We Can Rebuild It

[SLOTH Snr]

Well guys, since the 7k has died we've decided to do a full rebuild

It is coming out of the car this week. My engine rebuilder has never

done a 7k and said he has very little tech data on them.

If anybody has any info that may help it would be appreciated.

We hope to develop it beyond factory specs. So things like

cam angles , valve settings, basically anything and every thing.

When we have aquired as much info as pos we will then work

out what to do.

I will try to keep as much info as possible and post our results

when finished

[Super Jamie]

get yourself a copy of dyno2000 so you can play around with cam profiles (pm me if you'd like it), a 7k responds very differently to any of the other motors. get the head flowbenched to the parameters the program asks for if you want the results really accurate

 

the valves are definitely a restriction on 7k engines. i would say you couldn't fit big enough valves in the head to open out the full potential of the 1800cc bottom end

 

i hope you don't need new pistons, toyota prices are a rip off

[kangaroosa]

I have 81mm Hypertec Pistons in my 5K. They were packaged for a Gemini (they required machining though). They might be a cheaper option than genuine pistons........ if you need new pistons.

 

If you havent found someone to do your headwork:

Call "Eddie Woods"

THE HEAD STUD DEVELOPMENT COMPANY

31 Capella Crs Moorabbin 3189

(03) 9553 2517

 

He knows his stuff when it comes to corolla heads and engines.

 

I just emailed you a copy of Dyno2000.

[ikon_idol]

Hi.

 

I'm building a 7k at the moment. You can't use 5k pistons because the 7k pistons have a different pin height and a larger pin diameter. Also, it has a larger dish volume. If you find a non Toyota piston that fits let me know.

The thrust bearings in the ACL catalogue are wrong. They specified the same p/n as the 5k thrusts which don't fit. The ones that fit are the same as the 7A engines. They may have fixed this by now. I went for a Wade hydraulic cam profile with about 1.5mm higher valve lift and 20/60 60/20 timing. You may need to machine the valve pockets in the pistons deeper to clear the higher valve lift, you need to check this during assembly. Get an adjustable cam wheel set (Rollmaster make one) and degree the cam timing in carefully. I had the flywheel lightened a little and the pressure plate. flywheel. crank and pulley balanced after I matched the piston and rod weights.

 

Paul

[SLOTH Snr]

thanks guys , this is the sort of shit i was looking for.

hopoefully we can sort it out and put up a tough 7k thread.

Just read o book on lotus cars and found that they gave up

on thier 7k equivalent and went back to 1558cc and 1596cc

Sound familiar (5k)

Any more info is still appreciated.

[ikon_idol]

Hi.

 

I've got some piston info for you.

 

Pin height is 33.8mm. Pin diameter is 20mm and pressed into rod.

 

Piston "D" dish volume is 23.5ml.

 

Piston rings interchange with 5K ring sets.

 

Hope this helps.

 

Paul

[ikon_idol]

No, pistons don't interchange with 5k type.

 

Different pin height, pin diameter and dish volume.

 

Only the rings interchange, same ring grooves but for oil return holes instead of slots.

 

Paul

[Super Jamie]

wow, 20mm wrist pins. that's tough :D

[SLOTH Snr]

Iam sure i read somewhere that 5k & 7k bore is same

Extra capacity is gained by stroke and piston dish.

[Super Jamie]

that is correct

 

i understand what nick's saying. even tho the pistons are dissimilar in their wrist pin height, diameter, and deck design - the ring lands are the same size, location, order, etc

 

what happened to your 7k anyway, sloth? that's why i never did one, they're an expensive engine, and i had no idea wether i was going to kill the thing or not, so a rebuild wouldn't be cheap either

[SLOTH Snr]

I've been stuffing around and haven't pulled the motor yet

It just basically locked up while parked. When i turn it by

hand it jams at the opening of the 4th cylinder inlet valve.

I just ran a set of figures i was given in dyno2000.

Ithink they are wrong because i get.

155hp at 5500rpm to 6500 rpm

145 ft/lb at 5000 rpm.

Does that sound right.

[Super Jamie]

i just built a playaround 7k

bore and stroke 80.5x87.5

wedge head, pocket porting, stock valve size (37.36 and 28.98mm)

10.5:1, 720cfm @ 1.5inHg, individual runner (twin sidedrafts)

small tube headers with mufflers, solid lifters

 

25-65 cam with 400 thou valve lift

142hp @ 6000rpm, 146ftlb @ 4500rpm

 

it's hard to get em to make power huh, you basically just shift the powerband. did i include all doug and my collected K motor cam profiles in that zipfile? if not let me know i'll email them to you

[Super Jamie]

oh yeah, i generally find dyno2000 to be quite optimistic in its output figures. i usually take what it says, and about 83% of that number is what you should expect in real life. with carbs anyway

[SLOTH Snr]

O.K thoose figures were simalar to mine.

At 83% thats not to bad. I guess i just have to work out

where on the graph we want to fall.

I suppose i should plan what diff ratio will suit it.

[ikon_idol]

Sorry Nick, I missed your point. Yes the standard, +0.25 and +0.50 bore sizes are the same as the 5k and I known for a fact that the 5k rings fit my 7k pistons.

 

I'll try to take a photo of the pistons side by side and post them. My 7k came from an engine exchange place and appeared to be well stuffed. So much so that they didn't even want to rebuild it.

They installed a low km import for $2,200. The owner of the Town Ace had not changed the oil even once after the first service, only topped it up! 120,000km later it was drinking oil and making

clunk, clunk noises. There wes no compression but it turned over ok and the clunk sounded like the cam chain.

 

I took the chance and paid $400 for it as is. When I pulled it down it was so sludged up it was hard to believe. It was like a thick coat of tar gone solid on everything and it smelled really disgusting.

Main problem was blocked oil return holes in the pistons and rings so badly stuck with hard sludge I had to break some of them out. The cam chain tensioner had worn through and was seized, the

chain left to bang around. Hard to believe it ran at all. Crank, bores and pistons were fine after a clean up. The engine shop that hot dip cleaned the block prior to light honing it said they had never

seen such a filthy sludged up block in 30 years of engine reconditioning! Tough little engines.

 

Paul