While I am still figuring out how I'd like to be a 12s car, I'm still working on the 350 engine originally in the firebird. Today I took the cyl. heads to a friends shop to wrangle four stubborn bolts from the exhaust manifolds. He recommended I do a valve job. (Any sources on the internet for first timers would be appriecated). That's it for now. I plan on getting the heads back on and installing headers this/next weekend.

 

How to do a valve job? That isn't a do it yourself thing. Not unless you have a machine shop at your disposal. Take them to an automotive machine shop and have them checked to see if they do need a valve job.

 

ditch the pontiac 350 and find a 400 or a 455

 

Well, for those of you reading this who don't know old motors I will delve a little into the background. The Pontiac 350 has the same basic architecture as the big Pontiac 400 and 455's that get all the attention. It is small bore version made originally in '68 to be more fuel efficient. Kind of like the L99 is to the LT1. They stopped making them in ~1980. There are zillions out there. It is a small bore/long stroke motor: 3.875x3.75". They can take a pretty good overbore, like most older blocks.

There must be lots of Poncho guys who know specific tricks that apply to these motors. But in general, they will respond to the same things as any other OHV motor. Boring is a great idea not only due to the displacement increase but because the small bore hampers breathing. Head porting, better aftermarket heads and intake, cam and valvetrain upgrades, etc. Just like any other motor. If the valves aren't sealing well, a valve job is certainly in order. Even if they are sealing, a competition valve job may be worth 10-15hp in and of itself due to enhanced airflow.

I believe Edelbrock makes aluminum heads for the 350. In fact, they have a variety of stuff (I just checked their site). There must be some Poncho boards out there that can help.

Rich

 

Hey what heads do you have? (Casting #'s should be on the side). Before you go and do work on these heads, and spend your hard earned, make sure they are worth it. For a 350 you need heads that have smaller chambers, and valve shrouding sometimes is an issue as well.

 

when I said valve job I meant grinding the valves, not the three angle shenanigans.

 

Grinding valves requires machine tools too. Only thing you can do at home is lap the valves with lapping compound if the seats and guides are in decent shape. I do that sometimes to freshen up valve seats on good heads or to polish up the seats after I get heads back from the shop after a valve job to help improve seat seal.

 

Check out www.performanceyears.com for all your pontiac needs.you will be better off in the long run to get rid of that 350 for a 400-455.

 

As mentioned in an earlier reply, the Poncho 350 is a smaller bore, longer stroke 350 (3.875" x 3.75"), but it is still not a bad bore to stroke ratio. It shares the same stroke as the 389 and 400. I've always been in favor of the biggest bore/shortest stroke for a given CID, but there is nothing at all wrong with a Pontiac 350. It just wont rev really high as comfortably as a shorter stroke 350 (Chevy 4.0"x3.48"). Technically, it'll make more torque down low while giving up just a little top end HP. So, cam and gear it properly and it'll be a blast!

 

I like the Pontiac 350--it is an underdog

Had a 74 Firebird this engine--had 2.73s anda 2bbl + HEI and I think an upgraded cam...ran high 15's--torquey little motor.

I don't think the Edlebrock heads can be used on this small bore Pontiac--can't remember why...

There are stroker kits out there--end up with a 410 CID IIRC

 

If there's a reason Edelbrock heads cannot be used on a Pontiac 350, it's probably the 2,11" intake valve size hitting the 3.875" bore (hey Ponti guys, can the bore be notched enough?) But even if you can't run those heads, use small chamber-smaller valve heads, have them ported, you'll be alright. I'm not sure, but I believe the smaller valve Pontiac heads are still bigger than 1.94", and Chevy's run fine with 1.94's!.

 

I have had a lot of Pontiacs in the last 20+ years. i currently have a 68 gto with a pumped 455, and a 68 firebird with a stock 350. For a daily driver the 350 is a fine motor, but you will never get any real performance out of it. I personally would not put any money in a 350 when 400's can be found for a song and are so much more of an engine. I have several 400's. one 428 and some 455's that I may be willing to part with. but I live in Southern California which may be out of your way I don't know. You never want to put big valve heads on a 350. You will get valve shrouding and it will cost you power over the stock heads, and lower compression.

Hope that helps.