KAAMA

Okay Jerry thanks for straightening me around----my bad.

mcollinstn

overlap'll kill fuel economy under 3500 rpm.
And a blower will push most of it out the exhaust (fuel that is).

731 has minimal .050" overlap (4 degrees I think)
741 has I believe 16 degrees (at .050")

Everybody loves the 741 on 502s but I'm still a believer that the 731 is only down 25 hp at 5400rpm and probably gives 20% better 3500rpm fuel economy (with blowers at 7 psi). I have no hard data to back this up.

Does anybody have BSFC numbers on a blown 502 with a 731 vs a 741 at WOT and at 3000 rpm?? I'd be very interested in seeing those results.

GO4BROKE

0F820000 THRU 0K999999
454 MAG. ALPHA GM 454 V-8 1986-1988 0A631894 THRU 0B785148
454 MAG. BRAVO GM 454 V-8 1988-1992 0B721206 THRU 0D805068
454 MAG. BRAVO (GEN. V) GM 454 V-8 1992-1994 0D805069 THRU 0F304999
454 MAG. BRAVO (GEN. V) GM 454 V-8 1995-1996 0F305000 THRU 0F801699
454 MAG. BRAVO (GEN. V) GM 454 V-8 1996-1997 0F801700 THRU 0K999999
454 MAG. BRAVO MPI (GEN VI) GM 454 V-8 1996-1997 0F802350 THRU 0K999999
454 MAG. MPI BRAVO (GEN VI) GM 454 V-8 1998 0L010029 THRU 0L058399
454 MAG. MPI BRAVO (GEN VI) GM 454 V-8


I copied this from the Merc parts look up screen. It lists my motors as gen V. Although according to some literature I have from GM ("Crate Update, Inside the Gen VI big block) my motors are gen VI. gen IV and V blocks have a stamped steel timing cover, VI has a cast 6 bolt cover and an integral timing tab ( vs bolt on). GM started producing the VI in 1996. Merc probably had left over V's for a while, then got the VI. The VI also has a degreed harmonic balancer.

I definately have the gen VI. So I would like to find a good roller cam that can use the stock lifters.

Thanks so much for the info and the links, its all a big help, I'm running out of ink printing it all out!

US1 Fountain

mcollinstn,
Charles aka 27FOUNTAIN, has the 139731 in his Troy Dennis 502 with 250 blower. I think he is very happy with it.



from my dyno sheet.
stock 502 shortblock, mild head work, B&M250, 5#, 1050 Dominator, 139741

BSFC @3600 .64
@5200-5500 .56

GO4BROKE

I guess after looking at the cam sheets for the 731 and 741 I will be buying lifters!

I will run the cams on desktop dyno and see what it thinks.

Again lots of thanks! All this feedback is exactly what I am looking for!

US1 Fountain

Does the Gen#'s timing cover difference apply to 454's the same as it does to the 502's? Strange your serial number conflicts with the info. Is your motor a roller or flat?

GO4BROKE

US1, thanks for all the posts.
The timing cover difference applies to the block, regardless of displacement.
My motors are roller.
You're right about the conflicting info, but thats not uncommon in technical publications, I deal with it at work constantly. Found a fault in a service manual today, in fact.
My serial #'s have the OK prefix, My theory is that the OF's are gen V, and the OK's gen VI.

bobby daniels

You'll still like the 731 in your 454 tons better and it will be very quick and fuel efficent in your 454 ,,if you had a 502,509,540 ect.
the 741 would be o.k.,,, what is a 454 vrs. a 502 10% smaller

Scott

I would like to get some logical proven facts between the applications of the two ( I should start a new thread).
I think I will Guys please look for it and help me and a lot of others get this figured out
I will start it tommorow morning (need the sleep)!

Scott

Back4More

Anyone try the #761?
The one in between the #741 and #731...