Don Terrill’s Speed-Talk

this is how i figured what should have happened :

383 - 423 = 40 cubes = 40 hp gain minimum
2 points CR = 25 hp ? gain
850 - 1050 carb = 10 hp gain ?
also put on a real high dollar oil pan at the same time. = ?? 25 hp over a stock pan at high rpm ?

100 hp guesstimating. Would like to try a different cam, maybe the convertor you mentioned ?

prairiehotrodder wrote: ↑Wed Jan 15, 2020 3:28 pm this is how i figured what should have happened :

383 - 423 = 40 cubes = 40 hp gain minimum
2 points CR = 25 hp ? gain
850 - 1050 carb = 10 hp gain ?
also put on a real high dollar oil pan at the same time. = ?? 25 hp over a stock pan at high rpm ?

100 hp guesstimating. Would like to try a different cam, maybe the convertor you mentioned ?

If it’s going through the lights above the hp peak I’d think maybe you’re out of gear. I’m no expert, but if the converter is too loose or you’ve got too much gear at some point those things that helped a smaller power plant start to become a limiting factor with bigger torque and power numbers. Like telling Lance Armstrong in his prime to race the flat straights in his lowest gear.

BLOCKMAN wrote: ↑Wed Jan 15, 2020 12:43 am

Mikej26 wrote: ↑Tue Jan 14, 2020 9:57 pm

BLOCKMAN wrote: ↑Tue Jan 14, 2020 8:38 pm

Photo Bucket is have problems for some reason, The compression is 10:3 used the Mahle Power Pack Flat top pistons.

Here is a copy of the dyno sheet

Man, that would be perfect. Wasn’t expecting it to be that stout with only 10.3:1 comp. Great power with a conservative rpm that doesn’t threaten durability. Could easily be stepped up further with a smaller combustion chamber for a compression increase etc. I think this settles it, will go this direction with the short block and use my current heads, cam, intake etc as a starter. Will likely fall short of your build, but it seems I will have all of the room to grow with this short block as I will likely ever need.

If you need a machined block and balanced rotator let me know as I can set you up with what you need.

Best Regards

I appreciate your insights and will reach out for sure when I’m ready to move forward. I’m merely bench racing at this point while I get my funds in order.

BLOCKMAN wrote: ↑Wed Jan 15, 2020 12:43 am

Mikej26 wrote: ↑Tue Jan 14, 2020 9:57 pm

BLOCKMAN wrote: ↑Tue Jan 14, 2020 8:38 pm

Photo Bucket is have problems for some reason, The compression is 10:3 used the Mahle Power Pack Flat top pistons.

Here is a copy of the dyno sheet

Man, that would be perfect. Wasn’t expecting it to be that stout with only 10.3:1 comp. Great power with a conservative rpm that doesn’t threaten durability. Could easily be stepped up further with a smaller combustion chamber for a compression increase etc. I think this settles it, will go this direction with the short block and use my current heads, cam, intake etc as a starter. Will likely fall short of your build, but it seems I will have all of the room to grow with this short block as I will likely ever need.

If you need a machined block and balanced rotator let me know as I can set you up with what you need.

Best Regards

Blockman been following along. Would you use the AFR heads again if doing this engine today? Or is their a speedtalk vendor you would recommend for Mikej for better rrsults?

