Swaping my 351 cleveland for 408w stroker

[Don C]

Iron closed chamber or open chamber heads, with minor port cleanup, will do better than that at 351 cubic inches, and in the 500+ horsepower range with a 408.

 

[73pony]

Something is not right. It may be the manifold. I was running an old Holley street dominator manifold and it was running out of breath around 5,000 RPM. Switched to an AirGap and can pull into the 6,000+ range. What size carb are you running? Cam specs?

 

[EvilPuppetMaster]

Iron closed chamber or open chamber heads, with minor port cleanup, will do better than that at 351 cubic inches, and in the 500+ horsepower range with a 408.

Don, I have no doubt that If I can figure out what the restriction/issue is this engine will make over 500 HP. I am already happy with the torque numbers

Alex

 

[EvilPuppetMaster]

Something is not right. It may be the manifold. I was running an old Holley street dominator manifold and it was running out of breath around 5,000 RPM. Switched to an AirGap and can pull into the 6,000+ range. What size carb are you running? Cam specs?

The we discussed in  this thread last year:

Lunati 62503:

•Advertised Duration (Int/Exh): 268/276

•Duration @ .050 (Int/Exh): 227/233

•Gross Valve Lift (Int/Exh): .552/.564

•LSA/ICL: 110/106

•RPM Range: 2000-6000

We tried 3 different Carbs: 600cfm holley, 750 cfm and 900 something not sure.

The footprint was pretty much the same. It made less power with the bigger carb. 600 cfm was running around 405hp  at the same rpm but much leaner A/F ratio. Jetting was not right but the idea was to see  if we can get same footprint /graph on the dyno.

I included youtube video of the last run in my previous post so have a look and see if something jumps at you by looking at the vacuum gauge

Alex

 

[Hemikiller]

Hey, no hard feelings here. I knew what I was getting into. It was simple decision to save money. CHI heads are about 2400 dollars while these heads cost me 1000 and that is with all updated valve train components.

This is not going to be racing engine and it will not see lots of action past 5000 rpm but I am puzzled with this issue and would like to get to the bottom of it.

Alex

Let me get this straight, you bought cheap parts and got poor results, and you're going to spend more money on another intake from the same company? You didn't save any money, you're burning up whatever you perceived to have saved in dyno time and lack of return on your investment. A stock M-code 351C will pull those same numbers with a cam change, Holley 750 and a set of headers. A 408 should easily pull down 500hp even with a cam as small as yours.

FWIW, Speedmaster is just ProComp Electronics. They are using the Speedmaster name to hide from all the bad press and lawsuits they had over the last twenty years regarding blatantly ripping off other companies parts, deceitful packaging and poor designs.

 

[EvilPuppetMaster]

Let me get this straight, you bought cheap parts and got poor results, and you're going to spend more money on another intake from the same company?

You probably did not see my question from the previous post where I asked if I could use 3v CHI manifold with speedmaster heads.

So No, I do not want to buy manifold from the same company but will do if I cant use any other 3v intake that will fit those heads.

i'll just go with high-rise intake instead

 

[73pony]

Watched the video. Intake may help, as it appears you are running out of flow based on the vac gauge flutter and sound, but I would not recommend another Speedmaster item. I have lived and learned this lesson myself with them. Not sure if the another manufacturers intake will work with their heads though. Hopefully someone can tell you for sure. the 600 is WAY to small of a carb for this set up. Should be a 750-780 range with that cam and displacement. On a side note let's all try to be a little more constructive here. Yes he purchased questionable heads to begin with but I do think there are other things at play here.

 

[EvilPuppetMaster]

Watched the video. Intake may help, as it appears you are running out of flow based on the vac gauge flutter and sound, but I would not recommend another Speedmaster item. I have lived and learned this lesson myself with them. Not sure if the another manufacturers intake will work with their heads though. Hopefully someone can tell you for sure. the 600 is WAY to small of a carb for this set up. Should be a 750-780 range with that cam and displacement. On a side note let's all try to be a little more constructive here. Yes he purchased questionable heads to begin with but I do think there are other things at play here.

Thanks for your help. The carb we used for most of the pulls was 750 mechanical secondary's.

 

[kusanagi]

This thread is of interest to myself as I have got the same heads and inlet, one thing I do remember reading when I was trying to decide on a cam was that if the exhaust valve was not opened early enough ( around 80 to 84 BBDC ) it can cause the  top end torque to drop off like a brick  at higher RPM's ( https://pantera.infopop.cc/topic/sticky-3-351c-basics-and-performance-tuning ). Being that your cam opens fairly late ( 72 BBDC on a lunati 62503 ) it could be a contributing factor, I can imagine having a larger capacity would also make this a little worse ( more gasses to get out ).

