350 build

[bschiltz]

Haha, alright. You don't have to tell me twice

Thank you guys for all the help, I'll do some more looking and keep all that in mind. Does anyone have experience with the intake I linked to above? Any other suggestions?

[dr_hunt]

Yeah, it's a good one for your planned combo.

[Pyro]

I wouldn't run a cam with more than 215 degrees duration at 0.050" with a stock converter or less than 9.25:1 cr or less than a 3.50 gear. Over camming is a lot worst than under camming.

[grumpyvette]

"I wouldn't run a cam with more than 215 degrees duration at 0.050" with a stock converter or less than 9.25:1 cr or less than a 3.50 gear. Over camming is a lot worst than under "

 

 

IM forced to aggree with that basic statement, cams with more than about 215 durration at .050 lift reguardlees of LCA are very unlikely to work correctly with low cpr,s and a stock converter stall speed,s especially with a gear lower than 3.73:1

[pparaska]

Well, I have been accused of going too far down the page selecting cams.

However, a discussion of using .050" duration versus .004" or .006" (whatever the manufacturer uses for "advertised") on a hydraulic cam comes into play. With the differing lobe intensities out there, you could have a significant difference in .004" duration (and overlap) with two cams having the same or nearly the same .050" duration. The compcams High energy/Magnum lobes versus the Xtreme lobes show that.

 

If you take the two High Energy and Xtreme lobes that have 218 .050" duration and put them on a both the intake and exhaust with a 110 LSA, here is a comparison:

 

HIGH ENERGY

Grind: 12-210-2

268H

Advertised Duration (.006"): 268 268

0.050" Duration: 218 218

Lift: .454 .454

LSA: 110°

Grind Number CS 268H-10

Valve Timing At 0.006

Open Close

Intake 28 60

Exhaust 68 20 (Overlap at .006" is 48 degrees)

These Specs Are For The Cam Installed At 106 Intake CL

 

XTREME 262 lobes on both Intake and Exhaust (custom grind)

Advertised Duration (.006") 262 262

0.050" duration: 218 218

Lift: .462 .462

LSA 110

Valve Timing At 0.006

Open Close

Intake 25 57

Exhaust 65 17 (overlap at .006" is 42 degrees)

These Specs Are For The Cam Installed At 106 Intake CL

 

That's 6 degrees difference in overlap at the same "seat" timing point of .006". I'm guessing this will have a noticeable difference in low end performance, not insignificant anyway.

 

Just trying to point out why I don't like to depend on .050" timing comparisons when talking about low end performance, which is very much a function of overlap (using seat timing is more realistic than .050", according to Vizard and others).

 

Of course, I could be all wrong too!

[grumpyvette]

theres nothing WRONG with the cams themselfs,in fact they are milder than ideal for maximizing the hp, its the CONVERTER stall speed limiting what can be effectively used without having an engine thats a P.I.T.A. to drive in a street car engine with the gearing, because the converter won,t allow smooth operation at ideal and slightly higher rpms, you can easilly install and have a nice responsive engine combo or even a larger cam,with a MANUAL transmission or HIGHER STALL CONVERTER.

heres two SIMILAR CAMS

 

http://www.cranecams.com/index.php?show=browseParts&action=partSpec&partNumber=114132&lvl=2&prt=5

 

despite what the card info says this runs pretty smoothly with a stock converter and low compression 350 with a 2.87:1-3.07:1 rear gear ratio EVEN thought its designed and works BETTER with a 2500rpm stall converter and 3.73:1 rear gear or higher

 

 

http://www.cranecams.com/index.php?show=browseParts&action=partSpec&partNumber=114142&lvl=2&prt=5

 

this one produces noticably better upper rpm power but if used with a stock converter its a P.I.T.A. to opperate in traffic and jerks the car when you place it in gear and basically runs like crap untill you hit about 2300rpm, then pulls hard from about 2700rpm up to about 5500rpm

 

 

match either cam to a 3.73:1-4.11:1 rear gear and a manual transmission in that low cpr 350 and you have a nice torque band from about 3000-5500rpm which for a street cars not basd with that rear gearing.

 

bump the cpr up to about 10.5:1 and head flow rates up enought to support a bigger cam, in the rpm ranges it needs to effectively opperate in ,keep the same 3.73:1-4.11:1 rear gear and a manual transmission , you can use a good deal more durration and something like this works great, but youll need those mods and about a 3200rpm stall converter to run an auto trans

 

http://www.cranecams.com/index.php?show=browseParts&action=partSpec&partNumber=114681&lvl=2&prt=5

 

keep in mind as the durration increases the piston is much higher in the cylinder at the point both valves close so at low rpms your tradeing many more power strokes per minute but loosing effective cylinder volume being compressed and you never reclaim it all even at high rpms, your tradeing lower effeciency for more power strokes and higher rpms, which tends to kill off the low rpm tq.

compare the piston location in the cylinderr to the valve close points

 

http://www.iskycams.com/ART/techinfo/ncrank1.pdf

[bschiltz]

Just a quick update, I dropped the motor and crank off at the machine shop on Friday. Got a call yesterday morning saying there was a crack in the lifter valley, so I went out there and picked up the block. My guy had a bunch of extra blocks so I'm having him just use one of his (55 bucks, not bad!). The crank was scoured pretty bad in a couple places so it's getting reground.

[dr_hunt]

Remember that when getting a crank reground you can specify how you want that done so you can get bearing clearances in a range that will work for you. As always you can drop off the rods and bearings and have it ground properly to get the clearance you want.

 

Cast cranks IMO run better and longer alittle tighter than steel cranks. .001 to .0015 on the rods and .0015 to .002 on the mains for most street motors. Steel cranks work pretty well in most high performance applications at around .002 on both and I know some people that run .0025 and .003 although I have never had the inclination to run that much clearance as it ups the oil volume through the bearing and creates alot more oil flying around inside the engine which isn't all that good either.

 

But when grinding a crank there is a tolerance level on the crank which is .001 to .0015 or so. You can have it on the tight side, split, or on the low side. Say your getting it .010 on both rods and mains. You can get it .0095 to .011. Back in the old days alot of guys would grind the factory steel cranks to .011 and end up with .002 to .003 clearance. Mickey Caldwell, who held the 283 stock Corvette national record for many many years used to do that alot with his 283 steel cranks. I know several others who do that as well.

 

But if it's built right with straigh rod big end holes, straight crank throws, straight block saddles you can run .001 all day long but it takes awhile for the engine to break in and loosen up. Typically I like to run .0015 on the rods and no more than .002 on the mains. They will live longer IMO.

[Doc Hawk]

So as to avoid threadjacking, would some of you cam gurus please check in on my thread here? I have obtained some pretty radical heads, and I'd like to drop in a streetable cam that will take advantage.

 

Thanks!

[bschiltz]

Got a call yesterday when I was in class from the shop. The guy grinding the crank said it was already .020 under on the mains and .010 under on the rods, so it's going .030 and .020.

 

Other than that, I've been looking about a little at heads. There were some Iron Eagles on ebay listed as refab blemishes for ~400 a pair, any opinions on them?

[dr_hunt]

You know for $150 you can get a new cast crank. I'd opt for a new crank if it was me. You can get a forged crank for $350 or so which would be even better. My advice anyway, take it or leave it.

[Pyro]

iron eagles are good heads. But they come in a lot of different sizes. 64 or 72cc chambers, 180, 200, 215 or 230cc intake ports, and straight or angles plugs. So, which Iron eagles are you talking about?

 

journal size is not a big deal on a mild build. As long as you can get the right size bearing easily, it should be ok. Be aware that taking that much material may require chamfered bearings (depending on how the grind is done). A chamfered grind is stronger (radius at ends).

[bschiltz]

There's all different combos from this guy on ebay, but I was leaning towards these most. 64cc chamber with 230cc intakes

http://cgi.ebay.com/ebaymotors/NOS-Dart-Iron-Eagle-64cc-SB-Chevy-230cc-Heads-10720040_W0QQcmdZViewItemQQ_trksidZp3286Q2ec0Q2em14QQhashZitem29fd360ee2QQitemZ180341837538QQptZMotorsQ5fCarQ5fTruckQ5fPartsQ5fAccessories

[Pyro]

230 is real big. good for a max effort 350 (high rpm) or big cubes (420+).

 

I would use 180cc or 200cc with a mild/moderate 350.

 

use straight plug heads as they fit most headers.

[bschiltz]

So I was looking at one of the bearings from the old block last night an noticed how chewed up it really is. I think what was happening was a lack of oil pressure/flow. I believe the lighter patch around the oil hole is the less worn area, while the rest of the bearing surface is worn. On the opposite side of the oil hole (left side in the picture) there are copper spots, possibly worn through? In any case, it looks pretty bad.

I'll try to get a better picture when I get my camera back.

[bschiltz]

Here's a better picture. Can anyone verify or refute my idea? Was there a major oil flow or pressure issue?

[jt1]

That bearing doesn't look bad at all to me, just normal wear you expect to see in a fairly high mile motor, say 100K. No major scuffs of marks, just a touch of copper showing at the upper right. For a mild build, I would have probably polished the crank, checked the clearance with new bearings, and let 'er rip.

 

jt

[dr_hunt]

IMO when you see that and you check the align hone on the mains, you will find that it is off and that block will need to be align honed.

[dr_hunt]

There's all different combos from this guy on ebay, but I was leaning towards these most. 64cc chamber with 230cc intakes

http://cgi.ebay.com/ebaymotors/NOS-Dart-Iron-Eagle-64cc-SB-Chevy-230cc-Heads-10720040_W0QQcmdZViewItemQQ_trksidZp3286Q2ec0Q2em14QQhashZitem29fd360ee2QQitemZ180341837538QQptZMotorsQ5fCarQ5fTruckQ5fPartsQ5fAccessories

 

I managed to find these. Liked the flow numbers and the price. I bought these yesterday.

 

http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&item=150310087856&viewitem=&sspagename=STRK%3AMEWNX%3AIT

[Pyro]

flow number seem very good. almost too good. I wonder what pressure they flowed the heads at?