i have a 351 that i'm trying to build up to be street legal but have as much low-end torque and horsepower as possible. So basically i want to build it to have fast take off and acceleration but not necessarily with a mammoth topspeed.
Any suggestions on cam type, gear ratios, parts and anything else i should know?
The engine is going into my coupe if that helps at all and the trans is a C4 auto.
When you say street legal do you mean really street legal? That is, pass over the pits legal. If so you will need to keep the original carb and air cleaner etc (to comply with ADR 27A, as shown on your compliance plate).
You can get a street legal car going well but to keep it simple, change the diff ratio to the vicinity of 3.5:1 to 4.11:1. This will achieve a quick take off and also leaves the automatic transmission alone.
Another favourite is that of using 302 rods with ACL pistons to suit the 351 crank, cheap and easy. With respect to cams, once again keeping it simple, go the Dyntech PC 315 or something more lumpy, the PC316. Get the heads a good porting, ground out the bowls and put 4V valves in the exhaust only and you will be looking good.
I certainly owuldnt keep the top end stock but I wouldn't go berserk over it either. If you have the bucks a stroker will be the go but it would be wasted without a mild cam and a bit of clean up work on the heads etc.
In regards to the heads, first you have to chose either open or closed chamber. I origanally went open, as i wanted no hassels with fuel/detonation, but later found out closed would of been fine. If you wany to stroke it, maybe open chamber heads, to keep the compression practical, but if you want to stay 351 cubes, id go closed chamber heads, and leave the deck height standard. With a bit of porting, and the chamber cleaned up a bit, you would have about 10:1. Make sure you fit decent, 1 piece valves with single groove locks, and matching springs,retainers and locks. Then choose a cam around 220 degrees at 50thou, and about 540 lift and stick 3.7:1 rear gears, and a 650 double pumper, and you would have a stout machine. Keep a standard carby in case you have to be "inspected". You may need a matching stall for the auto if you go too big in the cam.
10.70 @ 125.00 on the black fun top
408 Cube Cleveland.
302 heads - if you are lucky you may find a set of recently recoed gas heads.
Port the heads as described by David Vizard in his 'How to build horsepower series'
Open the combustion chamber upto around 65cc. Calculate the desired comp ratio first.
Generic 214/224 hydraulic camshaft, and valve springs to suit. Factory retainers & rocker arms are fine if you are on a budget.
Factory 4 barrel 2v manifold. Use the XC style.
Thermoquad - source a 351 model if possible and overhaul it. You may wish to remove the choke mechanism, rods etc as it makes it much simpler.
Electronic distributor curved to suit. In the order of 12 degree static and 32 total. The XC distributors are getting hard to find.
Tri y headers - you can often source these second hand.
Stock bottom end
I had this setup in my XB coupe. It was almost too torquey with a 3.5 diff. In the wet it would brake traction at low revs in third gear. At Winton it matched a VX SS Commodore with an aftermarket cool air induction. Not bad since it didn't rev over 5000 rpm and cost me $600 to put together.
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