duntov cam adjustment for drivablity

[Duke W.]

Re: duntov cam adjustment for drivablity

"Duke, in your opinion, does the highway travel rpm speed at 3500 have a good or bad effect on a well balanced and built engine? other than this problem and perculation issues, the engine has been perfect. it was balanced when built early last year."

I don't think gearing has a big effect on long run wear, which is primarily ring and bore wear. (Modern bearings rarely "wear out" before major ring and bore wear force an overhaul.) Taller gears reduce piston travel per mile, but ring gas load is greater because more torque is required at lower revs to make the same cruise power, and the two tend to offset.

However, shorter gears definitely reduce highway fuel economy and generate more interior noise.

When you had the engine rebuilt last year did you install some decent connecting rods or use the spindly prone-to-break originals?

One other note for everyone. If you have a set of early big port heads that are beyond hope, find a salvagelable used set to rebuild. They are around gathering dust in many places because few are interested in them and a hundred bucks will usually get you an acceptable set of rebuildable cores.

Duke

[Matt L.]

Re: duntov cam adjustment for drivablity

"When you had the engine rebuilt last year did you install some decent connecting rods or use the spindly prone-to-break originals?"
we used originals and crank also.

"However, shorter gears definitely reduce highway fuel economy and generate more interior noise."
its not too bad with the hardtop on and i cant hear anything at all with the top down.its pretty loud with offroad exhaust and wind noise. but it sure sounds good going through the gears.
i get 17mpg using gps trip odometer and gas receipt math.

thank you for all the responses Duke and everyone else. i'm taking the car on a 100 mile trip tomorrow up and down the highway and see how it goes. at least if it's within 100 miles my collector insurance will pay for tow.

take care,
matt

[Bruce B.]

Re: duntov cam adjustment for drivablity

Matt,
Great posting, I'm learning a lot.
I just had a spare 327 built (0.060 over makes it a 337) and used the original rods and crank. Put in a new 151 GM cam which is the 327 350 HP hydraulic and also a set of roller rockers.
Can't wait to get it in a car.
Have a good trip to Knoxville (aka Seveirville) and have fun.
Bruce B

My 62 340 HP Duntov cam (098) runs forever with the valves adjusted at 0.012" and 0.018" lash with GM stamped rockers.

[Matt L.]

Re: duntov cam adjustment for drivablity

[QUOTE=Bruce Bursten (27670);605909]Matt,
Great posting, I'm learning a lot.
I just had a spare 327 built (0.060 over makes it a 337) and used the original rods and crank. Put in a new 151 GM cam which is the 327 350 HP hydraulic and also a set of roller rockers.
Can't wait to get it in a car.
Have a good trip to Knoxville (aka Seveirville) and have fun.
Bruce B

hi Bruce,
so far so good with the roller rockers upgrade. the engine seems to rev quicker. i can hit 6000rpm in an instant when before i could feel and listen when to shift. i was real surprised when i looked down and saw 6000. it sure got there quicker than before. plus my shifter doesnt have that annoying harmonic noise at highway speed. i used to throw a towel over the shifter on the highway to quiet it down.
my valves are also adjusted 12 and 18. i have your valve covers on there for good luck also.


take care,
matt

[Larry B.]

Re: duntov cam adjustment for drivablity

Matt, What type of roller tips are you running and do they clear the stock covers? Larry