388 Istroker initial dyno

[Roger D]

There is hp to be had in those stroked 348's.

Finally got some bugs worked out on the '63 Biscayne 348/388 stroker (409 crank) - had two pulls on a chasis dyno today to start to get it dialed in. The motor has been totally rebuilt, balanced and is running about 10.8:1 Ross pistons, cam and revalved 333's all by Mr. Bruneneau - over a 655 .060 block, 6.135 Eagle rods, etc. etc. and two very fat 600 Edel. Carbs. on atop of a 881 intake (port matched heads). BW ST10. 4.10 posi.

The first pull with the carbs set "out of the box: yielded 343 rear wheel horsepower.... I shut it down at 6,200 (where its top hp read) and the curve was still going up fast.

Torque was a bit more, peaking at 4,250 and it was very flat from 3,000 to 6,200 (no readings below 3,000).

The tech worked the carbs with a screw driver, the next pull yielded 355 hp at 6,200... hp and revs still climbing fast. Left side exhaust at the collector kept blowing off (needs to be welded) ... this was responsible for some excitable moments inside the dyno room. :eek: By the way, on the second pull, the AF ratio was mid 12 at 6,200 ...

I'll be back to get those pigs re-jetted, timing set ... I'm sure there's more hp to be picked up w/o pushing things to the edge.

I'm happy :clap

[Ronnie Russell]

Roger, Congratulations,,,, Very impressive. Good luck,,,:)

[1958 delivery]

What are you guys doing to get the tires to stay hooked? Many years ago, working on chassis dyno, trying to keep the rear hooked was almost impossible at higher horsepowers. The type of tire used seemed to play a big role. Slicks are definitely a no no on chassis dyno. We use to chain the rear of the car down hard but they seemed to crawl out of the rollers anyway.

[1958 delivery]

Oh yea, what size valves were you able to get in those 333's? Did you put in hard seats?

[jim_ss409]

Way to go!:beerbang

[CDNpontiac409guy]

Roger... 355 horse at the rear tires, out of a 388 inch small port W block ? !
I'm just as happy:cheers
I thought it would be a good combination of parts... but I didn't expect THAT:dunno

With my experience using those very same carbs on my 423 inch large port Stocker, I KNOW that those "pigs" are WAY rich... way WAY rich:eek: .
We went one step smaller in sec jet, and one size bigger metering rod, and jumped 22 HP:eek: ... and it was STILL fat.

I bet when you get that thing tuned-up there in the next few days, you should see near 375 HP at the rear wheels:deal .
Not sure what that is at the crank ?... perhaps around 420+:dunno
Pretty darn good for a rather modest/conservative small cube/port W engine:deal


To answer the question about the heads...
2.06" / 1.72" valves... DEFINITELY NO hardened seats.

This isn't a "big horsepower" car... not to mention, I think the 3600+ pounds ( and decent weight distribution ), makes it so tire "slipping" wouldn't be a problem.

[bignbad60]

Congrats, very impressive indeed, just the motivation I needed to finish my 427 cranked stroker and see what she will do. Glad to hear the success with the revalved 333, I am also running that set up but with the 3 deuces. Again congrats , I'm sure that belair will pull hard on the road


Tim:beerbang

[TomO]

VERY nice!!!! Thanks for sharing the dyno info it is really helpful.

TomO

[MRHP]

Good numbers. Sounds like a well built motor. Or is that engine? Either case, quite impressive.:cheers congrats.

[mac1]

Congrats Roger! :clap I'm curious about your heads. I have the same intake/heads you have. Where you able to port those intake runners all the way out to eliminate any mismatching, or did you work the intake to? It's nice to know you can get those rpm's with that head/intake combination. Mac

[rabid rat]

What are you guys doing to get the tires to stay hooked? Many years ago, working on chassis dyno, trying to keep the rear hooked was almost impossible at higher horsepowers. The type of tire used seemed to play a big role. Slicks are definitely a no no on chassis dyno. We use to chain the rear of the car down hard but they seemed to crawl out of the rollers anyway.

why are slicks a no no on the dyno?

[CDNpontiac409guy]

Where you able to port those intake runners all the way out to eliminate any mismatching, or did you work the intake to? Mac

With some determination, they are a direct match to the factory large port intake ports. Here are a couple pictures of them:

http://www.348-409.com/forum/attachment.php?attachmentid=5516&d=1162758281

http://www.348-409.com/forum/attachment.php?attachmentid=5517&d=1162758281

Despite that rather poor design of the factory manifold, I would say the combination is effective:deal . Maybe the manifold "likes" the slightly reduced cubic inches:dunno

[tripower]

Rodger, Congratulations very impressive. Can you tell me who's headers you are useing?

