70 olds 350 timing Help!

[DoubleV]

Stock 307 was 24 degrees initial timing I was just wondering if the 350 was going to be different

Stock is 20 just for the record 😋 but yeah, you'll want around 36 total and as much initial as you can run. Your combo may not like the full 20 initial but maybe it would. It's really hard to say. Gotta go down the long tuning road...

 

[Richie84cutlass]

I assume at least W31 valves and the bowls opened? My understanding Olds heads will accommodate that lift, you just need roller rockers with them. Yeah, the low compression Olds V8's will tolerate a lot of timing, the swirl port 307's ran timing over 60 degrees. I have personally ran close to 60 degrees on non swirl port, low compression Olds V8's. I am over that on my 260. You will want 20+ base with 230+ duration and around 36 total. You will have to experiment with vacuum advance and see what it will tolerate. I assume you have at least a 2500 stall and 3.73 gears with this motor?

I have the MSD Pro Billet distributor its mechanical timing advance and I haven't got a stall or gears yet I'm actually really disappointed with the motor as it is right now was expecting quite a bit more hoping once I put a stall in Gears in it it will makes a difference

 

[Richie84cutlass]

I have the MSD Pro Billet distributor its mechanical timing advance and I haven't got a stall or gears yet I'm actually really disappointed with the motor as it is right now was expecting quite a bit more hoping once I put a stall in Gears in it it will makes a difference

And from what ive read the 6a head have the biggest valve i also have two sets of 5a head my 6A heads just have mild or in Polish to the intake and exhaust ports they milled the heads down and I have Comp Cam Double Springs and stud mounted Comp Cam roller rockers and hydraulic roller lifters

 

[DoubleV]

You have 6 heads not 6A correct?

 

[olds307 and 403]

You have 6 heads not 6A correct?

I sure hope so. Hopefully the 2"/1.625" W31 valves were used. My 9 to 1 350 doesn't like the stock 1700 stall and 2.78 gears, your motor will be dreadful. You need at least 2500 stall, maybe more like 3000 stall and 3.73 gears. It will be night and day.

 

[fleming442]

I'm actually really disappointed with the motor as it is right now was expecting quite a bit more

This right here warrants a question I've been holding: This "10:1" compression you claim, is that calculated or theoretical based on the sum of parts? A low-compression 350 can be made worse very easily, but, more importantly, claimed gains from certain parts may only get you a stock rebuild. What is your cylinder pressure? How thick are the head gaskets? What size are the chambers in the heads? Are the pistons literally flat tops? How far in the hole are they? Also, since you did a 4/7 swap cam- did you revise the firing order accordingly?
These may sound like simple questions, but are very valid; we're not psychics.

 

[1bad79]

What was done to the heads to accommodate the lift of the cam?
Why 4/7 swap? That's questionable old school thinking for a Chevrolet.

Not at all there’s no horse power advantage but it is easier on the crankshaft especially with a heavy olds crank

 

[fleming442]

Not at all there’s no horse power advantage but it is easier on the crankshaft especially with a heavy olds crank

So, why is Howard's pretty much the only one making them? If you look at the really hi-po Olds builds, they never use a 4/7 cam.

 

[olds307 and 403]

Interesting on the 4-7 swap but the 350 doesn't have the bottom end issues of the 455. So unless constant 7000 rpm is in the plan, not sure of the advantage. That cam will be super soggy down low, gears and stall! What carb is being used? As said, is it 0 deck? The Speedpro pistons usually sit .025" below deck, would be closer to 9.6 to 1 with Felpro head gaskets. What exactly was done to the heads?

 

[1bad79]

So, why is Howard's pretty much the only one making them? If you look at the really hi-po Olds builds, they never use a 4/7 cam.

Not sure that entirely true I think if you talk to Bernard mondello or the guy in Florida cutlassfi I think they offer them in other brands I have also see this swap for dodge and ford also has two firing orders for some small blocks Bernard just had something about this posted on his Facebook page and not that mine is super nasty but I have it in my 455 also