Engine Rebuild - Constructive Criticism Required

[PRHeads]

One possibility for why it turned out like it did is a lack of familiarity with the platform, and/or a lack of having a proper “plan”.

One of the more puzzling aspects of the build is the heads being milled to 78cc.
Stock 452 heads are in the 88-90cc range.
It requires about .050” removed from them to end up in the 78cc range.
Doing the math, if the heads are indeed 78cc..... then you are at about 11.2CR.
If the heads were still 88cc..... the CR would be about a full point lower, which would likely take care of the pinging problem.

Seems like poor planning.

 

[Fran Blacker]

He sourced and supplied everything. The problem we have in the UK is that by the time the parts arrive with shipping and taxes paid, what costs you guys stateside $1,000 can cost us close to $1500. It’s worth it though!

The shipping and import taxes/duties sure put a dent or a head on collision with your wallet.

 

[PRHeads]

In my best “armchair quarterback” voice......

If I would have built it, it would have been about 9.5:1CR, and had a cam in it that utilized milder ramps that were easier on parts.

 

[The Flying Scot]

One possibility for why it turned out like it did is a lack of familiarity with the platform, and/or a lack of having a proper “plan”.

One of the more puzzling aspects of the build is the heads being milled to 78cc.
Stock 452 heads are in the 88-90cc range.
It requires about .050” removed from them to end up in the 78cc range.
Doing the math, if the heads are indeed 78cc..... then you are at about 11.2CR.
If the heads were still 88cc..... the CR would be about a full point lower, which would likely take care of the pinging problem.

Seems like poor planning.

I believe the 78cc stat to be accurate. I’ll check next week.

 

[PRHeads]

I believe the 78cc stat to be accurate. I’ll check next week.

The question to ask is.......why are they 78cc’s?

 

[493 Mike]

Thanks Mike. I can get 99 octane from the pump here.

I'm jealous!
Mike

 

[BSB67]

The question to ask is.......why are they 78cc’s?

Exactly.

Plus it is stated as 78.6cc, i.e. three significant figures. There is only one way they would know that, and it would not be what they stated on the job description. Also, it is silent on intake face milling. At 0.040" 0.050" head material removal (probably something off the block deck too), the intake might not fit.

PRH is right, a conversations is needed. However, understand that unless it is a one man shop and he did all of the machining himself, he might not actually know either.

How bad is it pinging?

Here is my guess - total guess: Its not 78 cc, but probably 88 ccs. Compression is still a little above 10:1 and still pings. That might be fixable without tearing into the motor.

If it is really 11.2:1 CR the lowest cost fix will be aluminum heads.

Did this place do the whole job turn key, including motor removal and installation?

 

[Fran Blacker]

What about Cometic .060/.070 head gaskets if machined surface has the right R/A. Milodon says their copper head gaskets don't need o-rings.
Have the plugs been mentioned if they're running lean from manifold leak or jetting issues? Is 99 octane in 6K same rating as US?

 

[BSB67]

What about Cometic .060/.070 head gaskets if machined surface has the right R/A.

If its 11.24:1 CR, a 0.070" gasket won't be enough.

Is 99 octane in 6K same rating as US?

No.

 

[BSB67]

A cranking cylinder pressure test would be a good thing to do before talking with the builder.

 

[Fran Blacker]

He has .048 now another I should have said .080 to .090 would get it into mid 10's to 1 compression.

 

[BSB67]

10.3:1 with 98 RON at 1000 ft will ping a lot.

 

[Fran Blacker]

10.3:1 with 98 RON at 1000 ft will ping a lot.

So the gas is like US 87 or 89 octane.

 

[BSB67]

So the gas is like US 87 or 89 octane.

93

 

[MoparLeo]

A little confused. In the beginning of the post he said he wanted "it" built to 68 R/T specs. Did they do a car restoration as well as rebuild the engine ?

 

[The Flying Scot]

A little confused. In the beginning of the post he said he wanted "it" built to 68 R/T specs. Did they do a car restoration as well as rebuild the engine ?

The car is a ‘68 R/T but with a replacement ‘78 motor. I wanted the motor rebuilt to R/T specifications.

 

[The Flying Scot]

I run the car on Super Unleaded 99 pump fuel here in the UK which I understand is rated 95 in the US according to this conversion table:

 

[The Flying Scot]

93

 

[The Flying Scot]

So the gas is like US 87 or 89 octane.

94-95.

 

[The Flying Scot]

Exactly.

Plus it is stated as 78.6cc, i.e. three significant figures. There is only one way they would know that, and it would not be what they stated on the job description. Also, it is silent on intake face milling. At 0.040" 0.050" head material removal (probably something off the block deck too), the intake might not fit.

PRH is right, a conversations is needed. However, understand that unless it is a one man shop and he did all of the machining himself, he might not actually know either.

How bad is it pinging?

Here is my guess - total guess: Its not 78 cc, but probably 88 ccs. Compression is still a little above 10:1 and still pings. That might be fixable without tearing into the motor.

If it is really 11.2:1 CR the lowest cost fix will be aluminum heads.

Did this place do the whole job turn key, including motor removal and installation?

It is a one man shop and I believe he did everything himself aside from crankshaft balancing and gearbox refurbishment.