Pump Gas Build some questions after dyno session..

Lem Evans wrote: If it has vacuum brakes you'll have to cam the brakes not the engine.

Totally true ... if this is to be a "driver" with power brakes then THAT is the priority here,  So, everything else, especially the valve timing, must revolve around that priority while getting it to make the most power it can within the range it is happiest.

Scot, how much is much?

Lem Evans wrote:Scot, how much is much?

Based on an 89% throat which is pretty typical for production performance stuff, at 6000 the airspeed is already faster than I would want. Personally, I would have a larger throat or even valve but the airspeed is within "acceptable" limits. At least with my program and IMO. YMMV.
That doesn't mean the engine won't peak higher and make power above there, it just means the cam is going to have to make up for it but I'd say above 64-6500 you're really looking at diminishing returns.

Lem Evans wrote:

Straubtech wrote:

Lem Evans wrote:

Straubtech wrote:

68galaxie wrote:

Scott Foxwell wrote:

dfree383 wrote:
The heads are big enough to feed this as a street engine,

A 588 with a 2.20 intake valve???
lol... hardly.

Still enough valve and head to make a very potent street engine.

Based on the math the 2.200 will support it to 5800 rpm.  After that it is a restriction.

Okay that's with a 588". What's the math say about 547"? 4.400" x 4.5" 6.700" rod.

Email me the engine specs and the rpm range you want the power.

I was just asking at what rpm the 2.200" valve would be the restriction in a 547".

6200 rpm. Stroke swallows up head potential at a much greater rate than bore.

Chris S.,

Are you basing your valve size/air speed/max rpm calculations to an 89% throat as Mr. Foxwell has stated?
For a performance build I don't think anyone would use an 89% throat. (I wouldn't)
Certainly not when one is building for a 500+ engine size.

68galaxie wrote:Chris S.,

Are you basing your valve size/air speed/max rpm calculations to an 89% throat as Mr. Foxwell has stated?
For a performance build I don't think anyone would use an 89% throat. (I wouldn't)
Certainly not when one is building for a 500+ engine size.

I'm basing the valve size on right at 90%.

68galaxie wrote:Chris S.,

Are you basing your valve size/air speed/max rpm calculations to an 89% throat as Mr. Foxwell has stated?
For a performance build I don't think anyone would use an 89% throat. (I wouldn't)
Certainly not when one is building for a 500+ engine size.

I used that number because very few heads that I see from a manufacturer with a 45* valve job have a 90% throat. In fact, I don't know of any. I do valve upgrades all the time and I'll go as big as 91.5% with a 45* valve job and that's the limit. Having said that, if the 89% throat gives you the area you need, there's nothing wrong with it. It certainly gives more bottom angles to work with and might be beneficial in some cases.

Wow Thanks guys this has been a real educational and interesting thread for me anyway... and has given me a direction to go forward with to make this mismatched conbination of parts into a more workable happier engine..

A new camshaft with apropriate valve timing to suit the engine and vehicle combination with a stronger power curve were it's needed with decent vacuum and reasonable street manners..

In all fairness the heads were originally ported to suit a smaller cubic inch combo by my head porter years ago..so most of the work was pretty much bowl seat and short turn work.. so i will talk to him about a bigger intake valve and i'm sure he will size the port correctly to suit the bigger engine and vehicle combo..

I'll re-check the valve springs pressures soon and check how far away from coil bind i am make sure there's no problem there...

Headers will need a rework but i have an old set of tri-y's that i changed the secondary to 2 1/2" inch and i'll make up some decent collectors worth a try..

I found some dyno runs of the engine on the day i'll see if i can load them maybe you guys will hear something i couldn't..i've only dynoed 3 engine over the last ten years so my experience is very limited..
The engine did sound a little flat to me at the top end of the run..but as i said before hopefully it wasn't close to valve float.. i checked the valve tips for any signs of the wagon wheel deal..but everything looked good to my newby eye..

Warning there may be some swearing! we are Aussie's haha..

Has the engine been ran in the vehicle yet?

It's been on the road since last september..running real well between killing stuff Lol (diff centre and gearboxes) finding the weak links in the drive train..the tune up seems pretty good for street driving 2 circuit 1050 domi.. 86 primary and a 4.5 powervalve plugs don't load up seems pretty crisp taken to 6600rpm once when i was testing and tuning in second gear got there quick...c6 has a terrible flair into top gear so i didn't push it..it's getting a new c6 as we speak we were waiting for months for parts for it..  

Never been able to get square-ish jetting and no powervalve deal to work on the street for me.. black bush in the dizzy and particularly the 2 light silver springs seemed to really help the most with idle quality off idle transition..

our racing season starts in about 2 months..problem is 10.99 in the quarter is the cut off ..so we will probably get told to take a hike after a couple of runs then it's his decision to cage or not to cage..Lol

So you are not running the 1150 QFX it was dynoed with.

Sounds like you have got some performance to get from behind the flexplate.

I did retard the camshaft timing 4 degree's on the crank keyway (worked out at 18.5 btdc) for the dyno session..from what compcams recommended it be installed at intake 22 btdc ..my rough guess was it may help it hang on longer in the top end as i was worried the 264 271 @.050 might get wheezy in the top end with the big cubes.. but of course we know now there were other factors in that..

 Anyway i may put it back to comps recommended spec as for now it will be a street driven vehicle for the rest of the year it may help it run a little better down low....I have to pull the timing cover anyway to repair a annoying light leak..

