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238* @ .050" Crane, what comp?

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guhfluh
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238* @ .050" Crane, what comp?

Post #1 by guhfluh » Sat Sep 19, 2020 5:47 pm

Anyone actually use the Crane cam H-238/3347-8 (500641) .539”/.539” 238/238 294/294 108deg?

Curious what compression should be best for it in a N/A build on 93 octane. And again if a turbo application.
1967 F-250 Crew Cab 2wd, 300 6cyl, T-170/RTS/TOD 4-speed overdrive
240 head, Offy C, EFI exhaust manifolds, Comp 268H, mandrel 2.5-3" exhaust, Edelbrock 500, Pertronix ignitor and coil, recurved dizzy. 200whp/300wtq

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xctasy
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Re: 238* @ .050" Crane, what comp?

Post #2 by xctasy » Sat Sep 19, 2020 7:54 pm

Use the online dynamic compression ratio calculator. Using Fords established static compresion, work out the dynamic CR with the Ford 268 at lash cam with degrees retard. That is your target dynamic CRfor the 238 at 50 thou. Adjust the static compression until it equals the stock cams dynamic compression.

Pop the plugs and do a cold cranking compression. It should not be above 190psi.

Ford Australia found that 10.7 1 allowed 93 octane to run on a 185 psi cold cranking compression with a pretty aggressive General Kinetics mechanical F5M 300-S or U 300 degree at lash, 242 deg at 50 thou cam with 494 or 524 lift for the Phase 3 version of US M code 351 4V Cleveland. WorldChampGramp used a F M 310-Z with 600 thou lift and even more 50 thou lift than yours on Preparation H.

The 3rd thing is to add a heap of idle timing, curtail total advance by all in tailoring. The turbo engine needs boost retard of a degree per pound of boost.

The way to set conservative ignition is to use the cam to guide your dynamic compression within stock levels by those methods of target static to get dynamic, and then that should bleed off Cold Cranking psi. Then a heap of base timing is needed, with curtailed total. Where "all in" advance is depends on engine.

We've discussed knock detection before. If you are on the ragged edge, Id look at a tell tale knock detector according to your creed. I really like means testing yes it doesn't knock now add more advance or hurting your total advance and using the Andy's Unity Garage variation which David Vizard uses. Mean Best Torque, hear the knock and back off 1.5 degrees.

Again, never used a 238 cam on a 300 but have used a bunch of 236 cams on X flow headed 200 and 250 sixes. Plus one each of 220 cams on 351C's and 350 LT1s

Using those two methods, you can then under sufferance try adjust cam retard, straight up or advance to add or bleed off cold cranking pressure. The working tappet clearance can be changed to reduce CCC psi if you accidentally over cook it.
Last edited by xctasy on Wed Sep 23, 2020 6:21 am, edited 2 times in total.
Image
XEC Ltd ICBE's Inter Continental Ballistic Engines-
FAZER 6Bi (M112 & EEC5) or FAZER 6Ti (GT3582 & EEC5) 425 HP 4.1L/250 I-6
FAZER 6V0 3x2-BBL Holley 188 HP 3.3L/200 I-6 or 235 HP 4.1L/250 I-6
X-Flow Engine Components Ltd http://www.xecltd.info/?rd=10

pmuller9
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Re: 238* @ .050" Crane, what comp?

Post #3 by pmuller9 » Sat Sep 19, 2020 9:51 pm

For a Ford 300 six we figure 93 octane pump gas pump gas will tolerate a Dynamic compression ratio of 7.5 and still have some margin so that the ignition timing and air/fuel ratio is not so critical.

If you figure setting the cam with a 2 degree advance with the intake lobe center at 106 degrees ATDC a Static compression ratio of 10.0 will give you a DCR of 7.5.
It has an .050" valve overlap of 22 degrees which will create a rough idle with a more abrupt transition into the power band followed by a strong midrange. Fun stuff.
It will work best with a large 1 5/8" primary tube header.
This is assuming a large valve, ported head.

