The Stovebolt Site Forums The Shop Area Engine Shop 261 caddy stroker almost ready.

I finally have this engine installed and assembled. I plan on starting it for the 1st time this Saturday. I still have to change/modify my manual choke cable to work with my dual carbs. They are new Daytona universal carbs with an adjustable main jet. They look a lot like the old Stromberg bvox carbs.. [img]https://www.stovebolt.com/ubbthread...name/1610400750601738484940648665665.jpg[/img]
The cable to my original Rochester is still in the truck, with the old mounting clip attached. Before I get into it, any advice, pics, etc, are appreciated as usual. What do you guys do to start a new engine?

Sure looks nice!

Ed

Way nice in fact. Almost crisp, i guess thats what id call it.

To me the most important thing to do is prime the oil system. Remove the distributor and use a long cutoff screwdriver chucked in a drill and spin it clockwise and continue until you have oil dripping from the #1 and #6 rockers.

Also don’t use starting fluid as it will wash the oil from the cylinders. If needed, use gas instead.

I’m sure others will chime in to help you get that beauty started. Good Luck!

Pull the distributor , prime the oil system , fit dist , start engine , run at fast idle to run the cam in (20mins) . Rejoice

Prime the carbs aswell so you don't have to crank it too long waiting on fuel to get to them from the tank.

While you're priming the oil system, spin the crankshaft a little with the starter. It distributes that pressurized oil evenly all the way around the bearings. Did you use plenty of assembly lube on the camshaft and lifters? DO NOT idle the engine after the initial startup. As soon as you see oil pressure, bring the RPM up to 1500-2K for about 20 minutes for cam/lifter break-in. Stovebolts don't have enough valve seat pressure to need special low tension run-in springs like the small block round track engines I used to build with triple springs.
Jerry

Boy that looks terrific. May I ask what all you did to fit the caddy pistons and later rods?

Dragsix. Man, it's been so long since I started this project. Tom Langdon is who supplied me with the right pistons and much of the knowledge. I can't remember what caddy they came from, but 289 comes to mind(fuzzy). The offset ground crank came from a guy out of Oregon who's name escapes me now. I got ahold of an engine builder through inliners.org who is not too far away. The engine was built 4 years ago and transfered into my truck. Since then, it's been in my garage waiting for me to get the carbs, fit the manifolds, do the linkage, oil lines and filter mount, etc...
Due to covid and lack of work, I've finally had time to get on this. I'm not complaining!
I'll post more info about the engine as I find it. I'm learning this all over again after so long...

I'm in the process of building a similar stroker engine that uses 292 connecting rods, but without the oddball grinding of the center of the rod journals. I made thrust washers for both sides of the 292 rods to match the width of the 235/261 crank journal, and TIG welded them to the rod caps, then reconditioned the rods to be sure any warp or out of round from the welding was corrected. I'm also using regular 235 or 261 pistons instead of the scarce and pricey Cadillac ones. I'm using bronze bushings in the small end of the 292 rod in the 235 engine, and Teflon thrust buttons to keep the original wrist pins centered. The 261 wrist pins will press fit into the 292 rod.

Here's a link to the original article, one that lists the Cadillac pistons:

https://www.angelfire.com/nv/conv/stovebolt.html

Jerry

Thanks Jerry! I just found that and was about to post, and you beat me to it!

I've got another stroker engine in the works that uses NASCAR style H beam rods and takes the stroke out to 4 3/8". It requires turning the crankshaft counterweights to a smaller diameter to prevent piston/crankshaft contact and possibly re-balancing the crank. That one will also work on 235 or 261 engines.
Jerry

The “Twelve Port News” Sept./Oct. 2003 issue discusses use of the Cadillac L61 6 liter 368” V8 3.800” piston.
The 3/16" stroke change only increases the displacement by 4.8% (261" becomes 273", etc.). All of the remaining increase is due to large piston oversizes.

The 300" engine mentioned in the article requires a 3.93" bore, or .179" (almost 3/16") over 261" bore. With that bore size, a 261" would be 286" with standard stroke.

A "261" with a 4 3/8" stroke and .060" overbore Chevy pistons ends up with 299 cubic inches. That's a lot more doable than chasing down scarce Cadillac pistons with the wrong size wrist pins. A "235" with a 60 overbore and the same stroke yields almost 263 cubic inches, also with readily available pistons.
Jerry

Bigmaccaddy I didb't hear any word about zinc additive to protect your new camshaft on start-up?? I suppose you have it in there ?? Great job !!!

