Which combo would win a race?

[90mustangGT]

I am on a budget, there is only so much I can do by next season. Please advise me on which combo would get me down the track faster.

My current combo:

Worn out factory 5.0 shortblock
Thumper Heads w/spring upgrade
B Cam on 1.7RR's
Edelbrock Performer EFI Intake
70MM Accufab TB+EGR
76mm C&L MAF
BBK Longtube headers 1 5/8ths,
O/R H pipe 2.5"
3.73 gears
TKO500 Trans
Spec III clutch.

I need to rebuild the shortblock, here is where money comes into play and I need advise. There are several ways to go. I can either:

Just a 347 stroker shortblock, maby a better cam, maby.
OR:
Build a 10.5 compression 306 using stock rods and crank, AFR 165 heads and a custom cam.
OR:
If the bores are acceptable and true, just clean it up and re-ring, hone, and put in new berrings, and of course the oil pump, shaft, ect. Replace the Thumper heads with a set of AFR 165's and put in a custom cam. Use the extra money saved for a manual steering conversion and electric waterpump.

 

[1qckFOX]

I would go with the 306 and the AFR's with a custom cam.

 

[stang2841]

Build a 10.5 compression 306 using stock rods and crank, AFR 165 heads and a custom cam.


that sounds the way to go, you can reuse both your rods and you crank? just buy pistons and rings? and get a rebuilt motor?

 

[90mustangGT]

If I can run a 1/8th of 8.4 at 85mph with a 1.8 60ft with my current combo, if I went with the 306-AFR-custom cam combo, what do you think I would be running compared to now considering that my shortblock failed a leakdown test badly. I'm loosing 50% of the compression through cylinder #6 and anywhere between 34-44% through the rest except #3 is only at 24% which is considered "acceptable" but not good.

I am wondering if the better top end of the AFR/FTI/306 would catch the torque of the 347.

 

[9 Deuce GT]

I would build the 347 now and then next year or whenever get better heads, etc. This will allow you to go even faster later on, but still run good now.

 

[RydeOn]

Dude, Thumper says his heads on a 347 goes 11's. So whats the predicament? Build that 347!

 

[tmoss]

347 will need some block clearancing. Going 327/331 is easier. Thinking of your budget.

 

[krahkin]

Hate to hijack. Just wanted to ask 90mustangGT if he races at Dallas?

 

[TT91]

347 will need some block clearancing. Going 327/331 is easier. Thinking of your budget.

The 331/327 requires the block to be clearanced as well. I would go with a 347 over a 306.

 

[25thmustang]

Id go 306 if it were me!

 

[TT91]

Id go 306 if it were me!

Why?

 

[tmoss]

The 331/327 requires the block to be clearanced as well. I would go with a 347 over a 306.

I haven't done this (yet), so what is required? Do you have to relieve the cylinders at the bottom for the rods?

 

[Grn92LX]

I think i'd do the 347 only because you'll have a better foundation. The 306 with afr's will be faster for now BUT once you ditch those junk E7's and get some good (but still mild) heads like afr 185's or TFS hi ports you'll be in the 400rwhp mark as opposed to the 315ish rwhp mark with the 306. Fwiw my friend made 323hp/348tq with his 10.5:1 306 with edelbrock heads, comp 270 cam and a tfs street intake, no custom cam needed for him. Food for thought.

A done right 347 all said and done is expensive, but doing it your way should be affordable because your only changing the shortblock. I was in your situation too and a new engine was just too much money, so I ordered a Vortech SQ S trim because I felt that was more cost effective and WILL net a lot more power. If my engine ever needs a rebuild I can just use a low comp TW specific piston, a decent I beam rod with arp bolts and stock crank.

 

[25thmustang]

Why?

Well my reasonings are simple. For the money he has now and what he wants to do, the 306 with AFRs and custom cam will probably be faster than the 347 with the thunper heads and cam he has. I realize the 347 will make more power later, but then again the 306 could be stroked later on as well...

Also I race in heads up classes, and 306s are allowed all over the place yet 347s arent allowed in very many classes. Even the ones that allow them are running 8s. I guess this is why I personally would buy one, so I could race in my class still, but as far as the original poster, because of the reasons stated above. Im a fan of small cube motors!

 

[IndyBlk5.0]

If I could do it all over, (and if I had the money) I would of done a 347 with the PTL 200cc heads. A buddy is trapping 117 with this combo and simple other bolt ons. Hopeing for 10's all motor.

347 all the way. or hell, do a 408

 

[89331SC]

A 331/347 is expensive to build. I know this from experience. Unless you plan to do serios racing and your stock crank and rods are good id go with the 306. You can always add a supercharger later if you want more power. A decent stroker kit and the block machining will easily cost more than $1000 where as if you do a 306 you avoid this cost if you stock parts are good.

 

[stealthracing]

for a budget, i would go with the 306, use the stock crank, rods get new pistons, try tfs heads. i made 347hp, 354ftlb at the wheel all motor, 480/590 with a 125 shot. i have had good luck using the factory parts, despite what some people have said. the car went 12.1 all motor @114mph 1.60 short time. consistent 11.02-7 with n2o at 124-125 mph.

 

[25thmustang]

for a budget, i would go with the 306, use the stock crank, rods get new pistons, try tfs heads. i made 347hp, 354ftlb at the wheel all motor, 480/590 with a 125 shot. i have had good luck using the factory parts, despite what some people have said. the car went 12.1 all motor @114mph 1.60 short time. consistent 11.02-7 with n2o at 124-125 mph.

Wow, 12.1 @ 114 with a 1.60 60'. I have gone 12.1 @ 110 with a 1.65 60'. Where did the car lose the times on that run? That mph is easy 11.7s!

 

[5spd GT]

I would do the 306 personally...

 

[thumper460]

Budget...?? The 90 engine has forged pistons..Ring and bearings, ARP on the rods, install the B @ 103ICL ( if you haven't done that yet) Have the heads milled .020 , spend money on a chip or computer tune, and suspension.. try and get the 1.8 short time in the 1.6's and that alone will put you down in the 8.0's !!

347 isnt that much when you compare.. IF you do the work !! Machine the block..200.00, rotating assy ( from me or others) 1500.00 ( steel crank and H beam) 185.00 to balance... notching the block is cake.. just different. add gaskets.. and your under 2000.00 for the 347!! Heads?? they are running 11's with the ported E7s !! SOOoo... that expence and upgraded cam is all up to you..cool??

Just me........................

Thumper