help with engine build

Who is the best person to rebuild your engine? You...

Moderator: sparkmaster1

Post Reply
petro53
Posts: 3
Joined: Mon Jan 09, 2017 9:30 pm

help with engine build

Post by petro53 » Mon Jan 30, 2017 9:03 pm

I am building a baja with bus reduction boxes, 1967 frame, I want a engine that runs cools, good low end power, runs cool, Florida temps, but with some extra grunt. Cost is somewhat of a factor, but you get what you pay for. Mild stroker, single or duel carbs, 1914-do they run hot, what compression? How about some ideas on what you have actually done not just a bunch of theory, This is not my first build, I was around "back in the day" was a parts manager at a VW dealer with an Empi distributorship, that said, a lot has changed and I want to get this right on the first go round. Primary use is weekend fun, back roads, fishing and camping, maybe tow a small trailer. Reliable and strong seem to be coming to mind, oh by the way building my own Johnson type RGB adaptors, this site is great.

petro53
Posts: 3
Joined: Mon Jan 09, 2017 9:30 pm

Re: help with engine build

Post by petro53 » Mon Jan 30, 2017 9:16 pm

I am putting new "good" pans and channels in this 67, pretty much leaving nothing untouched. I have a torch and and welder, don't tell me it can't be done. In honor of Fred.

User avatar
Marc
Moderator
Posts: 23727
Joined: Thu May 23, 2002 2:01 am
Contact:

Re: help with engine build

Post by Marc » Tue Jan 31, 2017 12:51 am

To keep things simple (and the budget low) stick with the stock stroke. Doesn't sound like you'll be needing to exceed 5000 RPM so a stock (non-counterweighted) crank will do, but DO have the crank & flywheel 8-dowelled. I wouldn't go overly light on the flywheel for what you have in mind, take off just a couple of pounds or leave it stock.
Stock heater boxes (or J-tubes) and "street" exhaust systems are good enough up to 4500-5000 RPM with stock-valve heads at around 1800cc. If you plan to go bigger than that, budget for oversize heat exchangers and a larger header...you may not care about heat at all in FL, so a "competition" style exhaust would work too.
1835cc (92mm bore) has a well-deserved bad reputation for poor durability due to the thin cylinderwalls, but nowadays you can buy "thickwall" 92s from AA that still go into a 96mm case register but require that the heads be opened up to the "94" size of 101.1mm. Worth considering, you end up with cylinderwalls thicker than 94 or even 90.5 and you're still in that ~1800cc realm.
There's exactly ONE combination for a mid-stroke engine that goes together without too much grief (you'd still need to clearance the case some, just how much would depend upon the choice of rods). That's 76mm stroke using "B" compression-height pistons and 5.5" rods. Ends up needing just a little cylinder-base shim so the package width is nearly stock. Any other "small-stroke" combo is more trouble than it's worth IMO, may as well jump up to 82mm.

petro53
Posts: 3
Joined: Mon Jan 09, 2017 9:30 pm

Re: help with engine build

Post by petro53 » Tue Jan 31, 2017 10:11 am

Thanks, food for thought, never built a stroker, but lots of hot 1600 and 1835s. Any ideas on carb for the 1835, I have used a progressive a couple of times and with proper set up work pretty good,but never for off road, seems like duel anything would be over kill and the single weber 44 was a gas hog.

User avatar
Marc
Moderator
Posts: 23727
Joined: Thu May 23, 2002 2:01 am
Contact:

Re: help with engine build

Post by Marc » Tue Jan 31, 2017 4:43 pm

If this is going to be a fair-weather ride, the Holley-Weber progressive would make your life simple and doesn't suffer from float-level control problems in the rough stuff the way most dual setups do. It'd limit top-end power considerably compared to some other choices but it doesn't appear that you're too concerned with that - plus you're familiar with it.

ALL center-mounted 2-bbls suffer to some extent from a hesitation on acceleration, exacerbated when the atmosphere is cool & damp. Maximizing intake manifold heat helps, but often it's still necessary to jet them overly rich and with a big accelerator pump shot to achieve decent driveability. On a warm sunny day it's nowhere near as bad. If it were not for the off-road usage I'd go with a pair of small 1-bbls, which'd give you better mileage, more power, and no flat spot. With good linkage, once they're set they shouldn't need much more attention than a single.

BUT when you start hustling through the rough stuff, especially with a swingaxle that starts rocking side-to-side, duals are going to have problems. Extending the bowl vents to reduce splashover helps some; "dry-sumping" the carbs by removing the float and filling the chamber with fuel-cell foam and adding a scavenge pickup to electric pump(s) is the ultimate solution, but risky if something fails - that's why it's illegal in sanctioned offroad racing.

Post Reply