Re: chasing stroker kit for 351clev (photos added, large!)
Tony,
I started with a bare, '72 351 CJ 4-bolt block from a Q-code Cougar. I used Milodon center main bearing caps. These have much more material throughout and especially in the area surrounding the outer bolts. They require a good machinest to properly register them and, obviously, to align hone them. I used a combination of ARP studs to fit the front factory 4-bolt caps and the taller Milodon caps used in the center caps numbered 2, 3 and 4.
I used custom JE/SRP Pistons with floating pins in a flat-top w/valve reliefs configuration. These give me a calculated 11.28:1 compression ratio with my 66cc heads and .040" gasket with a .008" deck. The oil ring does intersect the pin, but uses "buttons" to maintain/control the oil so that blow by and/or oil consumption is not an issue.
The rods are 6.000" long "Chevy" rods in an H-beam configuration made from 4340 chrome-moly steel. They are reasonably light and very strong. Not as strong or as light as a set of C&A or Oliver rods, but at only 25% of the price, too.
The bore is 4.030".
The balancer is a lower-cost SFI-rated part from Performance Products. The timing gear and chain set is Australian made and both gears are billet steel.
The block has both intake and exhaust valve reliefs typical of a "CJ" block.
I used a set of Ford Motorsports A3 cylinder heads that I bought bare from a guy. These heads flow much more than most other heads, but I am building a high compression "cousin" of this engine using a set of the AFD 4V heads due out soon. I believe that the AFD heads are a better overall design, especially with regard to the combustion chamber shape, spark plug location and port sizes. They also benefit by taking factory extractors, which the A3s definitely do not.
Flow figures at 28" are as follow:
Lift--int-/-exh
.200 152/100
.300 217/146
.400 266/194
.500 305/217
.600 341/232
.700 357/242
This is fairly significant flow for any small block application and resembles most big block "out of the box" cylinder heads.
I used a "Blue Racer Woverine" solid roller camshaft. Blue Racer cams was bought by Crane. I bought this camshaft for about $110.00 (US) new. While it doesn't necessarily sound like the "best" camshaft for the application, I spent considerable energy researching/searching for any cam that would make even a bit better power. I didn't find one that would justify the expense of something over $365 (US) for what amounted to perhaps a 3 HP gain. The details of the cam (single profile design) follow:
274/274 @.050" .709"/.709" lift 105 LCA
Crane apparently still has these cams and is getting rid of them at "basement bargain" prices. This particular cam would love additional compression up to about 13.5:1, IMO. It wouldn't be terribly radical for a street engine with 10.5:1 if that engine was a larger stroker size like a 393 or a 408. This camshaft definitely likes to run and sounds very aggressive at idle, even with the extra inches and free-flowing cylinder heads.
The part number is: WG 5016 MR
I must have compared 50 different mechanical roller cams and at least 10 flat tappet mechanical cams after I already purchased this cam just to see if I couldn't find a better choice for my combination. The best that I could do was simply push the RPM band where the engine made power farther up in RPM. While the heads would definitely support more RPM, I didn't want to build a really high RPM engine as I want to conserve parts and not have to change valve springs every week. As you can see by the details of this cam, .709" is not a lot of lift, especially for a "drag race-dedicated" engine. More lift didn't really help during software modeling of the engine, except in RPM ranges well beyond where I wanted to run. Interesting is the idea of using these heads on a 331" destroker at 9,000 RPMs on alcohol with a 25% nitromethane kicker for about 1100 HP and a serious Cleveland screamer. But I'm not that interested in changing valve springs.
I used titanium valves on the intakes because of the 2.19" size and extra .100" length, which made them a bit heavy for a stainless steel part. I used stainless exhaust valves, though.
Valve control is a very important topic to me. Most people do not realize that the valves bounce on their seats up to several times before finally settling down and seating completely. Reducing the bounces and seating more quickly is important as the RPM goes up where there is less total time. Any valve train "inconsistencies" need to be addressed so that cam timing is not adversely affected by misbehaving valves.
