Jack Gibbs - 409 Performance

[models916]

None of the cheap Ebay Chinese roller rockers can handle much over 350. I had ProForm and ProComp on mine and seized up both of them in less than one Summer. I called the vendors and got the open specs. I switched to Crower (700 open) and all is good. My springs are 450 open when new. As the fulcrum locks up, the pushrod will push on the rocker and force the stud to rock. After a couple of hours of this, the stud will snap off. Mine both times snapped the exhaust stud and every other rotation, the cylinder would pop through the intake valve and out the carb.

 

[Don Jacks]

The only way that I know to check the roller lifters would be to remove them and check each one.

 

[El Rat]

Buy the best available. Ask jack he can't afford to have a lifter fail.
It's a pain in the ass but back off rocker if it's going to sit for a long time. If I lived in a cold climate I would heat the oil before I started it. A hot plate against the pan will heat the whole thing in an hour or so!

 

[Don Jacks]

The reason that we backed off the rockers was to help the springs,not so much the rest of the parts.We are blessed with better parts now than we ever had before if we look for,and get off the wallet enough to buy them.

 

[61BUBBLE348]

What about the Harland Sharp stuff ?

 

[El Rat]

We used to say "the thing" would run over sub standard stuff in the first 60 feet and still go 3.50 in an eighth and make it to the first turn off!

 

[59K9]

can anyone post up jacks web site...he sounds like an interesting gent...I'm gettin ready to build my 348 and sure could use some sage advice...

 

[Iowa 409 Guy]

Search 409 Performance

 

[Don Jacks]

The web site it's self won't help you much,but it has a phone number.Call him,he's very personable,and will not steer you wrong.

 

[El Rat]

Just remember he has to make a living. Time is money...

 

[59K9]

I've been building cars for 30 years, I understand how that works...thanks

 

[Skip FIx]

I've had good luck with Harland Sharp with my Pontiacs. Their 1.65 Pontiacs do measure closer to 1.7 so I'd double check ratios-pretty much on anyone's rockers.

 

[59K9]

I spoke to jack today, wow, what a nice guy...boy does he like to talk about 409's...looks like I'm gonna have him build a motor for me, I can't see how I could do it for what he's quoting...besides, I have no knowledge on W motors and he knows the tricks...thanks for the referrals fellas...

 

[Don Jacks]

Yes ,just be realistic about what you want it to do,and relay that to Jack.If he suggests a different part or approach,go with it.You will not regret it.

 

[4onthefloor]

Jack put the best parts in there so not worried about quality. Just age.

 

[boxerdog]

Jack put the best parts in there so not worried about quality. Just age.

A lot of us are more worried about age than quality these days. Lol.

 

[59K9]

I told jack what I had, he asked what I've done...I told him my end goal and he told me what engine I was gonna be happy with...I was impressed and yeah boy he likes to talk...

 

[Iowa 409 Guy]

I told jack what I had, he asked what I've done...I told him my end goal and he told me what engine I was gonna be happy with...I was impressed and yeah boy he likes to talk...

Back in 2009 I was looking for a site that I could get info on the W engine. I was asking around on CT and someone sent me here. I ain't been right since. Several guys here spoke highly of Jack, so I contacted him. Jack's talking is what separates him from the rest IMO. He actually KNOWS of what he speaks. When I talked to him about my build he pretty well lead me to what I wanted. I didn't have a clue. I'd had 340hp in my Impala and thought it was time to take one of my spare blocks & heads out of the barrel of oil it had resided in for almost 20 years. The build ended up being close to a race engine, but still had good street manners. I had a 68 Nova with a 325hp 327 and thought it was kinda fast, but when I fired up this engine from Jack, I realized what real hp and torque was. A year later I went to the strip and raced my first legal race on the clock in a car. It's been down hill ever since, and that includes all the bad influences I've met here and at the track. The only wise thing I did was replace the whole drive train before I trashed it. Still learning......just got a lot of good racing advise on a thread last week................

 

[59K9]

I've spent at least 2 hours talking to jack in the last 2 days, boy he talks up a storm when he knows he's talking to a gearhead, they guys knowledge is crazy good, he rattles off numbers that are 60 plus years old like he was reading a script...I own and build a barn full of big block chevies but have no ideas as to whats inside a W motor...I came to the conclusion I couldn't build my motor for much less that he's charging me and with his it's run in and tweaked...that make life so simple...besides, he knows the tricks to make a good motor far better