[383Nova]

Have a problema dn looking for so help.

While racing my car it has now started laying over on the top of the rpm range. The car would once pull to 6400 without any problems.

It started to lay over at 6200 about 3 months ago and last night it is doing it at 6000 where I shift.

History on the motor:

383 with a roller cam (small)
38 total timing locked out
#8 line braided steel
#6 pounds of presure at the gauge

I checked the fuel pressure and ran it up to 7 1/2 pound from 6 and still the same thing. I can only tell you the front drops and it feels like your driving against 200 mph wind. No poping or noises just laying over.

 

[69NovaSS]

are your springs ok?

 

[novaboy009]

Sounds like valves are floating. Definately check your springs.

Kev

 

[383Nova]

we were thinking the same thing but they are new and not popping through carb or exh. I thought it would be popping if they were bad?

 

[Mike Goble]

We see weak springs occasionally on the dyno and the symptoms are just like yours - the motor just lays over at some rpm. We changed the springs on a mild 302" motor recently and picked up about 70 rwhp above 4600 rpm.

 

[DriveWFO]

we were thinking the same thing but they are new and not popping through carb or exh. I thought it would be popping if they were bad?

What's the seat pressure? Are they the correct springs for your roller cam?

 

[383Nova]

Have to check the seat presure again and they are the springs that go with the cam. The roller and springs are only about a year old.

Thanks for all your replys so far and we will check the springs first.

Mike,

Do you think it's best to check them on the car with the pull down spring tool or pull them off and check them that way?

Thanks again guys for all your help.

 

[Real McCoy]

I can't speak for Mike but I check them on the car with the Moroso torsion checker and it is pretty close if you use it right. RM

 

[Mike Goble]

You can use the Moroso spring tester. I just pushed hard of the springs and was able to unseat them. I pulled a couple of the springs and put them on the spring tester next door. The seat pressure was about 50#, compared to the 110# of the replacement springs, and the open pressure was about 2/3 of what it was supposed to be.

 

[66IISS]

just a thought, but if it's a mechanical roller, might it be possible that the rockers loosened up a smidge?

 

[Paul Wright]

I'm a little late to this party but I'd guess valve springs also.