f303 in a non ho motor

[shttygtstang]

i think the person who owned the car before me put a non ho motor in and i put my f303 cam in now it wont start because the timing order is not the same does this matter

 

[5.0Droptop]

change the plug wires to the 302 ho firing order.

Did it have roller lifters? non ho usually will not have roller lifters if its stock.

 

[shttygtstang]

non ho motors were non roller lifter but roller ready in many years so he could of just put them in and wouldnt the pistons travel at adiffent order still

 

[larrendeuce]

The crankshaft doesn't determine firing order on the 302, just the camshaft. I don't think a roller cam can be used without roller lifters, did you find roller lifters when you did the cam swap? If not then its not an ho.

 

[Michael Yount]

The other issue is the computer. Both the firing order (wiring order on the distributor) and the ecu's firing of the injectors should match the firing order of the cam. Crank has no bearing on this.

 

[shttygtstang]

ok it has roller lifters.Buton some flat tappet style blocks you can convert them over the the holes are pre drilled in the lifter valley and all.and if the the piston ist compressing on lets say number 5 and its firing at 8 that means somthing no

 

[shttygtstang]

how do i check the order then im abought 90 percent shure its a non ho motor

 

[Michael Yount]

If you're sure it's an F cam, then the firing order is HO. If you're not sure about the cam, put the wires on in the HO order - if it runs, it's HO; if it barely runs (or not), it ain't. If you can't crank it (engine's out of the car), and you're not sure about the cam, then you've got to pull the passenger valve cover, and starting with the number 1 cylinder follow the path that the valves are operating. If number 3 is opening after number 1 - it's HO. If number 5 is opening after number 1, it ain't.

 

[shttygtstang]

i put the cam in i know its a f im not shure if the cam prior was a non ho or ho its a roller cam though the car wont start for me at all can i tell by looking at the old cam

 

[Michael Yount]

Then the firing order you need on the distributor and the injectors is the HO order.

 

[shttygtstang]

your 100 percent that the crank and pistons will not matter i ask because it makes no sense that if the ehaust valve is open and lets say a pistons at bdc it wont fire right or piston is in mid stroke and it fires oh ya the pistons on my motor are notched

 

[larrendeuce]

A non HO crank and an HO crank would look identical in shape, when rotated in a shortblock the pistons would move up and down in the same order. If you replaced the cam in your engine with an f303 and there were already roller lifters in the block then it is an ho.

 

[shttygtstang]

thanks

 

[larrendeuce]

You also said that you can't start it, are you sure your having a spark issue?

 

[Michael Yount]

Like they said - cranks between the two motors are identical. Firing order in the 302 v-8's we have available to work with is set by nothing other than camshaft - when the valves are opening and closing.

Some of the NASCAR teams experimented with "flat" 180 degree cranks. This is the crank style for a V-8 that makes a Ferrari or Lotus V-8 sound so different from our engines - more like two 4 cylinder engines in concert. If you had a crank like that, you'd have a different choice of firing orders than we have - but it's a non-issue as a practical matter. Cam in our engines dictates firing order - nothing else.

Have you checked p to v clearance with the new cam?

 

[MrKwik]

any possibility you put the distributor in 180* out? You getting any backfiring or anything goofy like that when you crank it?

 

[shttygtstang]

p to v clearnce is fine i think im not setting my rocker arms the right way

 

[Michael Yount]

What'd'ya measure on p to v - intake? exhaust?

 

[shttygtstang]

i didnt but there edelbrock heads and they say there fine for the car ...i think all the valves are open a little bit or somthing when im firing it..the car wont even firer over

 

[Michael Yount]

You may end up being ok - but no one can tell you what clearance is, or if it's going to be ok on a particular motor. As long as you realize you're just guessing, and you're ok leaving it up to fate - then go for it. Of course, it's not just the heads - the cam and pistons play a big role in clearance as well. Anyone who says a particular head will be ok without cautioning you on the other variables is either misinformed or careless.