  I started a thread ..Australian Landau Coupe BBF Build.. in the proven builds section if anybody interested in seeing what it went into..

"the pushrods are 3/8 .80 thou wall ..I hated putting them in.. nobody sells thick wall pushrods here in Oz that i know of which is stupid.."

Considering the spring package and rpm range I don't see the rods to be critical. I'd direct that attention to a Jomar stud girdle kit.

[quote="Lem Evans"]So you are not running the 1150 QFX it was dynoed with.

Sounds like you have got some performance to get from behind the flexplate. [/quote

yes that's correct the 1150 QFX was my carb.. it did seem to help the numbers right through the rev range over the 1050 2 circuit.. though that was at wide open throttle... in the car the 1150 QFX ran like a Champ!! idle ..off idle transition was great.. when i put his 1050 back on it took abit to get it to idle decent and never has run quite as good as 1150 QFX that Bobby at Competition Carbs reworked did a great job inmo i won't sell it... you know the deal sometimes you go through 3 or 4 carbs before you get one that runs like a champ!..

Yes the rear of this car will need alot of work to put the power down..stock leaf spring suspension ...4 links etc are a no no here illegal for leaf spring vehicles mostly... i have a set of mono's and caltrac's for my car i'll try them on his..he is tire limited to about 29 x 11.5's or a little wider stock wheel tubs..

Lem Evans wrote:
"the pushrods are 3/8 .80 thou wall ..I hated putting them in.. nobody sells thick wall pushrods here in Oz that i know of which is stupid.."

Considering the spring package and rpm range I don't see the rods to be critical. I'd direct that attention to a Jomar stud girdle kit.  

100% .. they are on the shopping list!!...all i have to do is persuade my buddy to pay for them Lol..  

.

nascar429 wrote:Maybe you guys smarter than me could possibly see anything in this dyno sheet worth discussing.... Please ignore the air fuel ratio as i don't believe it was working at the time..

Anyway i read something i thought was interesting from a member on this forum recently " when a engine go's flat on power for 400 or more rpm it is smothering"....doesn't have enough exhaust duration to evac the cylinder.. At the peak rpm it starts this, the exhaust duration is maxed out".. could this be happening here?

Pulled the covers after the dyno.. didn't see any evidence of wagon wheeling on the valve tips...I'm assuming" ( not a good practice) it wasn't valve floating i could be wrong...I've read if an engine is still consuming air at peak rpm by the SCFM numbers on a dyno pull that it is usually not floating the valves..?

Ford Racing SCJ head 2.20 1.76 valves, Ti retainers, isky springs 235lbs seat 595lbs open..comp street solid roller 264 271 @ .050 689 698 lift 111 lobe..

i'm not a engine builder by any means only build an engine every 2 years or so for fun ..by the time i get round to the next engine i've forgotten half the stuff i've learnt   ..  any thoughts..?      

Is that cam a custom xtreme SR using lobes 4878 and 4879? Cause if it is I used those lobes ground on a 110 and developed 900hp in the A460 headed 566
https://www.429-460.com/t26283-566-a460-head

Racerrick wrote:

Is that cam a custom xtreme SR using lobes 4878 and 4879? Cause if it is I used those lobes ground on a 110 and developed 900hp in the A460 headed 566
 https://www.429-460.com/t26283-566-a460-head[/quote]

yes that's correct the same lobes..your A460 headed deal is a great build and you are obviously very fussy.. i've seen similar pumpgas A460 builds over the years and they make outstanding power even with conservative cams like yours..

A Higher Port and big valves is what is needed for serious power with a Big Cube BBF inmo..if you want to step the HP up, above the usual 650 to 800hp pump gas range...would love to try an A460 pump gas build.. but unfortunately our Aussie engine bays aren't wide enough..so most people i know here don't want to modifiy there engine bays.. licencing laws are pretty strict over here.

Straubtech wrote:Here is what the engine wants:

.689/670
258/276
107 LSA

Will make more average HP and torque by 41HP and 58#/ft then what is in it.  

Wow Chris that would be a great improvement to say the least...a smarter way of doing things..more average power/torque to excelerate this heavy brick down the track or street..would those improved numbers be in the same 4500 to 6500rpm range?..and maybe not get so wheezy at 6k onwards?....how would the 107LSA effect the driveability and vacuum over the current camshaft?..

264 271 @.050
689 698
111 lobe sep.

A heavier wall pushrod sure wouldn't hurt. I don't even run .080 wall in out hyd. roller engines.

nascar429 wrote:

Straubtech wrote:Here is what the engine wants:

.689/670
258/276
107 LSA

Will make more average HP and torque by 41HP and 58#/ft then what is in it.  

Wow Chris that would be a great improvement to say the least...a smarter way of doing things..more average power/torque to excelerate this heavy brick down the track or street..would those improved numbers be in the same 4500 to 6500rpm range?..and maybe not get so wheezy at 6k onwards?....how would the 107LSA effect the driveability and vacuum over the current camshaft?..

264 271 @.050
689 698
111 lobe sep.

Driveability and vacuum will improve. LSA is a sum of numbers.....its' meaningless except to a marketing guy because its quick and dirty to market with. The events are what matters.

Scott Foxwell wrote:A heavier wall pushrod sure wouldn't hurt. I don't even run .080 wall in out hyd. roller engines.

A stud girdle won't hurt either.

Lem Evans wrote:

Scott Foxwell wrote:A heavier wall pushrod sure wouldn't hurt. I don't even run .080 wall in out hyd. roller engines.

A stud girdle won't hurt either.

Absolutely!