7MGE Engine rebuild

[oregonjoe]

I’ve taken the head and block to the shop to have them cleaned up and inspected. The head and valves looked good for 20 years of use.

The good news on the block is no cracks after the magnetic test – so its just a hone on the cylinders and good to go. The bad news is the shop wants $500 to do a valve job on the head – even without replacing any valves. Claim the 24 valves takes a lot of labor and that OHC need to be ground to adjust!



So – I took the head back to do a little porting and polish. The head had some casting marks and ridges from 20 years ago. Since I bought the car I have learned a thing or two about engines. One of which is that they are massed produced from casting molds. These molds are not all created equal and there can many flaws that are left as is in production. Some flaws include sharp ridges from casting seams and defects in the individual molds. Other are sharp angles from the machining process after the castings are poured. In production - they are all ignored.



The cylinder chambers in the head have some sharp edges that can collect heat and cause preignition so I ground them off to smooth the transitions out the valve ports. Careful to not touch the valve seats.



I focused on the exhaust ports and smoothed out the walls and take out any burrs and casting ridges. Just a little touch up on the intake side to remove any large defects as I understand its better to leave the “sandpaper” effect on the walls.

[cvbikeguy]

Originally Posted by oregonjoe

I’ve taken the head and block to the shop to have them cleaned up and inspected. The head and valves looked good for 20 years of use.

The good news on the block is no cracks after the magnetic test – so its just a hone on the cylinders and good to go. The bad news is the shop wants $500 to do a valve job on the head – even without replacing any valves. Claim the 24 valves takes a lot of labor and that OHC need to be ground to adjust!

Attachment 2254

So – I took the head back to do a little porting and polish. The head had some casting marks and ridges from 20 years ago. Since I bought the car I have learned a thing or two about engines. One of which is that they are massed produced from casting molds. These molds are not all created equal and there can many flaws that are left as is in production. Some flaws include sharp ridges from casting seams and defects in the individual molds. Other are sharp angles from the machining process after the castings are poured. In production - they are all ignored.

Attachment 2255

The cylinder chambers in the head have some sharp edges that can collect heat and cause preignition so I ground them off to smooth the transitions out the valve ports. Careful to not touch the valve seats.

Attachment 2256

I focused on the exhaust ports and smoothed out the walls and take out any burrs and casting ridges. Just a little touch up on the intake side to remove any large defects as I understand its better to leave the “sandpaper” effect on the walls.

Attachment 2257

so you didnt have to take the head to the machine shop? will the replacement gasket be fine with just taking the block to the machine shop itself? sorry if im jacking your thread but this has been extremely helpful for me. thanks so much

[oregonjoe]

No - head was in shop for cleaning and resurface then I took it back once all the valves were removed to do the porting. Then - back to the shop to have the valve seats done, valves installed, and then adjusted with shims. Total machine cost for the head was $450.

You want tot do the porting before the valve seats are done so you don't mess up the seats. Critical since they determine adjustment and timing.

If you really want to do it right and can afford the time - take both head and block to machine shop so both surfaces can be done clean.

Then new head gasket will be fine - remember I used studs and tourqued down to 90 ft-lbs.

[cvbikeguy]

Originally Posted by oregonjoe

No - head was in shop for cleaning and resurface then I took it back once all the valves were removed to do the porting. Then - back to the shop to have the valve seats done, valves installed, and then adjusted with shims. Total machine cost for the head was $450.

You want tot do the porting before the valve seats are done so you don't mess up the seats. Critical since they determine adjustment and timing.

If you really want to do it right and can afford the time - take both head and block to machine shop so both surfaces can be done clean.

Then new head gasket will be fine - remember I used studs and tourqued down to 90 ft-lbs.

and you said the block was 400?

thanks so much for your help

[cre]

With the vGauge don't plan on using the stock oil pressure sender... the sender itself is internally dampened not the stock gauge.

[oregonjoe]

Originally Posted by cre

With the vGauge don't plan on using the stock oil pressure sender... the sender itself is internally dampened not the stock gauge.

True - I used all new senderds for this off a tee to keep the orginal

[oregonjoe]

Block was $200 to shave and dip tank, check for cracks. The total Machine shop bill was $750 wich was head job, block and crank, and alot of cleaning (all intank manifolds and oil pan) I bit high but around here I am luck to get anyone who can work an import engine.

[oregonjoe]

The block did not take but 2 days to do - it was the head that took so long - 2 weeks. But the total time in the shop was over a month due to needing to find enough POP CANS to get it out.

BTW - The cylinders were only Honed but not boared so that saved some money. After 20 years they were still good but you really need to at least get them honed to get a good ring seal.

Been driving like new since the job.