521 in 1969 Cougar problems
Hi my name is Mark and I live in the United Kingdom and I have a 1969 Mercury Cougar, originally a 351 but was fitted with an early 429 in California before it was exported to the UK. The shock towers have not been cut back and the engine has been installed with Boss 429 mounts, early water pump and D5TE Truck exhaust manifolds which run into a decent 2.5" system with magnaflow mufflers. The car has 3.25 gears and a Eaton Truetrac centre I installed.
Last year I installed a 521 engine but although it starts and runs very well performance is disappointing and I am after some advice where I am going wrong.
The engine is 4.39 x 4.3 with Probe flat top pistons, inlet valve cutouts for regular and scj heads. The engine is fitted with procomp heads which have been pocket ported to suit 2.19 and 1.76 valves but no enlargement of the ports themselves.
The camshaft is solid flat tappet 264/268 @ 0.050. It is advanced 4 degrees with a Cloyes 9 key timing set.
It has an Edelbrock performer manifold. Non rpm variety
It is running a brand new Holley 870 Avenger.
Ignition is via a Mallory Comp 9000 distributor and amplifier. I have locked out the timing and run 30 degrees advance all the time
Transmission is C6 with Hughes 2500 stall convertor and rear 3.25 gears
If you floor the throttle it will smoke the tyres from standstill but torque in normal driving is lacklustre.
All I can think is my cam is too big for the spec something like 240 degrees would be better for torque.
I have a Torker II intake but can't see how a single plane would improve response
The other thing is I could advance the cam to 8 degrees on the timing set.
I know my exhaust manifolds are terrible but there is so little room in the engine bay I don't want to change for headers
Also wondering about going to 3.7 rear gears.
Any advice would be great, thanks
Last edited by markyjt777; 03-01-2019 at 08:17 PM.