Time for rebuild

[69Shakar]

I have a 69 Torino with a390gt motor that’s really tired.... would like to stroke it to 445. I’ve found a local builder who has a long history building various racing fe’s something he mentioned that I haven’t seen on here or on the various forums is the breaking of main caps from the extra stroke with this build..do I need to take this into consideration or be worried?? What I’m thinking for my build is hydraulic roller cam, flat top pistons, either trick flow heads or barry’s Felony heads, rpm intake, quick fuel 850 carb, not sure if or which rockers to go with.. I know I have to do end stands for the rocker shafts, not sure about which lifters to use or stay away from. The Torino does have power brakes and steering, wide ratio c6, 3.25 gears and 28 inch tall tires. This car probably won’t see a track... just spirited driving, highway, stoplights,... looking for suggestions and or recommendations as I’m trying not to go crazy on the budget..

[chilly460]

Bunch of 445s out there and I’ve never heard of them breaking main caps.  I have read of some experiences with main web area cracking at the 600-650hp level with racing duty

There are quite a few builds out there similar to what you’re lookig to do

Performer RPM intake
Pistons to hit 9.5-10:1
Survival/BBM heads with light bowl blend or TFS
Hydraulic roller in the 230-235* area .575-.600 Light ballpark should give all around performance and still work with power brakes if you’re careful with overlap

[jayb]

I wonder why your engine builder is under the impression that the main caps could crack?  Never seen it, in any of my stroker builds. 

[blykins]

Never seen it, or even heard of it, on an FE.

I wouldn’t worry about it and I would actually be leery of how much “racing FE” experience that he has.  Cracked main caps is typically a Chevy problem.

[Barry_R]

Only time I ever saw split main caps on an FE was the earliest Genesis blocks.  They had a ductile iron cap with a threaded "pull hole" that was deep into the cap material - a natural stress riser.  Had a couple engines come in after racing service that had caps that came off in two pieces even though they were running fine.  Subsequent blocks had steel caps and bosses for the pull hole & problems went away.

[machoneman]

Perhaps he meant (or said) main bearing cam tunnel cracks...or he is a Chevy guy!

[69Shakar]

The reason for breaking main caps might lie in the fact the drag racers he built the engines for are winding them up to 7500.... with 4-5 grand launches.... I’m thinking 5.5-6k for max  rpm capability. When looking at the 70cc trick flow heads  with flat top pistons puts compression at 11-1or so which I assume is to much for 3600 lb car I have no problem with running premium fuel

[jayb]

7500 RPM isn't going to break those main caps.  The block will go before the caps do.  Cam and compression have to be selected together.  11:1 will be fine with pump fuel, if you have the right cam in the engine.  Do you have a horsepower goal?  That will help with cam and compression selection, but bear in mind that the more HP you want, the less friendly the engine will be at lower engine speeds.

[falcongeorge]

Perhaps he meant (or said) main bearing cam tunnel cracks...or he is a Chevy guy!

That’s my guess, engine builder said main webs, the poster heard main caps.

[69Shakar]

I don’t really have a horsepower goal.... I would love to tell someone the engine puts out 550 horse& torque at the rear wheel after showing them up.....am I going to be disappointed if it only does 525 not really... it will still be the most power under the hood of a car that I’ve owned. I realize I will have to  compromise on getting greedy with the power so I have enough vacuum for the brakes to work as they should. I’m trying to get the most bang for the buck without breaking the bank.

[fryedaddy]

i think its a bb mopar problem.i have a bracket buddy rebuilding a 440 right now and he decided not to stroke it because of this

[chilly460]

550rwhp = ~650hp at the crank, tall order with a 445 retaining power brakes.

[Barry_R]

Done several 500 HP 445s the will just tickle 10-11 on vacuum - - just enough for the brakes.

[falcongeorge]

i think its a bb mopar problem.i have a bracket buddy rebuilding a 440 right now and he decided not to stroke it because of this

built tons of bbm’s never cracked a main cap. More problems with rod big ends, but you really gotta be winging the sh*t out of them. Bbm bottom ends are very robust in my experience.

[blykins]

i think its a bb mopar problem.i have a bracket buddy rebuilding a 440 right now and he decided not to stroke it because of this

built tons of bbm’s never cracked a main cap. More problems with rod big ends, but you really gotta be winging the sh*t out of them. Bbm bottom ends are very robust in my experience.

My buddy that owns the dyno I use is hardcore Mopar.....he puts aluminum main caps on all his high-end BBM engines because of cracked main caps.  The aluminum caps absorb some of the bad harmonics.