This is not a cam that is compatible with a turbo.
Unlike the naturally aspirated engine that takes advantage of scavenging during the long overlap period by the header, the turbocharger creates high exhaust pressure that will delay intake charge into the cylinder during the overlap period.
The goal is to minimize the overlap period for turbocharging by making a wide lobe separation angle of 114 degrees or more.

guhfluh
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Re: 238* @ .050" Crane, what comp?

Post #4 by guhfluh » Sat Sep 19, 2020 11:53 pm

Thanks. I understand it's not a "turbo cam" I am just daydreaming and looking to learn.

I've been poking numbers into online calculators and the specs just don't seem to add up to the Crane catalog claims of 11-12.5:1 static CR and 6500rpm, unless race gas and a high flowing head. That's why I was asking.
1967 F-250 Crew Cab 2wd, 300 6cyl, T-170/RTS/TOD 4-speed overdrive
240 head, Offy C, EFI exhaust manifolds, Comp 268H, mandrel 2.5-3" exhaust, Edelbrock 500, Pertronix ignitor and coil, recurved dizzy. 200whp/300wtq

pmuller9
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Re: 238* @ .050" Crane, what comp?

Post #5 by pmuller9 » Sat Sep 19, 2020 11:59 pm

The catalog claims for compression ratio and rpm range are high in most catalogs when referring to the 300 six.

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Re: 238* @ .050" Crane, what comp?

Post #6 by xctasy » Sun Sep 20, 2020 9:10 pm

1. Diagram 1 "Blending Higher Octanes with Alcohol":

Your US 93 octane is quite good. Our 91 octane wasn't, our 95 octane would supply the needs for one specific kind of Zero decked QC Phase 2 and Phase 3 engine, specifically a 500 build engine made from US M- codes for two years. My next door neighbor Danny's 1970 LT1 350 powered 63 Chev used the hydraulic 351 W 4V cam profile with extra duration, 5 degrees, same as Blair Gregories 351 2V 4bbl 780 cfm Cleveland. Its a cam grind I recommended to everyone who didn't mind running more than 91 octane (our 95 octane ) and 10.5:1 compression.


I used the Vizard definition of Short, Medium and Long duration cams from my extensive experience with the 2000 cc OHC 1969-1974 Pinto engine used in Pinto's, Capris, Cortinas. My wife drives all my modified vehicles, so from 1992-1995, My wifes C3 automatic 1975 Ford Cortina XL used a very high compression 2.0 Cortina GT engine with 1600 cc head and oversize valves and reground 106 lobe center cam with Fords 264 duration cam profile on it. It was an awfully detonation prone engine (ex speedway, with the 1600 GT tubing headers removed and replaced with a stock iron exhaust, and I spent time with my first 2300 Holley 500 cfm carb conversion, then a 465 CFM Holley 4BBL on a Speco Thomas adaptor with water injection via Vizards washer bottle and window screen clean jets over the primaries. To run 11:1 with an auto and the wrong cam took window cleaner, acetone and deionized water.

A note on Diagram 2 below:


Short duration is 252 to 268 at lash, or 180 to 205 at 50 thou lift
Medium Duration is 268 to 295 at lash, or 205 to 220 at 50 thou lift
Long duration is 295 to 326 at lash, or 220 to 250 at 50 thou lift

The 2nd graph has some issues, because the A series 1275 Austin Healy and 2000 cc Pinto's were cammed up within the 252 to 326 range, and not outside that, so the graph 1 might have to be extended down and upwards, because the 144/170/200's ran 240 cams, and the 255 Ford 4.2 Liter, 244 cams, and the really worked racer engines, well over 326.

Very low are the stock Ford tractor cams, the 240-244, 165 to 180 at 50 thou lift
Very High are the Super Speedway Crane NASCAR cams well over the 326 at lash, and 250 at 50 thou lift

2.The two diagrams below will help you target working compression targets. Second is "Compression Ratio verses Cam Duration".