I've seen mentioned that single coil springs with dampeners are recommended, but I tend to recommend double coil springs with dampeners for anyone but the most obvious "RV cam" application where RPM is definitely under 6000 RPM and lift is under .500" at the valve and when a wide lobe separation is used or something greater than 112 degrees. There will always be someone around to tell me that they're running just fine with parts that satisfy them and do not fit my requirements. Pure flat hydraulic lifter cams are an excellent example of where it may make sense to avoid using too much spring, but you can achieve better valve control using double coils with reduced spring pressures compared to single coils while making each spring live even longer using two instead of one. Also, if you break a coil on an over rev or something, a dual coil spring might retain your valve whereas a single coil will likely drop it. I do not, as a rule, plan for failure, rather, as a rule, I build to prevent failures. The lower cost single coil springs would be adequate, IMO, for a truly street driven daily driver kind of car where the RPM is limited to 5500 and very rarely sees that much.
For a play toy with an abundance of ponies, I prefer to run it up to 7000+ and enjoy the look on the Holden drivers faces when you switch to 2nd gear after they're already all in. Of course, one must look quickly and in the mirror for that fleeting but worth it blank stare of disbelief, since one will quickly be accelerating from view in nothing flat.
I used a Mellings high volume oil pump with a chrome-moly oil pump drive shaft from Milodon. I used Moroso oil restrictors to keep the oil out of the top end and in the mains where it belongs. There are quite a few blokes out there who feel that the HV pump is not a good choice. It does use more power, but I don't play the absolute maximum power game anyway. Turning the engine over twice by hand is enough to fill a new oil filter on my engine. I prefer the "regular volume" Mellings pumps for street cars, since fuel economy is always an issue with a true daily driver.
I used an Edelbrock aluminum waterpump to save weight. I am a firm believer in saving as much weight in any car as possible. My entire car with me in it should weigh just 718 kilos ready to race at the starting line. This is an estimate based on weighing every major component and includes a bit of speculation on those items not currently completed on the car now. Included in the speculation is another 90 kilos of unaccounted for "miscellaneous" weight, so if I don't add anything more than what I've got on my list, it could be as light as about 630-650 KGs or about 1.05 KG/HP. That ought to be entertaining!
This image was taken right before making off to the dyno for its initial testing and tuning. It didn't have the valve covers on it or the stud girdles (left off to make adjusting the valves easier and quicker on the dyno) both which are now fitted.
This was dyno day. Power output after tightening up the lash (reduced torque readings) was:
[PRE]
RPM CBTQ CBHP
4500 443.3 379.8
4600 452.7 396.5
4700 454.8 407.0
4800 464.3 424.3
4900 472.4 440.7
5000 479.0 456.0
5100 490.0 475.8
5200 492.6 487.7
5300 492.0 496.5
5400 491.0 504.8
5500 494.5 517.9
5600 490.8 523.3
5700 490.1 531.9
5800 488.1 539.0
5900 487.5 547.6
6000 487.0 556.4
6100 484.5 562.7
6200 481.0 567.8
6300 482.1 578.3
6400 480.6 585.7
6500 475.9 589.0
6600 472.7 594.0
6700 468.4 597.5
6800 464.2 601.0
6900 458.7 602.6
7000 456.6 608.6
7100 445.6 602.4
7200 442.2 606.2
7300 435.2 604.9
7400 431.7 608.3
7500 421.3 601.6
7600 418.9 606.2
[/PRE]
Though I find it more useful to look at these numbers in the form of a graph.
This shows how flat the torque curve is on this combination. I believe that had I spent more time tuning, especially with adjusting the 1000 CFM 4150-style Holley HP carburetor, that I could have coaxed another 30 HP out of it and probably another 12-15 TQ.
...is the where this engine ended up. I've got a few odds and ends to source before I can install the rear end, but I've been working on plumping and wiring the car these past few weeks. The body is being painted and I hope to make some passes by September if the weather isn't still too hot at night.
I'm happy to share anything that I know about engine design and building, but from the point of what I know and what I believe and not as someone who knows everything or even thinks he does. Someone may be running very well on single coils and doing well with them, but you probably won't hear about it from me. I've been accused elsewhere of being a braggart and a know-it-all because I've tried to share what I've done with others who are similarly interested. I hope that I won't come across in that fashion on this forum. I also hope that I can help others understand some of the awesome potential of the Cleveland small block Ford.
:davis: