140 Heads on an Early

[jimbrandberg]

I asked a while back about the viability of using Late heads that have been milled significantly on an Early engine. There wasn't much discussion and I can't find that thread now in a search. I've answered my own question and thought some folks might be interested.

I started calling this engine my Rat Rod 102 but it may be a misnomer since I may no longer build the Rat Rod EM coupe and the engine is looking a lot less like a 102. The spirit of the project is putting together an engine from performance parts on hand here or using stuff gathering dust on someone else's shelf.

It started with a good deal on an abandoned EM crankshaft with bearings at Crankshaft Supply for cheap.

I thought if I'm not getting very far with stroke let's go for bore so I bought a new set of EM .060 pistons that someone someone wasn't using for a good price. Since .060 is getting out there I pulled a set of '60 full fin cylinders to have bored which the Machine Shop hasn't gotten around to yet.
Since then I've come into possession of an inexpensive set of scuffed up Clarks LM full fin cylinders. I never was real thrilled with how much head gasket surface I would have had with EM cylinders to .060.

So then if I'm using LM cylinders I'm not really locked into 102 EM heads. I had always wondered how much I could breathe through those little valves.
I have a pair of good looking 140 heads that someone has milled down to the squish. I wondered if the CC of those would be small enough given a EM stroke. I've heard the difference between EM and LM affects C/R about a point. Of course milling the heads can be a point, so perhaps I could I affect (effect?) a wash...

Today I measured a combustion chamber at 44 CCs. Given a 3.4975 bore; 2.60 stroke; .012 deck and .032 gasket it comes out to 9.02/1 C/R which is about what I dreamed of. The deck number is arbitrary.

I'm still wondering if someone has a EM performance cam they are never going to use. I know I can use a LM but a EM gathering dust would suit the spirit of this project. I've got two '62 102 cams.
I wish I had a nice '63 turbo cam for another engine project but I digress.

For the Rat Rod 102 I was going to use a 2-tube center mount manifold I have with a 2-barrel carburetor. I've got more than a few 4-leg. Or Rochesters.

I've always embraced the theory that it costs just as much money to rebuild a EM engine as a LM but you get 15% more displacement. Mr. Nash blew my mind with the theory you only have to turn a EM 15% faster to move the same amount of air.

I've got either a car or FC crankcase to pick from when it comes time. I don't suppose I'd have a high revving cam in a truck but maybe a Lakewood with some special air cleaners.

I suppose the next step is 140 heads into the oven for valve seat testing.

[66vairguy]

Good luck with the project Jim.

A VERY rough analogy would be a SBC 327 c.i. versus a SBC 350 c.i. The 327 likes to rev and compared to a 350 is smoother (in my seat of the pants experience). HOWEVER there is no denying the longer stroke 350 pulls stronger at lower RPM were most of us drive. There is an old saying "You advertise H.P., but you feel torque when you drive".

I still have a soft spot for the SBC 327. Just a nice engine to drive.

Anyway ---- let us know how your project goes and drives.