3200 vs 4200?

[rbrettctd]

Is there any drawbacks to the 4200 spring? I figure there must be or itd be more popular than the 32. Correct me if Im stupid, but I think I read something bout having to do some head work to prevent damage with the 4200.

[2001shrtbedcummins]

heavier valve springs to prevent them from making nice drawings on the pistons

[2muchtq]

Rampower put the 4200 spring in his truck. I have his old 3200 spring in my truck.


The difference (on his truck anyhow) in throttle response is VERY noticeable. It snaps to 3K very fast.


We clipped a few coils off the spring to make it the same length as the 3200 spring. So far... so good.


He has heavy springs to keep from valves floating and making circles in pistons.

[6DoubleDuece]

You can really notice a difference with the throttle responce, it's very fast compared to a 3200 spring.

You need to run 60lb valve springs.

some people trim it but I just bent the ends around until I got it the same length as the 366 spring.


I have no complaints so far! I have ran mine out to 3900 RPM and 433 HP

Thanks
Brenden

[oldestof11]

How much do 60lb springs cost?

[rbrettctd]

Looks like piers has them for $55.

[Begle1]

I don't see why you need the valve springs... It's not like the governor spring is going to make you rev above 3500 RPM.

I have a 366 spring, but my truck really doesn't like to go above 3000 RPM. I don't know if I'm just running out of fuel or if the spring isn't stretched out let, or if I'm not getting full travel somewhere, but I could sure use that extra 200 RPM. Well, I could use an extra 1000 RPM, but I'd be happy as a clam with an extra 200.

I spool right up to 90, but it takes as long to go from 90 to 100 as it used to take to go from 70 to 80.

[gman07]

I think different trucks are different. Begle, do you have your high idle screw backed out?

Mine has no problem with 3300-3400 RPM.

[PToombs]

My 3200 gsk pulls right to 3500. I get out of it 'cause I haven't put my 60# springs in yet. I asked Mark at PDR about 60# springs, he said change them all, intake and exhaust, if you plan on going above 3400 or so.

[Begle1]

I think different trucks are different. Begle, do you have your high idle screw backed out?

Err.... Humm...





Would that make a difference?

[bgilbert]

From my experience, with a 4200 gov spring trimmed to stock length, my engine defueled at 2700rpm on the dyno. With a 3200 spring it starts defueling between 3000 and 3200rpm. No other changes between the two dyno runs, only springs. Ask Brian where the VE makes the most power... it's well below 3200rpm. Where your engine/truck pulls to and where it defuels is two very different things. Just playing on the street ain't gonna show it. Only a dyno sheet.

[LEADFOOT93]

No, not a dyno sheet, sled pulling is why you want the 4200 beacause you need the rpm's, I run the 4200 and will never go back to a 3200.

From my experience, with a 4200 gov spring trimmed to stock length, my engine defueled at 2700rpm on the dyno. With a 3200 spring it starts defueling between 3000 and 3200rpm. No other changes between the two dyno runs, only springs. Ask Brian where the VE makes the most power... it's well below 3200rpm. Where your engine/truck pulls to and where it defuels is two very different things. Just playing on the street ain't gonna show it. Only a dyno sheet.

[6DoubleDuece]

Or Drag racing. It's nice to not have to make that shift into 5th gear.

I don't defuel with my 4200 spring until 3200-3300 RPM


Thanks
Brenden

[bgilbert]

No, not a dyno sheet, sled pulling is why you want the 4200 beacause you need the rpm's, I run the 4200 and will never go back to a 3200.

I'm pretty sure a p-pump would be better suited for sled pulling as the lowly VE don't make much if any HP above 3200-3500rpm, let alone 4000+. Don't forget a stock truck will spin 4000rpm. On a previous dyno run my truck was still making 350rwhp at 3800rpm, with a 3200rpm spring, go figure. I think it has more to do with timing. I think KTA's dyno sheets have shown big HP (can't remember exactly/maybe ~ 400hp) up to around 4200rpm, with a 3200 (366) spring.

I wish some of you guys with 4200rpm springs would dyno on a real dynojet and then post your sheets, with RPM, not speed on the bottom of the graph. This will show everyone how much HP you're making above say 3200rpm.

[Begle1]

Even if it doesn't make any extra power at a higher RPM, which is pretty likely, why wouldn't one use the 4200 RPM spring?

Sounds like it works fine with 5 minutes of trimming, no downside unless one is in the habit of playing ring-around-the-rosie with their tachometer...