Engine build question

steve from staten island

Well-Known Member
Local time
2:35 PM
Joined
Sep 24, 2012
Messages
6,747
Reaction score
8,315
Location
staten island,ny
Ive been following threads about compression ratios, CC combustion chambers and such and I wanted to get some advice
So I have a 69 383 engine in my car. The heads are from a stock 2 barrel single exhaust 383
They were redone with hardened ex seats, I think some or all new valves, just a basic stock head.
The short block was bored 30 over, decked and balanced, rods were checked and all good bearings and parts
The pistons are Speed pro L-2315 flat top with no valve reliefs
CAm is Comp cam part # 21-223-4. lift .477intake. exhaust .480.
duration 224 intake 230 exhaust
I have a Weiand dual plane manifold and Edlebrook 650 carb and factory HI po exhaust manifolds
I have a stock distributor recurved and rebuilt by our own Ray Halifax
The engine develops 14 to maybe 15 inches vacuum. The needle on gage vibrates slightly
The idle could be better but has no hesitation.
It was pinging and I have about 32 degrees total advance
Since I converted it over to a 4 speed I haven't heard any pinging
Car has a 3:55 sure grip
Compression is if I recall around 180- 190
My question is about the heads. Are there heads reducing HP and would it be advisable to change the heads
While im not racing this car, the performance with the 727 ( stock) was a little disappointing.
Any thoughts are appreciated
 

69L48Z27

Well-Known Member
Local time
2:35 PM
Joined
Nov 19, 2015
Messages
3,675
Reaction score
3,920
Location
York, Pa
Do you have any idea what the casting numbers are on the heads?

Was the cam degreed?
 

69 Sleeper Bee

Well-Known Member
Local time
2:35 PM
Joined
Feb 18, 2021
Messages
3,891
Reaction score
13,824
Location
Tallahassee Florida
If they are true 69 year heads they should be 906's and have 2.08 intake / 1.74 exhaust regardless of 2bbl /4bbl if I'm not mistaken. I am sure someone here can verify if this is true or not.
Good heads but no comparison to newer aluminum heads in performance.
Really just depends on staying stock vs. $'s for more h.p. than stock.
 

66Satellite47

FBBO Gold Member
FBBO Gold Member
Local time
1:35 PM
Joined
Jan 15, 2015
Messages
6,727
Reaction score
5,748
Location
St Paul MN
I presume they are a 906 head. If so, there is a lot of power/torque to be gained from some basic pocket porting on those heads. Grinding the terrible ridge under the stock valve seat is worth a lot. Also narrowing the valve guide boss helps. Not hard to do. The results are impressive.
 

PurpleBeeper

Well-Known Member
Local time
1:35 PM
Joined
Mar 20, 2011
Messages
4,978
Reaction score
3,725
Location
Chicago
69 is correct. 2 bbl and 4 bbl heads are the same. If you want to go faster, aluminum heads make sense
 

747mopar

Well-Known Member
Local time
1:35 PM
Joined
Oct 30, 2012
Messages
13,623
Reaction score
18,568
Location
ohio
Based on your cam specs those heads with a little work aren't going to hold you back if they are 906's. I'm running 452 heads which supposedly are very comparable and my car is definitely not a slouch, they've been ported of course. The problem you run into is the cost to do them, it's easy to sink a grand into a set of heads at which point the aluminum heads (preferably Truck Flows) start to look appealing. Then with the aluminum heads you also save weight, are less prone to detination and have a better combustion chamber.
 

Don Frelier

FBBO Gold Member
FBBO Gold Member
Local time
2:35 PM
Joined
Oct 11, 2016
Messages
6,405
Reaction score
8,617
Location
Ionia, NY
You may need some carb tuning (might be too lean) this can really make a difference.
For example on my Charger with the EFI I can dial up the AFR really high for a road trip like 15:1.
With the .455 cam its soft and smooth no grunt you can tell it's too lean from a stop light.
If I set the cruise AFR to like 14.0 or 14.2 it's a different animal you can feel the grunt.
What grade gas were you running?
Your cylinder pressures are pretty high but I wouldn't expect it to ping with 32 degrees total unless you have a bunch of vacuum advance too early.
Especially without many miles on it to get some carbon in there.
Cam timing is another big question this could be checked in the car with some equipment and a little time.
Does it have the right valve springs?
Likely your 727 had too low of a stall speed but on the highway it should still have pulled hard with your setup.
You might be able to get more out of what you have, tough to say without driving/riding in it.
 