As for the heads I found that they needed a little work in the chambers, they needed a bit of work around the valves as the valve area is a little shrouded, the chambers needed CC'ing and pointy bits needed removing and also a lot of casting flash needed removing in the ports ( most of this work is not needed on the CnC'd heads ).

And lastly I have read that the inlet is not that good with a carb as with it being a low rise open plenum it can suffer from fuel drop out due to turbulence and poor port velocity but this mainly happens at low RPM ( to get around this myself I am going sequential EFI with a drilled manifold ).

 

[EvilPuppetMaster]

This thread is of interest to myself as I have got the same heads and inlet, one thing I do remember reading when I was trying to decide on a cam was that if the exhaust valve was not opened early enough ( around 80 to 84 BBDC ) it can cause the  top end torque to drop off like a brick  at higher RPM's ( https://pantera.infopop.cc/topic/sticky-3-351c-basics-and-performance-tuning ). Being that your cam opens fairly late ( 72 BBDC on a lunati 62503 ) it could be a contributing factor, I can imagine having a larger capacity would also make this a little worse ( more gasses to get out ).

As for the heads I found that they needed a little work in the chambers, they needed a bit of work around the valves as the valve area is a little shrouded, the chambers needed CC'ing and pointy bits needed removing and also a lot of casting flash needed removing in the ports ( most of this work is not needed on the CnC'd heads ).

And lastly I have read that the inlet is not that good with a carb as with it being a low rise open plenum it can suffer from fuel drop out due to turbulence and poor port velocity but this mainly happens at low RPM ( to get around this myself I am going sequential EFI with a drilled manifold ).

Good call on the cam. I did not think about that. I'll run that info by the machine shop to see what they say.

 What cam did you end up choosing? I will also be running efi with this engine. I got fitech running on my old one really well. So I spoke to speedmaster techs and they agreed with my engine builder that the manifold is running out of air. I bought their smallest low profile manifold. They suggested that I go with their highrise (fusion funnel style) intake.

They just dropped it down to 220 bucks so I bought it. As I said, I am building a street car and cant complain with 480 lb ft of torque. I just want to see if this was an issue so I will pay them to swap the intake and run it again. 

Should not cost me to much for the labour as the engine is still on the dyno.

Let you know how it goes.

Alex

 

[kusanagi]

The cam I chose in the end was a Lunati 411A1 cam ( solid lifter ), this cam opens its exhaust valve at 77BBDC ( 60 @ .050 ) against the Lunati 62503 cam 72BBDC ( 50.5 @ .050 ), that means that 411A1 cam snaps the valve open earlier but also opens it a lot earlier at @ .050 lift aiding flow the downside to this cam is it has a steep ramp rate so it means it will need EDM lifters and will wear out a bit quicker than normal.

411A1 Solid Lifter specs

RPM 2500-6500

Lobe sep 112

108 Center line

4 Degree's Advanced

Lift at valve : Inlet .558 Exhaust .580

Valve lash : Inlet .018 Exhaust .020

Ex opens 77 BBDC ( 60 @ .050 )

Ex closes 25 ATDC ( 8 @ .050 )

In opens 28 BTDC ( 11 @ .050 )

In closes 64 ABDC ( 47 @ .050 )

Duration Inlet 272 ( 238 @ .050 )

Duration Exhaust 282 ( 248 @ .050 )

Overlap 53 ( 19 @ .050 )

34 degree intensity on both

 

[EvilPuppetMaster]

The cam I chose in the end was a Lunati 411A1 cam ( solid lifter ), this cam opens its exhaust valve at 77BBDC ( 60 @ .050 ) against the Lunati 62503 cam 72BBDC ( 50.5 @ .050 ), that means that 411A1 cam snaps the valve open earlier but also opens it a lot earlier at @ .050 lift aiding flow the downside to this cam is it has  a  steep ramp rate so it means it will need EDM lifters and will wear out a bit quicker than normal.

411A1 Solid Lifter specs

RPM 2500-6500

Lobe sep 112

108 Center line

4 Degree's Advanced

Lift at valve : Inlet .558  Exhaust .580

Valve lash    : Inlet .018  Exhaust .020

Ex opens 77 BBDC ( 60 @ .050 )

Ex closes 25 ATDC ( 8 @ .050 )

In opens 28 BTDC ( 11 @ .050 )

In closes 64 ABDC ( 47 @ .050 )

Duration Inlet 272 ( 238 @ .050 )

Duration Exhaust 282 ( 248 @ .050 )

Overlap 53 ( 19 @ .050 )

34 degree intensity on both

I just did Dyno Simulation and wow i think its that cam that loses all the power at 4700 RPM....

