This is my setup.... stock gw350 bottom end, al. heads with 195cc runners and 190-202 valves, comp xe274, roller rockers, holley 600cfm 4160 carb with <2000 miles, new hei dist. bowtie700 with 2400 conv.
I broke the cam in and have driven it a few miles. I am trying to tune it and am having some trouble, this being my first build up.

I set the timing by advancing it until it knocked and then backed it off. Tried using a light but had trouble but that is another story.

I set the floats by the holley manual then set the mixture screws. It is hard to start cold and idles a little rough even for that cam. When i acc. it runs great. It pulls hard, even squeled the tires shifting into 3 at 60.

The problem comes when i am just cruising, not acc. or dec. It does not want to run. It "sputters" at cruise. It's not real bad but there is definately something wrong. Give it a little gas and it is fine. The plugs look good so far but it hasn't been run enough to tell yet.

can anyone point me in the right direction?

thanks.

 

if it surges at cruise, check your floats first, then go up 2 jets in size. if you don't have the motor timed in properly it's never going to run right either. for that cam i'd run 20-24 initial and 34-38 total. get a timing light or post on the regional boards for a local member to possibly help show you what i'm saying.

 

Sounds either the cruise is too lean or too much timing. I have a 650 double pumper on my 11:1 350, with the same cam.

I've found that cam likes a minimum of about 14* initial timing. Mine is set at 8* initial plus 10*vacuum advance, so I'm running 18* initial. It runs nice like that, but unhook the vacuum advance and it idles like cat poo. I have it set up with a maximum of 36* total mechanical+initial, and its 46* at a 2700rpm cruise (vacuum advance hooked up). It seems fairly happy like that. My jetting is 71/79 also.

What kind of ignition are you using? MSD? HEI? mechanical advance only? vacuum advance?

 

i am using an aftermarket hei dist with vac advance. I reinstalled the dist. twice to be sure it was right. Brought #1 up on comp. and used a bent and taped screwdriver to find exact TDC, marked the pointer and installed dist. pointing exactly at #1. With the vac plugged it will not run at less than 50 deg. advance showing on the tape. I don't know what i have done wrong because it shouldn't run if it was that far advanced.

thanks for the replys. i will redo the mixture and floats tomorrow and see what happens.


airadam, do you know what kind of hp you have?
I was hoping for 350 out of mine.

 

I would guess something around 320-350hp with mine, but I don't know for certain. Never had it dyno'd or anything.. I just go off the trap speeds it runs out at the drag strip.

At what engine speed does it read 50* advanced? This is with the vacuum advance hooked up, correct? How does it run with the vacuum advance hooked up to the timed vacuum port (above the pass side idle mixture screw)?

IIRC, you can buy adjustable vacuum advance cans for HEI distributors. If it really is advancing this much at idle, then this may be the way you need to go to fix it.

 

sounds like you're using the wrong pointer for the balancer if it's idling at 50* advanced

 

I admit it, i am a idiot. I had the vac advance plugged into the wrong port. I reset the floats and mixture and it runs great.

I think i was backwards on the timing. The tdc mark is at 12:00 when #1 fires. It shows 45 on the tape at the mark i made on the pointer.

The pointer is at about 2:00 and i marked it when i found exact tdc.

 

Wrong port? You can use either... I have mine hooked up to manifold vacuum (small port, front of the base) but some people use timed vacuum too. Whatever your motor likes best I guess?