I took the block and heads to the machine shop. I was informed that if I didnt keep the lifters in order that there could be a potential problem.
Seeing as how a stock cam for the 2.8 costs as much as a performance cam I figured "what the heck" I want more bang for my buck, I couldnt find the Comp 270H, and thier new hot cam for the 60* V6 is the 264. I was also thinking the Crower "Baja Beast" I also figured I could put some 1.6 ratio rockers in while Im at it. I want a definate lope at idle, but I dont want it too rough for the computer to not adjust. Performance valvetrain parts arent expensive, so I dont have to worry about that.
The Crane H260 with stock ratio (~1.50 ratio) rockers is a good cam, and as high as you can go with the stock springs without some machine work (which it sounds like you might be doing anyway). 260H with 1.6 ratio rockers effectively makes it a 272H cam, and the valve guides should be replaced with hardened ones because of the added stress.
For a stock or mildly modified 2.8 V6, I'd suggest the Crane Powermax H260 or Edelbrock #3790. Both are available at Summit Racing. And both come with new lifters.
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11:02 PM
May 25th, 2011
Raydar Member
Posts: 41192 From: Carrollton GA. Out in the... country. Registered: Oct 1999
I had the H-272 in my 3.4 and really liked it. Had a nice thump at idle, but it idled at 950 RPM, and passed emissions with flying colors. However, due to compressed spring height, the 272 will probably require some machine work, and you will have to use aftermarket springs. Or just use the H260 if you don't want to mess with all that.
Since you're into it this far, just choose the correct cam and use 1.52 rockers. 1.6s will just put that much more strain on the lobes and tappets. If you want all that additional lift, just buy a bigger cam. I liked the Comp Cams roller tip rockers. They're a good compromise between stock and full roller.
Also, for any given cam, the smaller the displacement, the more radical the cam will appear. A 260 might be plenty for you.
I got my 272 from Summit.
------------------ Raydar 88 4.9 Formula IMSA Fastback Read Nealz Nuze!Praise the Lowered!
[This message has been edited by Raydar (edited 05-25-2011).]
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12:22 AM
Francis T Member
Posts: 6620 From: spotsylvania va. usa Registered: Oct 2003
If I get a higher lift cam, like the 272, by itself that should put the same amount of stress on as a 260 with 1.6 rockers right?
Everything is at the machine shop, I think I would like to go with a 260 if I can find one I like, but I'd want to put 1.6 rockers on, would that need any extra machining to the valvetrain or anything to make it work?
I'm thinking I want it to be a D.D. with a noticable increase in performance. I want it lopey but not so lopey that it kills in city mpg...
260 with 1.6 roller rockers? yes? no?
If I'm going with a 272 im using 1.5 roller rockers, but these are getting more uncommon.
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07:10 PM
Raydar Member
Posts: 41192 From: Carrollton GA. Out in the... country. Registered: Oct 1999
A 260 with 1.6 rockers has essentially the same lift as a 272. And the same potential coil bind issues. (I'm not sure how the duration works out when 1.6 rockers are used. Probably somewhere between 260 and 272 (advertised.)) The areas that will be under more stress with the 1.6 rockers will be the lobes, tappets, and fulcrums (ball, nut, and rocker stud.)
Having said that, the additional machine work is not a huge issue. Just adds a bit to the price of any head work you're having done. The shop doing your heads will be able to grind the spring seats appropriately if you give him the spec card that comes with the cam, along with your springs, retainers and keepers.
You never did mention what you were doing with the intake system. Stock? Trueleo? (Trueleo rocks!) Carb?
I am having the machine shop bore out the TB and where it mounts on the plenum, I will be doing a port and polish on the heads, intake and exhaust myself.
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08:49 PM
Francis T Member
Posts: 6620 From: spotsylvania va. usa Registered: Oct 2003
I am having the machine shop bore out the TB and where it mounts on the plenum, I will be doing a port and polish on the heads, intake and exhaust myself.
If the above will be the extent of you intake upgrade, the gains from a new cam will not be cost effective [worth the money and effort] - been there. done that-, whereas the engine is still not going to get enough air flow above 4K.
Also, I knqw a lot of people like the 1.6 rockers; but keep in mind they will add wear to cam , especially a high lift one pushing Hi pro valve springs. One other thing, if you do a lot mods, check/replace your rod and main bearings.
The 260 cam should be a good choice but make sure it doesn't have a LSA of 110, 112-114 would be better. Need to minimize the overlap for tuning and idle quality. The 112-114 will give a broader torque curve which would be good on the street. Same goes for the duration as far as tuning and idle go. Duration might only go up 1-2 points using the 1.6 rockers. I have 1.6 rockers on mine. You didn't mention if it was an automatic or stick. If auto I'd go with a bigger stall convertor 2100-2500. A 2.5" exhaust would wake it up too. These are just my opinions. Hope they help.
