Advantages of advancing the cam on a street engine?

[cjperformance]

E.Roy -- you would need to see the complete spec on that camshaft to judge why it worked the way it apparently did.
Aggressiveness, what are you meaning by this? -the idle quality, cammyness? -or the lobe style/ramp speed etc?
You can take a very mild cam and close the lobe centers up tight and have it idle with an agressive note and make reasonable tq/hp early on. But economy suffers! You cant have it all!
Why not fit a stroker crank or a very small turbo these will give you more low down tq!

[cjperformance]

X2 on QJ.

X3 on QJ.

One of my friends, a Buick guy, posts here every once in a while and he can make a quadrajet perform like no one I've ever seen.

You around, Cheaves?

Watch me get shunned by the world here but i prefer the Thermoquad. QJ and TQ are both good but hard to get many good cores over here and not a lot of folk can confidently work on/maintain them.
Another good factoy carb was the ford holley circa mid 80's with AD boost venturis and idle adjust in the baseplate. When modded they work really well.

[tuffxf]

Gday Craig,
Thermoquads are awesome when set up right! Agree 100%
Cheers

[cjperformance]

Gday Craig,
Thermoquads are awesome when set up right! Agree 100%
Cheers

They dont win in the beauty stakes! They must be one of the ugliest carbs around but yeah they certainly can work well !

[E.Roy]

E.Roy -- you would need to see the complete spec on that camshaft to judge why it worked the way it apparently did.
Aggressiveness, what are you meaning by this? -the idle quality, cammyness? -or the lobe style/ramp speed etc?
You can take a very mild cam and close the lobe centers up tight and have it idle with an agressive note and make reasonable tq/hp early on. But economy suffers! You cant have it all!
Why not fit a stroker crank or a very small turbo these will give you more low down tq!

For same agrresiveness I mean similar lobe profiles and lift. I find trying to make 500 lbft and 400hp a fun challenge and I don't need more than that for the car.
Also, I like keeping this project simple and attainable for me right now

[rfoll]

E.Roy -- you would need to see the complete spec on that camshaft to judge why it worked the way it apparently did.
Aggressiveness, what are you meaning by this? -the idle quality, cammyness? -or the lobe style/ramp speed etc?
You can take a very mild cam and close the lobe centers up tight and have it idle with an agressive note and make reasonable tq/hp early on. But economy suffers! You cant have it all!
Why not fit a stroker crank or a very small turbo these will give you more low down tq!

For same agrresiveness I mean similar lobe profiles and lift. I find trying to make 500 lbft and 400hp a fun challenge and I don't need more than that for the car.
Also, I like keeping this project simple and attainable for me right now

If you want 500 lb ft and 400 hp, toss the 350 and build a 400. I don't personally have the time to fight with an engine to make it do something it is incapable of achieving.

[E.Roy]

E.Roy -- you would need to see the complete spec on that camshaft to judge why it worked the way it apparently did.
Aggressiveness, what are you meaning by this? -the idle quality, cammyness? -or the lobe style/ramp speed etc?
You can take a very mild cam and close the lobe centers up tight and have it idle with an agressive note and make reasonable tq/hp early on. But economy suffers! You cant have it all!
Why not fit a stroker crank or a very small turbo these will give you more low down tq!

For same agrresiveness I mean similar lobe profiles and lift. I find trying to make 500 lbft and 400hp a fun challenge and I don't need more than that for the car.
Also, I like keeping this project simple and attainable for me right now

If you want 500 lb ft and 400 hp, toss the 350 and build a 400. I don't personally have the time to fight with an engine to make it do something it is incapable of achieving.

Good idea, 400ci for 550 lbft haha

[E.Roy]

Gaining TQ/ci is very difficult and gets harder the higher you get. You can't just put a smaller cam in and gain torque or make the runners smaller and gain torque. A certain amount of piston speed/rpm is necessary to get enough VE.

To get where you want would require some low friction components, thin rings, smaller journals etc. No special cam and heads will get you there alone. Bolt the EMC 353 heads, cam, intake and headers on a stock short block and you'd lose considerable torque. 500ft-lbs can be done, but I don't think it can at 3500rpm.

Rick

Rick,

I read over the HotRod article on the EMC 353 engine again. Seems like you're part of that team effort right? I see what you're saying about midrange being a big factor in the design of the engine.
I did notice the Motown single plane intake was used, so it seems a dual plane intake could help increase low rpm torque on that engine if desired.
Also, is the cam duration fairly moderate for what I'm assuming is a solid lifter cam?

