[69Ragtop]

I have a 69 350 with #47 heads. What I would like is to be around 350 HO power level. Is that an unreasonable expectation working with what I have? Could a head and cam swap get me closer to where I want to be without spending unreasonable money? I've done searches and the more I read the more I confuse myself so now I am asking for advise, suggestions, any kind of guidance. The reason for sticking with the 350 is because it is the original to my car which also has a Th350 automatic and I believe the rear end gear is around a 273:1. If I drive 70mph on the Interstate the rpm's are around 2100, 2200. Thanks

[72LuxuryLeMansLa.]

Originally Posted by 69Ragtop

I have a 69 350 with #47 heads. What I would like is to be around 350 HO power level. Is that an unreasonable expectation working with what I have? Could a head and cam swap get me closer to where I want to be without spending unreasonable money? I've done searches and the more I read the more I confuse myself so now I am asking for advise, suggestions, any kind of guidance. The reason for sticking with the 350 is because it is the original to my car which also has a Th350 automatic and I believe the rear end gear is around a 273:1. If I drive 70mph on the Interstate the rpm's are around 2100, 2200. Thanks

Define "unreasonable" money.

I have a 350/TH350/2.78:1 rear and 14" rims. My car hits 2100@55mph and at 70mph I'm spinning 2750rpm. What size wheels and tires do you have?

If those heads are near the advertised 72cc they will get you to the low 9.x:1 SCR so I would use them.

[screamingchief]

I would work with it.

#47 head's "nominal" spec is like 73-75 cc and it's rated @ 9.2:1 CR IIRC.

Now as SOP the CR is actually about a half point lower than that with like 80-83 cc chambers,as that was a common thing for pontiac to do back then.

So,I'd pull the #47 heads and mill them to a true 75 cc's,convert them to screw in studs,slot the pushrod holes for 1.65 rockers,cut the guide bosses for PC seals,and put some stainless 2.05" or 2.08" intake and fresh 1.66" exhaust valves in them,and when the larger intake valves get installed,the bowls should be opened up some to allow for the proper transition from the port to the seats,and be sure to use a good valve spring like the Crower #68404's,then add a nice port match and clean-up,and your done.

Only other head casting that offers any significant benefit IMO would be the '68 #18 350 H-O heads,as those have the smallest chambers of any of these heads (well those and #48 big valve heads that came on the '69 350 H-O and some GTO RAIII's,but I personally would'nt use those on a 350 myself).

After the head work,all you need is a decent cam.

And there are a ton of cams that would be able to reach the stated goal,really there's too many cams like that to list them all here.

Add the H-O style exhaust manifolds as SOP too.

With proper tuning and such on a healthy shortblock,that ^^^^ should easily make 320+ hp like the original 350 H-O's did.

There's a small group of us 350 aficionados here,but slowly were gaining numbers.

FWIW

Bret P.

[69Ragtop]

Yea, I knew that was subjective but for this case I'll say unreasonable is spending twice as much on a 350 to get to that power level than I would spend on say a 455. The rims were 16inch from a later model but I am going back to the original 14inch. Thanks

[PunchT37]

You might spend twice as much as a 455 if you were going 450 plus hp. but not at a 320 to 350 level. Even 455`s need screw in studs, springs, valves, etc.

[ponyakr]

You ask for cam suggestions to keep the project reasonable. My pick would be the Summit 2801. Cam and lifters for under $200. I'm sure the other guys can give you the science proving this is the wrong cam. But that's my suggestion. Hey, good luck with with your 350 project.

[Tim Corcoran]

I would do exactly what Bret said, very good advice. In fact I would print out his post and give a copy of it to ever does your heads for you. And make sure you get a top notch machinist to do your head work.

[PunchT37]

Originally Posted by ponyakr

You ask for cam suggestions to keep the project reasonable. My pick would be the Summit 2801. Cam and lifters for under $200. I'm sure the other guys can give you the science proving this is the wrong cam. But that's my suggestion. Hey, good luck with with your 350 project.

That`s exactly what I was looking at earlier to suggest. Keep the 47`s and add screw in studs at least.

[69Ragtop]

Once the heads are milled to 75 cc's what would be the recommended pistons? Domed or dished? Neither? The block will need to be bored 30 over. I do appreciate all of the help and patience. I think some of it is starting to sink in.

[dmac]

Since it is original, work with it. You can get whatever HP you want (almost) out of that original block and heads. You shouldn't need either domes or dish to get a compression ratio you can use with pump gas.

If you ever do want more cubes, you can install a stroker crank and get up way over 400 cubic inches if you want.

I have carted around the original 350 since I gave my son the 69 bird with a 400 in it. If I had to start over, I would have just done the original block and heads. There is some value in having the original parts, more so in the future, in my opinion, as fewer and fewer of those classics remain.

