Tuning my 400 with 915 heads and Hughes cam

[firefighter3931]

I used the steel shim gaskets on this engine
and  the Heads are fitted with 2,14 int valve and 1,81 exh valve, ferrea.
/Linus

That's encouraging news.  

Where is the initial timing set ? A low compression build with lots of cam is going to want lots of initial timing....probably 25+ at idle if not more.  

What i would do is adjust the base timing for max vacuum at idle and see what you've got....then modify the advance plate to limit mechanical advance. 



Ron

[mopar400]

Thanx Ron, The timing is now set at aprox 25*, I havent got a timin tape on yet but as soon as I do
I will be able to set the timing more accurately, and check total timing.
And I can try to use manifold vacuum ibstead of ported, and maybe play around with the mechanical advance..

Havent got around to do a comp test yet
but i dont think is is the problem, I leak tested the manifold
and carb and vacuum hoses with some start gas, no leaks found.
Its wacation time for me so I wont be able to work on the car for a week or so,
I´ll be updating the thread when I´ve know moore..

/Linus

[mopar400]

ok some update..
I did some tuning today on my "former smog engine"..
I did as U told Ron, set the timing for highest vacuum, this occured
at about 30* (its a little difficult to se cos the timing tab is in the way! so the tape isnt so much help anyway
but about 30*, the vacuum reading then was 10 mm hg

and then I tested total advance at app 2500-3000rpm it
read about 35-40*..
(maybe some of the figures arnt excact, little hard to read...)

I then took it for a drive and it behaved GOOD!
Takes of and runs strong through the whole range!

BUT I have one concern!
And I think its carb related.
When I take of the power dosnt come until I'm doing about 50-60 mph
Its like turning on a tap first slowly, slowly then Ka boom
its wide open and just takes of!
I figured its the secondaries on my thermoquad that needs to be adjusted
I´ve heard that u can set them to open soner, (the preload of the venturies or something)
Any ideas!

/Linus

[Nacho-RT74]

I figured its the secondaries on my thermoquad that needs to be adjusted
I´ve heard that u can set them to open soner, (the preload of the venturies or something)
Any ideas!

there is a link between both throttles shafts that can be bended to any custom setup.

[firefighter3931]

ok some update..
I did some tuning today on my "former smog engine"..
I did as U told Ron, set the timing for highest vacuum, this occured
at about 30* (its a little difficult to se cos the timing tab is in the way! so the tape isnt so much help anyway
but about 30*, the vacuum reading then was 10 mm hg

and then I tested total advance at app 2500-3000rpm it
read about 35-40*..
(maybe some of the figures arnt excact, little hard to read...)

I then took it for a drive and it behaved GOOD!
Takes of and runs strong through the whole range!

BUT I have one concern!
And I think its carb related.
When I take of the power dosnt come until I'm doing about 50-60 mph
Its like turning on a tap first slowly, slowly then Ka boom
its wide open and just takes of!
I figured its the secondaries on my thermoquad that needs to be adjusted
I´ve heard that u can set them to open soner, (the preload of the venturies or something)
Any ideas!

/Linus

That sounds much better....you're giving the engine what it's asking for with the increased base timing. The fact that the idle vacuum picked up 3in hg is a proof that you're headed in the right direction. 

I use Holley carbs exclusively and prefer double pumpers with mechanical secondaries. There is no question as to when they are opening. 


Ron

[Challenger340]

Dunno what you were looking for in the way of power ?
but,
IMO,
Ya get the Timing/Fuel/And Tune figured out,
Your gonna have a powerhouse on your hands !

I've used that Cam from Hughes a coupla times, (at the Customers supply/request), more just for the "Musclecar sound" THEY wanted, and I was PLENTY surprised at the output !
even at relatively lower CR's, 9.0:1 ?

I'm with Ron, in that "on paper" that Cam seems wrong for the Application ?
I'd have never "picked it" myself, good thing, I would have been wrong !
That Said,
I suspect Hughes are doing something goofy with the closing ramps, although, I've never V-Blocked & Plotted one to know for sure,
because,
the thing pulls Freight Trains for Power !

Just IMO
Bob out.

[mopar400]

there is a link between both throttles shafts that can be bended to any custom setup.

[/quote]

ok Nacho, si it the one going from the choke valve to the air valve?
How do you do it, do u just bend it..how much?

/Linus

[Nacho-RT74]

http://imperialclub.com/Repair/Lit/Master/290/index.htm

[mopar400]

HI there
Is it bad i any way to set the timing to high? I set it at 35* today (initial)
and it drove good, vacuum inreased, 
shouldn´t it detonate at those numbers?
Everyone says to me "dont push the ini timing to high or it will detonate
but i´ve had no such problems...yet
Is it cause my relativly low compression, i believe I´ve got "dished" pistons (I believe its called that)
/Linus

[firefighter3931]

HI there
Is it bad i any way to set the timing to high? I set it at 35* today (initial)
and it drove good, vacuum inreased, 
shouldn´t it detonate at those numbers?
Everyone says to me "dont push the ini timing to high or it will detonate
but i´ve had no such problems...yet
Is it cause my relativly low compression, i believe I´ve got "dished" pistons (I believe its called that)
/Linus

How does the engine restart when warm ? Does it start easy ?

Fwiw i had mine at 35* at idle...that's where it ran best !

Have a look at the plugs for signs of detonation (small black/silver specs on the porcelin) and if you don't see any leave it alone. Big cams + low compression like LOTS of timing....as you've found out 


Ron 

[mopar400]

ok thanks Ron
it seemed a litle harder to crank than usual so maybe
I´ll back it of just a bit..
and I look for black spots on he plugs to!
/Linus

[greenpigs]

Yep check the plugs and if good back off the timing a little. It should start easy and if not you might want to pull timing out.