I just got casting #s from builder of my engine and found out that I have the "880" block that is used for the ZZ4 crate so its roller. Builder says they put an in house ground flat tappet with specs...

Adv. Dur. for the Intakes- .260 Exhaust- .264.
Duration @.050 Intakes- .204 exhaust- .214.
Cam lift for the intakes- .284 exhaust- .300.
Valve lift for the intakes- .426 exhaust- .450.
Lobe separation is 113’

I have "191" heads, flat top pistons, and builder claims comp ratio is right around 9.5:1, holley TBI, 3704 intake, & long tubes.

This motor is in an 82 P/U on 37s and SM465 trans so I want the power to be from idle to 4-4500rpms tops.

Im trying to figure out if swapping over to roller cam is gonna benefit me enough to justify it. I understand the basic benefits of roller and the cost involved but I dont understand cams enough to really know what I can get out of one or what my limitations in terms of duration and lift are or how those have positive or negative effect on my goals.

I can datalog and I understand what tuning is involved but I don't know how far the TBI management can be stretched before tuning can't make up for it.

Due to vendor complications I don't know if I can mention the particular individual that is taking care of tuning for me but they are a member of this forum.

 

Since it's a factory roller block, you can use the factory roller stuff in it; not too much $$$ there.

IMO the initial cost difference between a flat-tappet and a roller is negligible, under those circumstances. Disappears in the noise. Especially when you consider the cost of a flat-tappet wipeout, and how common those are these days, the best efforts of all builders notwithstanding.

Don't even bother over-thinking it. Just do it.

 

Ok so cost aside. In my particular combo am I leaving much on the table by not running roller? How much bigger cam can I go or do I even want bigger? Low RPM torque is the goal.

I likely will swap to roller just for the efficiency and reliability of it but I would like to squeeze every last drop out of it at the same time.

 

Another vote for using a roller cam. Just look at a few cam specs for roller cams compared to flat tapper cams. With a roller you can run a higher lift while keeping a milder duration which will keep the powerband at a reasonable level while producing a larger amount of power. If cost is the only factor holding you back right now buy used lifters and cam. Rollers are far less likely to wipe out a lobe and the lifters are reusable making used parts ok to use.

 

Cost is not whats holding me back. The lack of cam knowledge is whats holding me back. What duration range is gonna best get me what I want? What LSA? Im assuming 114'-117' range? Compared to the cam Im currently running how does a LT1 cam stack up against it? How much lift and duration can I go with my TBI and heads? Do I even want higher lift or more duration?


http://www.compcams.com/Company/CC/c...csid=1550&sb=2

Big improvement with this cam? Still within TBI capabilities?

That cam is $300. Is it worth that much considering the price of a used LT1 or LT4 cam?

 

For a 4WD ... F-body ... that cam will be fine. FAR better than any stock cam.

 

You can get new Delphi OEM roller lifters thru Skip White for $100.As for cams,consider the Ramjet cam(#14097395).It is used in the 350 Ramjet w/ 1.6 rockers,& also used in the HT383.It would be a really good fit in your build.It produces a flat torque curve from just over 1600 rpms out to 4800 or so.They can be bought as new pullouts on Ebay for $120.LSA/ICL = 109/109. @ .050 dur= 197/207. Lift w/1.5 rocker = .431/.451.also,if you don't mind me asking,what flat top pistons are you using in this build?

 

I dont think it will make a huge difference for what youre doing.

 

I don't have a stock cam right now though.
That ramjet cam has pretty close specs to the flat tappet thats in there right now. I have no idea what the pistons are, the engine was built by bond mechanical in Vancouver BC. I called them and all they told me was that they are flat top pistons and comp ratio is 9-9.5:1. I bought it second hand.
Thats what I was wondering. I still think that going roller is a good idea just for the standard benefits of it but when comparing to the cam I already have in there is there really much more I can do?

I will either pull everything out of a vortec motor or just buy the whole conversion kit from GM. They sell it for $250

 

As far as lift,they are similar.The 109/109 is where you're gonna see the big difference.The Ramjet builds good cylinder psi down low to produce 375 to 380 ft/lb of torque from very low rpm up to about about 4800.You can usually expect to pick up about 10 HP using a roller vs a flat tappet of similar specs,not to mention all the other benefits.

 

It has LSA of 109' though. Will the TBI be ok with it?

With my current 113' flat tappet cam I get 21in-hg of vacuum with engine at 160f / 800rpm idle

 

Even with the 109 LSA,it runs good with TBI.It has very little overlap.I,ve seen them run OK with stock tunes,but,tuning it will really make a big difference.Smoothidle & good vacuum.it's also very easy on the valvetrain.Using 1.6 rockers works well too.

 

Awesome! Thank you.

Looks like that could be my best option. I like the 1.6 idea too. Would make overall lift I-.481/E-.459

Hows the math work to figure out how much rocker ratio effects duration @.50?

 

IDK the exact formula,but'from I've been told by experienced ppl,@ .050 lift will gain approx 2* goin from 1.5 to 1.6.

 

With a good tune & fuel along with a good exhaust,you should easily be in the 330HP/380ft/lb range.

 

I can confirm that 2 degrees. I have a CamPro plot right here of a similar cam, and the difference in duration between .050 and .053 lift is 2.2 degrees
Duration at .050" tappet lift doesn't change of course, but the effect at the valve, what the motor sees, certainly does.

 

That's what I had always beentold.I know some say it is much more,but,I have always used that when figuring.Thanks for the confirmation !!!