[PunchT37]

Originally Posted by 69Ragtop

Once the heads are milled to 75 cc's what would be the recommended pistons? Domed or dished? Neither? The block will need to be bored 30 over. I do appreciate all of the help and patience. I think some of it is starting to sink in.

Keep it a flat top. Work your 47`s like Bret said, throw in the 2801 cam, and I`ll bet it runs equal to or better than the 350HO you spoke about.

[PunchT37]

Later on, get a good 11 inch converter with about a 2500 stall and the car will perform even better.

[455Darren]

Build the 350. I have done 2. Both using #62 heads (cc'ed at 76), iron intake and log manifolds. One with a RA III 068 cam and current one with the Summit 2800 cam. One with 3 speed stick and current one with TH350. Both with 3.23 rear gear. Did mild bowl and port work on heads. Q- jet built to Cliff's specs and HEI. Nothing fancy. Great street power and manners. I have cars with a 400 and a 455, the 350 is a tad less powerful than the 400, but not by much.

[Blued and Painted]

there's still alot of 400's out there. Find one. IMO.

[U47]

Originally Posted by 69Ragtop

I have a 69 350 with #47 heads. What I would like is to be around 350 HO power level. Is that an unreasonable expectation working with what I have? Could a head and cam swap get me closer to where I want to be without spending unreasonable money? I've done searches and the more I read the more I confuse myself so now I am asking for advise, suggestions, any kind of guidance. The reason for sticking with the 350 is because it is the original to my car which also has a Th350 automatic and I believe the rear end gear is around a 273:1. If I drive 70mph on the Interstate the rpm's are around 2100, 2200. Thanks

Not a unreasonable expectation at all. The 355 is a great engine and too bad it's overshadowed by it's larger brothers. All you need is some 48's or "E" heads to be in that hp range with a 068 cam. When I bought my 69 H-O LeMans new it would run high 14's with 2.56 open diff and air bag in the rt rear( car came with a T-400 with that engine ), would go thru the traps at 92-95mph in 2nd gear. Funny thing was most "stock" 350hp GTO's on street tires ran about the same. I remember in a street race a surprised GTO driver as we were side by side at the end of it and he was all out of gear and I clicked third and walked away. Remember that 1969 SuperStock article of the F/S 355 Royal Firebird that with a Bobcat (#1) and slicks was driven down into the low 12's with fine tuning. Oh yea, no problem with that engine. FYI 69 H-O engines came with 48's.

[PunchT37]

Originally Posted by U47

Not a unreasonable expectation at all. The 355 is a great engine and too bad it's overshadowed by it's larger brothers. All you need is some 48's or "E" heads to be in that hp range with a 068 cam. When I bought my 69 H-O LeMans new it would run high 14's with 2.56 open diff and air bag in the rt rear( car came with a T-400 with that engine ), would go thru the traps at 92-95mph in 2nd gear. Funny thing was most "stock" 350hp GTO's on street tires ran about the same. I remember in a street race a surprised GTO driver as we were side by side at the end of it and he was all out of gear and I clicked third and walked away. Remember that 1969 SuperStock article of the F/S 355 Royal Firebird that with a Bobcat (#1) and slicks was driven down into the low 12's with fine tuning. Oh yea, no problem with that engine. FYI 69 H-O engines came with 48's.

Agreed. We have the 3.75 stroke on "our" 350. The chebbie guys have to go to the "stroker 383" to get that. They`re huntin for more torque that we already have on 350 cubes.

[PunchT37]

Course, when we go to 383 stroker, we are at a 4 inch stroke. And we can go to 4.25 stroke on a 350 block easily. How`s that for street friendly torque on a 350 block? The other guys gotta go big block for that.

Thank that rediculous 10.2 deck height 350 block for that.

[stockapearing455]

Back when I was in high school, when my 2 barrel 1968 350 spun a rod bearing, I I rebuilt it and installed a 268 h cam , eddelbrock intake , and headers. It was a decent street car. Ran high 14s with a 3.08 gear. Sounded good too.

[77 TRASHCAN]

Originally Posted by Blued and Painted

there's still alot of 400's out there. Find one. IMO.

X2
Maybe more 400's than 350's???

[screamingchief]

Originally Posted by Blued and Painted

there's still alot of 400's out there. Find one. IMO.

Yeah,and at least 1/2 of those 400's are probably 557 block castings nowadays.

IMO you can have all those,I'd build a 350 before I'd ever build a 557 based 400.

Got a pile of parts started to do so already,gonna be a 350/383 stroker build,got the pistons,cam,springs,intake,carb and some other assorted parts for it already.

And a 350 would especially lend itself towards a boost enhanced build as well.

Nothing inherently wrong with the pontiac 350 if you ask me,just a fair number of misconceptions that can make it hard for some to see the little motor for what it is.

To each their own I guess.

Bret P.