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fatgump 01-11-2013 09:45 AM

Motor flattens out at 5k
 
The motor runs quick to 5K RPM and then flattens out. I was hoping it would make it to 5600 where I have the rev limiter set. What could be the problem?

The specs are. 350 ( 0.030 over, 355) KB hyper 12cc dish, lunati BMII cam 292/292, .480 lift, 109 lobe with 1.5 roller rockers, Dart iron eagle platinum 64cc with 200cc runner, Edelbrock performer airgap intake, Edelbrock AVS 650 carb, Hedman 1 5/8 long tube headers, 4:10 posi, MSD blaster 2 coil, MSD vacuum advance distributor and MSD Street fire box.

Thanks,

Gump

hcompton 01-11-2013 10:02 AM

Whats the cam duration at .050?

Did you use lifters and springs made for this cam or stock. It sounds like you should eaisly hit 5600.

Have you tried to move the rev limiter up to higher rpm or take it off and see if it still wont rev.


Does it just flatten out or does it studder out like rev limiter. Also do you have a soft rev limiter. Some will hold the engine at certain rpm without the poping and shutter of old style rev limiters.

cdminter59 01-11-2013 10:29 AM

Motor flattens out at 5k
 
Do you have the matching springs for the Lunati cam or just the springs that came on the Dart heads? You might be having valve float. Also check your timing adjust the initial to about 16*-18* at idle and rev it to 3000 rpms and hold it adjust the total to 36*. Have you changed springs in the distributor for the mechanical advance? If not use 1 light spring and 1 medium spring, this let the mechanical advance come in sooner. Does this MSD distributor with vacuum advance have a part#? I hope it ain't the cheap StreetFire 8362!

techinspector1 01-11-2013 12:53 PM

Quote:

Originally Posted by cdminter59 (Post 1633568)
You might be having valve float.

That was my first thought.

fatgump 01-11-2013 02:16 PM

Quote:

Originally Posted by hcompton (Post 1633562)
Whats the cam duration at .050?

Did you use lifters and springs made for this cam or stock. It sounds like you should eaisly hit 5600.

Have you tried to move the rev limiter up to higher rpm or take it off and see if it still wont rev.


Does it just flatten out or does it studder out like rev limiter. Also do you have a soft rev limiter. Some will hold the engine at certain rpm without the poping and shutter of old style rev limiters.

It just flattens out.

Quote:

Originally Posted by cdminter59 (Post 1633568)
Do you have the matching springs for the Lunati cam or just the springs that came on the Dart heads? You might be having valve float. Also check your timing adjust the initial to about 16*-18* at idle and rev it to 3000 rpms and hold it adjust the total to 36*. Have you changed springs in the distributor for the mechanical advance? If not use 1 light spring and 1 medium spring, this let the mechanical advance come in sooner. Does this MSD distributor with vacuum advance have a part#? I hope it ain't the cheap StreetFire 8362!

I am running dual springs that came with the Darts. My timing is at 35@3000 RPM. I have the MSD 8361 Pro Billet.

jumbo2 01-11-2013 05:17 PM

That motor should scream past 5000 , I'm no expert but valve springs or ign box would be my guess

vinniekq2 01-11-2013 09:04 PM

I agree,valve springs,maybe ignition(not likely with MSD) fuel pump pressure?,timing could be very very late,but that would make it slow everywhere

cdminter59 01-11-2013 09:40 PM

Quote:

Originally Posted by fatgump (Post 1633653)
It just flattens out.



I am running dual springs that came with the Darts. My timing is at 35@3000 RPM. I have the MSD 8361 Pro Billet.

Have you changed any springs or bushings inside the distributor? Rev it on up to 3500 rpms to see if adds more timing. You should be able to rev it to 3500 and the timing stays at 35*. What is the timing at idle? What octane gas are you using?


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