[bubbletop1961]

great #'s I got to put my car on a chassis dyno last summer. Very fun for those who havent. You can learn a tremendous amount of info on how your car reacts to the changes your making. It was worth every dollar. And alot of fun. I had et streets when on the dyno, had no troubles went just fine. Again great #'s.

[Roger D]

Thanks for the responses.

I should note that I had a LOT of very qualified help with the engine. As I mentioned, Aubrey did the heads, spec'd out the pistons for Ross to make and provided the cam. He also provided advice on parts to make it all work in high rev'ing harmony.

The block and components were machined, with nothing spared, multi-anlgle valve job, file fit rings, the ENTIRE rotating assembly (including the alum. flywheel), was balanced. It took some time, but the machinest wouldn't let it go until everything was as close to perfect as possible - and purposely, slightly on the loose side. He told me it would rev. easily and I can tell you, it does.

The headers are Doug's, and I think with their 2.5 inch collectors they may hold back the hp a bit up top ... but, in the end, these were the onlhy ones readilly available. and I'm not looking to make the car and engine something they're not.

Its a very snappy package, and with all the Hotchkis parts, Wilwood front disks, elecric fans, alum. rad and line lock (for SUVs too close to my rear at stop signs on inclines), its a very easy car to drive.

I will post the final dyno numbers once I have them.

Roger D.

[rstreet]

Roger
Way to go...Impressive.....Who did the balance work?
Robert

[Roger D]

The machine shop was M&B in Stamford, CT - I was very please with the work, turn around and as an added plus, Mike is extremely knowledgable and a real pleasure to do business with. He impressed me as being an "OLD SCHOOL" hot rodder. :brow

I owe him a visit so he can drive the Biscayne so he can FEEL how it all turned out

[tripowerguy]

Boy would I love to see what a 3X2 setup would produce on your engine. I know it would be less but how much less. Your post just makes me salivate so bad. Roger that is tremedious amount of horsepower for a non 409 engine. That should push your car close to 108 or110 mph in the quarter I would think. :clap Roy

[boxerdog]

Thanks for all of the details! It always provides a little extra motivation for the rest of us, also. Sounds like a GREAT combination.

BTW, are the Edelbrock 500's as fat out of the box as the 600's? Or am I the only one planning on using 500's (on an Offy tall manifold).

Thanks

[Roger D]

Aubrey:

What say you about the Edel. 500's ....?

[CDNpontiac409guy]

Still "fat", Roger:p

Boxer, I think the 500's will be DEAD ON with that manifold. Still need to lean them out a step or two though. Not that there's anything wrong with them. It's just that they're jetted with the expectation that a single one will be used on a good running 350... and get the air "gasping" through it ! Protects against a potential lean condition... which in extreme cases, can be damaging to pistons, rings, valves. A little "rich" is safer.

One thing about these heads, Roy... they'll never be able to accept a small port intake again:coffee:

[1958 delivery]

why are slicks a no no on the dyno?

My experiences on a Clayton chassis dyno, we tried slicks once and rubber started to fly everywhere (too soft). Maybe someone else has had a different experience but narrow, street tires worked best for us. But with high torque and HP the cars were just never quite fully hooked, they always tried to climb out of the rollers. On real high horse ones, they JUMPED out of the rollers, even when we chained them down.

[mac1]

With some determination, they are a direct match to the factory large port intake ports. Here are a couple pictures of them:

http://www.348-409.com/forum/attachment.php?attachmentid=5516&d=1162758281

http://www.348-409.com/forum/attachment.php?attachmentid=5517&d=1162758281

Despite that rather poor design of the factory manifold, I would say the combination is effective:deal . Maybe the manifold "likes" the slightly reduced cubic inches:dunno


Aubrey, thanks for the pics. Nice job porting those heads!:cheers

[Bungy]

What are the specs on the cam you are using? Have any updated dyno info? I'm very interested in your combo as I'm assembling the same thing right now.

[CDNpontiac409guy]

Bungy... Roger is on holidays yet. The car is supposed to be back on the chassis dyno as we speak. Need to get jetting and timing finely tuned.

The specs ?
Pistons and cam are my design... so you MAY not get the same results;) :p

Cam:

M-242595D

Mechanical....
net lift after lash, actual at valve: .560" / .573"
Adv duration, 272 / 276... 242 / 246 @ .050" on a 108 centre line.