Challenger340

Well-Known Member
Local time
12:35 PM
Joined
Mar 4, 2014
Messages
851
Reaction score
941
Location
jaffray, B.C. Canada
Ive been following threads about compression ratios, CC combustion chambers and such and I wanted to get some advice
So I have a 69 383 engine in my car. The heads are from a stock 2 barrel single exhaust 383
They were redone with hardened ex seats, I think some or all new valves, just a basic stock head.
The short block was bored 30 over, decked and balanced, rods were checked and all good bearings and parts
The pistons are Speed pro L-2315 flat top with no valve reliefs
CAm is Comp cam part # 21-223-4. lift .477intake. exhaust .480.
duration 224 intake 230 exhaust
I have a Weiand dual plane manifold and Edlebrook 650 carb and factory HI po exhaust manifolds
I have a stock distributor recurved and rebuilt by our own Ray Halifax
The engine develops 14 to maybe 15 inches vacuum. The needle on gage vibrates slightly
The idle could be better but has no hesitation.
It was pinging and I have about 32 degrees total advance
Since I converted it over to a 4 speed I haven't heard any pinging
Car has a 3:55 sure grip
Compression is if I recall around 180- 190
My question is about the heads. Are there heads reducing HP and would it be advisable to change the heads
While im not racing this car, the performance with the 727 ( stock) was a little disappointing.
Any thoughts are appreciated

imo
My initial thoughts on the parts used would indicate a pretty nice 383 Engine you should be quite happy with.

Some thoughts for clarification in no specific order....
* Vacuum gauge 'flutter' typically indicates timing may be too advanced ? 'pinging' at 32* would seem to support that advanced condition ? nonetheless, 32* total should be fine so the "flutter" you are seeing may still be subjective ?
but then...
I see readings of 180-190 psi which IMO is waaay too high for that 274 Cam installed straight up on even a 10.5:1 engine ? and would 'ping' even on 91 Octane ?
and again here...
what may be another subjective assessment.... but apparently the Performance lacks ?

Questions
1.) What YEAR/Casting Number are these 383 2 Barrel Heads ?
and
2.) where is the rpm range does the performance lack ?

I'll just guess and throw this out there....
are these '516' 383 2 BBL Closed Chamber Heads that have had new 1.60" Valves/Hockey Puck hardened seats installed very high in the chambers ? that are now even more restrictive on the exhaust side ?
Because....
if you are seeing 180-190 psi with 2315 Pistons and that things a terd ? .... especially at any kind of rpm and it's pinging at 32* Total ?
You got waaay higher than 10:1 Compression or that 274 Cam is waaay advanced ?
because imo...
NO WAY you are seeing 180-190 psi from a 1969 '906' Open Chamber Head on 2315 Pistons ?


 
Last edited:

steve from staten island

Well-Known Member
Local time
2:35 PM
Joined
Sep 24, 2012
Messages
6,747
Reaction score
8,315
Location
staten island,ny
imo
My initial thoughts on the parts used would indicate a pretty nice 383 Engine you should be quite happy with.

Some thoughts for clarification in no specific order....
* Vacuum gauge 'flutter' typically indicates timing may be too advanced ? 'pinging' at 32* would seem to support that advanced condition ? nonetheless, 32* total should be fine so the "flutter" you are seeing may still be subjective ?
but then...
I see readings of 180-190 psi which IMO is waaay too high for that 274 Cam installed straight up on even a 10.5:1 engine ? and would 'ping' even on 91 Octane ?
and again here...
what may be another subjective assessment.... but apparently the Performance lacks ?

Questions
1.) What YEAR/Casting Number are these 383 2 Barrel Heads ?
and
2.) where is the rpm range does the performance lack ?

I'll just guess and throw this out there....
are these '516' 383 2 BBL Closed Chamber Heads that have had new 1.60" Valves/Hockey Puck hardened seats installed very high in the chambers ? that are now even more restrictive on the exhaust side ?
Because....
if you are seeing 180-190 psi with 2315 Pistons and that things a terd ? .... especially at any kind of rpm and it's pinging at 32* Total ?
You got waaay higher than 10:1 Compression or that 274 Cam is waaay advanced ?
because imo...
NO WAY you are seeing 180-190 psi from a 1969 '906' Open Chamber Head on 2315 Pistons
Thanks for your reply....Honestly the compression I thought was as stated but I could be wrong. However there was no big difference between cylinders that I would remember
The performance with the 727 trans and the 3:55 gears I thought could have been a little better however since the 4 speed it seems to have more get up and go. Either way I thought the vacuum should be more than what I stated and I thought the vacuum needle should be more steady on a fresh engine
 

747mopar

Well-Known Member
Local time
1:35 PM
Joined
Oct 30, 2012
Messages
13,623
Reaction score
18,568
Location
ohio
Just for a little reference my 456 reads 160 psi. I'm running 542 heads which I cc'd at 88cc, has flat top pistons (also cc'd the valve reliefs) and was decked to zero deck height.. the math came out to 9.8:1 taking everything into account including head gasket thickness. At 160 psi it really likes 91, I've tried 89 and it will run fine but feels as if it's borderline at times. Something else I've noticed and could explain your sudden change is the different fuel mixes, I don't know what all is changed in the fuels but there is a winter and summer blend.. if I get the winter blend it doesn't run as well?

