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302 to 351

Posted: Mon Jul 10, 2006 10:19 pm
by demo2
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

Posted: Sun Jul 16, 2006 9:20 pm
by demo2
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.

Posted: Sun Jul 16, 2006 10:21 pm
by CRUSHU
Sounds like it is all going smoothly, sweet.

Posted: Sat Jul 22, 2006 1:13 pm
by demo2
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 :D
Shud be runnin next weekend :armsup:

Posted: Sat Jul 22, 2006 5:22 pm
by CRUSHU
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.

Posted: Sat Jul 22, 2006 9:21 pm
by demo2
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]

Posted: Sat Jul 22, 2006 10:20 pm
by F'n_Rover
Are you running a 302 flywheel with a 351 crank?

I think they have different balance weights. :?

Posted: Sun Jul 23, 2006 11:42 pm
by demo2
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.

Posted: Sun Jul 30, 2006 11:56 pm
by demo2
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 :)

Posted: Mon Jul 31, 2006 4:55 am
by v6hilux
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.

Posted: Mon Jul 31, 2006 4:14 pm
by ludacris
What box is the motor bolted to. I had to use the old 3 finger clutch for my 302W to GQ 5speed.

LudaCris

Posted: Tue Aug 01, 2006 1:12 am
by demo2
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 :x
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 :)

Posted: Tue Aug 01, 2006 7:10 am
by CRUSHU
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.

Posted: Tue Aug 01, 2006 11:07 am
by demo2
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.

Posted: Tue Aug 01, 2006 11:40 am
by CRUSHU
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.

Posted: Wed Aug 02, 2006 11:47 am
by demo2
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?

Posted: Wed Aug 02, 2006 12:35 pm
by jessie928
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

Posted: Thu Aug 03, 2006 8:43 am
by demo2
Well mine had the ittle connecting linkage missing hence why the secodaries stayed open :cry: 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.

Posted: Fri Aug 04, 2006 10:47 pm
by demo2
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 :D Dont notice it much on standin starts but midrange pulling power there is heaps more power, roll on gettin off road wiv it :D

Posted: Fri Aug 04, 2006 10:55 pm
by CRUSHU
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.

Posted: Sat Aug 05, 2006 1:28 am
by Beastmavster
heh at 302 being small cube.....



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

Posted: Sat Aug 05, 2006 7:59 am
by CRUSHU
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!!

Posted: Sat Aug 05, 2006 11:44 pm
by demo2
The swb is only 1700kg :D a 460 wud be good i agree but cant be arsed wiv it anymore and its an mk at the end of the day.

Posted: Sun Aug 06, 2006 9:34 am
by CRUSHU
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.