'69 350 VS 70' 350 long block build.
 

Hey guys, I'm currently in the middle of parts collecting for a 70 Lemans project.

For the time being (until I source a 400 core) I will be doing some basic bolt-ons to the 70'

In the car now is the original 107K mile 350 with #11 heads, 69' 4-brl iron intake, Mallory Unilite Dist...decent compression, runs great with the Holley 4165. It is just gutless.

I recently picked up a complete 69' YE 350 from a kid gutting his papaws 'Bird to put an LS in...His dad mentioned he thinks it spun a rod bearing around 89-90 and it got put out under a lean-to until recently...Claimed to have TRW .60 pistons but i haven't bothered even pulling the pan cause its exceptionally grimey. Has #47 heads, the outboard exhaust bolt holes have been drilled and tapped. Has a Cam marked TQ40H...Appears to be an Erson cam from back in the day...also has chrome Erson valve covers. its also topped with a Holley street dominator, 2in spacer, 750 DP, and a fly eye...It was probably pretty cool for a 350p...

You guys think it would even be worth doing a tear down on this thing when my plans are a 400 anyway? The orig 350 runs just fine, and it appears there's nothing particularly special about the heads (looks like the #11's are .2 higher comp/ratio on a 350 anyway)

I got it in a package deal with some other parts so selling the 69' long block for peanuts is okay by me.

I would tweak the running 70 you have now.

The first bolt on should be a new timing chain and gears and if the motor is up out of the engine bay it should get a 60 psi oil pump and HD drive rod.

The heads even while they are on the motor should get new valve stem O-ring seals while your at it also.

What do you get when you do a cranking compression test on the engine in the car now?

Stan

Did a comp test recently about 3 hours after a good hour long cruise.

1-144
2-152
3-145
4-147
5-137
6-156
7-139
8-150

I have my eye on #5 and #7...

350 has the same crank as a 400, so tear down for crank, spare rods, Timing cover etc is worth the cleanings.

the #47 heads have a slightly smaller chamber than #11 heads ... i have both

47 heads worked a bit milled .030 bowl blended port matched with a 2801 summit cam dual plane intake is just about where a 350 starts to get interesting with a decent rear gear no 2.56 - 3.08 gears

this build level is like a std. 4bbl gm build

the original cam is junk from day 1 and is probably worn as well

just saw your compression test suspect flat cam lobes, my original 1970 350 engine had quite a few

350
 

the 350 has potential. of coarse cubic inches is cubic inches. i don't know your goals but i would not discount the 350. power can be had.

As far as goals...Car has a BOP 10-bolt 3.23 Eaton LS, 2800 Stall and 275/60r15 cooper cobras...I just want to be able destroy the tires, not concerned with E.T's. A wicked 60' and a reasonable rpm at 55 works for me.

oh i think you can get it done with a 350. there is lots of guys on here that will show you the way. i would tweak what i had. maybe headers,cam, clean up the ports and bowl. or change heads. parts will fit the 400 if you get one later if that is what you want.

So what would be the consensus on a head swap...

The #11's original to the engine are listed at 8.8cr but have pressed studs and do not have the most outboard exhaust manifold bolt holes.

The #47's I have from the 69' are listed as 8.6 c.r. but have threaded rocker studs and outboard exhaust manifold holes, also noticed single wound springs without a damper and shims perhaps matching Erson componentry from a cam kit? (not saying they don't need to be torn down but they get me closer to the goal post on potential machining costs...)

Is that .2 listed CR on the specs between them even a concern, seems that there's a lot of variance in real world cc vs what's "in print" for Pontiac head specs.

will at least cc the #47 heads since they are on a shelf anyway but i don't really want to pull the #11's in the middle of cruising season just to get a definitive answer.

this will turn into mission creep from picking best 350 parts on hand until larger new engine is done

to stroker crank roller cam nothing left on the table LoL

Just FYI if you read through archived 350 threads, the #11 heads are reported to be 88-92 cc. Despite the claimed 8.8:1, the truth is probably closer to 8.0:1. The 47s may not be much different - others might know.

The YE motor was listed as 9.2 compression which in reality was more like 8.6.
The 11 heads would be more like real numbers of 8 to 1.

This shows up in the factory rating of a 10 Hp different between the two motors which sounds about right.

Either way with these motors and your rear gearing I would not run anything more then a cam with a advertised intake duration of 270, or no more then something like the factory 066 cam.

Also no more then .450 to .460” lift.

Horseflop, gentlemen. 350s can and are built to amazing horsepower numbers with STOCK stroke. Have you not been following the 350P build in the race section? A street 350 built with modern parts will produce 400+ hp and be rock dependable. Build a solid, reliable short block with future upgrades in mind. Give me a day or two; I’ll work up my recipe for a street 350 that will give any 400 a run for its money.

If you are going to spend money, I'd try and get a set of 48's or even 12's.
They will pick up HP and use some good springs for a better cam later.
(then headers, etc, etc, etc)


:)

I think your kinda picking on us pertisapating in this string for nothing because I don't see where anyone is staying that a 350 can't be made to produce big level of power.

If the OP wants a 400 then let him go that route, plus there's no question that once you get into the heads that have even a 1.960" Intake valve that the stock Bore of a 400 is a plus .

Not picking on you at all. I am so tired of hearing “You have to use a 400 or a 455”! No you don’t! Tom S. built a 301T based 383 that made 478hp with small valve iron heads. Attempt to purchase a useable 455 Pontiac core around here( Louisville Metro). I haven’t seen one for sale in FIVE YEARS. Good 400s (non 557 blocks) are becoming scarce. 350P? Common as dirt. Some of you guys need to adapt to this reality; many here have to face it. I don’t have the time today, but I will setup and run my version of a streetable, stock stroke 350P that will surprise many.