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I am looking to wake up my 74 small block. The engine is the original 2 bolt main that my father had rebuilt in the early 2000s, but has less than 5000 miles on it since the rebuild, and runs well. For the rebuild it was bored 0.030 over, retained the stock heads and had a mild cam put in it. My dad cannot remember the cam specs.
Since the car has become mine I have installed headers, 2.5" exhaust, a edelbrock performer intake and changed the rear gear to a 3.55 behind the th400. I have some 64cc chamber e-street heads I am getting ready to put on it, which should bring my compression ratio to around 9:1. I am now trying to decide on cam for it. I plan to stay with a hydraulic flat tappet.
I was originally planning to go with the edelbrock 2102 cam, but it is on a long backorder. I discovered the summit K1102 which appears to be essentially the same grind as the edelbrock, but they also have the K1103 which seems to be a little "bigger" cam. Specs are listed below:
edelbrock / summit k1102: Duration @ 0.50: 204 int / 215exh. Lift: 0.420int / 0.442exh LSA: 112
summit k1103: Duration @ 0.50: 214int / 224exh. Lift: 0.444int / 0.466exh. LSA: 112
I think the 1102 should work well with my setup, but if the K1103 would fit better would I want to go that route? Does anyone have experience with these cams? I more interested in street performance than sound, but I imagine the bigger cam might sound a little meaner.
I should add that the car is only used for spirited street driving and occasionally commuting to work.
Any help / input would be appreciated!
Last edited by Lamouree351; 06-21-2021 at 08:08 PM.
Both of those cams sound very mild. How about a crane XE 268-H, Duration, 269/280. Lift 477 - 480. lobe separation 110.
Just a tad hotter than a L82 Cam. might actually make a bit of a difference. if Dad didn't already put one in.
next question. dad.s rebuild. same dished pistons? or flat tops? was block decked and how much? nobody puts dished pistons back in an engine. and if they are flat tops and zero-decked the block, you are already at 9.5 if flat tops and still the stock .020 in the hole those heads will put you at 10.3 that is not a bad cr, especially with aluminum heads. but you need to know what you have before you make changes.
next question. dad.s rebuild. same dished pistons? or flat tops? was block decked and how much? nobody puts dished pistons back in an engine. and if they are flat tops and zero-decked the block, you are already at 9.5 if flat tops and still the stock .020 in the hole those heads will put you at 10.3 that is not a bad cr, especially with aluminum heads. but you need to know what you have before you make changes.
I have asked those questions as well, Unfortunately his memory isn't what it used to be. He said the deck was machined but cannot recall how much. The pistons are a toss up, They only thing he could say for sure was that they were not domed pistons. The compression ratio I listed above was assuming worse case scenario of a stock dished piston and 0.025" deck clearance. I am leaning more and more towards pulling a head off and seeing what I have for sure.
Last edited by Lamouree351; 06-22-2021 at 07:41 AM.
I have asked those questions as well, Unfortunately his memory isn't what it used to be. He said the deck was machined but cannot recall how much. The pistons are a toss up, They only think he could say for sure was that they were not domed pistons. The compression ratio I listed above was assuming worse case scenario of a stock dished piston and 0.025" deck clearance. I am leaning more and more towards pulling a head off and seeing what I have for sure.
Yep...pull a head and see what ya got.....
Is this an auto or 4 speed car?
I went with the voodoo 262/268 cam which I just removed after 8 years to go with a retro roller comp 270 cam. Strangely enough the comp roller cam which is bigger still feels stronger at lower RPMs in my build with 10.15:1 compression 64 cc heads and flat tops and 1.6 rockers.. (.024 in the hole and .015 steel shim gaskets)
I believe this is due to the advantage of the roller cam profiles. my dyno software shows about a 30hp gain just going from a tappet to roller cam in the same size range. Thats noticable and no more worrying about oil additives.
