302 to 351

Post by **demo2** » Mon Jul 10, 2006 10:19 pm

All ready now 2 do the conversion this coming week, had the crank reground, bought a 600 holley and intake manifold and a crane cam and anti pump up lifters. Im keeping the 302 closed chamber heads on so c/r will be roughly 11.3-1. Will take some pics and post em up next week

Post by **demo2** » Sun Jul 16, 2006 9:20 pm

Well, pulled the motor friday arvo, ripped to bits and started re-assembling over weekend. Just gotta drop rods and pistons off 2mora and get them changed over on2 351 rods. Shud be up and running by the end of the week.

Post by **CRUSHU** » Sun Jul 16, 2006 10:21 pm

Sounds like it is all going smoothly, sweet.

Post by **demo2** » Sat Jul 22, 2006 1:13 pm

All the bottom end is assembled, one inlet valve guide was worn so put heads in 4 recon and told them 2 fit the later 4v intake valves whilst there at it, come back end of week nicely refaced and beadblasted

Also found out it was only running a 6 cyl pressure plate so i upgraded 2 an 11.5inch f350 plate and a clutch disk off a 99 patrol turbo deisel.
They had 2 machine a bit out of the centre of the flywheel 2 clear the springs on the disk and take a bit out of the centre of the pressure plate and refaced the flywheel whilst they were at it and best part of it they only charged me 13 bucks 2 do it

Shud be runnin next weekend

Post by **CRUSHU** » Sat Jul 22, 2006 5:22 pm

I would have left the 2V valves in personally, As the 4V valves flow more, and will slow down the air speed, reducing low end torque, and will flow more up top, when your little carby has run out of puff. Also the valves get shrouded by the cylinder walls, affecting the airflow pattern.

Did you get the chambers smoothed? Pretty helpfull if you are going to run high comp with iron heads, to remove sharp edges in the combustion chamber, so there are no pionty hotspots, to reduce the chances of detonation.

Post by **demo2** » Sat Jul 22, 2006 9:21 pm

Hadnt thought about smoothing heads 2 be honest, good idea. I can tell em not 2 fit the larger valves, so used to building performance engines i didnt think about airspeed reducing torque. The cam is one higher than i wanted but it was on back order from the states so had 2 choose next one up, its a crane 272-2.[/img]

Post by **F'n_Rover** » Sat Jul 22, 2006 10:20 pm

Are you running a 302 flywheel with a 351 crank?

I think they have different balance weights.

Post by **demo2** » Sun Jul 23, 2006 11:42 pm

My engine was originally an auto, i got given the flywheel so couldn't tell you whether ita a 302 or 351. I would think it was a 351 coz it had a twin plate on it at some time.

Post by **demo2** » Sun Jul 30, 2006 11:56 pm

All finished, engine runs a treat, needs a few little teething problems sorting out but nowt to drastic. I did change the clutch in it 4 an 11.5 inch one instead of the 9.5 one it had b4, i now dont get enuf travel on the slave cylinder so need a smaller bore one, u have to press the clutch rite 2 the floor 2 be able 2 engage gear which isn't ideal. I think the gas will need seting up now as it has more power on petrol where as b4 it was the same on gas or petrol. I drove it down the road on gas and didnt notice alot of extra power but when on petrol it has quite a bit more grunt than when it was 302. C how it goes

Post by **v6hilux** » Mon Jul 31, 2006 4:55 am

demo2 wrote:i now dont get enuf travel on the slave cylinder so need a smaller bore one, u have to press the clutch rite 2 the floor 2 be able 2 engage gear

Have you checked to see if the slave starts to move at the top of the pedal? Could be pedal adjust reqired.

If that's OK, the you can get a stainless sleeve heat glued into the slave to reduce bore size - should cost about $60 at a brake place and mine had to be sent away for 2 days.

Post by **ludacris** » Mon Jul 31, 2006 4:14 pm

What box is the motor bolted to. I had to use the old 3 finger clutch for my 302W to GQ 5speed.

