[John Milner]

I am running a 428 in my 74 Ventura and it just dosen't run as hard as I would like. Here is my set up...428, 6x-4 heads @85cc, 9:1 compression, Summit 2802 (224/234 .465 .488), stock '69 cast intake, good 800cfm q-jet, stock HEI with stock weights, etc., stock log manifolds and a too small exhaust system with crossflow muffler, 4 speed and 3:73 gears.

I was really looking for something that would pull hard to around 5,000 rpm and smoke the tires pretty much when I wanted to. It dosen't break the tires loose in 1st unless I dump the clutch. What should I do to make this 428 run better?

[Kybird]

To get things started, I would suggest re-curving the stock HEI. Most had too much vacuum advance and not enough mechanical advance. The Jim Hand book or internet search would have article on re-shaping the stock weights and aftermarket springs, then change the vacuum to an adjustable or other with limited amount of advance. Exhaust should not impact the low RPM's much but will be more of an issue mid range and above. Also need to find optimal initial and total advance. Many posts on this topic.

[Will]

Something's not tuned right. Should have plenty of low end torque.

Kybird's suggestion is a great place to start. How much initial timing (no vac advance) and how much mechanical timing and at what RPM? A good starting place would be 14-16 initial and 34-36 total all in by 2600 RPM.

I'd also be looking at the carb.

As kybird said, the restrictive exhaust shouldn't be hurting the low end much, but it will certainly put a damper on things above 3000 RPM. Get some headers and a minimum 2.5" mandrel bent dual exhaust with X-over on there. That will make a BIG difference to power output from 3000 - 5000 RPM. That cam should easily pull to 5500.

[screamingchief]

Was the cam degreed when installed?

If not I highly recommend doing so.

If you want more bottom end,then you can go ahead and advance the cam some during the degreeing job if it's not already installed advanced a bunch.

Also sounds like some standard fuel/ignition tuning issues too,most certainly the ignition.

Loose the logs for some long branches or get some decent tube headers.

Upgrade the exhaust from there back.

That combo should be plenty strong,so likely there are some small hiccups in the execution of the build somewhere.

[John Milner]

Thanks for the replies. I did not degree the cam when installing it. I simply installed it "dot to dot." Also, what springs do you guys recommend for my HEI? Should I use the weights in the kit or just springs? Hopefully I can get this 428 running like it should.

[AllRise]

Get in touch with Suntuned, he sells a kit that I hear is superior to anything else out there. -Travis

[Hillard]

IMO, definitely update the exhaust. I also think that cam is hurting you. With a 114 lsa it's closing the intake valve too late and bleeding off cylinder pressure. If you were closer to 10:1, that came would work o.k. (although I'm not a big fan of the Summit cams for any application, but that's just my opinion). I'd switch to a Comp Xtreme Energy cam like the XE274H. With a 110 lsa and more aggresive ramp profiles it will have more cylinder pressure and be more responsive.