70 olds 350 timing Help!

[1bad79]

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?

It’s definitely not as heavy as the big block but it’s not any more money for a swap cam so it it takes care of some harmonics then why not it’s certainly not hurting anything

 

[Richie84cutlass]

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?

Carb is holly 750 hp and i have forged flat top pistons not sure if they Deck The Block but they definitely Mill down the heads

 

[Richie84cutlass]

Carb is holly 750 hp and i have forged flat top pistons not sure if they Deck The Block but they definitely Mill down the heads

And only mild port and polish to the intake and exhaust ports

 

[Richie84cutlass]

You have 6 heads not 6A correct?

Yes sorry #6 heads

 

[Richie84cutlass]

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.

Motor man that ask if i wanted pump or race fuel i said pump and he said he built it 10 to 1 .....soooooo???? I wish I could answer all those other questions but I am certain that they are Eagle forged flat top pistons and I know when he port and polish the intake and exhaust ports he also milled the heads down 2 lower chamber size and increase compression

 

[fleming442]

Who is your "motor man"? Did he spec the cam? In case you couldn't tell, I'm not a fan of that selection. To me, it's got too much duration on too short of a center. Probably has a wicked idle chop, though. The Comp hyd. roller in my 10.58:1 468 is only .491/.510 @236/242 on a 110, and it pulls like a freight train. You mentioned not having headers; that thing needs to breathe as it's set up for high rpm. Until you get exhaust, a converter, and 3.73 gears (minimum) or better, It's probably going to be a dog. Getting the engine built was simply the first step in the process, and trying to tune it now will be somewhat pointless.

 

[olds307 and 403]

There is a 30 hp gain along torque with long tube headers. I noticed a difference going from manifolds and 2" od dual exhaust on a 260 to 1 5/8" shorties and 2.5" X pipe exhaust. So get some Hedman full length and have at least 2.5" exhaust once you get gears and a converter. Get a posi like a Trutrac, the little spider gears in the posi will only take so much. Used gears and Torsen worm gear posi along Moser 28 spline axles is a good, affordable upgrade.

 

[DoubleV]

Motor man that ask if i wanted pump or race fuel i said pump and he said he built it 10 to 1 .....soooooo???? I wish I could answer all those other questions but I am certain that they are Eagle forged flat top pistons and I know when he port and polish the intake and exhaust ports he also milled the heads down 2 lower chamber size and increase compression

Unless you know your builder well or unconditionally trust em, don't EVER assume the job was done right. Ask me how I know?

Lot's of 'high compression' engine builds out there with cool 'high performance' cams and fancy 'ported and polished' heads that in reality are nothing more than low compression, over cammed, stock headed turds.

 

[Richie84cutlass]

And only mild port and polish to the intake and exhaust ports

Yep😭😭😭

 

[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.

Here’s one that’s not a howards cam