Im in the slow process of building a new engine for my mud truck.. i am building another 302 as this one has served me great.. this is being built as a "torquer" engine..i was looking at cams to get an idea of what i want to do.. the one i found that i think will suit my needs is a comp cam xtreme energy


(Xtreme Energy XE262H Hydraulic Flat Tappet Camshaft Only
Lift: .493''/.500''
Duration: 262°/270°
RPM Range: 1300-5600)

((jegs.com is where this info came from))

This cam seems to do what i am needing out of the engine.. but several people have been trying to convince me to use a roller cam in this engine.. where some others have told me the flat tappet would be fine but with high rpm's to use roller rockers.. and i have also heard there is a problem with flat tappet cams getting "flat spots" on the lobes.. is this a true statement.. or people "blowing smoke up my ^&(%"..

Would i go in the wrong direction using a flat tappet cam shaft compared to a roller.. i personally feel that the flat tappet is a better option where im building on a budget.. This is the first performance engine that i am building by myself.. been involved in alot of our race car engines.. but im alone on this one.. any advice would be greatly appreciated...

 

It really depends also and what block you have. If you have a non roller block, then you have to purchase the conversion kit for a roller cam.

I'm not expert by any means, but have owned a few 5.0's with both the roller and flat tappet. I have been more pleased with the roller blocks by far. Better gas mileage, and better RPM's.

I would think if you want a truck in the mud, the RPM's and horsepower is what would need the most attention!

 

What RPM range are you looking to run in? From what I understand, teh 302'a are high revvers that make HP in the upper end. If you are building a lower RPM engine (which I think you are, since you are going for torque), I would go with the flat tappet. I have a Comp Xtreme in my GMC and am VERY pleased with it.

 

WHAT IS THE DIFFERENCE BETWEEN A ROLLER & FLAT TAPPET BLOCK? I have never heard that before & I'm an old retired mechanic.
If I was building a motor these days I would spend the money to go ROLLER. The reason is motor oils these days lack zinc & are designed for ROLLER CAMS. Why because no car manufacture uses flat tappet cams in their engines anymore.
If you read about cam failures today they are flat tappet cams & there seems to be three reasons. modern oils, cheap lifters, wrong break-in procedure. There was a great article in Hot Rod Magazine some time ago about this.

 

What are you wanting to use the engine for?

Torque is generally produced in the low end in trucks, 1 - 3,000 or so RPM. I rebuilt my 400
last summer and stayed with the flat tappet cam as it was way more cost effective. I add a
bottle of ZDDPlus to the oil at each oil change.

ZDDPlus™ - ZDDP Additive for Classic Cars - Agricultural Equipment & More

 

I think it was FordMuscle that also had an article on it a little while back, too.

 

the highest i have ever turned that engine was 6400 (not the re-builder..) but i prefer not to go that high.. i have heard about the zinc needing to be added when running flat tappet (also rumor that they are no longer going to make a flat tappet) .. im looking for my power to be around 4500.. i am running a standard transmission (borg warner t-19) so i need all the rpm's possible in one gear.. but building in a budget i am not going to be capable of building an engine to turn 7000+...

i was told as well if i do a flat tappet to run roller rockers to aid while turning the engine at high rpm's as well.. i think that 1300-5600 rpms (the cam i have the specs posted for) is the range i am going to use.. if i ran an automatic.. than i can use lower ranges.. i was looking into some roller cams. but the ones i was finding were like 2-5000.. i do drive this truck on the street.. so i need to keep a good cruising power as well..

currently the pickup has a 302 that (as far as i know) is stock other than carb and intake.. and it made me an 8.5 second pull in the last mud run here.. i am pleased with what they can do.. just want a few more "ponies" under the hood to help turn the 35x15x15 super swampers that i have on it.. i already have 4.11 gears.. so i feel my changes need to be in the engine rather than drive line..

im leaning hardest towards the flat tappet.. i just want to make sure i choose correct for what i am doing.. as well as engine life..

the plans-
standard pistons and rods (at the moment cant afford the upgrade..)

plaining the heads and block.. (not much compression difference.. but every little bit helps)

simple hone..

roller rockers and heavier valve springs (nothing drastic)

i think this little bit of mods that i am looking at doing will do me just fine.. as im not competing in points races or anything.. just i have heard both ways on the camshaft of choice.. like ii stated earlier.. i just want to build it right the first time (with exception of the really high dollar parts).. just want a little more power.. and a good life to it..

 

Flat tappets are designed to rotate in their bores to promote even wear. The roller cam follower needs to stay inline with the cam axis for obvious reasons. Some achieve this by tying 2 lifters together in a pair, Ford originally achieves this by a 'spider' plate that stops the lifters from turning. Non-roller blocks do not have the fixtures required to bolt in a standard ford spider. I think also that the lifter bores are longer too.

One of the main benefits of roller is that you can go to a more aggressive cam profile easier.

 

i dont know if i should post this under a new thread or not.. but i do have another question..

will the heads off of a fuel injected 5.0 fit this 1981 engine block and the carborated intake bolt to it?? i had a set given to me that had just be rebuilt not long ago (said 33,000 miles if i remember correct) and would these heads be any better than the older ones??

like i said.. new to the performance world.. i spend all day working on o.t.r. trucks and heavy equip. so im kind of lost when it comes to auto..

thanks again for the replys thus far.. i hope i can get my mind made up in the really near future so i can get to putting it together...

 

I read here on FTE that the Shell Rotella line of motor oils has a good amount of zinc in it. I think it was in the same topic that ZDDPlus was also mentioned.

I'll see if I can find the topic, if I do I'll post a link.

 

Have you thought of 4.56 gears?

 

i have had that thought.. the gears for the 9" rear would be pretty inexpensive.. but the dana 44's in the front would be a little pricier.. my worry with going to the 4.56 is loosing to much ground speed... i may need to calculate it out and see what i will loose.. but the thought has crossed my mind..

 

I understand the lifter bore being longer, I wasn't aware of that. But where do these spider plates connect? Where can I find a picture of what your talking about. I never fail to learn something. Also what years & was it just the 302 that had this? I know the last year for the 302 at least in the Mustang was 1995, I owned a 95 Mustang GT that I bought new & in 96 they went to the 4.6. I really didn't think the 95 had a roller cam.
Thanks for the info, again I never fail to learn new stuff.
I agree with you on the roller cam. IMHO Flat tappet cams are OLD SCHOOL. With all the design changes in modern engines, oils, & etc roller is the way to go. I mean heck $10 for ZDDP every oil change, Not for me if I'm building a motor. My 86 F250 4x4 460 has close to 200,000 miles when I rebuild it I will go roller cam.

 

Some basics here from someone that has both a 302 and 351 in the same truck and converted a 302 from flat tappet to roller cam.

First thing is.. a 302 does not produce much low rpm TQ.. doesn't matter how it's setup, so if you want 0-4500rpm grunt go find a 351 to replace it, the difference is hugh. As for the cams.. both types can produce similar powerbands and peak HP, it just takes slightly different specs to do it. The roller setup eliminates on if the biggest sources of friction in the motor, but the cost to convert a pre '87 block is steep, you need linked roller lifters to use a factory style roller cam or a custom small base circle cam to use the factory spider and dogbones(see below), both of these options are easliy $500+. So in my opinion it's not worth it to convert an older motor, just select a flat tappet cam and forget about it.

 

For some reason my photo isn't showing up, it's a pic of a factory spider and dogbones in a late model roller block. Here's a link

IMG_0524 on Flickr - Photo Sharing!