TR6 Gp 2 cam, head shaved ,shorter pushrods, with a rough idle

[DennisT]

I installed a gp2 cam, had the head shaved , got shorter pushrods, experiencing a rough idle, I went through the timing and had degree the cam 8 degrees BTDC. I did a smoke test and not aware of any leaks, the compression is uniform @160psi on each cylinder. the vacuum reading is bouncing between 15 and 16, the idle is random plus or minus 50 rpm. Carbs appear to test lean and I have them adjusted full rich. I ordered the richer needles from Curto and will try them this weekend. I read some posts about the distributor needing its curve adjusted due to the cam change. Any help would be appreciated
Dennis

 

[poolboy]

Was the cam timing advanced 8 degrees ?
That's what it looks like you wrote.
If so why so much ?

 

[mctriumph]

Welcome to the rabbit hole!! AKA slippery slope. Not sure what you did on the cam install. Hope you did NOT advance it 8.deg
usually + or - 2 deg depending on the desired torque needed. But now on to the crabs...... Two is not as good as 3 for a host
of reasons. Lose the old intake and add one more Strom. Even better 3 SU's. Weber's are too much unless choked down a lot.
You need an experienced carb man to even get close with this motor.Make double sure you have no intake leaks, Header??
MD

 

[charlie74]

Verify your valve lash is set correctly. The BP270 cam (a Newman cam) has a valve lash of 0.014” (I) and 0.016”(E). I just went through this with mine; once it was set properly the idle smoothed out nicely…

 

[DennisT]

Was the cam timing advanced 8 degrees ?
That's what it looks like you wrote.
If so why so much ?

Should I redo the degress on the cam to 0 to 1 degree btdc?

 

[poolboy]

I timed my cam to 4 degrees BTDC.
My cam is the stock 311399 cam that was in the 73 thru 76 TR6 engines.
You may want to discuss things with Richard Good since it's his cam, though.

 

[DennisT]

I timed my cam to 4 degrees BTDC.
My cam is the stock 311399 cam that was in the 73 thru 76 TR6 engines.
You may want to discuss things with Richard Good since it's his cam, though.

He said the straight up gp2 cam timing is 3.5 btdc, he says to have the number two lifter at .050 lift, is that what you would do?
Dennis

 

[poolboy]

Yes, I would do exactly what Richard said, just make sure you have a good understanding of his instructions.
He won't mind if you have more questions..
If you get that right and still have problems at least you'd know it wasn't the cam or cam timing causing problems

 

[DennisT]

This is a picture I took today with the first intake lobe at .050 lift, the damper indicates 16btdc, is that marker accurate and would it be able to run with that much advance?

 

[poolboy]

Was that where it was when you wrote that first post ?
As far as the question of accuracy of the timing marks, you'd have to determine that...I use the piston stop method for that. Turn the crank ClockWise until it stops then mark the damper ...CounterClockWise until it stops, mark the damper... and TDC is in the middle of the marks.

 

[DennisT]

Hi,
I did 015 on intake and 017 on exhaust lash and was able to adjust the cam sprocket to 6 degrees , since the straight up timing on the gp2 is 3.5 , R GoI’d said that would be fine. I did check td on the damper with a rod in #1 plug hole and it was dead on. Also the mark on the timing chain cover was accurate. I must have made a mistake when I put the degree wheel on the crankshaft when I used the piston stop. I had the head off and used the piston stop with a dial indicator. Any way I put the motor back together and started it up. I attached a movie file below. Whe I was trying to synch the carbs, I could not get the front carb to pull any air. Not sure what is causing that. The engine starts and runs smooth when you goose throttle but still has a little stumble and will only idle at about 1700 -1800.
it seems to run better the longer I ran it. I can’t attach video Sorry