L-100 cam

[pineapple]

I know this subject has been beaten to death, but maybe not to these exact specs. I would like to hear the extremely educated opinions of the old timer (much respect meant) engine builders here. I had Dave at cam techniques grind me an L-100 and reface some old johnsons, I was thinking of putting these in 8rt truck engine I have that has a .040 overbore with very low miles. I will do a bit of valve work and clean up the ports a bit. I was gonna use a fenton dual with 97's as well. Most likely headers. Going in my 51 f1. Ordered a chevy distributor from bubba as well. I guess my question is..Do I need to bore bigger to take full advantage of this cam? Am I wasting time using this cam in a mild overbore engine?

Thanks fellas..

[TomT/Williamsburg]

I do not have the knowledge to give you the definitive answer. But, that being said, what you have described does not seem to warrant any additional bore - leave some for the next rebuild in 150K+ miles!

[my4dv8]

Bigger is generally always better, but you will have just as much fun with the bore size you already have and money left in your pocket. We have an L-100 cam in our coupe and its not called the smiley cam for nothing . Fit it and enjoy.

[pineapple]

Hi Tom, I saw your roadster out at bonneville, but never made it over to meet you. sorry for that. Sounds like you had an epic road trip. Thanks for the response..Thanks my4dv8! I was saving this stuff for another 8ba long block I have, was gonna bore 3 5/16. I just had not yet bought pistons and have this other engine with the .040 overbore, thought it may work out, and , like you said, save a buck or two.

[Barn Junk]

Should work out nice as is. The 4" Merc crank really gives a nice bump in torque and works well, when and if, you go to the 3 5/16 bore. Besides you have to upgrade the pistons anyway.

[OLD...BILL]

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Originally Posted by my4dv8

Bigger is generally always better, but you will have just as much fun with the bore size you already have and money left in your pocket. We have an L-100 cam in our coupe and its not called the smiley cam for nothing . Fit it and enjoy.

Please tell me what the cam sounds like at ideal, and it's pull off the line ??? thanks .....OLD....BILL

[Ol' Ron]

Everybody here knows I support the use of this cam. I've used it in several 239 engines in light cars. The use of a long duration cam in any engine will bead of low end torque. Check out JWL's book and see the results of the relatively mild Max #1. This cam reduced the 2000RPM torque by several lbs. although it increased the torque at 3000 rpms by quite abit. The cure for this is higher compression and displacement, thus More torque building a 248 ci engine and using a set of EAB heads milled for .40/.050" piston clearance will more than compinsate for the loss of low enf torque and improve mileage at the same time. When using a converted SBC dist have Jim set the Mach adv at 16* abd the Vac at 8 degs, set inital at 4 degs. This should put you ibn the ballpark. Your on your own from there. Jetting the carbs willbe your next project, this is best done with a AF meter. Good luck.

[pineapple]

Thanks for the response Barn Junk and Ol Ron. Ron, I have your book, need to get a copy of JWL's still. I have a set of offy .400 early style heads with an unknown history, so I was going to mess around with em on the bridgeport, see if there's anything left once I've learned something. Was going to mill em for the .050" clearance and try doing your 5* valve pocket trick as well, depending on my success, maybe try to make a doming tool as well, if the domes aren't in the right spot for a good fit. I've marked off the 4* and 26* on the crank pulley after finding tdc as described in your book. Jim's sbc distributor is only mech. advance, from what I understand. I know tuning the carbs will be a bit of a chore, but I'm excited to figure it all out.Hopefully I'll be able to share something of all this..

Thanks again for the input.

[Richard in Florida]

Originally Posted by pineapple

I've marked off the 4* and 26* on the crank pulley after finding tdc as described in your book.

Twenty-six degrees is way too much for just about any flathead. JWL has stated that NO flathead needs any more than 20 degrees to develop full power.

Jim's sbc distributor is only mech. advance, from what I understand.

No, Jim will add an adjustable vacuum advance canister if you beg him.

[52merc]

jim also has vac dizzys you have to ask for

[Pete]

Originally Posted by Richard in Florida

Twenty-six degrees is way too much for just about any flathead. JWL has stated that NO flathead needs any more than 20 degrees to develop full power.

I think he was speaking of nearly stock engines.
Anyone who has run 100% nitro in these engines usually runs up to 42 degrees.
I run 34 on av gas.

[pineapple]

I like the sound of adjustable vacuum advance. Hopefully it's not too late to have that done. Thanks again fellas!

[Ol' Ron]

The advance curve is dependent on many things. Richard and I have varied the timing to get the best results. Too much mechanical advance leads to detonation and that can damage the engine. Not enough advance in cruise can waste fuel. Taking all these things into account has determined the actual timing requirements for most street engines. 20 degrees mechanical all in by 2000rpm and 8 degrees vacuum. This usually means only 16 in the dist with 4 initial. This is just a starting point and will depend on the modifications you've made to your engine. Now with all this said NITRO burns slow so you might want to advance it some.

[pineapple]

Jim said he would add an accel vacuum can to the build, (thanks again JIm!)
I'm guessing I'll have to do some messing around till I get it right..Hopefully wont damage anything.
Thanks for the input!

[Richard in Florida]

Originally Posted by Ol' Ron

20 degrees mechanical all in by 2000rpm and 8 degrees vacuum. This usually means only 16 in the dist with 4 initial.

Just a personal preference, but since the maximum mechanical advance is THE most critical number, I always set that FIRST.

With a converted Chevy, large or small, you just remove the springs so the weights will go right to maximum advance, start the engine, and set the pointer on 20 degrees or whatever you want. This is with vacuum advance absent or disconnected. Then put back the springs.

If your distributor is set up to have a range of 16 degrees, the static advance will be 4 degrees. The initial advance will be whatever your springs and weights and idle rpm make it.

Maximum mechanical is what's important.

[Richard in Florida]

Originally Posted by pineapple

Jim said he would add an accel vacuum can to the build, (thanks again JIm!)
I'm guessing I'll have to do some messing around till I get it right..Hopefully wont damage anything.
Thanks for the input!

Ask Jim to preset the vacuum canister for 8 degrees of advance.

Leave the vacuum advance disconnected until you get your mechanical advance set right. Once you're happy with that, add the vacuum; you'll need to readjust ONLY your idle SPEED, that's all. The rest is "automatic."

[pineapple]

Richard, Thanks for the tips, sounds easy enough. I know how "easy enough" can go sometimes though.