LudaCris

Post by **demo2** » Tue Aug 01, 2006 1:12 am

Gearbox bolted to standard 5 spd, didnt reaise pedal had adjuster, tried it, didnt have much travel left but has helped alot cheers. Had a bit of a disaster 2nite, modified the throttle setup as was only gettin 3/4 throttle, then nailed it up the road, put me foot on the clutch 2 change gear and throttle stuck open and it revved the absalute nuts off it. Anyway, it started tappin and i drove it slowely home,removed the rocker cover hoping to get away with a bent pushrod but no such luck. No 1 and 3 cylinder inlets springs have spreadthe spring retainers and the spring has sliped about 1mm up the valve. The spring now its above the valve tip which is why its tapping. Dont think its bent a valve as it still rus fine and idles ok apart from the tappng caused by the excess clearence. I think it wud run ruff it it had a bent valve but never the less i still gotta remove the heads 2 check i guess. 16 new crae retainers on the books i guess

Guess i was lucky that te retainer didnt break and drop a valve. How come u cant upload pics on re anymore, some nice pics of the engine on pc

Post by **CRUSHU** » Tue Aug 01, 2006 7:10 am

Did the accelerator cam go over centre?? what carby and manifold are you running? what carby gasket are you running?
I have seen the butterflys get caught on 4 hole gaskets, and on stock 4 hole manifolds, causing stuck throttles.

Post by **demo2** » Tue Aug 01, 2006 11:07 am

usin a 600 vacumn secondary on an xb GT ( 4 hole) manifold. Got a gasket that has the whole centre cut ot not a 4 hole one.

Post by **CRUSHU** » Tue Aug 01, 2006 11:40 am

yeah, the XB GT Auto manifolds have fairly small holes, and the butterflies can get jammed a little on the edges of the holes. It is an idea to run a thin open spacer under the carb, unless you have thoroughly checked that it doesn't bind at all.

Post by **demo2** » Wed Aug 02, 2006 11:47 am

It appears the vacumn secondaries are slow in closing whch is what i reckon caused it 2 over rev, but as it is operated by vacumn what snaps it shut? It has no return spring to close it so surely ts fighting against the vacumn?

Post by **jessie928** » Wed Aug 02, 2006 12:35 pm

th r throttle linkage closes the secondarys. If you have a look at the linkage on the secondary shaft you will see that once you close the throttle, it forces the secondary butterfly closed.

make sure you have a spring on the main linkage though!!

JEs

Post by **demo2** » Thu Aug 03, 2006 8:43 am

Well mine had the ittle connecting linkage missing hence why the secodaries stayed open

Replaced all the retainers as a few had split. Fired it up and still tapping, not as bad but still tapping, so ethr a stffed lifter of cam lobe. I wouldnt have fort it wud be the cam, i checked the underside of the lifters and they were fine so poped em back in. They are anti pump up lifters, never used em b4, bet u cant bye them individally like u can OE lifters.

Post by **demo2** » Fri Aug 04, 2006 10:47 pm

All sorted, turned out the end of a pushrod had gone oval which gave the excess clearance, motor running fine now, jesus what a differance between the 302 and 351

Dont notice it much on standin starts but midrange pulling power there is heaps more power, roll on gettin off road wiv it

Post by **CRUSHU** » Fri Aug 04, 2006 10:55 pm

sounds like your quite happy with it!
I don't know why anyone would bother with small cube motors though.
Glad you got it all sorted now.

Post by **Beastmavster** » Sat Aug 05, 2006 1:28 am

heh at 302 being small cube.....

253 small cube..... 2.8 MQ small cube...... but 302 is a stretch to call small......

Post by **CRUSHU** » Sat Aug 05, 2006 7:59 am

It is all perspective I guess. A 302 is small in a 1500kg Falcon, so is really small in a 2000kg Patrol. Bigger than standard, Yes, but big in general, No.

In my world, 302 is small, 351 is OK, 400 is good, 460 is great, 514 is awesome, 600 is Sh1t Hot!!

Post by **demo2** » Sat Aug 05, 2006 11:44 pm

The swb is only 1700kg

a 460 wud be good i agree but cant be arsed wiv it anymore and its an mk at the end of the day.

Post by **CRUSHU** » Sun Aug 06, 2006 9:34 am

Thats not what I meant. But a 460 would be nice!!
What I meant, is if you were shopping for a Windsor, I would pick the 302 or 351, depending on space, and if I were shopping for a Clevo, I would pick the 351 or 400, also depending on space. With a Holden, I wouldnt go with a 253, I would go with a 304/308 or 348.
I don't see the point in using the smaller versions of the same block, eg 289, 302clevo, 351m, 253 etc.

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302 to 351

302 to 351

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