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Advice needed

3K views 16 replies 9 participants last post by  CLEVELAND JUNKY 
#1 ·
hey all.
i'm about to start peicing together a 351 for my XB coupe.
behind the 351 will be a toploader and 9" LSD with 3.25:1 gears. (both currently taking up space on my shed floor)
the car will mainly be used for street duties, with the odd run at the street drags and the occassional bit of circuit fun. nothing too spectacular.
anyways, i've been collecting parts for a while and this is what i have:
clean standard bore american cleveland block,
4MAB crank
standard 351 rods
cam with "520 lift at the valve"(my mates got it, thats all hes told me so far, supposed to have a rev range of 2500-6500rpm)
Offenhauser 'port-o-sonic' single plane inlet man.

i have a pair of close chamber heads, and a pair of opens.
question time:
i have three options with the heads, (a)open chamber with standard size valves, (b)relieved close chamber (semi-open chamber)with standard size valves, or (c) relieved close chamber with 4V valves fitted.
whichever heads i go with, they'll have port work done on them.
which heads should i use?
and should i use tri-y or 4-into-1 extractors?

which is the best combination, and with a decent-sized holley (eg 750dp)
what sort of power should i be expecting?
thanks guys, all advice is much appreciated.
 
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#4 ·
Closed chamber, don't put 4v vavles in it though.
power around the 240-270 hp at the wheels, i think your cam will let you down for too much more power. As racer said don't use a second hand cam, find out what type it is and buy a new one the same if you have to.
I'd use mandrel bent 4 into 1's and a dual 2 1/2" with "X" pipe, if it were mine.
 
#7 ·
Some put 2v intake and 4V exhausts in.

TICK4D said:
Closed chamber, don't put 4v vavles in it though.
power around the 240-270 hp at the wheels, i think your cam will let you down for too much more power. As racer said don't use a second hand cam, find out what type it is and buy a new one the same if you have to.
I'd use mandrel bent 4 into 1's and a dual 2 1/2" with "X" pipe, if it were mine.
 
#8 ·
2v intake yeah, helps air speed. But 4v valves in a 2v head makes it hard for the air to turn in, then you have to take time to port properly to get this right again, when all you need to do is to port the 2v's in the first instance.
With that cam it is not going to rev alot, and you do not need the 4v's which are for top end.
 
#10 ·
I agree with Racer. Stick with Tri-y's. XBWGN's 251 wagon with a cam in the same power range did 212rwkw with components of lower spec. With what you've stated and a can within the range of 2500-6500. That'd mean the cam would have about 220-238 or so duraction @ 50 on the inlet. Which should make good torque and should make over 200rwkw @ the treads.

XBWGN's 2 tonne XB wagon blew away modded FPV vehicles. lol Imagine getting your $50k car blown into the weeds by a 2 tonne 30y0 wagon.

Brenden
 
#11 ·
I might take a liberty here and clarify Brent's wording. ;) When he says "lower spec", what he is saying is that WBWGN has got a perfect combination. 212KW is a great result for "lesser parts" (if i remember his specs correctly)

Its the correct and balanced combination of parts as a whole that make good power, not just individual components alone. And this is a good example of it.
 
#12 ·
the cam is brand new, never used, still in the box etc. My mate bought it for his motor that was getting rebuilt, but it came back from the shop with a cam already in it... i'll have the specs on the weekend.
 
#13 ·
monty.v8 said:
hey all.
i'm about to start peicing together a 351 for my XB coupe.
behind the 351 will be a toploader and 9" LSD with 3.25:1 gears. (both currently taking up space on my shed floor)
the car will mainly be used for street duties, with the odd run at the street drags and the occassional bit of circuit fun. nothing too spectacular.
anyways, i've been collecting parts for a while and this is what i have:
clean standard bore american cleveland block,
4MAB crank
standard 351 rods
cam with "520 lift at the valve"(my mates got it, thats all hes told me so far, supposed to have a rev range of 2500-6500rpm)
Offenhauser 'port-o-sonic' single plane inlet man.

i have a pair of close chamber heads, and a pair of opens.
question time:
i have three options with the heads, (a)open chamber with standard size valves, (b)relieved close chamber (semi-open chamber)with standard size valves, or (c) relieved close chamber with 4V valves fitted.
whichever heads i go with, they'll have port work done on them.
which heads should i use?
and should i use tri-y or 4-into-1 extractors?

which is the best combination, and with a decent-sized holley (eg 750dp)
what sort of power should i be expecting?
thanks guys, all advice is much appreciated.
how r ya mate. go closed clamber with 4 V exh valve and relieve chamber around ex valve head.go single groove valves too. 4 into 1 extractors with 2.5" X type exh system. get a steel f/wheel and dont use finger type 11" clutch if u value your feet! only advantage with yankee block is they tend to have less corrosion, strength is same. use 750 or 780 vac sec with those diff gears, mech sec if ya go lower than 3.7. get or make a decent L.H. engine mount. have fun
 
#15 ·
TICK4D said:
2v intake yeah, helps air speed. But 4v valves in a 2v head makes it hard for the air to turn in, then you have to take time to port properly to get this right again, when all you need to do is to port the 2v's in the first instance.
With that cam it is not going to rev alot, and you do not need the 4v's which are for top end.
I mean 2V intake valve and 4V exhaust valve and NOT 2V and 4V manifolds !! I hope that is what u meant and what I mean ???
Thanks
 
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