Thumpr 279TH7 Cam issues

[woodsnake]

Before you pay for another cam, have you tried to just just bump it into neutral at a stop? A lot of labor and expense, for a basically mild change in driving style...

Also, what is your idle and timing set at? (exactly) If you are anywhere near the stock 6-8 degree, and 650 rpm curb idle, that is the problem right there.

If your builder thinks "that much" cam is like the 4th nastiest engine he's ever built, he hasn't built a lot....

 

[OpiemusRex]

He was not trying to imply that it was nasty it has just been a pain in the butt getting it to idle right with pwr steering, pwr brakes, auto trans and air conditioning.

We went with the milder cam and now it has plenty of vacuum to operate everything on the car.

I had no desire to either two foot it at stop signs or bump it into neutral. Comp Cams told me that we could only expect 10 inches of vacuum max. That was just not enough to have a reliable car with my setup. If it had been a manual trans with now pwr options or a/c it would have been a whole different story.

Regardless it is done now.

 

[woodsnake]

So then what are your impressions with the new cam?

 

[OpiemusRex]

So then what are your impressions with the new cam?

Don't know yet, I haven't heard it run. We decided to replace the harmonic dampener while it was down because we noticed that the outer part had spun about 3/8". Just got the new one today.

He also has to recharge the A/C, mill another shifter rod for the adjustable modulator on the side of the auto transmission because he had to make an extra long one to obtain correct shift points because of the lack of vacuum created by the other cam.

Then he's going to drive it for a bit to make sure there are no other issues. I'll post a video as soon as I get the car back. He's had it since May of last year.

 

[woodsnake]

Woooooow, May of 2012? And still not done? That's worse than my bodywork guy. But not as bad as my engine guy (me)..

 

[OpiemusRex]

LOL, tell me about it. I've heard it will be ready next week about 25 times now. he has done a lot of work from the radiator to the rear end everything is new including the suspension frame ties motor transmission brakes air conditioning rims tires gauges etc etc

 

[Don65Stang]

That's not a "lot" of cam, so to speak.

First, it sounds like the carb is too rich at idle/just off idle. I agree with the possible float level issue too.

May simply require a carb tuning with the Edelbrock kit (rods, springs, etc).

What rear gear, trans and converter will you be running?

We have already tuned the carb with the Edelbrock calibration kit and my builder says that the carb it tuned just right for the camshaft. My builder is not only a mechanic but a mechanical engineer and builds cars from Texas to Florida. He is well known for how meticulous his builds are and he says this engine is about the fourth most aggrevating one he has encountered.

I have a 3:55 tru-track rearend and it has a 2400 stall converter.

Who's your guy? I have an engine that'll need rebuilding at some point.

 

[OpiemusRex]

That's not a "lot" of cam, so to speak.

First, it sounds like the carb is too rich at idle/just off idle. I agree with the possible float level issue too.

May simply require a carb tuning with the Edelbrock kit (rods, springs, etc).

What rear gear, trans and converter will you be running?

We have already tuned the carb with the Edelbrock calibration kit and my builder says that the carb it tuned just right for the camshaft. My builder is not only a mechanic but a mechanical engineer and builds cars from Texas to Florida. He is well known for how meticulous his builds are and he says this engine is about the fourth most aggrevating one he has encountered.

I have a 3:55 tru-track rearend and it has a 2400 stall converter.

Who's your guy? I have an engine that'll need rebuilding at some point.

Pat McCutcheon of Pat's Hot Rod Fabrication, he's built a couple cars that made Hot Rodding Magazine and deals with T-buckets a lot but does a bit of everything. He has all of the fabrication tools to custom make anything and has an Engineering Degree to boot. He is out of Lexington SC. You and I have the same rear end gear and I had the same stall converter with the Thumpr Cam but it has been downsized some now with the new cam.

 

[MeZapU]

That new cam looks to be very similar to the B-303 cam I used to have in my 85 GT. If I remember I used to pull about 15in/hg, idling at sea level. Idle had a great sound and would get many compliments. It ran best after I installed a old Holley 4010 carb with annular boosters. Pretty much the same as the new Summit Racing 600's carb. The annular boosters picked up torque down low and I could easily roll into the throttle and spin the tires in 1st and 2nd gears, where the original Holley 4180 was a bit soft.