[Navarro's XR-7]

Hey Cougar pals!I am going to rebuild my 302 engine.it has low compression in all cyl, 80lb to 85lb.should be 150lb.i want to add a cam and some hedders?can you help me pick something out.the car is a 1968 XR-7 and any help on rebuilding my engine:1zhelp:

 

[sixt9coug]

rebuild it, or just get a late model 5.0L with the roller cam. if my car didnt get between 175 and 180 psi in all of the cylinders i would probably do the same. well, with a 351 anyway

 

[dan]

swap it out

I would go with a 351 or mmm428, unless your going original.nothig like MORE POWER

 

[FoKKerj]

headers

Go with a set of headman headers, but the cam has way to many variables, in other words what are you looking for to get out of your motor? The edelbrock kit in jegs with a cam, lifters, intake, and carb would be a good easy choice.

 

[jdalu]

So, If I wanted to check my 351-4v M-code's compression, the number should be in the 150 psig range. I could just do the bore & stroke calc real quick, but I don't have those numbers in front of me right now. Any thoughts?

 

[Cougrrcj]

Checking cranking compression

Checking cranking compression can be a deceiving tool. The reason I say this is you don't know what sort of modifications to the cam have been done. A hipo cam generally will have a longer duration which means the valves are open longer. If the valves are open longer, you'll have less cranking compression.

Also, when performing a compression check, you have to make sure that the carb (throttle) butterflies are wide open. You can't suck in air past a closed throttle! Not keeping the throttle wide open will give an errant reading. Also, make sure that you have all of the other sparkplugs removed. You want to make sure that your battery is fully chargerd as well so the cranking speed is the same for all of your testing.

What a compression test will show you is the relational compression between all cylinders. You don't want to have any once cylinder off by more than 10-15% of the norm. If one or more cylinders are that much lower than the others, that would indicate a problem. You could have either a burnt valve, broken rings, a hole burned/cracked through a piston top, a blown head gasket, a 'torch hole' between two cylinders in the block itself (I have seen this in person, BTW), the list goes on, but you get the idea. If the low compression reading cylinders respond to a squirt of oil down the sparkplug hole by jumping back up to 'normal' on a retest, you have worn rings. If not, well, you'll have to tear the heads off to check.

 

[Navarro's XR-7]

THANKS FOR THE RESPONSE

Thank guys for all the info keep it coming i just want simple stuff and low budget,so i can spend on other things like cut of the rear valance i just bought the chrome parts all i need is to cut the valance.then move my pipes up.i know my car is not a g car but i like the way it looks.also want to add a hood scoop.what do you guys think if if i take take off the rear red reflectors?and just keep the front side lights.and just put and emblems there?keep the info coming in:

 

[leonbray]

I have an Edelbrock Performer set up on my 68 XR7 (carb, manifold, cam) and it is great. Really streetable and goes when you get stck in to it. I'd also recommend that you balance everything and add roller rockers. Not sure I'd recommend headers, other than hi-pos because they are a pain with power steering hoses. Make sure you also get the correct harmonic balancer (needs to be rebuilt) as the 68 balancer is unique.

 

[bruter]

On Originality...

I too have thought about originality when doing repairs to my 67. But the bottom line is that it's your car and if you like the modifications, then go right ahead and do it!! I would try a photo editing software to modify a picture of the cat and see if you like it. Lot cheaper if you don't like the mods!!!! Have fun!!!!

 

[cougar1]

As far as rebuilding and going with cam and hedders, it all depends on what you want from the car. Will it be a daily driver? A car you want to be streetable or you want a 1/4 miler and don't care about it rattling your neighbors windows?

As a general rule of thumb: The more power you want, the more it will cost and at an exponential rate.

:1poke:

 

[Navarro's XR-7]

hey guys

Hey guys i just fix my front side lights to go off with my blinkers just wired them toghter looks good and i just want my rebuild to go easy and not waist alot of $$$$$$$$$$$$ thanks for the reply's

 

[Navarro's XR-7]

new help

hey guys its me again!i have bad news a wire got on fire when it touched the exhuast manifold and my car turn off the wire was from the msd ignition to the battery now i dont have power anywhere? the fuse box seems ok battery too.i replaced the wire and try to start but not dice no power i think the burnt wire touched the the wires from the neutral switch any help guys its sad to see my car like that

 

[TheRktmn]

No power anywhere?
If it was your neutral safety you would still have power but the engine will not turn over.
If you have power but no starter do you have 12V+ at the ingition side of the coil?
If you do, try jumping the solenoid to turn over the engine.
These are the basics - we need more info to get into specifics.

 

[Navarro's XR-7]

wont turn over

i turn the key and nothing,and the lights dont go on.so the car doent turn over seems like no power from the switch the power i think?