I was just wondering if you guys believe an LT4 hotcam with 1.6 roller rockers is an appropriate choice for an LB9. I know stock this might be overkill but I plan later down the road on installing a superram base (The plenum is already portmatched to SLP runners) and trickflow super 23 heads.

 

If your using stock heads now, you will definitely need new valve springs too. That is way to much lift for the stock ones. They max out at .460-.480 lift at valve.

I think that cam is too much duration for TPI. I wouldn't go past 214-215 duration @.050 for intake.

A good choice would be a Comp XR 264-HR-12 which is .488/.495 (w/1.5 rockers) 212/218 @.050 for duration with 112 LSA. I have that cam in my 92 and I am very happy with it.

Anyway you go with the cam (other than stock) you will need tuning to get the most from it.

 

That's the only thing I was afraid of with the LT4 hotcam was that the duration was gonna annihilate my low end torque.

Thanks for the recommend. I'll give it a look.

 

FYI, Comp has this same grind available with a 110 LSA. If you get this cam get the 112 LSA. It will work better with your computer.

 

Personally I would not mind running a 110 LSA. It would help scavenge the cylinders better and give a meaner sounding idle. The only problem I see with this is it might cause a large drop in vacuum at idle and I would have to increase the idle speed (Which would circumvent the meaner sounding idle LOL!). Or is there something else I should know about?

As far as the ECM, I think a retune is a given with any cam change, so I should be able to properly tune it right?

 

If you were using a carb I would say go with the 110 LSA. The extra overlap would give idle you're looking for.

You are exactly right, the idle vacuum would be the problem with using the 110 with TPI.

With the XR-264-12 I have a hair over 16 inches at idle.

As for tuning, read up on DIY tuning on this site. Lots of good links and info.

Good luck with your build up.

 

Thanks for the advice. How to you feel this cam worked out for your 305?

 

I am very happy with this cam (XR 264-12). The low end torque is even better than the stock cam. The mid-range is awesome. It pulls hard up top too.

The torque seems to hold on longer and it doesn't fall on its face above 5K. It revs good to 6K now, but I also have a ported Edelbrock base and runners.

The heads. I'm using are World SR Torquers, but I would get the TFS heads if I were building it up again.

With 1.6 rockers this cam has .521/.528 valve lift. I think that's close to the Hot-cam IIRC. The duration is more computer friendly with 212 @.050 on the intake side.

 

With your stall/rear the hotcam would be OK. It would want to shift around 6k. It would also give you something to grow into and work wonders with those TFS 175's and upgraded TPI.

The springs are not the lift limiting factor it's the clearance between the valve seal and the retainer. The stock springs are crap though and have a hard enough time handling stock cams so they need to go. Z06 Ls valve springs are the way to go. They don't carry that "vette" price tag so don't be wary, they are cheaper and better then aftermarket springs at this level. They are like $50 a set. Get the retainers and locks too.

Don't build you're 305 for torque build it for HP.

 

TPI already make excellent torque I am looking to improve on top end HP. What I don't want is for there to be a large shift of torque higher in the RPM range.

I should probably mention I intend on swapping out different rear gears. I was planning 4.10 this car used to be a DD so at one time those gears were not feasible but it has since been retired to project/weekend cruiser with an occasional trip to the strip.

You don't think that's too much lift for a 305? I was told anything over .500 is excessive.

That comp cam also will not work with my engine without a retro fit kit. I have a flat tappet valvetrain.

 

The hotcam is roller too though.

No it's not too much for a 305. The lift limit is as I described before, it has nothing to do with cubes. On my '86 305 heads it was .480 max lift with the stock setup. Aftermarket retainers with standard locks brought it to +.500. With the stock retainers a set of +.050 locks would work too.

Z06 valve springs install at 1.8 (that's .1 higher then stock) you should have plenty of clearance. I'm not sure that would be enough pressure for a flat tappet though.

Why not just copy one of the awesome 305 builds already documented on TGO? The 356RWHP TPI with your stall and gearing would be just nasty.

 

[QUOTE
That comp cam also will not work with my engine without a retro fit kit. I have a flat tappet valvetrain.[/QUOTE]

I'm sorry, I thought you had a later 1pc block since you were considering the hot-cam

 

so what would it take to run the xr264 roller cam in a non roller block ? besides cam what would be some part numbers or parts list of whats needed ??