I looked it up, I don't know if saying it ignites easily translates to burns faster? If so winter blend is essentially a lower octane. Given where you live and the timing of this your last tank may have been a winter blend?
Screenshot_20210423-141329.png
 
Last edited:

Don Frelier

FBBO Gold Member
FBBO Gold Member
Local time
2:35 PM
Joined
Oct 11, 2016
Messages
6,405
Reaction score
8,617
Location
Ionia, NY
I think the suggestion to get the head casting is a good one.
Assuming it's zero decked and even with a metal shim gasket you would have to be around 78cc's of head volume to have 10.4:1 and get that kind of cylinder pressure.
A lot of guesswork.
 

Challenger340

Well-Known Member
Local time
12:35 PM
Joined
Mar 4, 2014
Messages
851
Reaction score
941
Location
jaffray, B.C. Canada
Chief Complaints seems to be....
Power not as expected ?
and
with "pinging" evident ?

with given information:
2315 Pistons
Camshaft XE274H
Rebuilt HEADS with Hardened Exhaust Seats(can be restrictive and pollute incoming A/F charge = ping), especially if 383 head is "516" casting/1.60" Valve retained
32* Total Timing
180-190 psi (now in question when the Cylinder Head Casting Number is requested)

This entire thread... and any further MEANINGFUL Diagnostics ?
IMO....
is utterly USELESS without knowing WHAT CYLINDER HEAD CASTING is being utilized ....

given...
you are indicating POWER LACKING and PINGING present at 32* TOTAL Timing with 2315 Pistons ? which should not be happening under those TWO parameters unless the THIRD parameter being the HEADS are contributing ?

HEADS are the next logical parameter in Diagnostics.... FULL STOP... go get the Head Casting Number !

 

451Mopar

Well-Known Member
Local time
12:35 PM
Joined
Oct 25, 2011
Messages
3,249
Reaction score
2,589
Location
Aurora, CO
The heads for 2-bbl and 4-bbl are the same, the changes in head part numbers is really more what years they were used.
I had built a 383 like that. Just a bit too much cam for the stock torque converter, so a bit slow from a stop.
The pinging with 32-degrees does not sound correct. Verify the balancer timing mark matches zero when #1 piston is at TDC.
 

RemCharger

Well-Known Member
Local time
1:35 PM
Joined
Apr 5, 2014
Messages
3,442
Reaction score
3,090
Location
Sask
The heads for 2-bbl and 4-bbl are the same, the changes in head part numbers is really more what years they were used.
I had built a 383 like that. Just a bit too much cam for the stock torque converter, so a bit slow from a stop.
The pinging with 32-degrees does not sound correct. Verify the balancer timing mark matches zero when #1 piston is at TDC.
You beat me to it. I have a 440 build right now and was surprised to find .... the TDC mark was off 10 degrees
 

Challenger340

Well-Known Member
Local time
12:35 PM
Joined
Mar 4, 2014
Messages
851
Reaction score
941
Location
jaffray, B.C. Canada
You beat me to it. I have a 440 build right now and was surprised to find .... the TDC mark was off 10 degrees

YEP.... GREAT Advice !

I just piqued on the OP's original information provided of 180-190 psi Compression recorded with:
* the 2315 Pistons
and
* XE274H Cam
because
that would suggest a Static Compression Ratio approaching 10.75:1 being seen from the 383 2-Barrel HEADS using any of the available Dynamic Compression Calculators ?

Seems strange to know V/Seats replaced.... rebuilt Heads....180-190 psi test... but NO clue what Casting Number/Open or Closed Chamber Head ?
 
Last edited:

451Mopar

Well-Known Member
Local time
12:35 PM
Joined
Oct 25, 2011
Messages
3,249
Reaction score
2,589
Location
Aurora, CO
As I recall, the compression ratio should be around 9.0: to 9.5:1 depending if the block was zero decked, using a 0.020 or 0.040 gasket thickness, and open chamber heads like the 906.
The best I see with using an 85cc head chamber (stock is usually more than 85), a 0.020" gasket, and zero deck, the compress should be 9.85:1
A 0.040" gasket drips compression to 9.387:1.
With 0.040" gasket and -0.005" deck height (piston below block deck) = 9.28:1
Same as above but with 89cc chamber heads = 8.95:1
All this assumes your not using the early closed chamber design heads with much smaller chamber volume in the mid 70's cc.
 

Babyblue66

Well-Known Member
Local time
1:35 PM
Joined
Feb 25, 2010
Messages
140
Reaction score
106
Location
MN
I just built a 383. Same pistons, 906 heads, felpro gasket. Pistons 10 thou in the hole. Came out to 8.8 to 1. Comp xe268, 2.14 181 valves, pocket ported. On the dyno it wanted 38 degrees and made 380 hp. That cranking compression doest sound right at all.
 
Top