[70lemansport]

Hello all,
I havent posted in a while, i got into 4x4's for a bit. But i'm back and am finally gonna pull the engine in my lemans. Its a tired old 350 with a bad valve knock. I want to replace the old heads-cant tell what the number is the previous owner put like 10000 coats of paint on the block. I have a line on some rebuilt # 11's i can get for less than 500$. are they worth it? i plan on running this combo with a xe262h k kit, a performer and a 650cfm edelbrock.. O and its my first engine build up...Any suggestions?
Edit:.I know to magnaflux and im having a machine shop chech the cylinders and put new rings on the pistons

[scott cedergren]

The first thing i would recommend would be to find a 400 and build it. In the long run you will be better off and it should not cost any more but will make alot more power.

[70lemansport]

But, I already have everything except the heads...i have the cam kit intake carb and all parts for the rebuild and only have about 500 left to do something with. And, i kinda want to keep the 350, its different and i wanna keep the original engine in it. Also, i want to get a set of higher flowing heads. so would they be a good choice? I've tried to find #18s but had no luck, same with #17's

[70lemansport]

Did a little paint chipping to find out i already have #11 heads. i feel dumb sorry for the wasted time

[wrenchmen]

Do a search for "350" there is tons of info here!

[70lemansport]

K, did a little research. i found some 670 heads out of a 67 gp. But from some other stuff i found when searching it says the valve size may be a problem. So will they fit well without mods?

[chiphead]

Does your block have the valve relief notches? If so, you'll be OK with 670 heads clearing the block.

I ran 670 heads and 17 heads on a 350 with headers. I didnt notice much of a performance difference, with the XE256 camshaft. Ran within .2 at the track. Likely you wont notice much if using a moderate camshaft grind. With a 350 and moderate cam, compression is more important than head flow. They don't need as much airflow. Find a set of 72CC heads, even if they're small valve. With flattop pistons, you'll be in the low to mid 9s for compression.

[wrenchmen]

Im not 100% positive on this, but It looks as if all 350's had the small valve heads, 1.96/1.66.,....with the exception to the 1969 350 HO, it had a #48 heads with large valves, 2.11/1.77, so I am going to say it is possible for the large valve heads to work on a 350 block, but as already stated, the block must have valve chamfers...here is a post that has excellant info and pic's explaining this...http://www.pontiaczone.com/forum/showthread.php?t=15973

I have also read here that the #11 heads would be sufficient to make good power with the 350, as there is an issue referred to as "shrouding" that has a negative effect on the large valve heads in a 350.....someone should come along and confirm this as I am still a "newb" here in training.

[70lemansport]

I have heard great things about the xe256h but was wondering about how mild it seems. i was thinking the xe262h. Would this be too radical for a street driven car. Probably gonna have headers,2.5inch exaust, 3.55 posi gears, and a 2200??? stall(would this be an ok choice?).
I dug up this old post and it seems at would be ok according to them:
"Here's the specs as I have written down:
69 350 +30
216/218 454/480 Crane 272-2?
Stock rebuilt #47 heads
Edelbrock performer
Holley 600cfm
3 tube headers
2400 stall
stock th350
3.55 posi
Car weighed 3500# and went 13.82@98
I will call Jaqtec and have him double check on what I listed above.

Shotgun has my old combo right. My car was fine on pump gas...I did run premium. You don't need no stinkin' 400 to run 13's!!! Shotgun was almost in the 13's with his 301 powered car! It's all in the whole combination! I'd recommend not dumping a ton of $ in the heads...the 350 can only pump so much air anyway. Put a cam similar to what I had...a 600-700 CFM carb, and get some 3.55, or 3.73 gears...performer intake...and have fun!!!"

---the 262 seems to have similar numbers to the crane mentioned

[shotgun]

Hey, I have seen the post before?!

I have bone stock #11 on the 400 in my LeMans that runs high 13z. It is a street car that can and has been driven to the Jersey Shore( I am in Pa), driven to Cecil (Maryland) raced and driven home.

I just put a set of rebuilt #11z on the customers 400 ( XE262H),very similar to mine and it runs great with 3.55 gears.

I think the large valve deal is way overrated in a true street car, velocity over volume.

If you plan on reusing the #11,remember to have the outside bolt holes drilled and tapped so you can use headers.

[70lemansport]

But would the 262 grind be too lopey/extreme for a street driven car with above specs-
(2200 stall,3.55)?

[chiphead]

I ran the XE256 with a stock converter and 3.23 gears. 350 with 17 heads, performer, Q-jet. Cast piston, stock rod, stock oiling system. Pulled hard to 5200. Had a noticable lope. Ran low 14s in the quarter. Would run right with newer GT mustangs.

XE262 would be about right for a 350 with 9 compression, 3.55s, and a mild converter. The cool thing about the XE256 (and I think the XE262) is you can use the stock rockers, studs, and nuts. Just use the COMP valvesprings, keepers and retainers, and check installed height of the springs.

It would have a good choppy sound for sure. I wouldn't recommend the XE262 for less than 8.5:1 compression. Have the block zero decked to prevent detonation with the timing curve you'll need. My engine had poor deck height, and I had issues from that. The XE cams build cylinder pressure, so they work well with low to moderate compression engines. You might could get away with cast pistons and stock rods in a 350, just have it balanced. I tried to blow up my stock-rod 350, drove it around at 5800 in 2nd gear. I ran it hot, I ran it with too much timing, poor fuel, etc. It kept coming back for more. I finally pulled & stored it when the oil pressure got low. The P350 is a tough SOB.

[shotgun]

Yep, XE262H can be used with stock valvetrain.
The 272-2 that jagtec was running has lift like the xe262 and duration closer to the xe256.
I think you will be fine, I am getting 15/16 hg in the 400s at idle.

[wrenchmen]

Anyone know how the Crower 60240 would compare to the XE262H?..
I have seen the 60240 recommended here in several posts for the 350.
Also the 68 advanced 4 degrees was another favorite.
Which would be better suited for a 4 speed trans with 323 rear gears?

[70lemansport]

Just compare the specs...thats how i found my equivelents. O and i think since im trying to keep it cheap, im gonna go with the 256 for the smoother idle since it will get some miles put on it and i don't have the dough for a new converter yet. im still goin with 3.55's though. Also, when i install it i know im going to replace the bearings, How hard is it to install these/ do i really need the install tool? And do i install it straight up? Chip head-what did you run yours at?

Side Question- When i replace the piston rings( do i really need to do this? it sat for like 8 years but still ran) should i replace rob bearings??