402 cam advice for lifted 4x4

[RThree]

Hey guys,

I’m building a 72’ 402 bbc for my 72 4x4 k20 which has a NV4500 5 speed / 205 transfer case 4.10 gears and 35” tires.

The engine is currently totally stock with stock heads. (Photos attached)

I’m looking for a roller cam which will still allow me to tow and use it like a truck but also bump the HP a bit and Give it a little lope.

Any suggestions?

Thank you!

[Mike C]

A 4" stroke crank makes it a small bore 427 and would be a nice power bump if you are buying pistons. Not that much more $ to get the extra displacement.

Really need more info about what the other specs on the motor are.

You don't want much cam if you are planning on using overdrive. The 35's knock the 4.10 gear down to more like a 3.30.

Comp XM 270HR would probably be the biggest I would choose for a mild, mostly stock small displacment big block. Considered a marine cam with 218/224 duration at .050 and 112 LSA.

Howards has a cam that is 209/213 @ .050 with 112 LSA as well which would be even better with the 402 I think.

[RThree]

Originally Posted by Mike C

A 4" stroke crank makes it a small bore 427 and would be a nice power bump if you are buying pistons. Not that much more $ to get the extra displacement.

Really need more info about what the other specs on the motor are.

You don't want much cam if you are planning on using overdrive. The 35's knock the 4.10 gear down to more like a 3.30.

Comp XM 270HR would probably be the biggest I would choose for a mild, mostly stock small displacment big block. Considered a marine cam with 218/224 duration at .050 and 112 LSA.

Howards has a cam that is 209/213 @ .050 with 112 LSA as well which would be even better with the 402 I think.

Hey Mike thanks for the response!

The 427 is tempting but i am also trying to do a semi budget build, is it only the crank and pistons which need to be changed for that setup?

The engine is in really good shape so i wont be boring it over at this point and it looks like the 3999241 heads are pretty decent so ill be keeping them.

I believe my main expenses will be a new roller cam and new pistons to bump the stock 8.5 compression ratio to 9.5. The casting number on the stock pistons is 3993849


What other information would you need to know about the engine? Its probably pretty obvious by now but this is my first engine build.

[Mike C]

Personally,
The roller cam is a BIG expense that probably cannot be justified in a budget build. Pistons will require balancing as well which means more $.

I would do rings and bearings, a good valve job on your head and a small flat tappet cam. An aftermarket intake manifold and good dual exhaust.

I like the Howards Max certified no-fault cams. I would look at either the 259/269 cam which is 205/215 @ .050 or the 267/267 cam which is 213/213 at .050. Both are on 112 LSA and I would get the direct lube lifter (has a tiny hole in bottom to directly oil the cam) Cam and lifter set $285.

Here is link but they show the smaller one out of stock.
https://www.competitionproducts.com/.../#.XupTs0VKjIU

https://www.competitionproducts.com/.../#.XupUBUVKjIU

[68Gold/white]

Originally Posted by Mike C

Personally,
The roller cam is a BIG expense that probably cannot be justified in a budget build. Pistons will require balancing as well which means more $.

I would do rings and bearings, a good valve job on your head and a small flat tappet cam. An aftermarket intake manifold and good dual exhaust.

I like the Howards Max certified no-fault cams. I would look at either the 259/269 cam which is 205/215 @ .050 or the 267/267 cam which is 213/213 at .050. Both are on 112 LSA and I would get the direct lube lifter (has a tiny hole in bottom to directly oil the cam) Cam and lifter set $285.

Here is link but they show the smaller one out of stock.
https://www.competitionproducts.com/.../#.XupTs0VKjIU

https://www.competitionproducts.com/.../#.XupUBUVKjIU

I agree with Mike!!!

DO NOT< DO NOT use a comp XE cam!!!

THe Comp 260H or 268H would be good choices, also, just NOT in the XE versions!!!

Knowing the chamber volume of your heads is one of the most important things when selecting a cam.

[RThree]

Originally Posted by 68Gold/white

I agree with Mike!!!

DO NOT< DO NOT use a comp XE cam!!!

THe Comp 260H or 268H would be good choices, also, just NOT in the XE versions!!!

Knowing the chamber volume of your heads is one of the most important things when selecting a cam.

After looking it up it looks like my heads are large oval 113cc heads.

I have always been told flat tap cams will go flat so i better go with a roller cam, is that incorrect? the cam i pulled out had a flat lobe so im a little hesitant.

[weq92f]

.
...same here on the worries over eating lobes either during break in or sometime after, so I went the roller route. XR270hr on the 402 w/063's... It's strong off idle to around 5500. I justified the expense convincing myself steeper ramps would translate to more go. Certainly coupled with some higher lift!

-klb

[Mike C]

Use good oil, break it in properly. And buy the Howards cam with the face oiling lifters and the 5 year no-fault warranty.

I have (2) 427 with hydraulic rollers, but not for truck type usage. One marine cam, the XM284 which is 230/236 on 113 lsa and the small nitrous cam which is 224/236 @ .050 on 112.

I would NOT consider going bigger than 215 @ .050 or so as a good bench mark based on your usage/gear/tire size.

I have a 402 and a 454 that both might need cams, and they are otherwise stock so the Howard's cam is what they will get.

[dennislbrooks]

Mike C, just to get a little more info on the 4 inch stroke. Is that a 454 crank?

Would you use a 454 crank and rods with the 402 pistons to achieve the 427 from a 402 block?

I have a 71 10.5 compression stock engine which runs a flat tappet 396/350 cam in my 67 4x4. Excellent vacuum and will lug in OD lockup with 3.73 and 32 inch tires.

I do not actually need any more engine but the 427 small bore sounds cool for a 4x4.

[Mike C]

I installed one for a guy in a 69 Camaro using an original 396 block. I will have to look and see if I have the details on it, but I think that is correct, using a 4" stroke crank.

Here is a link to a thread on the Chevelle board. There is more info out there if you search.

https://www.chevelles.com/forums/155...454-crank.html