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10:46 PM
May 26th, 2011
Raydar Member
Posts: 41192 From: Carrollton GA. Out in the... country. Registered: Oct 1999
If the above will be the extent of you intake upgrade, the gains from a new cam will not be cost effective [worth the money and effort] - been there. done that-, whereas the engine is still not going to get enough air flow above 4K.
X2
My 3.4 ran out of steam at about 4500-5000 with a ported TB, but stock upper intake. The intake neck is a *huge* bottleneck. It's too restrictive for porting to be really effective. A 2.8 won't be quite as bad, but the restriction will still tend to minimize the benefits of a big cam.
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12:08 AM
PFF
System Bot
Blacktree Member
Posts: 20770 From: Central Florida Registered: Dec 2001
My old 2.8 (bored & stroked to 3.2) had the stock intake, ported and gasket-matched all the way down to the heads. Then the heads were ported. And the exhaust "logs" were replaced with Trueleo headers. And finally, it had the Edelbrock camshaft with Comp Cams 1.52:1 roller-tip rockers. Midrange torque was nice (180 ft-lb at the wheels). But the power band still took a nose-dive past 5000 RPM. That's just the nature of the beast, with the stock 2.8 intake.
That said, the engine still had a fair amount of pep. It pushed my Fiero down the drag strip in 15.3 seconds. And it was fun to drive around town. But it was definitely not a high-RPM screamer. Actually, I think trying to turn a 2.8 V6 into a high-RPM engine is kinda like trying to turn Rosie O'Donnel into a swimsuit model. Sure, you can eventually accomplish it... but it'll cost ya.
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01:32 AM
AL87 Member
Posts: 2578 From: Bradenton, Florida, United States Registered: Mar 2010
Its an automatic, where would you get a higher stall torque convertor? I really want more torque, that'll help with the cam. I want to free up the stock intake and exhaust system a little, I already know its limitations.
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08:59 AM
AL87 Member
Posts: 2578 From: Bradenton, Florida, United States Registered: Mar 2010
Ok, so I went to the machine shop to chat face to face, and here is what I found:
it turns out the block needs boring out .020 over (machinist says a few bores were out with .008 being the worst). the heads need resurfacing (one .004 out and one .005 out, if im correct on the measurment type used). the heads need a valve-job. (the h.o. heads used a 4-cut grind, yes?). the stock cam needs replacement (OMG YES! cam upgrade coming anyways, lol). and the '85 block had an 84 crank kit already put in... but the crank is junk (hence the re-conned 84' crank).
its to my understanding that if anything is out by .005 or more, then it needs some sort of work to put it back into spec. I figure I can save on the head resurfacing, but I'm definately going with the valvejob.
Idk what its going to cost for the cylnder boring. and new pistons and rings...
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07:19 PM
AL87 Member
Posts: 2578 From: Bradenton, Florida, United States Registered: Mar 2010
After some research and pricing, I think I'll go with most of CompCam's products.
Comp 252H or Comp 260H? (cam and lifter kit 210.46) 1.52 roller-tip or 1.6 roller-tip? (rocker and pushrod kit 143.60)
I think I'll be as agressive on the porting and polishing, and get the most I can. I'm thinking I'll still bore out the TB and where it mounts on the plenum.
252 with 1.6? or 260 with 1.52? The rule of thumb I keep getting from some of you is that the higher the ratio of the rocker, the more stress it adds to the rest of the valvetrain components (cam, spring, retainers, keepers, pushrods)
Its come down to money right now, I'm assuming that if I go with a 260H and 1.6 roller-tip rockers, it will cost the most because I'll have to pay for extra machining, and upgraded valvetrain parts. Does a 252H with 1.52 roller-tips sound like a feasable option as I see its the cheapest option while still upgrading performance? Comp Cams is telling me that the stock springs (at minimum) cant be used if I get the 260H, but the 252H should be fine with it all.
Oh, and one more thing, I do want some lope, will a 252H do that? If I get the 260H do I have to upgrade to a high-stall torque convertor?
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07:52 PM
TopNotch Member
Posts: 3537 From: Lawrenceville, GA USA Registered: Feb 2009
You don't have to get a higher stall convertor for the cams you have selected, just a little nicer having a good launch. Don't think you'll have any lope with the H260 cam, slight if any.
------------------
85 GT 3.4 14.9 @ 90 1.9 60' Old TH125/3.06 Unknown New 4T60/3.42
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11:47 PM
May 27th, 2011
AL87 Member
Posts: 2578 From: Bradenton, Florida, United States Registered: Mar 2010
