to cut the bore to stroke ratio as a downfall. Its kinda funny to me that that very bore to stroke ratio is used in a small block combination with very high regard in the dirt short track world and doesn't the new LS7 427 use that bore to stoke ratio? (4.125x4.00) I realize that different engine designs react differently depending on a truckload of factors that come into play. To me it all comes down to right combination of parts to get the results you want or need.

Well, it is over a year and a half later and I'm bringing this thread back from the dead. I just finally picked up my engine from the machine shop. In order to remedy the low HP output the machine shop double checked the cam and found that it had mistakenly been made with the wrong lobe profile. They ordered a new one with the lobes they wanted and it now has .610 lift with the same 236/244 duration. They also machined the valve reliefs at the top of the cylinder bore larger to ensure proper airflow. Everything else stayed the same and it was dynoed on 91 octane pump gas from the local QT. Final numbers are 481HP and 477TQ. Needless to say, it has been a long time coming but these are the numbers I was hoping for in the beginning. Not bad for a stock appearing, numbers matching 396 running through a Q-Jet. They also ran it with a Holley DP and picked up another 8 HP but I will gladly skip the Holley in favor of the original looking Q-Jet. One thing I will say is if it wasn't for the numbers matching, low mileage car I would not choose to go this route again. Unless you already have a 396/402 it would be far easier to go with a 454 or 496 instead.

Glad you got it detailed out. I nearly built one of the 434's too, but had a good solid bottom assembly at the time and just bored it to the 408. I wouldn't hesitate to build one if the crank was bad and in need of replacement. Baby BBC's are fun!

Why not use a Holley? Sounds like a really nice car though :) Good year too, ha.

Well, it is over a year and a half later and I'm bringing this thread back from the dead. I just finally picked up my engine from the machine shop. In order to remedy the low HP output the machine shop double checked the cam and found that it had mistakenly been made with the wrong lobe profile. They ordered a new one with the lobes they wanted and it now has .610 lift with the same 236/244 duration. They also machined the valve reliefs at the top of the cylinder bore larger to ensure proper airflow. Everything else stayed the same and it was dynoed on 91 octane pump gas from the local QT. Final numbers are 481HP and 477TQ. Needless to say, it has been a long time coming but these are the numbers I was hoping for in the beginning. Not bad for a stock appearing, numbers matching 396 running through a Q-Jet. They also ran it with a Holley DP and picked up another 8 HP but I will gladly skip the Holley in favor of the original looking Q-Jet. One thing I will say is if it wasn't for the numbers matching, low mileage car I would not choose to go this route again. Unless you already have a 396/402 it would be far easier to go with a 454 or 496 instead.
================================================== ==

Wow,nice job!!!

481HP and 477TQ are very nice #'s for a streetable stroked 396 bbc to 434 cubes.

I know you already gave some info on the build but since there arent thatrmany people stroking 396's could you please take the time to list the complete build & specs for others to follow if needed for similar results.

What are rpms for max hp & trq?

Whats heads and work/porting if any was done?

What compression?

Are you runninmg a roller cam with .610" lift or a FT & is it hyd or solid?

Are you running the stock flat type cast iron intake with the q-jet?

Was the holley dbl pump 750cfm like the stock q-jet was for your BBC?

But it goes to show a q-jet can hold its own against a holley only being down 8hp on top end but the q-jet will get better mpg and is also more reliable over yrs/miles then the holley is.

Not that the holley is unreliable but when properly maintained (meaning regular fuel & air filter changes) q-jet's are known to go 25+ yrs at times without a rbld which is not common for holleys to do on a regular basis which i have experiened 1st hand mult times over the yr's.

Scott

Why not use a Holley? Sounds like a really nice car though :) Good year too, ha.
===================================

Considerably better mpg and the ability to go 25+ yrs without any attention or rbld is reason enough to go q-jet over holley for a street motor of this perf lvl with only 8hp hp diff between the 2 carbs which most people would never feel on the street anyway.

Scott

Dr. J's Performance prepped set of 063's flowed over 300 (intake) and well over 200 (exhaust) with 2.19/1.88 valves.

The stock flow numbers with std. valves and prepped flow numbers are posted on that website for your info.

Charles

Here is some more info on my 434 build. The best thing about this combination that I see is probably the torque plateau (not really a curve). Basically I have over 460lbs-ft from 1800rpm to 5100rpm with the peak being 479.2 at 3000rpm. The HP peak is at 5500rpm. The compression ratio is 9.8-1 with the 063 heads (103cc after bowl cleanup). When I originally dropped the engine off at the machine shop we had a goal of 475-500HP so the heads were only ported enough to support that goal. I'm sure there is more flow to be had if more time was spent on them but an all out race motor was not what I was after. Basically they flow 271.8cfm intake and 202.8cfm exhaust @ .650 lift with the 2.19/1.88 valves. I am using a CNC machined GMPP aluminum dual plane intake (bowtie removed for stealth appearance) because it looks close enough to the factory intake to fool most people. 850cfm Q-Jet, HEI ignition, NGK plugs. For the cam it is a 236/244 @ .050 with .610 lift on both int/ext. It is not a roller, just a hydraulic flat tappet. It is a custom grind from Erson with higher than standard grind valve lift and faster ramp rates. Sealed Power lifters, Comp Cams Magnum roller rockers and 3/8 pushrods. Cloyes double roller billet timing chain advanced 4 degrees. Melling HV oil pump. Keith Black 361 pistons, resized 1969 factory rods with ARP bolts and Eagle 4.00" stroke cast crank. I forgot to mention that this was dynoed through my Hedman Elite 1.75" headers and Hooker Aero Chamber mufflers. I'm sure with open headers horsepower would have been higher but I wanted it run with the mufflers for a more accurate number. Also with a single plane intake I'm sure it would have been over 500HP but that would not look original and the torque would drop dramatically. Basically when I'm at the car shows the only thing that won't look original at first glance is the headers and HEI ignition. Both of which are usually considered acceptable modifications even by most purists. If somebody really looks close they might notice the larger harmonic balancer and the intake manifold. Car is a 69 Chevelle SS396 with 56K original miles, TH400 and 3.90 12 bolt posi running on F70-14 Firestone Wide Ovals. Needless to say, traction will be a problem and I will have to invest in some drag radials or slicks when I actually want to use the power. Timing was 38 degrees and it was tested on 91 octane from the local QT station. With the very broad torque curve and only 9.8 compression it should be a very streetable combination. Haven't bought a torque convertor yet but I probably will keep it pretty mild as I don't really like the high stall feel. Probably something around 2200-2400 rpm. Anyways, hopefully that answers some of the questions on what a 434 is capable of doing while looking mostly stock. I'm sure with aftermarket heads, a single plane intake, higher compression and more cam it might be possible to reach 550HP but it would be at the expense of drivability.