Thread: crate 350/290 hp engine head swap and a few questions on cam timing

Tweet

I have a 71 c-10 with 373 gears and turbo 400 trans with a 350/290 hp engine with headers and performer intake and q-jet with upgrade and jets by cliffs high performance, anyway I was not pleased with the engines low rpm power it was a dog on low end, I bought a new set of brodix IK 180 heads and some 1.6 full roller rockers and installed them. It really woke the engine up in midrange and top end and helped a little bit on low end. I was wondering if advancing my cam timing may help the low end some it has plenty on top end if I have to sacrifice some there it would be fine.
the engine has the cam that came in the engine it is a 450 intake and 460 exh lift and the original heads had 76 cc chambers and the new ones have 64 cc. I am going to get a 2400 rpm hughes converter for it soon it is running stock now.
do you guys think advancing my cam timing will help my low end some?

Where have you got it set now,,what kind of dizzie are you running?Keep in mind,,that a lot of those crate engines cams,,give you very little leeway past zero on advance.I tried advancing a crate that I had gotton from GM,,and if I remember right,,I could only go as far as 2*BTDC,,send me,,or post,,if you have them,,,all of the cam specs.You're obviously going in the right direction with your tune,,but like you asked,,YES,,advancing will help,,but it will depend on what you have already,,OH,,,and what kind of distributor are you running.

Originally Posted by slowpoke1

I have a 71 c-10 with 373 gears and turbo 400 trans with a 350/290 hp engine with headers and performer intake and q-jet with upgrade and jets by cliffs high performance, anyway I was not pleased with the engines low rpm power it was a dog on low end, I bought a new set of brodix IK 180 heads and some 1.6 full roller rockers and installed them. It really woke the engine up in midrange and top end and helped a little bit on low end. I was wondering if advancing my cam timing may help the low end some it has plenty on top end if I have to sacrifice some there it would be fine.
the engine has the cam that came in the engine it is a 450 intake and 460 exh lift and the original heads had 76 cc chambers and the new ones have 64 cc. I am going to get a 2400 rpm hughes converter for it soon it is running stock now.
do you guys think advancing my cam timing will help my low end some?

You might find the power curve right where you want it when you change the converter.Be cautious of piston to valve clearance if you do advance the cam.A crossover pipe in the exhaust could also help low end torque.

the cam specs are cut and pasted from the manual for the engine i have
The 350/290 HP engine uses an aggressive flat tappet camshaft to achieve the level of performance for its intended
usage. Camshaft lift is .450” intake / .460” exhaust. Camshaft duration (@.050”) is 222 degrees intake and
exhaust. Lobe centerline is 114 degrees. Normal engine manifold vacuum for the 350/290 HP engine is 10-12”
Hg at idle (650-750 rpm).
the dist is a GM performance parts HEI and my timing now is 11 deg at idle with vacum disconnected, and i think the total is around 32,
thanks for the reply I appreciate any help, I will get the converter soon the heads were a little expensive so i will have to wait a little for the converter.
the manual says to leave vacum advance disconnected but i have tried that and with it on both vacum ports on the carb and the full vacum port seems to have better low end results which makes me think more ign advance may help a little??

I already have a cross over pipe about 1 foot behind the header collectors I forgot to list it in my post. thanks for the advice, I do appreciate the input.

Here's a couple of pointers. Be sure the vacuum port on the carb you are connecting to is ported vacuum. If you feel real adventurous remove the timing chain cover and advance the cam timing 4*.

thanks I may get the offset key to play with until i find what i like then i will get a double roller set up, it is possible i may have to get a cam with more bottom end and midrange instead of mid to top end.

don't forget the advance curve. The low compression 350 290 needs to rapidly advance the timing and be all in at 3000 rpm. My MSD distributor uses a light weight and a medium advance weight spring. I set the base timing 12-14 BTC 32-34 Total timing.

Originally Posted by BOBv

don't forget the advance curve. The low compression 350 290 needs to rapidly advance the timing and be all in at 3000 rpm. My MSD distributor uses a light weight and a medium advance weight spring. I set the base timing 12-14 BTC 32-34 Total timing.

You are posting to a 5 year old thread and I would assume that by now it's either running right or he blew it up.

Originally Posted by NTFDAY

You are posting to a 5 year old thread and I would assume that by now it's either running right or he blew it up.

Originally Posted by BOBv

don't forget the advance curve. The low compression 350 290 needs to rapidly advance the timing and be all in at 3000 rpm. My MSD distributor uses a light weight and a medium advance weight spring. I set the base timing 12-14 BTC 32-34 Total timing.

Hey BOBv,
Welcome to CHR! I hope that you find things here that make you want to come back and stick around for a while.

Like Ken says, the thread you added your comment to is from April 2012, and on top of that the guy who was asking dropped off three days later and hasn't ever logged on again. When you see a thread title that looks interesting look at the original posting date under the title, beside the name of the guy/gal posting. Not saying that the info in the thread is low value, but if it's more than a year or two old they likely aren't looking for a response.