Box Stock (bp) clone build

Chris611

New member
I built a box stock clone for a backup engine and just to have fun.

I used:
ARC bullet rod.
Bp2 cam
Billet flywheel
32 deg timing.
.06 coil gap
.036 main jet.
26 lb spring.
.004 ring gap.
Hone cylinder to max diameter
.018 head gasket.




Is this close?

Reason I ask is that I build a break in stand out of an electric trailer brake to break in motors. I had it on there doing my normal break in and the exhaust got so hot it started the exhaust sleeve (black rubberish covering with fabric on the inside. Not sure what it's called) on fire. The exhaust pipe is shades of purple. I'm assuming it was too lean. I pulled the plug and the insulator wasn't white, it looked normal (black)

Any advice would be appreciated.

Thanks.
 

DynoDon

Moderator
When you say fire do you actually mean flames? No temp gauge I assume? I don’t think you have a problem. You didn’t turn enough rpm under load to create that kinda heat. Put a temp lead on it and try again.
 

DynoDon

Moderator
You do mean .060 coil gap correct?
 

DynoDon

Moderator
Ya, definitely not a box stock build
 

Chris611

New member
I think I was 180 out of time... Reset it and seems to be right on the test stand. econeconosprint2, thanks for the advice.

rules:
Valve Train: Stock valve-train only in stock configuration except: Any single valve springs and
valve spring shims are allowed; Any 5.5mm stem steel valve (including stainless) that uses stock
retainers OR 2 PICE RETAINER allowed. Intake valve head Max OD .982” +/- .005” and
Exhaust valve head Max OD .945” +/- .005”. Valves must be one angle only, 45°. No knife edging
of valves (1mm min. margin). Valve length is non-tech. No additional support for rocker studs
permitted. Champion rocker arm assembly and valve cover allowed.



What springs would you guy recommend? 22 lb?

 

MoreHP68

Member
I built a box stock clone for a backup engine and just to have fun.

I used:
ARC bullet rod.
Bp2 cam
Billet flywheel
32 deg timing.
.06 coil gap
.036 main jet.
26 lb spring.
.004 ring gap.
Hone cylinder to max diameter
.018 head gasket.




Is this close?

Reason I ask is that I build a break in stand out of an electric trailer brake to break in motors. I had it on there doing my normal break in and the exhaust got so hot it started the exhaust sleeve (black rubberish covering with fabric on the inside. Not sure what it's called) on fire. The exhaust pipe is shades of purple. I'm assuming it was too lean. I pulled the plug and the insulator wasn't white, it looked normal (black)

Any advice would be appreciated.

Thanks.
I believe the stock clone springs are 10 Ib. And I do believe you are running too lean. Can you take a picture of the spark plug??
 

Chris611

New member
I believe the stock clone springs are 10 Ib. And I do believe you are running too lean. Can you take a picture of the spark plug??
We ran 10.8 lb springs in restricted box class. Box stock has no rules on spring stiffness (i.e 10.8, 22, 26 lb.).

The rules say "stock" but then go onto say any single valve spring allowed.

Spark plug was black like normal. 3910x.
 
I think I was 180 out of time... Reset it and seems to be right on the test stand. econeconosprint2, thanks for the advice.

rules:
Valve Train: Stock valve-train only in stock configuration except: Any single valve springs and
valve spring shims are allowed; Any 5.5mm stem steel valve (including stainless) that uses stock
retainers OR 2 PICE RETAINER allowed. Intake valve head Max OD .982” +/- .005” and
Exhaust valve head Max OD .945” +/- .005”. Valves must be one angle only, 45°. No knife edging
of valves (1mm min. margin). Valve length is non-tech. No additional support for rocker studs
permitted. Champion rocker arm assembly and valve cover allowed.



What springs would you guy recommend? 22 lb?
Cam timing is 180 degrees out. Have done this with a 305 sprint motor. Seemed to run OK but the headers were cherry red.
How exactly can the timing be out 180 degrees? please explain the mechanics behind such an event.
 

DynoDon

Moderator
I never tried it or made that mistake so I can’t say BUT in theory I can’t think this engine would even run
 
Interested in where a 180 valve theory came from in the first place. A camshaft cannot be installed in one of these motors 180 degrees out no matter how hard you try.
 
Last edited:

DynoDon

Moderator
Ya now that I think about it
 

tecbigdog

Premium User
There is a real easy way to see if your cam is timed correctly. Roll the engine over until both valves are open the same amount. The piston should be very close to TDC (within thousands). Just from the quick scan of this thread, I would bet on timing (too fast or compression too high). maybe a slipped degree wheel while trying to time the engine.
 
There is a real easy way to see if your cam is timed correctly. Roll the engine over until both valves are open the same amount. The piston should be very close to TDC (within thousands). Just from the quick scan of this thread, I would bet on timing (too fast or compression too high). maybe a slipped degree wheel while trying to time the engine.
both of your suggestions would most likely lower EGT
 
Top