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Discussion Starter · #1 ·
Im in need of some help picking out a camshaft for my 306 build. This engine will be replacing the old and tired 200 inline 6 thats currently in my car. It will be paired to a Tremec T5z transmission along with a 4.11 limited slip rear axle. The engine originally was 302 from a mid 70s truck or free candy van. It's been bored 0.030 over and now has flat top pistons. I plan on running the AFR 185cc Enforcer cylinder heads, Edelbrock RPM Air Gap intake, Edelbrock 600cfm carburator.

I don't know much about camshafts and how their specs affect engine performance, but ideally I want one that would have a nice and choppy sounding idle, decent enough vacuum to run power brakes, and a useable RPM range somewhere between 1500-6,000 RPM.

So far, I've come across these 2 camshafts that seem like they fit the bill.



Would either of these cams work for my build? What would be the difference between the two?
 

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Im in need of some help picking out a camshaft for my 306 build. This engine will be replacing the old and tired 200 inline 6 thats currently in my car. It will be paired to a Tremec T5z transmission along with a 4.11 limited slip rear axle. The engine originally was 302 from a mid 70s truck or free candy van. It's been bored 0.030 over and now has flat top pistons. I plan on running the AFR 185cc Enforcer cylinder heads, Edelbrock RPM Air Gap intake, Edelbrock 600cfm carburator.

I don't know much about camshafts and how their specs affect engine performance, but ideally I want one that would have a nice and choppy sounding idle, decent enough vacuum to run power brakes, and a useable RPM range somewhere between 1500-6,000 RPM.

So far, I've come across these 2 camshafts that seem like they fit the bill.



Would either of these cams work for my build? What would be the difference between the two?
My observation is that the Summit cam would be very mild and certainly have enough vac for power brakes. However, it is very old school with lazy lobes and you could probably do a lot better if you care about power. It will probably idle pretty smooth and I would guess it would stop making power by 5500 rpms or so which kind of defeats the purpose of the 4.11s.

The comp cam will idle more lopey but not terrible. It is somewhat close to mine which idles with about 12.5 to 13 inches of vac at idle. I can get it to idle about as low as 900 rpms. Mine is a solid Lunati Voodoo cam.

All of that being said before you pick a cam you need to take a close look at what your final compression will be. If the AFR enforcer heads are like the other AFR heads they have anywhere from 58 to 60 ccs. Couple that with the fact that 73 and later blocks have a slightly taller deck height and you may not have enough compression for the comp cam. Even with flattops the pistons may be slightly down in the hole. I would start figuring the specs for everything and plug the details into a compression calculator like those at Wallace Racing. This requires the compression height of the pistons, the head gasket volume, the cylinder head cc, the deck height, etc. How much compression you have will help you decide which cam you want to run

Finally, just a reminder that if you stick with a flat tappet cam you MUST run an oil with extra ZDDP added or an additive or you will wipe out the cam lobes.
 
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I would pick up the phone and call one of the Ford-oriented cam grinders. Cam Research, Bullet Cams, Lykins Motorsports etc.
 

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I'd stay away from the Summit brand cams. My buddy rebuilds motors on the side (primarily Chevys) and has not had very good luck with these.
 

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What do you expect your compression ratio to be? What size exhaust are you running and what length headers? Is this a street or strip car, or both? These are additional questions the camshaft manufacturers are going to be asking you in addition to the information you've already provided.
 

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Every time this question comes up, most of the response is that you have to make a pilgrimage to some mystical artisan cam guru just outside of Machu Picchu.

I went to compcams.com and downloaded their free CamQuest software. It allows you to enter all of your other specs and it will spit out some recommendations with simulated dyno curves. Sample output below. This is several years old - they have probably updated it since.

Over the years it seems that people have better results using something other than a "flat pattern" cam (such as the Motorsport cams), where the intake and exhaust have the same lift duration.

798658
 

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Im in need of some help picking out a camshaft for my 306 build. This engine will be replacing the old and tired 200 inline 6 thats currently in my car. It will be paired to a Tremec T5z transmission along with a 4.11 limited slip rear axle. The engine originally was 302 from a mid 70s truck or free candy van. It's been bored 0.030 over and now has flat top pistons. I plan on running the AFR 185cc Enforcer cylinder heads, Edelbrock RPM Air Gap intake, Edelbrock 600cfm carburator.

I don't know much about camshafts and how their specs affect engine performance, but ideally I want one that would have a nice and choppy sounding idle, decent enough vacuum to run power brakes, and a useable RPM range somewhere between 1500-6,000 RPM.

So far, I've come across these 2 camshafts that seem like they fit the bill.



Would either of these cams work for my build? What would be the difference between the two?
Ditch those power brakes and hence the vacuum requirement, get a nice big solid roller to take advantage of the heads, transmission and gear you have. That's my pick
 

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Discussion Starter · #10 ·
What do you expect your compression ratio to be? What size exhaust are you running and what length headers? Is this a street or strip car, or both? These are additional questions the camshaft manufacturers are going to be asking you in addition to the information you've already provided.
Based on the Summit Racing compression calculator, I'm expecting around 9:1 compression based on the extra deck height of the mid 70s smog era 302 blocks. However, if the block already has been decked, then I'd be expecting around 9.5:1 compression. I'm planning on running Tri-Y headers to a 2.5in exhaust system with an X pipe and Black Widow Neighbor Hater mufflers.
 

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Based on the Summit Racing compression calculator, I'm expecting around 9:1 compression based on the extra deck height of the mid 70s smog era 302 blocks. However, if the block already has been decked, then I'd be expecting around 9.5:1 compression. I'm planning on running Tri-Y headers to a 2.5in exhaust system with an X pipe and Black Widow Neighbor Hater mufflers.
So lots of good suggestions. If you want maximum power I would suggest a custom cam which is not that much more expensive. If you go that route I would recommend Mike Jones at Jonescams. Like someone suggested you could use the free software at Comp cams with your suspected compression.

I would observe from my car that the low gears and the overdrive make more cam more driveable. I have what I think is a mild cam (which some on here would think is radical) and what some would think are too low gears. I drive my car all over because the overdrive of the T5Z lets me only turn 2000 rpms at 55 and about 2500 rpms at 70. I do have fairly tall rear tires but yours should be even better so you can tolerate more cam than some combinations. It all depends on what your expectations and driving will be. Do you want a weekend toy to take out and impress your friends or do you want something you can drive a lot that will tolerate sitting in traffic, doesn't foul spark plugs,etc.
 

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Gold66, I'm not sure about either of those cam choices. Are you open to others ? And which flattops do you have ? I know of SIX different pistons for 289 and 302 engines that are all marketed as 'flattops'. Your compression will be VERY different depending on which piston you have. AND the taller block you have can make a huge difference also. LSG
 

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If you want a lopey idle, and something that will lug along in 5th gear at 1500 RPM without being pissed off, plus pull cleanly to 6000, and have enough vacuum for power brakes, I like the E303. The LSA of 110 I believe contributes to its cool idle. I have Sniper programmed to idle at ~750 RPM. Anyway, that's the cam that I have in my 306 (roller cam SBF). Very similar to what you're building except it has Edelbrock Performer RPM heads vs AFR. Air gap intake, JBA headers, 3.70 axle, T5 transmission, Sniper EFI. I am sure you can do better in the aftermarket with a custom grind, but this is what the builder put into mine and so far I am very happy with how it performs. Here's the idle:
 
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