My personal experiences with my 422 (4.165x3.875) in its first incarnation it had a set of Brownfeild 205cc which were pretty much like the pre-elimantor AFR heads . The cam was solid roller 245/255@.050 .624in/.600ex lift w/1.6 rocker on the intake . Brodix intake with the cast in turtle and round to 4 hole tapered adapter, holley 850 street HP carb . Good 1-3/4 headers with 2-1/2" exhaust w/x pipe and pypes m-80 straight thru mufflers dumping in front of the rear . 4.56 gears 3800 stall 10" converter. Hoosier guick time pro dot slicks . Off the trailer it went 7.12 @96+ mph 1.42 60' with turbo 400 tranny. 3200lbs '72 camaro . Only got to the track afew times that summer best I could do was 7.0's @98+ . I felt it should do better so I pulled it to install a fresh HR 383 I had built .
Its 2nd incarnation was with a set of Dart 220 raised runner heads and matching Dart intake with the same carb . Cam is now a Erson 260/268 @.050 .675 in .645 ex again with 1.6in /1.5 ex rockers. headers now are hooker super comps 1-7/8 x 3-1/2 no exhaust system just 3-1/2" turn downs on the collectors. Pg tranny with brake w/5300 stall converter. Off the trailer went 6.45@105 1.40 60'. Got to 6.31@ 108 1.38- 60' before I started detuning to run 6.50 index class .
The short block was the same 6" rod Ross flat top pistons as before . I think the comp ratio is around 11.6 to 1 . Both ran on 93 octane w/ VP octanium mixed to 100 octane.
In retrospect I think the less than stellar ex port the 1-3/4 headers and the 2-1/2" exhaust system was really choking the engine. It was suffering from reversion so bad the intake runners were black with soot almost back to the plenum .
Just my experience. By the way the 383 ended up going mid 6.90's @98 just to show cubes aren't everything if the entire package isn't right . Dan

prairiehotrodder wrote: ↑Wed Jan 15, 2020 2:41 pm i have an experience doing what you mention that i am still trying to understand Mikej26.

I helped along a friends engine :

stock block 383 with AFR 227 CNC heads, T&D shaft rockers, flat top icon pistons, 11 - 1 CR, comp solid roller (12-863-9) 263 / 272 .648/.648 108 AFR titan plastic intake, 850 quick fuel carb, 1.75" headers. Most people would say that it was a too big head deal but the intent was to gather good parts (we already had the 383 short block) and eventually put a bigger bottom end under it. The car ran 10.60's with this combo.

last winter we did that.

purchased from Steve Scmidt a 423 short block ( Dart little M block (not shp) with 4.165' bore, 3.875" stroke, domed JE pistons (13.3 CR) and transfered the heads, cam , intake and headers to this new motor. Also added a 1050 CFM carb (QFT with 4150 base). We expected 100 hp. In truth we got about 40. The car has gone 10.30. Still trying to figure out what happened.

Brian

I wonder, if same induction parts, the only real change is compression, the motor cubes increased cfm demand more but since induction was same, it wasnt able to supply it. Peak rpm would come down but peak power would be somewhat similar except the change in compression and bigger bore would draw alittle more flow from the head. Perhaps the head was making near all it could make.

prairiehotrodder wrote: ↑Wed Jan 15, 2020 2:41 pm i have an experience doing what you mention that i am still trying to understand Mikej26.

I helped along a friends engine :

stock block 383 with AFR 227 CNC heads, T&D shaft rockers, flat top icon pistons, 11 - 1 CR, comp solid roller (12-863-9) 263 / 272 .648/.648 108 AFR titan plastic intake, 850 quick fuel carb, 1.75" headers. Most people would say that it was a too big head deal but the intent was to gather good parts (we already had the 383 short block) and eventually put a bigger bottom end under it. The car ran 10.60's with this combo.

last winter we did that.

purchased from Steve Scmidt a 423 short block ( Dart little M block (not shp) with 4.165' bore, 3.875" stroke, domed JE pistons (13.3 CR) and transfered the heads, cam , intake and headers to this new motor. Also added a 1050 CFM carb (QFT with 4150 base). We expected 100 hp. In truth we got about 40. The car has gone 10.30. Still trying to figure out what happened.

Brian

Brian I would be interested to hear this story in detail, if you're bored some time gather up every last detail and start a thread here, lots of brainpower here, might figure out the issues or at least give you some direction for the coming season.

I have a 422 ci dart little m block
235 AFR heads
1 3/4 equal tube headers
Super victor ported with 950 dom
Cam is 750 lift 274-281 duration
11.28 flat top pistons
Running 92 octane chevron
Car with me in it weight 2500 lbs
Best time 9.17 @ 147 mph

The difference between the 3.750" stroke and the 3.850" stroke will be only about 17 hp at 1.6 hp/ci. With a single 4v and smallish heads, you will be pushing it to make more than 1.6 hp/ci . Joe-71

My brother and I have been running 4" stroke LilMs with 210 AFRs (10.7:1) that were put together about 15 years ago (by FastTimes). Both have over 50k miles on them of mostly street driving. He runs a 300 shot and has been mid-9s in a 3600lbs Camaro and hits the track 1-2 times/year. I've run low 11s in a 4000lbs Chevelle (mid-10s with a 125 shot), but only hit the track about one time each year. The Chevelle has been autocrossed and run on Sebring a bunch. Both cars have survived Hot Rod Power Tours and if I could get my brother conned into caging his Camaro, we'd love to do Drag Week.

Both cars use 248/254 CC HRs with .6/.62 lift. His engine peaked at 630hp/6200rpm (no dyno for mine). I think if we could do it over, we might make similar choices since these cars are both mostly street and get a lot of use. If we were more serious about racing, I think I'd avoid the 4" stroke w/o a raised cam block (only 1" for Piston CH) and look to increase rpm (new heads/cam & maybe pistons?).

I would like to build a 434 or 454 sbc using the stock block kept at 5500 rpm's or less. I am kind of a block and head casting purist. A 454 sbc will pull a open trailer easy.

CPMotorworks Inc of Janesville, Wisconsin built 420ci SBC using SRH VFactor 2.50PF CNC heads. 11:1 CR, 237° @ .050" intake lobe hydraulic roller cam, CPM ported 2925 SV intake, QFT 4150 carb, 1.75" × 3.5" headers. 640hp/585lbs on pump gas and MS109.

And that is 1.52 hp/ci for the 420 ci. Take that number and multiply it against any cubic inch you want to build, and you will have a "ballpark" number to work towards. Joe-71

SpeierRacingHeads wrote: ↑Thu Jan 16, 2020 10:18 am CPMotorworks Inc of Janesville, Wisconsin built 420ci SBC using SRH VFactor 2.50PF CNC heads. 11:1 CR, 237° @ .050" intake lobe hydraulic roller cam, CPM ported 2925 SV intake, QFT 4150 carb, 1.75" × 3.5" headers. 640hp/585lbs on pump gas and MS109.

Chad, when I get around to stepping up the breathing capacity I will be coming your way for a set of these heads.

This may be of some interest to you.
I have a 68 Firebird full weight street car - 3620lbs with me in it. It is 90% street but does go to the track 2-3 times a year.
3.73 gears.
275/50/15 MT drag radials.
T400.

I had an old 406 SBC that was built back in the late 90's, swapped the heads, cam & intake.
406 bottom end, GM crank, 5.7 Eagle Rods, TRW flat tops, 10.7 comp, street port AFR195's untouched, 242/248@50 Hydraulic roller, Super Victor, 830DP, 1.75" press bent headers into dual 3" dumped in front of the diff. Never went on an engine dyno but got the car down to 11.08@122mph with a 9.5" 4000rpm converter.
Had that engine for a long time & gradually collected gear for a new engine, just as a refresh.

New engine -
Dart Little M, 4.155 bore, 3.875" stroke so 421 cubes. AFR 210 competition port heads untouched, 11.7 comp, 246/250@50 Hydraulic roller, Super Victor match ported to heads & plenum ported, 850QFT carby. Same headers.
Made 580HP@ 6000rpm & 550TQ @ 5000rpm with shop headers. Ran it first up with the 830 which was an old modified annular. Made 550 as the carby was so put the QFT on it.
Put the engine in the car & it ran exactly the same times & mph but did not like the converter so I had it modified to 5000 stall but it was not nice on the street so I changed converters again to an 8" 5000 converter, much nicer on the street. Has since gone 10.8@122.
Feels like the top end of the track its just cruising down there so have just put a set of 1 7/8" mandrel pipes on it with 3.5" collectors. Am yet to run it at the track.