68 390

[xracer390]

This waposted at another forum but got no response ? I guess they were to buisy talking about engine paint ? lol Here it goes, I hope you can help


.......Hey guys, I am looking to do some work to my 68 390. The motor has developed a water leak and I want to paint the underhood area so its time to pull the motor. Also I am planning on going to the Kenosha show at the end of july so I want to get it done by then.

Heres what I have..... first a limited budget, an 80,000 mile 68 390, seems to have good compression(havent tested it), no oil burning and no blowby. I just picked up a set of 291 c heads and a torker intake. Its a 4 speed car with 3.54:1 rear gears. I can machine the intake to fit either heads, I have heard of other problems mounting "late" intakes on "early" heads?

Heres what I want.....to run on pump gas.....I do drags from time to time, track and street, but mostly a cruise night car. I want to be the quickest in the car club lol

I dont think I can afford a bore and pistons at this time....can I get away without re-ring? If I pull the pistons to do this and the cylanders are out of speck I am screwed. I was thinking bearings, T-chain, cam-lifters, and get these heads worked a little then slap the torker on top with either my stock carb or a 750 Holley I have. If theres any $ left over maybe some roller rockers?

What cam do you recomend? What do I want/need to do with these heads ? I also have a set of lower compresion dog leg heads.

Recomendaton for a clutch also?


Thanks in advance, Xracer390 = Bryan

[mrtazwrench]

i remember there's a post somewhere on the late intake on early heads, just can't remember where. :oops: i'd do a cyl leakage test to check eng condition, lots of trouble with unleaded gas eating the valve seats on these old motors. hope i was a little help and good luck with it.

[jeepsr4ever]

Bryan

You can rering their are two theories

1. if cyl allows the bore can be fitted with the size rings that were originally used with the pistons

2. You can also go with a .010 overbore rings...ex if your .030 get .040 rings..check end gap and run (this is dependant on your ridge)

Alot of guys think that when their rings are gone its time for a major overhaul....sometimes it is and sometimes it isnt. You got cast pistons? Check them for cracks...they usually crack on the skirt and top ring mount.

You may just want to swap heads and not rering....why rering at this time?

If you have the intake all you have to do is drill 4 new holes in the center of the intake manifold. If you want a cheat hint...look on a valley pan gasket...the slot tells you precisely where to put the extra holes :t: I dont reccomend doing rings at this time...wait untill next spring when money and time will allow it.

Bryan....the quickest car in the club :shock:

[fuzz401]

to use the 291 heads you are going to need step dowl rings for the heads to the block due to the 68 motor used 7/16" head bolts and the 291 heads used a 1/2" head bolt plus the 291 heads are dog leg ex ports and the 68 -390 was sq ex ports

[xracer390]

........Im with you, i dont want to do the rings at this time so i think i will try it without. I also know about the step dowels, Thanks

Hey Jeeps....you know anyone good (you trust) with heads around here ?

Maybe after all this thinking I will just do the intake (i think thats whats leaking anyway) collect money and parts over the summer and go Gung Ho on her over the winter, that way I wont have to worry about my exaust. :t:

Keep in touch dudes !