Recently, i've acquired a new daily driver. it's a '72 model so outside of the HAMB scope, but the engine should be familiar to some: The Chevy 153 L4. Right now i'll leave it bone stock, but in the future i want to build it up a bit. The goal would be a street engine on pump gas, nothing crazy, on the 120-150hp range (should be enough to move a 2300ish Lb car around) Problem is: almost all that i've found about building these engines (save for some good info here on the Jalopy Journal), either revolves around old racing parts, mercruiser 181 engines or dirt track/drag engines, so i decided to ask a more general group about the mods i would want to perform on it (since i have no experience in building engines). First of: I should point out we also had 151 engines in Brazil but not The 151 (the Pontiac Iron Duke), ours was the same 153, but with 4" bore, 3" stroke and 6" rods from the factory. the 151s also did away with the siamese head ports. (power didn't change much though) Ok, so on with my plan, to which i ask your opinion on: Starting on a 151 block, with 153 crank, i can build a 163CI engine Here, we had Ethanol powered 151s, so i could use a set of Ethanol spec pistons to raise the compression ratio. i'm not sure if gasoline and ethanol heads are different (i know the ones on 250 L6s are), so i might have to use an E head to get the 10.5:1 CR they had (too much for 70's gas, but ok on today's) Speaking of the head, like i mentioned before 153 have siamese intake ports, while 151s have individual ports (pictured below). i've been told that when fully modified, the individuals don't flow as much as the siamese, but throttle response should be better. So, for a street engine with little head mods (maybe some polishing) i should go with the 151 head, right? 151 head 153 head The cams, one of the most important parts for the behavior of the engine are a big doubt for me I can find almost no info on cams (people around here only know how to compare advertised duration and go saying things like "this 292° cam is better than that 268°" with no regard for duration at .050 or LSA, so even aftermarket ones only show advertised duration, and sometimes LSA) Out of the stock ones, the only one i could find somewhat reliable (even if dubious) info was the one found in the 250S version of the L6, which is available on the aftermarket for the L4 as well (around 250° adv, 200 @ 0.050" and 112° LSA), but i think that cam might be too mild for my goals. Onto the bolt ons: Intake and exhaust would be pretty simple, a dual barrel carb (maybe 2x1s) and a tuned header. Stock cam gear is made out of fiber, but a L6 aluminum gear is a bolt on Harmonic balancer/damper That's basically it. Is there any reason why my combo wouldn't work? or any signs it would be too much/little for my goals. If any of you know of a "recipe" with similar results to what i want, feel free to share. Thanks in advance.
The Jalopy Journal
