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Engine/Cam gurus

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skyhigh4by

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I got the company that built my engine to pull the build card for me to get casting numbers. The block according to mortec is..

10243880...350...95-00...2 or 4...Vortec truck, Gen.I crate motors and "ZZ4", roller cam, one piece rear seal

The heads are 191 cast and I know all I need to know about them.

Builder said they make their own cams in house and the one they put in was flat tappet and that they put in flat top pistons. My cam specs are....

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’

My question is am I safe to assume that block is "roller ready" and would there be a lot to gain by switching to roller based on what Ive already got AND how big of a roller cam could I go before Ive gone beyond the ability of the TBI computer and the stock 191 valve springs.

I don't really understand cams that well beyond knowing that more overall lift = more power
 
If '95-00, definitely "roller ready". Need all the pieces, but I was looking at a kit the other day that GM put together that was all lifters, lifter retainer piece, and the individual "dog bones", so that option is out there for new.

Roller cam over a hydraulic all else equal isn't going to make a ton of difference. You've got some increased power due to decreased friction, but IMO you need to get into solid roller territory before the cam profile really matters roller vs. flat tappet. And running TBI, I doubt that is where you are going.

Any cam besides stock is beyond the ability of the computer. It may feel like it runs ok with a different cam, but it's not "right". Your engine has no method of making sure that the engine is running at the proper air fuel ratio under load.

I think the best approach to a cam is make sure you know what you need/want to get out of the engine, and what you will use it for. Then make sure all the components work together to meet that goal...proper size throttle body, correctly sized injectors, enough intake, proper head flow, proper cam, proper compression, proper exhaust, proper torque converter stall speed, proper gears.

If you need upper end power, you build it for that. If it's low end power, build for that. Your cam will end up being whatever it needs to be, but to extract the most power out of the motor (and make sure you don't destroy it), the programming of the ECM will always need addressed.

TBI can be made to work with pretty wild setups, for most with any dreams of driving on the street at any point, it will likely handle anything you'd be likely to throw at it.

I can't stress this enough: there is no "computer friendly" camshaft. That is an utter lie.
 
Sorry I forgot to mention that I am data logging and working with a well respected tuner. I was only curious how far a cam can go before even tuning can't make up for it in the TBI system.

I have a holley TBI w/65lb injectors, Edy TBI intake, longtubes, and above mentioned cam/heads.

Its all in an 82 sm465 w/tons, 4:10s on 37s. Its more of a low rpm kind of machine. Idle to maybe 4500 tops. Just want as much "twist" as I can possibly get out of it. Over all HP isn't the real goal.

So with proper tuning how much bigger of a cam could I go? Would switching over to roller really be worth it given my combo?

Thanks, Ryan
 
You are beyond my expertise in cams...you'd have to start looking at cam profiles, and honestly some of the software out there (desktop dyno, etc) can help in determining how a given cam might work in your setup.

I have no clue how techs for some place like Comp Cams might be able to help, but they might be an option too.

Almost universally, you are going to trade low end for upper end, and IIRC even most simulations don't reflect the power figures at the extreme low end, most start at 2000RPM, which is great with an automatic I suppose, but no good for us with manuals where you may not particularly be lugging the engine, but in 1st and crawling along and want to stomp on it. I'd prefer to be able to have an engine that would be able to power through the gear it's in, instead of having to drop a gear to get the RPM's where the cam and motor start making power.
 
A little bit of playing around on desktop dyno 2000 is showing me that with a similar cam there are gains of 30+hp and 40+ft/lbs to be had by switching from flat tappet to roller.

I was using the Comp XE256 cam file and L31 vortex head file for reference
 
I think DD2K tends to be a bit optimistic in the roller profile vs. flat tappet. I can't confirm that, but I do recall that was one input where the exact same specs gave a large margin to roller, which isn't the case from everything I've ever seen. That exceeds what headers are known to provide, and nearing what a Vortec head will do over an older head.

Anyway, FWIW, this looks like the GM PN you'd want if you were going after all the roller lifter components: 12371042. Pretty reasonable at ~$222.

I'd verify everything about that before ordering, it almost seems too good to be true, unless aftermarket roller lifters have come way down in price. When I did my engine, retrofit rollers were expensive and not as durable as stock ones.


 
I don't know how thrust was handled on the roller motors as factory. Probably would need some sort of thrust button, but that's pretty simple to rectify.

As far as I know, that's pretty much everything, but pushrods would need changed if lifter height is different, which I would expect, and as you mentioned, the roller cam.

Would be interesting to compare the stock Vortec (roller) cam against stock TBI cam specs. I know the Vortec is pretty mild.
 
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