Looking at the simulation is almost identical to the real thing except my power drop happens much faster after 4700 RPM. Regardless not sure if i should be buying another cam or just keep it the way it is.

This is exactly what George Pence was talking about on another forum:

https://www.tapatalk.com/groups/clevelands/camshaft-lunati-voodoo-62503-t17527.html

This cam selection business is very confusing indeed .

 

[tony-muscle]

The cam I chose in the end was a Lunati 411A1 cam ( solid lifter ), this cam opens its exhaust valve at 77BBDC ( 60 @ .050 ) against the Lunati 62503 cam 72BBDC ( 50.5 @ .050 ), that means that 411A1 cam snaps the valve open earlier but also opens it a lot earlier at @ .050 lift aiding flow the downside to this cam is it has  a  steep ramp rate so it means it will need EDM lifters and will wear out a bit quicker than normal.

411A1 Solid Lifter specs

RPM 2500-6500

Lobe sep 112

108 Center line

4 Degree's Advanced

Lift at valve : Inlet .558  Exhaust .580

Valve lash    : Inlet .018  Exhaust .020

Ex opens 77 BBDC ( 60 @ .050 )

Ex closes 25 ATDC ( 8 @ .050 )

In opens 28 BTDC ( 11 @ .050 )

In closes 64 ABDC ( 47 @ .050 )

Duration Inlet 272 ( 238 @ .050 )

Duration Exhaust 282 ( 248 @ .050 )

Overlap 53 ( 19 @ .050 )

34 degree intensity on both

I just did Dyno Simulation and wow i think its that cam that loses all the power at 4700 RPM....

Looking at the simulation is almost identical to the real thing except my power drop happens much faster after 4700 RPM. Regardless not sure if i should be buying another cam or just keep it the way it is.

This is exactly what George Pence was talking about on  another forum:

https://www.tapatalk.com/groups/clevelands/camshaft-lunati-voodoo-62503-t17527.html

This cam selection business is very confusing indeed .

Cool! What software are you using?

 

[EvilPuppetMaster]

The cam I chose in the end was a Lunati 411A1 cam ( solid lifter ), this cam opens its exhaust valve at 77BBDC ( 60 @ .050 ) against the Lunati 62503 cam 72BBDC ( 50.5 @ .050 ), that means that 411A1 cam snaps the valve open earlier but also opens it a lot earlier at @ .050 lift aiding flow the downside to this cam is it has  a  steep ramp rate so it means it will need EDM lifters and will wear out a bit quicker than normal.

411A1 Solid Lifter specs

RPM 2500-6500

Lobe sep 112

108 Center line

4 Degree's Advanced

Lift at valve : Inlet .558  Exhaust .580

Valve lash    : Inlet .018  Exhaust .020

Ex opens 77 BBDC ( 60 @ .050 )

Ex closes 25 ATDC ( 8 @ .050 )

In opens 28 BTDC ( 11 @ .050 )

In closes 64 ABDC ( 47 @ .050 )

Duration Inlet 272 ( 238 @ .050 )

Duration Exhaust 282 ( 248 @ .050 )

Overlap 53 ( 19 @ .050 )

34 degree intensity on both

I just did Dyno Simulation and wow i think its that cam that loses all the power at 4700 RPM....

Looking at the simulation is almost identical to the real thing except my power drop happens much faster after 4700 RPM. Regardless not sure if i should be buying another cam or just keep it the way it is.

This is exactly what George Pence was talking about on  another forum:

https://www.tapatalk.com/groups/clevelands/camshaft-lunati-voodoo-62503-t17527.html

This cam selection business is very confusing indeed .

Cool! What software are you using?

Dyno2000. It's old but seems to be fairly accurate.

 

[EvilPuppetMaster]

So I got the engine back and look what I have discovered.... they had trouble installing their headers and covered 30-40% of exhaust port . No wonder engine had hard time pushing all that air out at high rpm

 

[kusanagi]

I had a similar misalignment with my headers on these heads. To fix this I made a template up using the port on the head as a guide ( a piece of cardboard ) then I modified the flange area on my old headers to match, as they were an old set of Blackjack 2v headers they did not require much work ( the ports were very closely aligned and only required a little welding and grinding to enlarge them to match ).