I am swapping my rear end to 3.55 soon and installing an OD transmission but if you are planning on keeping the 3.08 gears you may find it interesting that car and driver found the l82 engine (cam) was not as responsive and fun to drive due to the loss of low end torque with those gears. they favored the L48 in 74 for street driving.
Personally I only use my vette for spirited street driving so I want as much torque down low as possible. I never take it to even 5,000rpm so building for high rpm HP #s with the tradeoff of less torque where I need it is not really ideal for my use and combo.
The 262 cam performed well but in hind site if I did it all over again I would have just gone with the cam (xe270HR) I have now. I bought the retro lifters from rock auto for $128 for the set which saved me quite a bit and brought the entire conversion with pushrods below $500
btw your th400 has about a 2000rpm stock converter if you dont already know.
Last edited by augiedoggy; 06-22-2021 at 10:53 AM.
The L-82 cam needed headers......there is enough lift and overlap here to need scavenging that the Ram Horns can never do.......it also needed correct timing specs much more than the L-82, although both benefit.....both engines factory specs were pathetic.
Add headers and a nice dual system to a bone stock 74' L-82 and it will pick up huge.......and it will add the needed torque down low......
Are you doing the cam swap yourself? If so, why not decide on a new cam after you pull out the existing one? If you can identify it then you won't risk putting in something milder.
Are you doing the cam swap yourself? If so, why not decide on a new cam after you pull out the existing one? If you can identify it then you won't risk putting in something milder.
I am planning to do the swap myself. Not sure why, but I had just assumed I would not be able to identify the old cam...
I am planning to do the swap myself. Not sure why, but I had just assumed I would not be able to identify the old cam...
I'm not sure this is always possible either. One thing you could do, if you have access to a dial indicator with a magnetic base, is check the lift of the cam lobes measuring off a lifter, turning the engine by hand. (This is with the intake manifold removed.) The lift at the cam lobe, multiplied by the rocker ratio, i.e. 1.5, would give you the advertised cam lift. Higher lifts usually mean bigger durations.
I'm not sure this is always possible either. One thing you could do, if you have access to a dial indicator with a magnetic base, is check the lift of the cam lobes measuring off a lifter, turning the engine by hand. (This is with the intake manifold removed.) The lift at the cam lobe, multiplied by the rocker ratio, i.e. 1.5, would give you the advertised cam lift. Higher lifts usually mean bigger durations.
Most all cam companies stamp the number on the front or rear journal of the cam.
One thing you can do if it is not identifiable is measure the base circle and the lobe peak with a dial caliper and subtract the two.....then multiply by rocker ratio. Gets you very close when the car is out. BK's suggestion of doing it in the valley off a mag base is good too.....
If you at least know the cam manufacturer....the lobe lift numbers narrow down the suspects pretty well......so make sure you measure both lobes.
2nd cam will run real well, nice manners strong toruqe...and will sound decent.
The 1st one is practically a stock replacement cam I always thought it was doggy. Kind of an "rv" cam
Well I pulled the heads off tonight and confirmed the worst case scenario..... The pistons are dished. They are marked with "020" which I assume means a 20cc dish?? I also confirmed the deck clearance is 0.035". Which means with my new 64cc head and a 0.041" thick head gasket my compression ratio will only be 8.28:1...... I see that felpro offers a .015" thick head gasket, that would get me up to 8.7:1. Even with that I imagine that I will need to go on the smaller side of cams.
With decent heads and 9:1 compression I would go with the k1103.
The first cam is close to the old crower Baja beast, which worked really well on low compression engines with stock heads. It was a decent improvement over the stock flat tappet cam even though it wasn’t much bigger.
I ran the 268H with stock bottom end and 64cc heads. It had good mid range but with 3.08 gears the bottom end was pretty lame. With tall gears the first cam might feel quicker but have less mid-high range power.
To properly CC them would mean removing one or pulling the engine to get it level. for the price of a set of pistons. I would replace them with flat tops.
06-21-2021, 08:06 PM
74 Small block cam selection.
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