camshaft upgrade

mattbaker302

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Apr 18, 2019
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hey, guys so I just bought a new cam and lifters that I'm gonna install in my 71 302. I wanted to see if yall knew how much preload I should go with when I tighten the rockers down?
the cam isn't anything crazy here are the specs on the flat tappet.... ?Also is this a good performance cam?
  • Valve Lift .498/.498
  • Advertised Duration 282/282
  • Duration At .050" Lift 222/222
 
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rbohm

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hey, guys so I just bought a new cam and lifters that I'm gonna install in my 71 302. I wanted to see if yall knew how much preload I should go with when I tighten the rockers down?
the cam isn't anything crazy here are the specs on the flat tappet.... ?Also is this a good performance cam?
  • Valve Lift .498/.498
  • Advertised Duration 282/282
  • Duration At .050" Lift 222/222
its not bad cam for the street, perhaps a touch larger than what i normally recommend, but it will do fine, even with stock heads. i recommend upgrading to a four barrel carb though, using something like the edelbrock performer rpm intake and a 600cfm edelbrock performer carb. you should also be considering a head upgrade in the future to something like the AFR185 heads, or something similar. these heads will let you take full advantage of the cam you have selected.

by the way, the cam you selected will give you good mid range power, and will operate best in the 1500-5500 rpm range, meaning a bit of a soggy bottom end power curve, but easy enough to drive around without issue, though steeper rear gears will help a lot.
 

rustaddict

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Aug 23, 2014
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its not bad cam for the street, perhaps a touch larger than what i normally recommend, but it will do fine, even with stock heads. i recommend upgrading to a four barrel carb though, using something like the edelbrock performer rpm intake and a 600cfm edelbrock performer carb. you should also be considering a head upgrade in the future to something like the AFR185 heads, or something similar. these heads will let you take full advantage of the cam you have selected.

by the way, the cam you selected will give you good mid range power, and will operate best in the 1500-5500 rpm range, meaning a bit of a soggy bottom end power curve, but easy enough to drive around without issue, though steeper rear gears will help a lot.
I'm not trying to disagree with any of this, just putting a topic out there that maybe I can learn something from, but I always thought the stock heads were garbage from a performance standpoint and would be a cork for anything over a 2 bbl. If the OP is doing a cam swap, would even a cheap pair of heads like GT40Ps give him a noticeable performance increase if he's on a tight budget? I agree AFR makes the best out there.
 

rbohm

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I'm not trying to disagree with any of this, just putting a topic out there that maybe I can learn something from, but I always thought the stock heads were garbage from a performance standpoint and would be a cork for anything over a 2 bbl. If the OP is doing a cam swap, would even a cheap pair of heads like GT40Ps give him a noticeable performance increase if he's on a tight budget? I agree AFR makes the best out there.
ye teh stock heads would be a restriction, but the cam isnt large enough to cause drivability problems, and will still show a performance increase. and yes teh gt40 heads would also show an improvement over the stock heads. but remember that a lot of us used the stock heads back in the day when that was all there was available for cheap. remember that shelby used the stock heads with a 715cfm carb on the GT-350s in the production classes and pretty much cleaned up.
 

rbohm

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Be surprised what a good port job and larger valve will do with the stock heads
yep, and you dont even have to do a full port job. port matching, and then blending back about 3/4" into the ports, and then cleaning up the port bowls will help you to pick up about 30hp.
 
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Ray65-71-73

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As an aside: oil. 2015, 2016, and 2017 I bugged every oil guy I could at SEMA. What to use for a flat lifter cam.

I went to a presentation where the presenter had a wagon wheel graphic. He said every spoke represented an oil attribute. And the object was to optimize each spoke. However, increasing the length of one spoke would often shorten the length of other spokes. So it requires balance.

So I asked; does that mean we should not be dumping zinc in our crankcases? He said; absolutely don't do it. It is not that simple.

So for three years I went looking for an oil that would work with a flat lifter cam. But, an oil that is readily available, not some exotic stuff. I chose Rotella T6. It is full synthetic diesel oil. I now use it in everything. My engines are 351W, 460, 7.3 IDI and 7.3 PSD.

I just replaced the complete drive train in my 65 Mustang. 427W. I spent a bit extra for a roller cam. That sent me back to SEMA to chase distributor gear material. That was surrealistic. I concluded the gear should be hard steel, all the way thru, no surface treatment (Melonized), no consumables (bronze, "composite").

And how to get a distributor with a steel gear is another fun game.
 

rbohm

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comp cams, and ford both sell the proper steel distributor gear for a reasonable cost, like $30iirc.
 

rustaddict

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Be surprised what a good port job and larger valve will do with the stock heads
That's true. I once had a 5.0 that I had the heads ported and a performance valve job because I thought I couldn't afford better heads. By the time I got the bill back from the machine shop I could have bought a used set of nicer heads but live and learn. I was surprised at the difference the guy made in those E7s over stock though.
 

mattbaker302

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Apr 18, 2019
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thanks for all the input, I replaced the 2 bbl with an Edelbrock 4 bbl and the intake with an Edelbrock 289 performer intake and headers with some new exhaust. I've got stock pistons and stock heads.
what would be the heads to look for?
 
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rbohm

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depending on your budget, you can look for a good pair of used GT40 heads, or step up to used AFR185 heads. take someone with you who knows what to look for to make sure you dont get a set of heads that have been heavily milled, or are cracked or have other damage. you can also find good used world products windsor jr heads. basically any aftermarket head with a 170-185cc intake runner will do just fine for the street, though i would stay away from the pro comp heads(yes a brand name, just not a good one) as they are inconsistent quality qise.
 
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rustaddict

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The cheapest thing going in my part of the country right now is people are hitting these U pull it yards and getting the GT40P heads off late 80s Explorers. We have at least one place that will let you have anything you can carry in one trip across the scales for $50. Every 5.0 Explorer they get is stripped down to the short block within days of arrival.