If you run into trouble, you'd apply the emergency remedy Vizard suggested in the source book I raided it from below, Diagram 1, using the lowest grade 87 octane pump gas with an octane boost via race fuel. That is a get out of jail card to quell detonation. Then change cam center degrees on the timing set, and fiddle with your preload for cam lash to control idle and cold cranking pressure if you get stuck.


viewtopic.php?f=1&t=72433&p=556526&hilit=vizard+compression#p556526
Our old iron headed 1971-1975 4.1 log and 2v and 4.1 cross flows from 1976 to 1980 with just 9.15:1 compression would run very badly on 91 octane, great on 96 to 97. Same with any Cleveland 351. Downgrade the octane, and it would detonate. These were 16 thou deck engines, where the piston stopped short 16 thou, not 103 thou like the 250, or 25 thou like the old log 200.

The Classic Inlines is a modern redesign of the 2V 250, and its alloy construction and high swirl mixture motion gives you detonation resistance with your 89 aki pump grade gas. To be safe, use 93 octane, but the cylinder head isn't canted valve, and is made of alloy, and it should handle a lot of compression with even a short duration cam.


The three US pump grade gasolines has more variation than NZ fuel, as you have oxygenated blends now, but all NZ fuel is aromatically inferior, and has less controls in place for the levels of benzine and aromatics. In Kiwiland, three grades of It can go from the bowsers 91, 95 or 98 call rating to just 83, 87 or 93 in just a six weeks. Our rating is MON+RON/2. Your rating is either AKI or RON. Our fuels are 3 to 5 % aromatic benzenes, a lot more than US blends. The so called octane difference is explained fully in this article

http://www.scribd.com/doc/26804743/How- ... vid-Vizard

*Source: How to Modify Ford SOHC Engines (Pinto/Cortina/Capri/Sierra 1.3- 2.0 lit"re" 1970 to 1982) by David Vizard, published 1984 by Fountain Press.

ISBN 0 86343 9856, Dewy Decimal No 629.2504 Viz
See Chapter Nine on Page 119-124

This is a very old article but it covers most of it. You can blend
1. alcohol race fuel to get a target r+m/2 octane ratio,
2. or use a water injection system with pure water or as Anti Detonation Injection in a 50/50 water/alcohol ratio
3. or use a water injection system as Anti Detonation Injection (ADI) in with a 50/47/3 blend of water, alcohol and acetone with a small amount of fuel conditioner to create a very high compression, long duration cam engine that runs on standard grade gasoline. You can run them like Mustang Geezer used to. I use ADI to operate 12.7:1 on my 3.3 engine, while still using 91 r=m/2octane, our lowest grade.

Image

He noted
It was also pointed out in the cylinder head chapter (CHAPTER 2) that high compression ratios are needed if long- duration cams are used because the valve overlap causes much of the incoming charge to be pushed back into the intake duct at low rpm. This leads to a "soggy" feel of the engine. By utilizing a high numerical compression ratio the cam can be made to work much more effectively


He noted in Chapter 2
In some areas of the world, such asthe U.S.A., the octane rating of available fuels is little better than that of peanut butter. Once compression ratios start exceeding about 9.7-9.9:1 the engine is likely to run into detonation problems, even on premium-grade fuel. Where 100 octane fuel is available, compression ratios up to about 11.5 or 12.1 can be used.



Image


The X-flow and log heads were a lot like the early Pinto 2000 engines, they didn't cary a lot of compression before detonation set in, but the Classic Inlines head has a lot more mixture motion and always is mated with a wilder than the short period 240, 252 or 256 degree cam....everyone seams to go for medium duration cams like the 260 and 270 Schneider, the 260 Comp Cam, or 264 and 274 Clay Smith cams, and they bleed off effective compression. Down here, we go a lot more radical flat tappet and roller cam durations than the US does, and use much higher lift with 300 thou longer 5.16" Holden 308 valves and common deep dish pistons. That's how come you see 250 sixes pushing the 350 to 410 hp barrier often in oval track and drag race engines. The detonation issue drops off with long duration, high lift cams and deep dish pistons. Experts say that the shallowest piston with relief for flame front travel is the best to curb detonation, but that is for NAscar engines. For the street, whatever gets the compression ratio into the sweet spot for a medium duration cam also yields detonation resistance. The decimalized 87/89/93--->8.7/8.9/9.3 is a good rule for iron heads, not alloy ones. You've got quite a lot more head room to play with when the head is aluminum.

I used for 8 years 100 MON+RON/2 Liquid propane Gas, and it allowed 9.65:1 compression with just a 252 degree Heatseeker cam and 500 cfm Holley 2-bbl and 348 cfm mixer on my 1984 Falcon 4.1 X-flow. 34 degrees total, 9 degrees static, and it was hammered and never detonated due to the compression ratio. It did get some rtv stuck in the carb, and melted a combustion chamber and blew a gasket, but it was easy to reweld the camber, and the pistons and bearings were fine. High compression alloy Canted valve heads and propane are the worst combination for detonation...I never got any. The Classic Inlines head is more like the FE and Windsor, HSC/HSO Tempo/Topaz/ inline four and Big Six head, and they are much more detonation resistant than my X-flow heads were.

I think 9.8:1 with the Classic Inlines head, a 264 Clay Smith cam and a good carburation system with the well tubes that aren't damaged, and power valves working, and the right Power Valve channel restrictions and a good ignition system without more than 34 degrees total and a quick advance with a lot of static timing should like 93 AKI, and the odd fill of 89 AKI.
Image
XEC Ltd ICBE's Inter Continental Ballistic Engines-
FAZER 6Bi (M112 & EEC5) or FAZER 6Ti (GT3582 & EEC5) 425 HP 4.1L/250 I-6
FAZER 6V0 3x2-BBL Holley 188 HP 3.3L/200 I-6 or 235 HP 4.1L/250 I-6
X-Flow Engine Components Ltd http://www.xecltd.info/?rd=10

pmuller9
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Re: 238* @ .050" Crane, what comp?

Post #7 by pmuller9 » Tue Sep 22, 2020 9:18 pm

Do you mind telling us your engine build plans?

guhfluh
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Re: 238* @ .050" Crane, what comp?

Post #8 by guhfluh » Wed Sep 23, 2020 6:11 pm

I'm assuming you mean mine? I'm just dreaming, theorizing and contemplating, but...

End goal dream would be port injected lower EFI manifold with box top and single entry throttle body. Home ported 240 head, deshrouded, possible Manley Pro Flo 1.94/1.60 SBC valves, Harland rockers. Bottom end would be LS 6.46 rod, Wiseco 4.030" 1.425 C.H. 5CC shelf piston. It puts the static CR in realm of 8.7-8.5 for an end goal of turbocharging. OR the 6.56" LS rod that would put the static up at 10+ that would probably have to stay N/A.

The goal with this cam would be to keep initial cost down as well as maintenance being hydraulic, and push the operating range up in RPM for more power, less torque, less peak cyl pressure, etc.

I'd love to build it now, I just don't have the spare funds. I have found the parts for super cheap, but total cost would still be quite a bit with the machine work. The only work I could save on might be assembly, piston/rod spacer bushing machining for guiding and maybe weight matching if below 600g.
1967 F-250 Crew Cab 2wd, 300 6cyl, T-170/RTS/TOD 4-speed overdrive
240 head, Offy C, EFI exhaust manifolds, Comp 268H, mandrel 2.5-3" exhaust, Edelbrock 500, Pertronix ignitor and coil, recurved dizzy. 200whp/300wtq

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