91 camaro racer

iTrader: (2)

i am looking at upgrading my cam. here is the engine specs...

pre 86 350 4 bolt, trick flow 195 62cc heads, edelbrock performer rpm dual plane intake, holley 4160 600cfm carb, current cam is a lunati bracket master 2 cam with .458 lift, 218 duration @.050, 110 LSA. i have a 700r4 transmission with a 2400 stall converter in it right now. i have 3.73 gears. also, i have full exhaust, hedman longtubes, 2.5" x-pipe with flowmaster super 44's.

i will change the converter if i need to. this will be a mostly weekend trip to the strip car and the occasional weekend drive. it is definitely not a daily driver or anything close to it. max lift with the heads/springs i have now is .520.

right now i am looking at comp cams xe274 p/n 12-246-3 and 286H p/n 12-326-4

would either of these be a decent upgrade from my current cam? or is there any other cam you all would recommend?

sofakingdom

iTrader: (1)

XE274 or XE268. (12-242-2, NOT the 268 you mention)

cardo0

Always match your cam to your compression ratio. To much duration for your compression and its drunk at low RPM. To little duration and u could have detonation while leaving hp on the table.

Measure you piston volume and head chambers with liquid and let us know please.

91 camaro racer

iTrader: (2)

compression ratio is 9.5, cylinder head volume is 62cc.

91 camaro racer

iTrader: (2)

so the 286H is too big of a cam then? or just not suited very well for what i have?

86LG4Bird

iTrader: (1)

Yes, too much intake duration for your CR.
With only 9.5 CR, I'd want no more than the XE268H (224/230). Maybe take advantage of those heads by running 1.6 rockers.

What quench clearance, head gasket, are you running? Any opportunity to improve that and raise your CR at the same time.

cardo0

I see now u have a non-roller block. I think a retro roller is expensive for u but that is where u will find more pwr w/o larger changes. If a retro hyd-roller is to much then a solid roller can be 1/3 or even1/2 less. Something w/single pattern (u have good exh sys) lobe and 110 or less LSA with less than 270* full duration. U will have to do some shopping but that's kinda fun too.

Good luck and hope this helps.

91 camaro racer

iTrader: (2)

not sure about the quench clearance...it is this motor...http://www.summitracing.com/parts/na...7353/overview/ ... with the trickflow heads and not sure about the head gasket thickness. it has been a few years since i put the heads on.

yeah i would like to do a retro fit cam but they are not cheap! looking on jegs and summit it looks like a solid roller is just as much as a hydraulic roller unless i am looking at it wrong. i can search around for hydraulic flat tappet cams with the info you gave and see what i can find. thank you for the help everyone! the search continues.

86LG4Bird

iTrader: (1)

Since you say you're at 9.5 compression now with that motor, that would imply about .026" head gaskets. You could improve things a bit by swapping to .015" gaskets, but I don't know if that 1/4 point of compression is worth your trouble. IIRC, those pistons are the full dish type without a compression pad, so reducing the quench clearance doesn't give the same gains as on a good piston with a quench pad. It still helps some though, with just the 1/4" band around the top of the piston.

cardo0

Oh so u have a Goodwrench 350 also. well Super Chevy did a series of articles on that crate motor called The Goodwrench Quest and u can still call them all up with google. Chevy HP even put them in a book called Small Block Chevy Engine Build Ups that u can still buy on Amazon for
U really need to read it as it dynos that crate 350 w/TFS 195cc heads and a comp HE-268H-10 making 416hp @ 5700 rpm.



Myself i think u need a single pattern cam w/more lift and less full duration (more intensity) like the comp Magnum 270H. And if your heads/springs allow 1.6 rockers i would put them on the intakes only for some more lift/torque (0.501" lift). The next step down from that cam is the 268H High Energy which puts u back to the Lunati cam lift and 0.050" duration but a lot less full duration so if u use that cam definately go with 1.6 rockers on the intakes (0.484" lift). Isky has some interesting flat tappet cams but their online catalog is terrible to use.

Good luck

sofakingdom

iTrader: (1)

Right: where they basically took it apart and threw away every piece except the short block, about the same as anybody else would do with any other smogger 70s POS except for the fact that they voided the only thing that motor has going for it in the process namely the warranty, and built some COMPLETE OTHER motor out of it, same as anybody else would do. And spent ... well, anybody else would have to spend, ... about $2500 or so in the process, on top of the original cost ... to anybody else ... of around $1500. To get around a 350 HP motor as-installed in a chassis, NOT the same as HP you measure on an engine stand.

That article series isn't about "Goodwrench", it's about buying aftermarket parts and bolting them to a block.

TF heads are well and widely known to be hostile to high valve lift. I would not use 1.6 rockers on them AT ALL.

Roller-tappet cams are a YUUUUUUUUJE upgrade over flat-tappet ones in a number of ways, but that's A CHUNK of $$$$. Cam, lifters, push rods, & incidentals are in the neighborhood of $800.

The Comp 268H isn't all that much different from the old BM cam you already have. Not worth busting down the gaskets for IMO.

86LG4Bird

iTrader: (1)

Why would that be? Does TrickFlow use some kind of junk valve guides? Or are you thinking Twisted Wedge heads? I never had a set of those, but a couple of my Ford buddies each ran them over 100k miles without problems.

I agree with that. But he asked......

sofakingdom

iTrader: (1)

2 reasons:

First is, the geometry of where the valves go, is different from stock; which is part of where their particular design emphasis is, to improve flow. Which causes mechanical problems at high lift.

Second, the port design is such that increases in lift produce proportionally lesser gains as the valve opens. Some heads, flow increases more or less linearly with valve opening; others, (Vortec) have really good low-lift flow; others again, the flow isn't all that great at real low lifts, increases rapidly through the moderate lift range, then the increase levels off and slows down when some point is passed. TF heads tend to be in the 3rd category, again, as part of their design (make power w/o requiring high valve train stress).

Not saying "they're no good", "won't work", etc. etc. etc.; only that, whereas some heads respond to high valve lifts, TF heads in general don't.

cardo0

Hostile to high lift? 0.5" high lift?

Yea, I don't know where he got that info. An aftermarket sbc head that can't handle 0.5" lift is unheard of and would be outa business in seconds.

Those long ramps on his current Lunati cam is costing him some compression and 1.6 rockers would add some torque - intakes only though. Flat tappet cams are cheap so why not?

sofakingdom

iTrader: (1)

Didn't say anything about "can't handle".

Why is it that all the n00bz like this one feel it necessary to put words in my mouth that I didn't say? Is THE TRUTH so much at odds with their preconceived prejudices they've developed by reading magazine articles instead of DOING STUFF just that hard to accept? Must be a real shame to go through life like that. I don't mind having a rational discussion with someone who wants to know why I think why I think or who genuinely disagrees for informed reasons; but just making stuff up and attacking me for it, is a whole other level of vermin.

In the case of TF heads vs other heads, graph the curve of lift vs flow. It's REAL instructive as to selecting a cam. You can clearly see the differences in the change in flow rate vs lift, and therefore, whether with any given set of heads, you'll get a benefit from increased lift. Or looked at another way (since a can only creates "peak" lift for a VERY SHORT part of its cycle) where you want your cam's AVERAGE lift to be. In the case of TF heads, they apparently spent a great deal of time and effort in the design, to make high lift unnecessary; especially since in their earlier days, the geometry changes they made, created mechanical issues at higher lifts. But... I guess a n00b wouldn't know about stuff like that. That's OK though, we were all there at one time, some of us just had the sense to keep quiet and LEARN instead of spouting off and ... not learning. As the 2-way radio people would say, your receiver can't be working while your transmitter is running.

cardo0

Trick Flow 195's w/62cc chambers flow 250cfm @ 0.5" lift. Anyone on this planet knows that good airflow. Oh so that lift is to much then at 0.4" they only flow 230cfm putting 0.45" lift somewhere near 240cfm. U rather flow 4% less then what can i say? Enjoy your lesser flow. Hey why not install a 0.4" lift cam all the more fun.

OK break is over and now get back on your head.

big hammer

Could always go to a .015 head gasket and shave your heads around .020 to get you closer to 10:1 static compression. That's what I plan on doing

91 camaro racer

iTrader: (2)

yeah i think that is about right for the thickness. i know it wasnt a .041 one.


what would you consider high valve lift? max lift i am looking at is around .515 or so. would that still be under the hostile area?

yeah retro rollers are a no go for me. way too much money for the kit. would you say the xe274 would work good for me?

sofakingdom

iTrader: (1)

XE274 w/ 1.5 rockers should work fine and be a significant upgrade from what you have now. Should give a few hundred more RPM on top (within the limits of the small carb and whatever else) without costing too much low-end torque. Prolly a good idea to renew the valve springs regardless.

91 camaro racer

iTrader: (2)

awesome thank you. yeah i will probably get the whole kit with springs and timing chain

ASE doc

Sofa, it sounds like you're thinking of the twisted wedge heads, where high lift/duration can cause an obvious issue with piston to valve clearance. I use the twisted G2s myself with a very aggressive cam. ABSOLUTELY have to verify clearance before assembling the valve train.

The TFS 23 degree heads, which I believe the OP is using, use stock valve angles and locations. Shouldn't be an issue anymore than any other head. TFS uses sintered bronze guides, the better option of guide materials.

ASE doc

To the OP, I would say that first off, your carb is too small for your combination. For any performance 350, I start with 650 and go up according to power level goal. If you really capitalize on those heads with an aggressive cam, you will want more like 750cfm. I believe the 23 degree 195s flow about 250 or so at .600" that's a 450hp head on a pump gas 350.

If you really want to make the most of those heads, I would look at something in the area of 225-230 degrees at .050. You will run into loss of pressure at low rpms as you get more aggressive. Those heads would love 240 degrees and .600 lift, which you can do with the spring upgrade offered by TFS for that head. The limiting factor is your CR of only 9.5. You can inch your way up to 230, but you will want a looser converter.

I'll tell you what I have right now. I run TFS twisted wedge G2s that flow 270 with my port job. I run 10.2 CR with flat tops, .010 deck and .039 gaskets. My cam is the ZZX from TPIS. Its a single pattern 240 at .050/ .560 lift. I run the .600 lift 1.46 spring package from TFS. I tested cranking compression last year and found 145psi. It starts a little bit touchy but I'm used to it. The idle is really pretty nice. I set idle at 1,000 rpm. I know it used to idle better and some of the low pressure is due to ring and skirt wear on the cheapo pistons and low tension ring package I used 35K miles ago. That will get fixed either with the new 406 build I'm planning or, if I can't get the 406 built soon enough, with new pistons and rings(maybe a bump to 3.75 stroke too) in the meantime.

The motor still screams, even with TPI. It should really like the Edelbrock Pro Flow XT that I'll be installing soon.

Your motor, while CR is lower, is close to what I'll have with the XT in place of the TPI. I would aim for something just a little milder than the ZZX. The 274 is right in that neighborhood. For single pattern, consider something from Comp's Magnum line. The 280 runs 224 at .050/ .525 lift. The 286 puts you right at 230 at .050/ .560 lift, which becomes .600 lift with 1.6 rockers. While most of Comp's roller line states gross lift with 1.6 rockers, the Magnum line is stated with 1.5.

A hyd roller retrofit is just about the best $800 you could spend. JMO

91 camaro racer

iTrader: (2)

yeah i have the 23 degree heads.

91 camaro racer

iTrader: (2)

this is the head i have... http://www.summitracing.com/parts/tf...make/chevrolet

254 at .600 and 253 at .500 230 at .400

yeah i want to upgrade the carb eventually, just not sure when. i would love to put a roller in there but it is way too much for the kit.

ASE doc

If you do stay flat tappet, you need to hang back about 5-10 degrees at .050 to get the same cranking compression. By cranking compression, I really mean idle quality, ease of starting, low speed driveability, all that. In that case the Magnum flat tappet 12-211-2 is 224 at .050 and is probably as big as you should go to be safe. If you want to go for the gusto, the 12-212-2 is 230 @ .050. You do give up lift, along with area under the curve with the flat tappet. No way around it and I wouldn't recommend raising rocker ratio for fear of pealing lobes. If you aren't already, you definitely need to use an oil with as much zinc phosphate as is practical and HTHS of at least 3.5. Use a good break in oil, like comp cams brand, for the break in and 500 miles after. Then something like Valvoline's VR-1 racing oil will do well.

My cam is huge for my engine combination. I decided to go with it because I wanted to push the top end limit of my ported high flow TPI. My heads are capable of much more than the TPI will support anyway. What I found is that I can live with the small loss of low end. In fact, driving it around town even with the 2,300 stall I had before I built the second trans is not a problem. The power I gained with the ZZX over the SLP(224/230 @ .050 503/520 lift) is worth the low speed issues. Like I said, the low speed thing has gotten a little worse over the years due to the cheap rings and pistons I used in the build. It was budget claimer rotating assembly from Speedomotive. You get what you pay for. Upside is, the balance of the assembly was perfect and the tolerances, which my machinist verified for me, were dead on. That;s why the motor has held up as well as it has.

I'll swap to the Pro Flo intake and play with this motor for a few more years. If the cranking pressure gets much worse before I'm ready for the 406, I'll yank this motor, swap in a nice 3.75 stroke crank, have the cyls cut another .010 and maybe have another 50 ponies more than I'll have with the Pro Flo on the 355 as is.

skinny z

Lots of cam advice here (save your money and get a roller!) but you may want to check out this paper on engine oils.
It seems the notion of adding zinc is largely a myth and the proper thing to do is use a quality oil that has the properties you're looking for. Namely high wear properties. Further to that, using an additive can actually reduce the quality of the oil you select.
https://www.thirdgen.org/forums/tech...gine-oils.html

big hammer

I would rather **** glass than use a flat tappet these days

ASE doc

I think I mentioned that while ZDDP is important, it's HTHS rating that really counts. The High Temperature High Shear rating is an oil's ability to hold up under extreme pressure and heat. A rating of 3.5 or higher is a heavy duty oil. The Mobil 1 15W-50 that I use in my 87 is rated at 4.5, which is very good. It also has 1,100ppm of ZDDP. Another thing to look for is A3 or B3 approval. These are the better oils for high load service.