Thanks, Eric

[Geoff2]

Thermoquad, great carb, the most underrated 4 bbl carb ever made.

I have installed dozens over the years. QJs are good too, but the TQ with the dual float bowls is better. TQ, a QJ on steroids!

[ptuomov]

Over generalizing, is it correct to take as s starting point that “too small” cams run best retarded and ”too large” cams run best advanced?

[cjperformance]

Over generalizing, is it correct to take as s starting point that “too small” cams run best retarded and ”too large” cams run best advanced?

As a very loose over generalization yes.

[Rick360]

Gaining TQ/ci is very difficult and gets harder the higher you get. You can't just put a smaller cam in and gain torque or make the runners smaller and gain torque. A certain amount of piston speed/rpm is necessary to get enough VE.

To get where you want would require some low friction components, thin rings, smaller journals etc. No special cam and heads will get you there alone. Bolt the EMC 353 heads, cam, intake and headers on a stock short block and you'd lose considerable torque. 500ft-lbs can be done, but I don't think it can at 3500rpm.

Rick

Rick,

I read over the HotRod article on the EMC 353 engine again. Seems like you're part of that team effort right? I see what you're saying about midrange being a big factor in the design of the engine.
I did notice the Motown single plane intake was used, so it seems a dual plane intake could help increase low rpm torque on that engine if desired.
Also, is the cam duration fairly moderate for what I'm assuming is a solid lifter cam?

Thanks, Eric

You might want to read this Speedtalk thread about that engine too. Randy331 and CGT who post here are Creason team members too https://www.speed-talk.com/forum/viewtopic.php?f=1&t=51911

The 353 cam has about as much velocity as a stock lifter diameter can have. It had high ratio rockers to help the open/close rate at the valve and stay under the .600" valve lift rule.

A ported dual plane intake was tested but hurt the score a LOT. I don't remember for sure but I think the torque rpm was lower with the 2-plane but the torque peak was not any higher than with the single plane.

Rick

[E.Roy]

You might want to read this Speedtalk thread about that engine too. Randy331 and CGT who post here are Creason team members too https://www.speed-talk.com/forum/viewtopic.php?f=1&t=51911

The 353 cam has about as much velocity as a stock lifter diameter can have. It had high ratio rockers to help the open/close rate at the valve and stay under the .600" valve lift rule.

A ported dual plane intake was tested but hurt the score a LOT. I don't remember for sure but I think the torque rpm was lower with the 2-plane but the torque peak was not any higher than with the single plane.

Rick

Awesome, thank you for the link. Congrats on the results in EMC.

Another engine I just found for evidence is a 372ci engine they dyno'd on the Engine Masters show episode 19 "Camshaft Specs explained" using the same Comp XE276HR cam I was considering.

That cam resulted in an impressive 467 lbft about 4,400rpm and 470 hp @6,000 with AFR 195s and claimed ~10.3:1 compression. Yeah I know I don't have same heads but I feel my carefully ported vortec heads might match or beat those in the 3,000-4,000 range. It's good to see that cam in action to help choose the right specs.

https://m.youtube.com/watch?v=9LTDHiUftlU

[GARY C]

You might want to read this Speedtalk thread about that engine too. Randy331 and CGT who post here are Creason team members too https://www.speed-talk.com/forum/viewtopic.php?f=1&t=51911

The 353 cam has about as much velocity as a stock lifter diameter can have. It had high ratio rockers to help the open/close rate at the valve and stay under the .600" valve lift rule.

A ported dual plane intake was tested but hurt the score a LOT. I don't remember for sure but I think the torque rpm was lower with the 2-plane but the torque peak was not any higher than with the single plane.

Rick

Awesome, thank you for the link. Congrats on the results in EMC.

Another engine I just found for evidence is a 372ci engine they dyno'd on the Engine Masters show episode 19 "Camshaft Specs explained" using the same Comp XE276HR cam I was considering.

That cam resulted in an impressive 467 lbft about 4,400rpm and 470 hp @6,000 with AFR 195s and claimed ~10.3:1 compression. Yeah I know I don't have same heads but I feel my carefully ported vortec heads might match or beat those in the 3,000-4,000 range. It's good to see that cam in action to help choose the right specs.

https://m.youtube.com/watch?v=9LTDHiUftlU

It would have been interesting if they had followed up the first test with a higher ratio intake rocker, tested intake center-line for best position and then tried a small single plane.

[CGT]

It would have been interesting if they had followed up the first test with a higher ratio intake rocker, tested intake center-line for best position and then tried a small single plane.

Or adjusted the intake centerline to the 500ftlb level? Just messing with you E.roy!