Success! Kind of. We had some fuel pump issues. At first, it wouldn't start. We narrowed it down to the fuel pump not working. The glass bowl type that I bought from Jim Carter many moons ago. Diaphragm is good, but one way valves are shot. Worked great and then sat a while, unused, for the last 4 years. So no surprise. I found my original pump and we tried it. The engine started and sounded GREAT! Sadly, the pump was leaking due to the old diaphragm, and we had to shut it down. So now, I will either rebuild one of these pumps or buy a new one. I would love to hear from you guys about your knowledge and opinions about these pumps. I don't expect an agreed consensus, but let's have it😁

Fixite7 , yes camshaft was treated, and everything prelubed, prior to start-up.

Unfortunately, the quality of "rebuilt" fuel pumps these days ranges from "Bad" to "Terrible", to "Totally useless". "New" ones aren't much better. As much as I hate to say so, you might need to gut out one of those pump housings and convert it to a dummy with a hidden electric pump actually supplying the fuel. Loop a piece of tubing through the pump housing and remove the lever arm and other hardware, then use a blank gasket between the fake pump and the crankcase. Hide the electric pump back under the cab somewhere and use an oil pressure controlled relay to shut the pump down in case the engine stalls.
Jerry

The disadvantage of using any commercial piston is that the only compression increase is from (perhaps) tighter deck clearance (not much better) and more displacement.
If the deck and chamber are untouched, a 300" (261 + .060" X 4.375" stroke) increases static CR from about 8.00:1 to 9.03:1.
Although extremely valuable, it's not high enough to tolerate very late intake valve closing. If you want significantly above 9.00:1 you need a custom domed piston, $$$.

Turns out my neighbor(he rebuilds vintage Ford stuff for a living) had a new diaphragm for my original pump. He rebuilt it in 20 minutes this morning. I'm lucky...
He also pointed out that I could have likely used the good half of both pumps as a quick solution.🤦‍♂️
For now, I'm going to take care of one oil fitting leak, repair a wonky fuel pump bolt hole in the block, and finish hard line to the carbs, before we try start up again. I'll update in a week or 2.

It's finally run in! Sounds nice, and I'm "reasonably" close to having it tuned proper. I took a day to redo my fuel lines from the pump to the carbs, and did it all with steel line. I forgot how much fun bending and flaring is!

Looks great!. Congrats! The lines came out nice. Now we need a road report!

Any thoughts on plug gap? The minimum research I've done just makes it more confusing. I'm running AC R-45 plugs. 848 head. Tom Landon mini HEI. Right now, they're currently set at .044.

I think anything between 40~45. I have Tom's mini HEI and I'm using .045. Starts right up and runs nicely.

The only thing plug gap differences affect is the minimum firing voltage with clean, new spark plugs. 40-45 thousandths will produce a spark somewhere in the 10-12 KV range, compared to 8-10 KV with an .035" gap. That's why "40,000 volt" coils are so ridiculous- - - - -that's open circuit voltage capacity which has nothing to do with real world ignition system operation. 40 KV or more would fire plugs with the ground electrodes completely cut off! They just might miss a little under hard acceleration.
Jerry

When you guys build this engine with the mentioned modifications do you try to get squish/quench down close to around .040 ?

With the shape of the combustion chamber, that's virtually impossible. How many stovebolt engines have you built?
Jerry

Snap. Everything was going so great. This week, the engine was fine tuned, timing set, clutch adjusted, carbs synced, etc...
It was running so well! Amazing really. I decided to take it out today to break in a bit. I got on it very little, actually driving conservative, (for the most part) and then came the smoke. I limped about 10 minutes to my work as temp was rising. No water in Radiator, oil looks like milk. So either a bad head gasket or cracked head. I'll retrieve it next week and disassemble.

The quench areas in the chamber are comparatively small and oddly distributed (compared to a conventional "wedge" chamber such as SBC). It does resemble the Mercedes-Benz 230 SL L6 and Jaguar V12 "Fireball" chambers.
The rising stovebolt piston does expell mixture from a small area lateral to the intake valve seat toward the exhaust pocket (where the largest volume is contained) as it approaches TDC on the compression cycle, and closing this distance to a safe practical dimension was part of the original design.

You talking to me?