[b-man]

Originally Posted by ericwoo

Ok, I will check them out but do want to be sure it will help before continually dumping money into it without having much improvement. I am still surprised the performance isn't much better after getting the driver side head milled down correctly to match the passenger side.



Yes, I believe I even tried up to 40 degrees advanced. It seems this engine is pretty forgiving on running decent when the timing is adjusted quite a bit whether it is retarded too much or advanced too much. There may be a slight performance difference but not much to really noticed much of a distance.

Your 65k mile 350 short block may be in good shape and your really should be running better than what you’re experiencing.

However if the harmonic balancer is also original the outer ring may have slipped making it impossible to accurately set the timing. It’s really not an unusual problem actually pretty common. Even new balancers should be checked to verify the TDC mark using a piston stop.

Plenty of folks have had nice running 326 and 350 engines.

Your heads are similar in airflow to the 5.7 LS1 heads which are a 260 cfm head. Those engines make 1 horsepower per cubic inch (346 cubes) and easily propel a 3600 pound car into the mid to low 13z factory stock with a rather small 196/208 @ .050”, .467”/.479” cam. Throw a cam similar to your 60916 into that LS1 and they really wake up.

Your 200-4R 2.74 low gear combined with a 3.55 should move out nicely, a 9.727 ratio. It compares well with the 3.06 low 4L60E and 3.23 my 2002 WS6 came with, a 9.8838 ratio. By the way the standard LS1 cars had a 2.73 rear. So I don’t see any issue with your choice of transmission and rear end gear.

I still think there’s some kind of serious basic tuning issue here.

I had a mild low-compression 8.6:1 bracket race 455 that I was just beginning to get onto the race track. In my first few outings I conservatively set the timing at 30 degrees. I couldn’t get the car into the 12s, it was stuck in the 13.0 area.

As soon as I bumped the timing to 38 it instantly responded with a 12.60 time slip. The combination of low compression and the high altitude track (2700 ft) required a lot more timing advance.

Look at your balancer. Perhaps try a different timing light as well, some are inaccurate.

if you do end up building up a new short block with more displacement just be aware that your small 59cc chambers and smaller valve sizes might be a better fit for a 400 or possibly a 428 short block due to the size piston dish required to get a reasonable pump gas compression ratio. Actually the valve size isn’t much of an issue at all it’s the small chambers which might require a pretty cavernous piston dish (reverse dome) to be used on a street 455-type engine .

Once you work out the compression numbers you can decide whether to keep the 3.75 stroke 400 crank or go for a 4.00” or 4.25” crank in your future 400 block.